Approved by: John Stapleton Authorised by: Richard Hitch A/Principal Engineer Chief Engineer Civil Technology & Standards
Disclaimer This document was prepared for use on the RailCorp Network only. RailCorp makes no warranties, express or implied, that compliance with the contents of this document shall be sufficient to ensure safe systems or work or operation. It is the document user’s sole responsibility to ensure that the copy of the document it is viewing is the current version of the document as in use by RailCorp. RailCorp accepts no liability whatsoever in relation to the use of this document by any party, and RailCorp excludes any liability which arises in any manner by the use of this document. Copyright The information in this document is protected by Copyright and no part of this document may be reproduced, altered, stored or transmitted by any person without the prior consent of RailCorp
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Document control Revision Date of Approval Summary of change
1.0 July, 2010 First issue as a RailCorp document
Summary of changes from previous version Section Summary of change
Document Control
First issue as a RailCorp document
All Previously published as Structures Construction Technical Specifications in TMC 304
All Minor editing throughout for consistency and clarity
8 Added requirement to comply with RailCorp Environmental Management System
17 Editing and formatting of S20 for clarity of requirements
21 S25 only applies to bridge girders; miscellaneous steelwork to comply with RTA specification
29 Change “rock anchors” to “ground anchors” to be consistent with the revised RTA Specification
31 Section on gabions replaced by requirement to comply with RTA Specification
32 S45 reference to design of reinforced soil retaining walls deleted and included in ESC 350
34 Section on soil nailing replaced by requirement to comply with RTA Specification
Contents 1 Scope and application ............................................................................................................................. 4
2 References ................................................................................................................................................ 42.1 Australian and International Standards ......................................................................................... 4 2.2 RailCorp documents ...................................................................................................................... 5 2.3 Other references............................................................................................................................ 6
1 Scope and application This specification details the requirements for the construction of new structures and the upgrading of existing structures.
The requirements in this Specification are applicable to structures construction works on the RailCorp network. Structures include bridges, tunnels, retaining walls, platforms, overhead wiring structures and lighting and communications towers.
The construction or upgrading of structures may typically include some or all of the following activities:
− excavation and backfilling for foundations;
− piling (e.g. driven piles, bored piles and special pile types);
− in-situ concrete works (e.g. footings, pile caps, abutments, piers, walls and aprons);
− precast concrete components, either reinforced or prestressed (e.g. girders, slabs, culverts, wall panels);
− steel components (e.g. fabricated components such as girders, walkways, handrailing and decking, or miscellaneous components such as bolts and proprietary fasteners etc.);
− brickwork and masonry construction;
− general earthworks (embankment widening and strengthening, ground contouring, backfilling etc.);
− scour protection works (e.g. revetment mattresses, stone pitching);
− demolition works.
In the existing rail environment, it is common for the above activities to be undertaken under live rail traffic conditions. Special track possessions and isolation of the overhead traction power supply are generally necessary for the new works to be commissioned and completed.
RailCorp has generally adopted RTA Specifications for use in the construction of it’s structures.
The construction requirements in this document are in a format to suit contract documentation. They form part of the “Technical Specifications” section of tender documents.
This Specification should be used by personnel:
− responsible for specifying the technical requirements for the construction and upgrading of structures;
− responsible for the implementation of construction and upgrading works including in-house labour, supervisors, quality control personnel and contract administrators.
The specifications may be used for either quality control (QC) or quality assurance (QA) type works.
2 References
2.1 Australian and International Standards AS 1012 Methods of testing concrete
AS 1100 Technical drawing
AS 1110 ISO metric hexagon bolts and screws – Product grades A and B
AS 1111 ISO metric hexagon bolts and screws – Product grade C Supe
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AS 1214 Hot-dip galvanised coatings on threaded fastenings (ISO metric coarse thread series)
AS 1237 Plain washers for metric bolts, screws and nuts for general purposes
AS 1252 High strength steel bolts with associated nuts and washers for structural engineering
AS 4671 Steel reinforcing materials
AS 1365 Tolerances for flat-rolled steel products
AS 1553 Covered electrodes for welding
AS 1554.1 Structural steel welding - Welding of steel structures
AS 1554.5 Structural steel welding - Welding of steel structures subject to high levels of fatigue loading
AS 1580 Paints and related materials – Methods of test
AS 1594 Hot-rolled steel flat products
AS 1627 Metal finishing – Preparation and pre-treatment of surfaces
AS 1710 Non-destructive testing – Ultrasonic testing of carbon and low alloy steel plate and universal sections – Test methods and quality classification
AS 1796 Certification of welders and welding supervisors
AS 1858 Electrodes and fluxes for submerged-arc welding – carbon steels and carbon-manganese steels
AS 1966 Electric arc welding equipment (superseded by ????)
AS 2159 Piling – Design and installation
AS 2214 Certification of welding supervisors – Structural steel welding
AS 2312 Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings
AS 2436 Guide to noise control on construction, maintenance and demolition sites
AS 2601 The demolition of structures
AS 3012 Electrical installations – Construction and demolition
AS 3610 Formwork for concrete
AS 3678 Structural steel – Hot-rolled plates, floorplates and slabs
AS 3679 Structural steel – Hot-rolled bars and sections
AS 4100 Steel structures
AS 4680 Hot-dip galvanised (zinc) coatings on fabricated ferrous articles
AS 5100 Bridge design
ASTM A123 Standard Specification for Zinc (Hot-Dip Galvanised) Coatings on Iron and Steel Products
WTIA (Welding Technology Institute of Australia) - Technical Note 1 – Weldability of Steels
3 Approved design All structures shall be constructed to an approved design
Structures shall be constructed to meet the requirements of RailCorp’s Engineering Standards for the specified structure type.
4 Competency requirements Structures shall be constructed and inspected by persons with competencies for work activities as detailed in RailCorp Engineering Manual TMC 001 – Civil Technical Competencies and Engineering Authority.
5 Technical specificationsThe following sections contain the Technical Specifications for structures construction work. The historical specification reference number, e.g. S01, has been retained.
6 S01 Quality assurance & control This Specification provides instructions on the use of the RTA QA Specifications and adaptation for use on quality control projects.
Most construction projects are now implemented under quality assurance procedures. This is reflected in the contents of the Technical Specifications.
For some minor works, quality control procedures may be considered to be adequate in preference to full quality assurance procedures. The QA specifications however can still be utilised as detailed in Section 7.2.
6.1 Quality assurance specifications The Technical Specifications in this document are in Quality Assurance (QA) format.
The various RTA QA Specifications referred to within these Technical Specifications are prepared and maintained by the Roads and Traffic Authority of NSW (RTA). RTA's latest QA Specifications Su
are available from the RTA's web site www.rta.nsw.gov.au/doingbusinesswithus/specifications/ . The applicable version of the relevant RTA QA Specification is the version available from the RTA web site on the closing date for tenders.
Where the RTA Specification refers to the "Superintendent" this shall mean the "Principal" or the "RailCorp Representative" as defined elsewhere in the tender document.
6.2 Quality control specificationsWhere the contract is a Quality Control (QC) contract, then the following shall apply:
− 'Hold Point' and 'Witness Point' shall be interpreted as 'Inspection Point' or "Submission Point". Where a submission is required the Contractor shall provide this to the RailCorp Representative at least two working days prior to the date of commencement of the process that is the subject of the Hold Point or Witness Point. Where an inspection is required the Contractor shall give the Railcorp Representative at least two working days notice prior to the date of commencement of the process that is the subject of the Hold Point or Witness Point and arrange for the inspection to be undertaken.
− The requirement for the submission of a 'Quality Plan' shall mean that the Contractor shall submit a detailed 'Project Plan' using MS Project or other acceptable software. The Plan shall include all major milestones, resources, subcontractors, sampling and testing regimes as applicable.
− Where the RTA QA Specifications reference other RTA QA Specifications and Test Methods, this shall mean the relevant RailCorp Technical Specification or RailCorp Standards, or relevant Australian Standards wherever applicable.
− Where the RTA QA Specifications include clauses on measurement and payment, direction from the RailCorp Representative on the applicability of these clauses shall be obtained by the Contractor.
− Where the RTA QA specification includes clauses on collection of material samples and delivering them to RTA laboratory, this shall mean that the contractor shall submit test results of test undertaken by a NATA accredited laboratory.
7 S03 Miscellaneous earthworks This Specification sets out the requirements for:
− site clearing,
− construction of embankments,
− excavation of cuttings and
− installation of capping layers
− earthworks near structures
− drainage
in conjunction with the upgrading or construction of structures.
The preparation and clearing of sites for the construction of structural works shall in accordance with good engineering and environmentally-friendly practice and as specified in TMC 411 - Earthworks.
Railway embankments may be required to be constructed, extended, widened or strengthened in association with structural works, e.g. the construction of underbridges or retaining walls. The embankments are to be constructed to the dimensions and extent shown on the Drawings and in accordance with the requirements of TMC 411 and SPC 411 - Earthwork Materials.
Railway cuttings may need to be widened or modified in association with the construction of structures such as overbridges and retaining walls. Excavation shall be carried out to the lines, levels, dimensions and slopes shown on the Drawings, and in accordance with the requirements of TMC 411. Su
The supply of material for and the installation of the capping layer to railway formations shall be in accordance with SPC 411and TMC 411.
The construction of structural works may require excavation or compaction works adjacent to existing structures. These structures may include bridge abutments, piers and wingwalls, retaining walls, station platform walls, overhead wiring structures and signal gantries. Particular care is to be exercised in these circumstances to ensure that no damage is caused to the existing structures. The precautions and requirements detailed in TMC 411 are to be followed.
Drainage works are to be constructed to the detail and extent shown on the Drawings. Cess drains, sub-surface drains and top drains are to comply with the requirements of TMC 421 - Track Drainage.
8 S04 Excavation and foundations for structures This Specification sets out the requirements for shoring, excavation, placement of unreinforced concrete blinding layers and backfilling of excavations (up to adjacent ground levels) and disposal of surplus materials for structures.
All aspects of the shoring, excavation and backfilling of excavations for structures shall comply with the requirements of the RTA QA Specification B30 “Excavation and Backfill for Bridgeworks”.
Environmental protection of the site shall be in accordance with the RailCorp Environmental Management System.
Where backfilling above adjacent ground levels is required, the requirements of RailCorp Technical Specification S03 shall apply.
9 S07 Post-tensioning of concrete This Specification sets out the requirements for the;
− Supply and installation of post-tensioning tendons (including ducts, anchorages and other components) for post tensioned concrete members, and
− Post-tensioning and grouting of tendons.
This specification shall not be applied to post-tensioning with un-bonded tendons or with tendons which are located externally to the concrete to be prestressed.
All aspects of the post tensioning of concrete members shall comply with the requirements of the RTA QA Specifications B113 “Post-Tensioning of Concrete” and B119 “Approval of Post – Tensioning Systems”.
Associated concrete works shall comply with the requirements of RailCorp Technical Specification S10 “Concrete Works for Structures.”
Not withstanding the requirement shown in RTA B113, the Contractor shall request the RailCorp Representative to nominate a Post-Tensioning Supervisor at least one week before the commencement of the post-tensioning works.
10 S08 Steel piles This Specification sets out the requirements for supply and installation by driving of:
− H section steel piles
− Tubular steel piles (with or without concrete plug at the toe with reinforcement concrete infill)
− Sheet piles
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All aspects of the supply and driving of steel H piles shall comply with the requirements of the RTA QA Specification B53 “Driven H Section Steel Piles”.
All aspects of the supply and driving of tubular steel piles shall comply with the requirements of the RTA QA Specification B54 “Driven Tubular Steel Piles”.
11 S10 Concrete works This specification sets out the requirements for concrete work for all structures for:
− the supply and delivery of all concrete, cement mortar, and grout for in-situ and precast concrete elements used in the Works
− the design, construction, erection and removal of formwork
− the supply, fabrication and fixing of the reinforcing steel, and other embedded items
− the placing, compacting, finishing and curing of the concrete, cement mortar and grout
All aspects of concrete work shall comply with the requirements of the RTA QA Specification B80, "Concrete Work for Bridges".
Concrete test panels and colour control of concrete where required shall be provided in accordance with AS 3610, to suit the class of finish defined in RTA QA Specification B80.
12 S11 Driven concrete piles This Specification sets out the requirements for the manufacture and driving of:
− reinforced concrete piles
− prestressed concrete piles
− composite piles
All aspects of the manufacture and driving of reinforced concrete piles shall comply with the requirements of the RTA QA Specification B50 “Driven Reinforced Concrete Piles”.
All aspects of the manufacture and driving of prestressed concrete piles shall comply with the requirements of the RTA QA Specification B51 “Driven Prestressed Concrete Piles”.
All aspects of the manufacture and driving of composite concrete piles shall comply with the requirements of the RTA QA Specification B61 “Driven Composite Piles”.
13 S12 Cast-in-place concrete piles This Specification sets out the requirements for the:
− Design, testing and installation of piles classified, in accordance with AS 2159 – Piling – Design and installation, as driven cast in place displacement piles
− Installation of reinforced concrete piles which are constructed by progressively driving or sinking non-structural steel casings (which form part of the Works) into the ground, excavating all material from inside the casings, placing reinforcement and then filling the casings with concrete.
− Construction of reinforced concrete piles which are formed and cast in place without the use of permanent casing.
All aspects of the construction of reinforced concrete cast in place piles (with permanent or temporary casings) shall comply with the requirements of the RTA QA Specification B57 “Driven Cast-in-Place Concrete Piles”.
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All aspects of the construction of reinforced concrete cast in place piles (with permanent casings) shall comply with the requirements of the RTA QA Specification B58 “Permanently Cased Cast-in-Place Reinforced Concrete Piles”.
All aspects of the construction of reinforced concrete cast in place piles (without permanent casings) shall comply with the requirements of the RTA QA Specification B59 “Bored Cast-in-Place Reinforced Concrete Piles (without permanent casing)”.
Concrete work shall comply with the requirements of RailCorp Technical Specification S10 “Concrete Works for Structures”.
The Contractor shall give advance notice of at least 1 day of its intention to place the reinforcement cage into the pile hole.
14 S13 Precast reinforced concrete members This Specification sets out the requirements for the manufacture and supply of precast reinforced concrete members that are not pretensioned, including precast concrete members that are to be post tensioned.
All aspects of the manufacture and supply of precast reinforced concrete members shall comply with the requirements of the RTA QA Specification B115 “Precast Concrete Members (Not Pretensioned)”.
Concrete work shall comply with the requirements of RailCorp Technical Specification S10 “Concrete Works for Structures“.
15 S14 Precast prestressed concrete members This Specification sets out the requirements for the manufacture and supply of pretensioned precast concrete members.
All aspects of the manufacture and supply of pretensioned precast concrete members shall comply with the requirements of the RTA QA Specification B110 “Manufacture of Pretensioned Precast Concrete Members”.
Concrete work shall comply with the requirements of RailCorp Technical Specification S10 “Concrete Works for Structures”.
16 S16 Erection of precast concrete members This Specification sets out the requirements for the erection of precast concrete girders and planks in bridges. This Specification does not apply to piles.
All aspects of the erection of pretensioned precast concrete members shall comply with the requirements of the RTA QA Specification B150 “Erection of Pretensioned Precast Concrete Members”.
All aspects of the erection of precast concrete members shall comply with the requirements of the RTA QA Specification B153 “Erection of Precast Concrete Members (Not Pretensioned)”.
17 S20 Structural steelwork fabrication for underbridges
17.1 Scope and Application This Specification sets out the requirements for the fabrication of new steel girders for rail underbridges.
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The fabrication of steel underbridge girders is to comply with the various Australian Standards and other reference documents as prescibed in the following technical specification. All work is to be undertaken in accordance with the Project Drawings.
Reference should also be made where applicable to the following Technical Specifications for associated works:
− S22: fabrication of miscellaneous steelwork for underbridges, e.g. safety walkways;
− S24: protective paint coating
− S25: protective galvanised coating
− S26: erection of structural steelwork
− S27: erection of minor steelwork
− S30: pot-style bearings
− S31: elastomeric bearings
− S32: installation of bearings
17.2 Fabrication Requirements17.2.1 General
Work covered by this Section includes the supply of all labour, equipment, and materials to fabricate, shop assemble, protective coat, transport and deliver main girders, cross girders and other steelwork for railway underbridges.
17.2.2 Materials
17.2.2.1 Standards Materials, shall be new, free from defects and shall conform with the Standards specified hereunder:
Steel plates not manufactured by BlueScope Steel Australia shall be fully tested in accordance with AS/NZS 3678 and all other associated Australian Standards to prove its equivalence to the quality offered by BlueScope Steel.
17.2.3 Ultrasonic testing of plates Prior to fabrication, all plates that are thicker than 16mm for girder flanges, webs and bearing stiffeners shall be ultrasonically tested continuously along the cut edge of the plate and along all lines away from the cut edge of the plate where welding will be carried out, to establish that the plates are free of laminations. Ultrasonic inspection of plates before welding shall be in accordance with the Specification for Ultrasonic Testing as detailed in Section 18.4 of this specification. The Contractor shall arrange and pay for an independent NATA testing laboratory to carry out this work.
A written report on each line tested shall be forwarded direct from the testing laboratory to the RailCorp Representative within 24 hours of the test. The location and extent of inclusions and/or laminations shall be detailed and sketched in the report. Where discontinuities extend for a length of 100 mm along any weld line the extent of discontinuities in the area shall be assessed to verify that the plate conforms to AS 1710, Level 2E.
The RailCorp Representative shall have the sole right to decide whether a suspect plate may be used in the work or be rejected. If a plate suspected of containing discontinuities is accepted by the RailCorp Representative, the position in which it may be used in the structure will be designated by the RailCorp Representative.
If a plate is rejected by the RailCorp Representative, it shall be replaced by the Principal at the Contractor's works without cost to the Contractor, in the case of NVR steel plate originally supplied by the Principal. It shall be replaced by the Contractor at his cost in all other cases.
17.2.3.1 WeldingWelding shall conform to the standards specified in Section 18.3.1.
17.2.4 Recording of steel plates and fabrication details A register shall be kept for each steel plate built into flanges, webs, bearing stiffeners and bearing plates. The register shall be kept up-to-date and be available at the Contractor's works for inspection and shall be forwarded to the RailCorp Representative on completion of the Contract.
Information to be recorded in the register shall include the following items:
− The mill heat and plate number obtainable from the as-rolled plate.
− Each fabrication process carried out to the plate.
− Production welds and weld repair.
− A means of identifying welds.
− A diagram showing the location of each plate and location of each butt weld in a finished girder.
To simplify shop marking and records, each plate shall be allotted a "shop serial number" which shall be recorded for plate identification. When an as-rolled plate is to be cut into a number of pieces, each piece shall be given a separate shop serial number. Butt weld splices shall be identified by the shop serial numbers of the two plates spliced, that is for splicing of two plates having shop serial numbers 2 and 6, the butt weld would be identified as 2-6.
17.2.5 Shop drawingsThe Contractor is required to produce shop drawings for all steel fabricated under this Contract. At least one week prior to commencement of fabrication of any portion of the work, the Contractor shall submit two copies of the relevant shop drawings to the RailCorp Representative for review and approval. Drawings shall comply with AS 1100.
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One set shall be returned and the others retained by the RailCorp Representative. The checking shall be for general compliance only with the design drawings and the correctness of all dimensions and other details shall be the sole responsibility of the Contractor.
Shop drawings shall indicate clearly splice locations, the various types of welds, corresponding edge preparation required and the order in which welds at a truss joint are to be carried out.
17.2.6 Storage of materials All structural steel stock or fabricated steelwork shall be stored above the ground on platforms, skids or other supports, and adequately protected against corrosion. Steel which has been bent, damaged or excessively rusted will be rejected.
Fasteners and other small steel components shall be stored in a weatherproof building or sealed weatherproof containers.
17.2.7 Marking and Inspection Identification markings, match-marking or marking the mass of members shall be by stamping or stamped metal discs wired through holes.
The RailCorp Representative shall be permitted at all reasonable times to enter the Contractor's premises for the purpose of inspecting work, and no work shall be taken down or packed until it has been inspected and passed. The Contractor shall supply all labour, tools and falsework required to permit convenient access for inspection of the work.
17.2.8 Dimensional tolerances Members and parts of members shall be true to dimension and line, either straight or curved as shown on the Drawings, and free of undetailed twists and bends. Acceptability of steelwork shall depend on proper fitting together on erection and compliance with the tolerances stated hereunder. If closer tolerances are called for on the Drawings, such closer tolerances shall govern.
17.2.8.1 Cross sections Tolerances on any cross-section of a rolled section or plate shall comply with the requirements of AS 3678, AS 3679.1 or AS 3679.2 as appropriate.
For built-up sections the deviations from the specified dimensions shall not exceed the following:
Dimension Application Tolerance
Width of flange For all values of flange width + 10 mm, - 0 mm
(see Figure 1)
Eccentricity
(see Figure 1)
Offset between centrelines of web and flange
+ 2 mm
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Twist Deviation from parallelism to not greater than
(see Figure 3) longitudinal axis, of line joining corresponding points
LD/4,000,000
on two similar cross-sections along the length of the member for I-section girders of depth D millimetres, where L is the distance in metres between cross sections.
Depth and width Deviation from detailed depth not greater than + (D/500 +
(see Figure 4) D at a web centreline or span 3mm) or + (W/500 + 3mm) Supe
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(Combined effect of warpage, tilt of flange and "pull" due to welding at any cross-sectionof welded I-shaped girders)
(see Figure 5)
Offset at the toe of flangefrom a line normal to theplane of the web through theintersection of the webcentreline with the outsideface of the flange
This offset shall not exceed1/100 of total width of flangeor 6 millimetres, whicheverthe lesser, at any point alonga member, or 3 millimetres atany bearing, as welded.
Top and bottom flanges the flange is not permitted toslope upwards away from theweb thereby creating aponding area.
For box girders the offset shall not exceed1/40 of outstand length.
D
(Met
res)
Figure 3: Twist
DEVIATION
POTENTIAL ERPONDING AREA
WAT
DEVIATION NOT PE R MI T T E D IN UPWARD DIREC T I ON
Figure 5: Warpage & tilt in se ction
CL W EB CL WEB
DEP
TH
D
SPAN WIDTH W
Figure 4: Girde r fl a n ge d e pt h a n d wi d th
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17.2.8.3 Alignment at splice joints Where two plates are spliced by butt welding together ends with the same cross-section, the plate centrelines in the immediate vicinity of the joint shall coincide, with the following tolerances on alignment:
Dimension Application Tolerance
Maximum offset between the plate centrelines in the immediate vicinity of the joint in the direction of the plate width or in the direction of the plate thickness
1/10 of thickness of the thinner plate joined, but not more than 2 millimetres.
Butt welded plates
(see Figure 6)
Maximum angular deviation between these centrelines in the “direction” of the plate width or in the “direction” of the plate thickness
1 in 25
OFFSET
TI HCKNESS
WDTH
I
BTT
U +1 MAX
2 5
+1 MAX25
±/10 t MA X
±/ t 10 MAX
But
notexceeding2mm
JOI N T
BUT T
JOINT
ANGULAR DEVIATION
Figure 6: Plate Misalignment
17.2.8.4 Bearing seatFlatness of bearing seat shall not exceed the following:
Dimension Application Tolerance
Out- of-flatness
(see Figure 7)
Bearing seat 0.25 mm maximum
Max 25 mm Max 25 mm.
Figure 7: Bearing seat flatness
17.2.8.5 Plate flatnessDeviation from flatness or detailed curvature of panels of plate elements shall be determined by measuring offsets perpendicular to a template edge having the detailed straightness or curvature Su
pers
eded
by
T H
R C
I 120
03 S
T v1
.0, 2
0/10
/202
0
RailCorp Engineering Specification — Structures Structures Construction SPC 301
and a length not less than the smaller of d1 or d2 as defined below, and not more than 1.5 times the smaller of d1 or d2 – refer to Figure 8.
The measurement shall be taken between points of contact of the template edge with the plate. The template edge may be placed anywhere within the panel of plate. The maximum offset in millimetres shall not exceed the values computed as follows:
Dimension Application Tolerance
For girder webs without intermediate stiffeners
d/50t, but not greater than 0.5t.
For all stiffened plate elements
d/30t, but not greater than 0.8t.
In the above expressions, d is the least dimension in millimetres of:
d1 the transverse distance between longitudinal flanges, edges or stiffeners,
d2 the longitudinal distance between transverse edges or stiffeners, or
d3 the clear distance between points of contact of the template with the plate or web.
Plate flatness
(see Figure 8)
T is the minimum thickness of the plate within the panel in millimetres
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17.2.8.6 Secondary membersDeviation from detailed position of secondary parts and connections, the detailed position being the detailed distance from the member, connection, centreline of bearing or other primary working point or line.
Dimension Application Tolerance
Deviation from detailed position of secondary parts & connections
For bearing stiffeners and for each secondary part used for the connection of secondarymembers (that is, a part used for connections in which, ifthe connections were bolted, holes would be permitted tobe drilled full size)
+ 3 millimetres.
For all secondary parts not included above (that is, a part such as a plain stiffener plate or bar)
+ 6 millimetres.
17.2.9 Cambering
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17.2.10 Plates and flats Plates and flats shall be aligned in such a manner that the main stresses will be in the direction of rolling unless otherwise approved by the RailCorp Representative.
Plates shall be stripped by flame cutting and shall be finished square, straight or true to designed curvature, and plane without burrs or imperfections that are in excess of the specified tolerances.
17.2.11 Cutting
Girders shall be cambered, at a uniform radius if so detailed, to the shape shown on the Drawings. Camber shall be measured with the girder on its side, as the offset of the bottom flange, from a wire stretched tightly between the points of intersections of the web centreline with the outer face of the bottom flange at the two ends of the girder. If the girder cannot be placed on its side to measure camber, it shall be supported upright at the ends, and an allowance shall be made for deflection due to its own mass.
Built-up girders shall have the camber formed by cutting the web plates to suit, making allowances for shrinkage due to cutting and welding. Cambering of rolled sections and adjustment to the camber in built-up sections shall be done by methods approved by the RailCorp Representative. Moderate deviations from the specified camber may be corrected by a carefully supervised application of heat but in no case shall the tension flange be heated above 300 degrees Celsius.
Where girders are to be galvanized, the camber is to be within the specified tolerances shown on the drawing, after galvanizing. To ensure this is achieved, the Contractor shall contact the galvanizer to determine what, if any, change in camber will occur during galvanizing, before deciding how much camber is to be provided during fabrication. The Contractor and the Galvanizer shall decide at the start of the contract what methods are to be used for rectification, if the camber after galvanizing is not as specified, these methods are to be advised to the RailCorp Representative.
As far as possible, adjacent girders in the same span should be within 5mm of the same camber.
Flats with reasonably square and true rolled edges may, at the discretion of the RailCorp Representative, be accepted as a substitute for plates or flats with flame cut or machined edges. Such flats shall not be used if in service they are subjected to main stresses other than in the direction of rolling. The radius at the edge of the flat that is to be fillet welded along the edge shall not exceed 25 percent of the nominal fillet weld size.
Steelwork may be cut by flame cutting, sawing or shearing unless specified otherwise below. Surfaces produced by such cutting shall be finished square (unless a bevelled edge is called for), true and smooth to the required dimensions.
All exposed cut edges shall be cut to a standard comparable to Class 1 oxy cutting in accordance with a standard sample supplied by Australian Welding Institute. Where the finish is not to this standard cut edges shall be ground until the required standard is achieved. All corners on exposed edges shall be rounded to a radius or bevel of not less than 2 mm.
Flame cutting using a template-guided machine approved by the RailCorp Representative may be used, provided the Class 1 finish referred to above is obtained. Cutting equipment shall be maintained in good working order. Suitable regulators shall afford the operator complete control over the pressure and rate of flow of gas. Torches and nozzles shall be of proper size and type for the work in hand. Flame cutting by hand shall not be used except where specifically approved by the RailCorp Representative. Re-entrant corners shall be smoothly rounded to a radius of not less than 20 mm.
Striations and gouges from flame cutting, which are less than 3 mm in depth, shall be removed by grinding so that the resulting depression, which shall not exceed 3 mm, is tapered out smoothly for a distance of 25 times depth of defect on both sides of the defect. The finished plate size shall be within the specified tolerances. Striations and gouges having a depth greater than 3 mm shall be repaired using methods approved by the RailCorp Representative, but severe gouging or notching or frequent striations may be cause for rejection of the plate. Su
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17.2.12 Flange platesPlates, after stripping, shall not be handled using any equipment which can cause notching or marking the edges in excess of the tolerances specified for cutting above. Any plate exhibiting damage beyond these tolerances shall be rejected and replaced at the Contractor's expense.
Both compression and tension flanges shall be straightened to the specific tolerances prior to assembly into girders. If flame straightening is used, the plate shall not be heated beyond that required by the Australian Standard for the particular plate size. The cooling medium shall be dry compressed air. In no circumstances shall water be used to cool the plates.
Bottom (tension) flange plates shall be pre-set prior to welding to web plates so that the finished flange of the girder is flat or nearly so. On no account shall the bottom flange distort upwards so that dirt or water can accumulate on its upper surface. A pre-heat, in accordance with the sub-clause 2.23 "Preheating" shall be applied along the centre line of the flange plate before pressing for pre-set.
Flange plates shall be inspected and built into the girder so that any surface rectification by grinding will be on the underside of such plates. In the event of both surfaces of plates having been rectified by grinding, the grinding on the top side shall be brought out to the edge of the flange plate.
17.2.13 Grinding Any defects, score marks or bruises found in steel plates during fabrication shall be ground out to the satisfaction of the RailCorp Representative so that:
− The grinding does not reduce the thickness of the as-rolled plates below the minimum thickness specified in Table 3.1, AS/NZS 1365.
− The direction of grinding is in the direction of applied stress, that is along the length of the plate, in such a manner as to avoid over-heating, flow, unnecessary deep scores or grooves. The area to be conditioned shall be uniformly flared so that the ratio Flare Distance/Maximum Depth of Imperfection is greater than 50.
Plates which are damaged and reduced by grinding below the minimum thickness specified in Table 3.1, AS/NZS 1365, will be rejected and replacements obtained at the Contractor's cost.
17.2.14 HolesThe Contractor shall be responsible for the accuracy of all holes regardless of variations in dimensions of rolled sections or tolerances allowed in fabrication. Holes in plates thicker than 16mm may be either drilled full-size or reamed to full size after sub-drilling or sub-punching. Holes in plates of 12mm or lesser thickness may be punched full size and deburred by grinding. Punching may only be carried out using numerically controlled equipment.
The finished diameter of a bolt hole shall be 2 mm greater than the diameter of the bolt shown in the Drawings unless otherwise noted. Sub-punched and sub-drilled holes shall be smaller in diameter than the nominal diameter of the bolt, by 5 mm for a bolt greater than 20 mm in diameter and 3 mm for a bolt 20 mm in diameter or smaller.
The diameter of the hole in the die used for sub-punching shall not exceed the diameter of the punch by more than 2 mm. All sub-punched or sub-drilled holes shall be clean cut, without torn or ragged edges and shall be located with an accuracy such that after the steel is assembled and before any reaming is done, a cylindrical pin 3 mm smaller in diameter than the nominal diameter of the hole may be entered perpendicular to the face of the member, without drifting, in at least 75 percent of the holes in close groups in the same plane. If this requirement is not fulfilled, the badly punched or drilled pieces will be rejected. If any hole will not pass a pin 4 mm smaller in diameter than the nominal size of the hole, this will be cause for rejection. Drifting to enlarge holes will not be allowed.
Reamed or drilled holes shall be cylindrical and perpendicular to the face of the member. Reaming and drilling shall be done by mechanical means. Connecting parts shall be assembled and held Su
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securely while being reamed or drilled and shall be match-marked before separating. Burrs on all surfaces shall be removed. Assembled parts shall be taken apart for removal of burrs caused by drilling and reaming. All reamed or drilled holes shall be located to an accuracy such that, after the holes have been reamed or drilled, 85 percent of the holes in any close group shall show no offset greater than one millimetre between adjacent thickness of metal. If this requirement is not fulfilled the badly drilled or reamed pieces will be rejected. Where major members are rejected, the Contractor may submit a proposal for repair. Acceptance of both the proposal and the repaired work, if applicable, will be at the discretion of the RailCorp Representative.
Holes for field connections shall be reamed or drilled with the members assembled in the shop in their correct relative positions. Holes for field connections of minor members may alternatively be reamed or drilled from the solid to a hardened steel template not less than 25 mm thick, and all corresponding holes in the members to which they connect shall be reamed of drilled to the same template.
Each main member shall be assembled full length before reaming or drilling is commenced. The assembly, including camber, alignment, and accuracy of sub-punched or sub-drilled holes shall be approved by the RailCorp Representative before reaming or drilling is commenced. All joints shall be match-marked before the structure is dismantled.
17.2.15 High strength structural bolts High-strength structural steel bolts, nuts and washers shall conform to the requirements of AS/NZS 1252 for manufacture and supply.
High-strength bolts, nuts and washers shall be hot-dip galvanized in accordance with AS 1214. Threaded elements shall be centrifuged on withdrawal from the molten zinc bath. Nuts that are not of a manufactured internal diameter to accommodate hot dip galvanizing shall be re-tapped and their threads oiled for corrosion protection. Galvanized fasteners shall be test-assembled as specified in AS 1214, and then lubricated by the manufacturer ready for assembly, using an approved anti-corrosion coating.
The lengths of the bolts shall be so chosen that, after final tightening, the bolt will protrude through the nut by not less than 10 mm.
High-strength structural bolts shall be installed in accordance with the procedure for the installation of high-strength bolts using the part-turn method of tightening in AS 4100.
High-strength bolts shall not be used to correct bad fitting of connecting parts. Contact surfaces shall be brought into solid seating by grinding or machining before high-strength bolts are installed.
17.2.16 Shop assembly of steelwork On completion of fabrication and before dispatch to the site, all steel components except the walkway shall be assembled in the shop into complete spans for checking of dimensions, levels, squareness and fit.
Each span is to be shop assembled complete with cross girders and stringers. The shop assembly is a trial assembly only and shall be made using service bolts. However, new bolts, nuts and washer complying with the Drawings and this Specification shall be used in the final assembly and a sufficient supply of these including 5 percent surplus shall accompany the components to the site.
No steelwork shall be dispatched to the site unless and until the RailCorp Representative has inspected and passed the shop assembly. Before dismantling a successful trial assembly the components shall be match-marked to assist subsequent erection.
Alternatively, full assembly of steel bridge span shall be carried out in the workshop after the steelwork protective treatment, if the transportation of the bridge span from the workshop to the site is feasible. Inspection approval shall be sought from the RailCorp Representative prior to the dispatch of the fully assembled steel span to site. Su
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17.2.17 Protective coatingBefore dispatch to site, steelwork shall be given the protective coating as described on the Drawings.
17.2.18 Handling and transport The fabricated steelwork shall be braced and handled for transport and erection in such a manner as to prevent distortion and to ensure protection from damage. The method of transporting and handling shall be subject to the approval of the RailCorp Representative.
Specially prepared slings, lifting points, timber dunnage, edge protectors and rubber or other covering for lashings shall be provided by the Contractor to minimise damage to the steelwork and its protective coatings.
Where so instructed by the RailCorp Representative, long girders or spans shall be loaded and marked so that they may be delivered at the bridge site correctly positioned for erection without turning.
Delivery instructions will be issued by the RailCorp Representative as appropriate to the on-site construction program.
The Contractor is to supply lifting crane to unload and stack the nominated fully assembled steel spans at the two designated locations near the bridge ends as directed by the RailCorp Representative.
17.2.19 Name plates The name plate shall comprise of a 200mm X 350mm brass plate with the following information engraved on a raised surface. Each letter or number of the text on the first or second line shall be 20mm high and suitably wide. The information to be shown on the name plate is shown below.
The raised portion and the edges of the name plate shall be polished. The name plate shall be fixed on at approximately 500mm from the edges of the external steel main girder’s webs at Sydney abutment end.
The fixing shall be by 4 off 10mm diameter countersunk brass screws. The Contractor shall submit details of the name plate including the size and location of attachment to the RailCorp Representative for approval prior to commencement.
17.3 Welding Requirements 17.3.1 Standards
Welding shall conform to the standards specified hereunder:
Structural steel welding of plates and sections for the main steel girders, cross girders, lateral restraint bar, restraint bracket, restraint angle and bearing assembles: AS/NZS 1554.5.
Where there is a conflict between the Standard and this Specification, the Specification shall take precedence. Wherever special welding requirements subjected to fatigue are not covered by AS/NZS 1554.5, specific reference shall be made to American Structural Welding Code, ANSI/AWS D1.1 – 96. Special welding conditions as described in Clause 2.9 shall be met.
Particular requirements of AS/NZS 1554.5:
− The nominal tensile strength of the welds that are required to comply with AS/NZS 1554.5 is to be 480 MPa.
− The Charpy V-notch impact test for the heat affected zone is only required to qualify welding procedures where the preheat temperatures do not comply with clause 5.3 of AS/NZS 1554.5.
− The preparation of special test pieces as described in AS/NZS 1554.5 clause 4.7.2 will be required for a number of welds (e.g. all full penetration butt welds in the areas where apply to Su
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flange to flange, web to flange, stiffeners to flanges and gusset plate to flange) as instructed by the RailCorp Representative. A Provisional Item may be included for the preparation and testing of test pieces. The cost of re-submission and re-testing failed procedures will be at the Contractor’s cost and will not be measured for payment.
The hardness of the heat affected zone is not to exceed 350HV10.
17.3.2 Welding equipment and methods In assembling and joining parts of a structure or of built-up members, and in welding reinforcing parts to members, the procedure and sequence shall be such as will minimise distortion and shrinkage. Before the start of fabrication the Contractor shall be required to submit for the RailCorp Representative’s approval proposed fabrication and welding procedures. These proposals shall include:
− methods of plate preparation
− temperature and method of preheating (for plate preparation and welding)
− weld joint geometry
− welding processes
− types and sizes of electrodes and other consumables
− sequence of welding
− methods for minimising distortion, residual stresses and stress concentrations.
In making welds under conditions of severe external shrinkage restraint the welding shall be carried continuously to completion or to a point that will ensure freedom from cracking before the joint is allowed to cool below the minimum specified preheat and interpass temperature.
The parts to be joined by fillet welds shall be brought into a close contact as practicable.
Flange-to-web welds of fabricated girders shall be made by the submerged arc automatic process.
Transverse tack welds on tension flanges of flexural members are prohibited. Tack welds shall be subject to the same quality requirements as the final welds except that:
− Preheat is not mandatory for single pass welds which are re-melted and incorporated into welds made by the submerged arc or gas metal-arc process.
− Defects such as undercut, unfilled craters and porosity need not be removed before final welds when final welds are made by the submerged arc or gas metal-arc process.
Tack welds which are not incorporated into final weld shall be removed. Tack welds which are incorporated into the final weld shall be cleaned thoroughly.
Backings, extension bars and run-off plates used for groove welds shall be of steel of at least equal strength and weldability. Backings shall be removed from all members carrying live load stress, and from other members where the backings are exposed. Backings shall be removed by a procedure that does not injure the base metal or the weld metal, and the weld metal surface shall be left flush or slightly convex with the full throat thickness. Extension bars and run-off plates shall be removed upon completion of the weld and the ends of the weld made smooth and flush with the abutting parts.
All welding shall be carried out completely under cover and the fabrication factory or plant shall be sufficiently large to accommodate the steelwork to achieve this requirement.
Welding shall be carried out by an electric arc process and wherever possible, by automatic or manually-guided machine. In the event that the welding is carried out by electroslag or consumable electrode process, normalising or other approved supplementary process shall be included to ensure refinement of grain size and satisfactory physical properties in both the deposited metal and the heat affected zone. The flange-to-web welds shall be carried out by the automatic submerged arc process.
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Equipment and electrodes for welding shall be of approved types and shall be used in the circumstances and manner recommended by the manufacturer and specified herein. In the event of inconsistencies between these requirements, this Specification shall prevail. Sizes of electrodes, currents, voltages, polarity, arc lengths, speeds of travel, number of passes, sequence of passes, position of welding, edge preparation, fixtures and jigs shall be as recommended for the particular class of work and shall not be varied without written approval of the RailCorp Representative. Where a machine or a method is not of a conventional type, adequate demonstration of its satisfactory performance may be required by the RailCorp Representative before approval for its use will be given.
Electric arc welding equipment and plant shall conform to AS 1966 and shall be maintained in good condition at all times. Adequate safety precautions shall be taken during welding operations to protect operators and persons in the vicinity of such operations from electric shocks and the effects of radiations.
17.3.3 Electrodes for weldingElectrodes shall comply with the relevant requirements of AS/NZS 1553. Types of electrodes to be used for the various parts of the Work shall be subject to the approval of the RailCorp Representative and shall give physical properties in the weld metal and heat affected zone not less than those of the higher grade of parent metal being joined. Electrodes shall be stored and protected during use so that characteristics and welding properties are not affected. Electrodes which have been wet or subject to conditions which the RailCorp Representative may deem to be detrimental shall be liable to rejection.
All manual welding shall be performed with low hydrogen (Class 3) electrodes. All low hydrogen electrodes shall be dried in an approved drying oven at a temperature of not less than 260 degrees Celsius for not less than one hour, and shall subsequently be maintained at a temperature of at least 120 degrees Celsius in an approved holding oven. Any low hydrogen electrode which is allowed to cool below 120 degrees Celsius for a period exceeding one hour shall be reheated for not less than one hour at a temperature not less than 260 degrees Celsius. Immediately before use a low hydrogen electrode shall be allowed to cool so that at the time of use its temperature shall be in the range of 50 degrees Celsius to 100 degrees Celsius.
For submerged arc welding the wire electrode and flux used in combination shall conform to AS 1858. The flux shall be dry, warm and free of contamination from dirt, mill scale, or other foreign material. Flux shall be baked and then kept heated before use as specified for electrodes in the preceding clause. Methods of recovery, cleaning and drying flux for re-use shall be subject to the approval of the RailCorp Representative. Flux fused in welding shall not be re-used.
Test requirements may be fully or partially waived for electrodes that are of a type generally approved and subject to periodic tests by Lloyds' Register or other approved competent authority. Where the Contractor wishes such waiving of tests he shall make written application to the RailCorp Representative giving adequate guarantee that the electrodes conform to the approved type.
17.3.4 Qualification of welding operators Welding shall be carried out by welding operators authorised by the RailCorp Representative, and who have had suitable training and practical experience in the execution of this form of construction. An "A" Grade Welding Operator's Certificate for Electric Welding of the Australian Welding Institute shall be deemed satisfactory proof of a welder's training and experience. Welding operators not holding this qualification will be tested as prescribed in AS 1796. If the RailCorp Representative considers the quality of an operator's work to be below the required standard, he may require the operator to undergo re-qualification tests which shall be carried out in the presence of the RailCorp Representative. All tests of welding operators are to be undertaken at the Contractor's cost.
Where a method or process of manual welding is not of conventional type the RailCorp Representative will require that the operator be subject to tests of generally similar type and Su
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standard to those stated above, using the process in the manner intended and under the circumstances likely to pertain to the Work.
All welding shall be carried out under the immediate and continuous supervision of a welding supervisor employed by the Contractor and who is acceptable to the RailCorp Representative. The qualifications of welding supervisors shall conform with AS 2214. In addition they shall have adequate training and experience in the type of welding required for the Contract.
17.3.5 Procedure qualifications for welds Welding shall not commence until the procedure is approved in writing by the RailCorp Representative. Before approval is given, the Contractor will be required to submit such test assemblies as the RailCorp Representative requires for examination and testing. These test assemblies shall duplicate as far as practicable the actual conditions in the work, particularly with regard to plate thicknesses and geometric arrangements. After the procedure has been approved, it shall not be altered except within the limits approved by the RailCorp Representative.
Test assemblies will be required for all main welds, which are defined as web-flange welds, flange splices, web splices, bearing stiffeners, and any other welds nominated by the RailCorp Representative.
The size of test assemblies shall be of size adequate to carry out testing of welds as specified in AS/NZS 1554.5. The cost of supply, welding and testing of test pieces shall be borne by the Contractor.
Welding of test assemblies shall be done in the presence of the RailCorp Representative who will record the information listed below:
− Operator's name
− Type and make of equipment
− Weld preparation
− Type and size of wire or electrode
− Type of flux
− Preheat temperature
− Welding speed (automatic and semi-automatic)
− Welding current
− Welding voltage
− Welding size and number and sequence of passes.
Testing of test pieces will be carried out by the Contractor at an approved NATA registered laboratory at his cost. Test results are to be provided to the RailCorp Representative within 7 days after dispatch of a test piece for testing.
Additional payment will not be made to the Contractor for test pieces that fail and require new test pieces.
The cost of preparation and submission of weld procedures for the various types of welds required for the project is to be included by the Contractor in his scope of work.
17.3.6 Preparation of material for welding Surfaces and edges to be welded shall be smooth, uniform and free from fins, tears, cracks and other defects which would adversely affect the quality or strength of the weld. These surfaces shall also be free from loose scale, slag, rust, grease, moisture or other material that will prevent proper welding. Mill scale that withstands vigorous wire brushing may generally remain but all mill scale shall be removed from the surfaces on which fillet welds are to be made by submerged arc welding or by manual metal-arc welding with low hydrogen electrodes. Surfaces within 50 mm of any weld Su
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location shall be free from any paint or other material that may prevent proper welding or produce objectionable fumes while welding.
17.3.7 Assembly of parts for welding Members to be welded shall be brought into correct alignment and held in position by bolts, clamps, wedges, struts and other suitable devices, or by tack welds, until welding has been completed. In the design of holding devices suitable allowances shall be made for warping and shrinkage. Joints that are not sealed by welds throughout their length shall be a sufficiently close fit to exclude water after painting. The use of joint fillers is prohibited except where called for in the Drawings or approved by the RailCorp Representative.
Parts to be joined by fillet welds shall be brought into as close contact as practicable and in no event shall be separated by more than 2 mm. The legs of fillet welds shall be increased by the amount of the separation.
Parts to be joined by butt welds shall be carefully aligned. The misalignment of parts to be joined shall not exceed 10 percent of the thickness of the thinner part joined, nor 2mm, whichever is the lesser. In correcting misalignment in such cases, the parts shall not be drawn into an angle greater than 1 in 25.
Tack welds shall be subject to the same quality and procedure (including preheat) requirements as the final welds. Tack welds shall be cleaned of all slag and shall then be fused thoroughly with the final weld. Only tack welds which are wholly consumed by subsequent final welding will be permitted. Defective, cracked or broken tack welds shall be removed before final welding, except where specifically allowed to remain by the RailCorp Representative.
Improperly fitted and misaligned parts may be cut apart and rewelded subject to the approval of the RailCorp Representative.
17.3.8 Distortion and shrinkageIn assembling and joining parts of a structure or built-up members, and in welding reinforcing parts to members, the welding procedure and sequence shall be such as will minimise distortion and shrinkage. All welds shall be deposited in a sequence that will balance the heat applied to the assembly while the welding progresses.
The direction of the general progression in welding on a member shall be from points where the parts are relatively fixed in position with respect to each other towards points where they have a greater relative freedom of movement. Joints which are expected to have the largest shrinkage shall be welded first with as little restraint as possible. All shop splices in each component part of a built-up member shall be made before such part is welded to other parts of the member.
Subject to the prior approval of the RailCorp Representative, members distorted by the heat of welding may be straightened by mechanical means or by the carefully supervised application of heat, but in no case shall the steel be heated above 300 degrees Celsius.
17.3.9 PreheatingWelding shall not be performed when the surfaces are moist, during periods of strong wind, or in showery weather unless the work and the welding operators are adequately protected from the elements.
Immediately before welding, all weldments shall be flame scavenged to remove mill scale, moisture, paint and other foreign material from the assembled joint for a minimum distance from the point of welding of 75 mm. The parent metal within a distance of at least 75 mm from the point of welding and measured on the opposite side of the work to which the heat is applied, shall be then brought to the minimum temperature of 10\degrees Celsius or as specified in the Table below, whichever is the greater. The preheat temperature may be achieved by flame or electrical methods and shall be maintained as a minimum interpass temperature throughout the welding process. Preheat and interpass temperatures shall be sufficient to prevent crack formation. Temperature above the minimum shown may be required for highly restrained welds. Su
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Thickness of thickest part at the point of welding.
Shielded metal-arc welding with other than low-hydrogen electrodes,
Cored arc welding
Gas metal arc welding
Shielded metal-arc welding with low - hydrogen electrodes,
Submerged arc welding
or flux
Up to 20 mm 10 oC 10 oC
Over 20 to 40 mm 65 oC 21 oC
Over 40 to 65 mm 105 oC 65 oC
Over 65 mm 150 oC 105 oC
Alternatively, preheat may be calculated to the requirements of the Australian Welding Research Association Technical Note No. 1 (1972) for the size, joint configuration and type of material. Full details of such calculations shall be submitted to the RailCorp Representative and approval in writing obtained before being adopted.
17.3.10 Welding techniqueButt welds in any part of a member shall be completed by the Contractor and approved by the RailCorp Representative before that part is welded to any other part.
Run-on and run-off tabs shall be used for all flange, web and flange-web butt welds. Each run-on or run-off tab shall consist of two plates each minimum 100mm long and 100mm wide, cut from the same plates as the joint being welded. These tabs shall have the same weld preparation and the same thickness as the thinner plate, with the direction of rolling parallel to that of the plates being welded.
Root runs of butt welds shall be back-gouged by flame, grinding or other approved means to expose sound metal and then checked with dye penetrant to ensure an absence of cracks. Where back-gouging is performed using the air/carbon arc process, adequate care shall be exercised to ensure water is not introduced to the weldment from the compressed air line. The groove formed by back-gouging shall be filled with weld metal fused completely to the adjacent metal. Roots of submerged arc butt welds may be sealed with a root pass made by manual shielded metal-arc welding with low hydrogen electrodes when such sealing is necessary to prevent burn-through of the initial submerged arc welding pass.
Before welding over previously deposited metal, the slag shall be removed and the weld and adjacent parent metal shall be brushed clean. This requirement shall apply not only to successive layers but also to successive beads and to the crater area when welding is resumed after any interruption.
Stray arc strikes shall be avoided. Scratch plates shall be provided and used to strike the arc. Accidental arc strikes which occur shall be inspected by the RailCorp Representative before any attempt is made to rectify the blemish.
Each time the arc is started, either to begin a weld or to continue a partly completed weld, the arc shall be manipulated to obtain complete fusion of the deposited weld metal with the parent metal, and with any previously deposited weld metal, before any progression of the arc along the joint. At the completion of a weld pass, the arc shall be manipulated so as to fill the crater with sound metal.
The following list of restrictions and limitations shall be observed for manual welding.
− The maximum size of electrode for downhand position welding, excepting root runs of multiple pass welds, shall be 6mm unless the work is in the flat (natural-vee) position where 8mm electrodes may be used. For welds made in all other positions and the root runs of multiple pass weld, the maximum size shall be 5 mm. Su
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− The maximum size of fillet weld which may be made in one pass shall be 8mm, except that 10mm fillet welds may be made in the flat (natural-vee) position subject to the approval of the RailCorp Representative.
− A single layer of weld metal, whether deposited in one pass or made up of several parallel bands, shall not exceed 3mm in thickness except that the bead at the root may be 6mm in thickness if the position of welding and viscosity of the weld metal are such that it does not overflow onto unfused parent metal.
− When welding in the vertical position the direction of welding for all passes shall be upward.
The following list of restrictions and limitations shall be observed for submerged arc welding.
− Fillet welds may be made in either the flat or horizontal-vertical positions subject to single-pass fillet welds made in the horizontal-vertical position not exceeding 8 mm.
− The maximum size of electrode shall be 6 mm.
− The thickness of weld layers, except root and surface layers shall not exceed 10 mm. The split layer technique shall be used in making multiple-pass welds when the width of the layer exceeds 16 mm.
− Neither the depth of fusion nor the total width of fusion at any point in a single weld or weld pass shall exceed the width of the face of the weld or weld pass.
− The welding current, arc voltage and speed of travel for submerged arc welding shall be such that each pass will have complete fusion with the adjacent parent metal and weld metal and there will be no overlap or undercutting. The limits within which these parameters can vary will be established as part of the procedure tests, but as a general guide they would be +5 percent for welding current; +7 percent for arc voltage; and + 10 percent for speed of travel.
17.3.11 Welding and weld repair records A record shall be kept of all production flange butt weld splices and flange to web Tee-butt welds as specified in the Clause "Recording of Steel Plates and Fabrication Details". The records shall include all important welding parameters and full details of any repairs found necessary.
Before application of the protective coating system a diagram of each span shall be prepared and forwarded to the RailCorp Representative, showing the location of the centre line of each flange and web splice accurately in relation to the ends of the girders. The plate identification number, recorded in the Plate Register, shall be permanently stamped on the end face of each girder flange plate.
Run-on and Run-off tabs for each weld shall be permanently stamped on the "top" surface, that is the side welded first, with the shop serial numbers of the plates being joined and whether it is a Run-on or Run-off tab. The run-on tab shall be the tab where the first run commenced.
Run-on and Run-off tabs shall not be removed from the plates welded until non-destructive testing procedures specified (radiographic and/or ultrasonic) have established that the weld is satisfactory.
17.3.12 Appearance and finish of welds Exposed faces of welds shall be made reasonably smooth and regular, shall conform as closely as practicable to specified dimensions and shall not at any place be less than the specified dimensions. The acceptance of welds with dimension s in excess of design requirements shall be at the discretion of the RailCorp Representative. Acceptable and non-acceptable weld profiles are illustrated in Figure 9.
The surface of fillet welds shall junction as smoothly as practicable with the parent metal. Butt welds shall be finished smooth and flush with abutting surfaces on the exterior faces of steelwork which will remain exposed to view, where required for assembly, where specified in the Drawings or where the welds are to be X-rayed.
Run-on and Run-off tabs shall be removed to no closer than 2 mm of the member after the joint has cooled and the ends of all welds shall be finished smooth and flush with the faces of the abutting parts. All weld spatter shall be removed from the surface of the weld and the parent metal. Su
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Tabs shall be stamped to identify them with the joint and delivered to the RailCorp Representative
for testing as specified in the Clause "Welding and Weld Repair Records". The splice shall then be dye-checked to ensure no defect remains at the plate/Run-on or plate/Run-off interfaces.
17.3.13 Weld defects and correction
SIZE
SIZE
SIZE
SIZE
SIZE
SIZE
SIZE
SIZE
NOTE: Convexity C shall not exceed 0.1 times actual leg size, or the longer leg in the case of an unequal legfillet weld, plus 1.5mm
The presence of any of the following defects in excess of the limits specified will result in rejection of the weld:
− Incomplete fusion or penetration between weld metal and base metal, and between successive passes in the weld.
− Craters.
− Overlap of weld on base metal.
− Undercut in welds transverse to the longitudinal axis of a primary member.
− Undercut in excess of 0.25 mm in welds other than (iv) above.
− Cracks, regardless of length or location
− Internal porosity or fusion type discontinuities less than 1.5mm greatest dimension may be allowed only if dispersed evenly, and provided that the sum of the greatest dimensions does not exceed 10mm per linear 25mm of weld. Porosity includes gas pockets and other similar globular type voids. Fusion discontinuities include slag inclusions, incomplete fusion, inadequate penetration and similar defects.
− Internal porosity or fusion type discontinuities (as defined above) 1.5 mm or larger may be allowed provided such discontinuities are smoothly rounded. Porosity or fusion type discontinuities with any dimension greater than 12 mm will not be accepted.
− No porosity that extends to the surface of a weld as such will adversely affect the performance of the protective coating system to be applied to the finished steelwork. Nevertheless, surface porosity within the limits specified in sub-clauses (vii) and (viii) may be corrected with the approval of the RailCorp Representative.
− Web-to-flange tee-butt welds having a heat affected zone or weld metal hardness exceeding 280 Vickers.
Consideration may be given to correcting rejected defective welds but the specific approval of the RailCorp Represntative shall be required of the proposed methods and procedures before making each correction. Caulking of welds will not be permitted. Where the approval of the RailCorp Representative is obtained, defective welds shall be corrected as specified below.
Defect Corrective Measure
Excess convexity or Reinforcement Reduce to specified size by removal or excess weld metal.
Craters, excessive porosity, slag inclusions, overlapping and lack of fusion.
Remove defective portions and deposit additional weld metal.
Undercut, undersize welds, excessive concavity, removal of adjacent parent metal during welding.
Clean and deposit additional weld metal.
Cracks in parent or weld metal. As directed by the RailCorp Representative.
Where the removal of part or all of the weld or a portion of the parent metal is prescribed above, such removal shall be effected by gouging with flame, grinding or other approved means. Gouging shall not extend into the parent metal by any substantial amount beyond the depth of the weld penetration unless cracks or other defects exist in the parent metal. The weld or parent metal shall not be nicked or undercut in gouging. A weld which is cracked shall be removed for the full extent of the crack and then checked with dye penetrant to ensure that the crack has been removed completely.
Where corrections require the deposition of additional weld metal, the electrode used shall preferably be smaller than the electrode used in making the weld and shall be to the approval of the RailCorp Representative. Before adding weld metal or re-welding, the surfaces to be welded shall be cleaned thoroughly and checked with dye penetrant.
Where work performed after making a defective weld has made the weld inaccessible or has caused new conditions which would make the correction of the deficiency hazardous, detrimental Su
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or ineffective, the original conditions shall be restored by removal of welds or members, or both, before making the necessary corrections. Alternatively, the deficiency may be remedied by additional work as specified by the RailCorp Representative.
17.3.14 Inspection of welds
17.3.14.1 Welding supervision All welding on the Project including Qualification of Welding Operators shall be carried out under the immediate and continuous supervision of welding supervisor employed by the Contractor and who is acceptable to the RailCorp Representative. The qualifications of Welding Supervisors shall conform to AS 2214. In addition they shall have adequate training and experience in the type of welding required for the Contract.
All material and workmanship shall be subject to inspection by the RailCorp Representative during and after fabrication. Methods of inspection which may be used will include visual inspection, using penetrant dyes, magnetic particle inspection, radiographic inspection and ultrasonic inspection. No work shall be dispatched from the shop until it has been inspected and approved by the RailCorp Representative.
The Contractor shall lay out and arrange the individual members or units to be inspected so that identification marks on each may be readily distinguished and so that each member or unit is accessible for such inspection as the RailCorp Representative may deem necessary. The Contractor shall assist the RailCorp Representative by turning the members or parts to permit examination on all sides. The Contractor shall supply free of charge all labour and equipment for handling the work during inspection.
Radiographs will be made either by x-ray or gamma ray. The RailCorp Representative will select the portion of welds to be subjected to radiographic inspection. The reinforcement on the weld that is to be radiographed shall be prepared to the RailCorp Representative’s instructions. The extent of radiographic inspection will be as listed below and the Contractor is to allow for this cost in his tendered rates.
Location of Weld Minimum Length of Weld to be Radiographed
All full penetration butt welds 100 % of total length
All fillet welds shall be 100 percent Magnetic Particle tested and all defects as defined in the Clause above shall be identified. The Contractor is to allow for the cost of this testing in his Lump Sum Tender Price.
All ultrasonic and radiographic inspection shall be performed by an approved NATA registered testing laboratory at the Contractor's expense.
Where repairs are required the weld is to be reinspected using the same inspection technique after completion of repairs at the Contractor's cost.
All single-run fillet welds on intermediate web stiffeners shall be checked with Dye Penetrant for cracks after both sides of the stiffeners have been welded.
17.3.15 Special requirements for welding subjected to fatigue loadings
17.3.15.1 Butt welds
17.3.15.1.1 Flange butt welds Flange butt welds shall be ground flat and smooth in the direction of applied stress with overgrinding of 0.5mm below the deepest undercut at the fusion line. Where a very good weld profile is achieved, close to flat and smooth, this will be acceptable provided all four fusion lines are TIG dressed in accordance with ANSI/AWS D1.1-96 Section 8.4.1 Fatigue Life Enhancement, and Su
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Commentary C8.4 (4) TIG dressing. The RailCorp Representative shall decide where the second option can apply.
17.3.15.1.2 Web butt welds Web butt welds shall be treated as for flange butt welds, for 200mm from and above the bottom flange (for negative moment areas, “from and below the top flange”).
17.3.15.2 Base of stiffeners
17.3.15.2.1 Stiffeners connected to cross girders, sway bracing or diaphragms The bottom 100mm of all fusion lines of these welds, including across the bottom of the stiffeners, shall have fatigue life enhancement in accordance with ANSI/AWS D1.1-96 Section 8.4.1 and Commentary C8.4.1, as follows:
− Profile improvement in accordance with C8.4.1 (1) as required by the RailCorp Representative
and
− Toe grinding of fusion line to a minimum of 0.5 mm and a maximum of 2mm, in accordance with C8.4.1(2)
or
− TIG dressing of the fusion line in accordance with C8.4.1(4)
17.3.15.3 Bearing stiffeners Welding bearing stiffeners shall be continuos, including welding to the bottom flange. Where bad bridge ends exist or are likely, at sharp curves and high speed curves, fatigue life enhancement of highly stressed welds to flanges and the adjacent 200mm of web will substantially postpone fatigue cracking. In negative moment areas, over intermediate supports, the bearing stiffeners should be bolted to the top flange and the weld to web fatigue life enhancement to 200mm below the top flange.
17.3.15.4 Cross girder end connection All cross girder end connections, including end cross girders, should bolt to the bottom flange of through girders. For end cross girders it may be necessary to use the bearing bolt to provide this connection. Stainless steel packers should be used between cross girder and through girder bottom flanges to ensure good fit up.
Where geometrically, it is not possible to connect cross girder bottom flanges to the bottom flange of through girders, the base of stiffeners shall be bolted to the bottom flange, except for bearing stiffeners which are welded (see Section 18.3.15.3 above).
Wherever cross girder flanges are not bolted to through girder flanges the end of the cross girder flange to web weld shall be fatigue life enhanced, including across the end, to Section 18.3.15.2.1.
17.4 Specification For Ultrasonic Testing 17.4.1 Scope
This section specifies the method for the ultrasonic testing of carbon and low alloy steel plate of thickness 12 to 100mm inclusive, prior to welding for use in railway bridge fabrication, but does not include the examination of welds.
17.4.2 Test equipment The test equipment shall be as described in Section 2 of Australian Standard AS 1710, except that the sensitivity of the equipment is thus: -
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“The gain or sensitivity of the equipment shall be such that, on a discontinuity-free portion of the plate under test, the second back echo scan be consistently maintained at full speed height of +6 dB with a grass level not exceeding 5% of the full screen height.”
17.4.3 Ultrasonic testing procedure
17.4.3.1 General The operating characteristics of the equipment shall be checked at the beginning and at intervals not exceeding 1 hour while tests are in progress to establish that the ultrasonic equipment is operating under conditions of reproducible sensitivity throughout the test.
The instrument shall be adjusted at a plate location free from ultrasonic interference so as to produce a suitable number if back echoes. A minimum of 2 back echoes shall be displayed.
The gain shall be adjusted so that the grass level is approximately 10% of full screen height. Where a defect is indicated the area shall be examined and the discontinuity sized and classified in accordance with Section 18.4.4.
17.4.3.2 Surface preparation The condition of both the testing and reflecting surfaces of the plate shall be that there is no significant interference with the test.
17.4.3.3 Scanning Scanning shall be carried out along either:-
− A strip 50 mm wide from the edge of the plate to be welded along it’s edge;
or
− A strip 50 mm wide either side of the centre-line of the proposed weld line.
The scanning pattern shall be of zig-zag or similar form covering the entire 50 or 100 mm strip with a maximum pitch of 50 mm at the weld line. Alternatively, longitudinal scanning is permissible provided that there is overlap between successive scan-lines.
17.4.3.4 Measurement of defects
17.4.3.4.1 Examination of discontinuities All discontinuities shall be examined, classified and recorded where the discontinuity indication has been:-
− An energy ratio of more than –12dB [see Section 18.4.4.3] and
− An area greater than 300mm2 and/or
− A length exceeding 25mm
The examination shall include the assessment of:-
− Size, i.e.: length & width [where discontinuity extends beyond the area defined in Section 18.4.3.3 the entire discontinuity area shall be examined];
− Depth; and
− Energy ratio.
17.4.3.4.2 Determination of energy ratio The energy ratio of defect indication amplitude to back echo shall be determined either by:-
− Adjusting the back wall echo to the top of the screen and noting the level of gain then adjusting the gain until the discontinuity indication reaches the top of the screen and noting level of gain – the ratio is the difference between the 2 readings; or Su
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− Where both signals can be simultaneously displayed on the linear potion of the screen the ratio may be determined by scaling off the screen.
Note: that the energy ratio is negative [-] where the back echo is greater than the discontinuity indication.
17.4.3.4.3 Evaluation of discontinuities The discontinuities shall, as far as possible, be evaluated by using either:-
− The discontinuity indication between the first and the second back echoes, and the second back echo, or
− The discontinuity indication between the initial pulse and the first back echo, and the first back echo.
17.4.4 Classification of discontinuities
17.4.4.1 General The discontinuities shall, be classified by their ultrasonic response as described below, as one or more of the following:-
− Laminar
− Inclusion cluster
− Inclusion stringer
17.4.4.2 Laminar discontinuity Laminar discontinuity is an area of discontinuity located parallel to the rolled surface which totally reflects acoustic energy or which has a reflectivity equal to or greater than the back echo.:-
NOTE:
1. A laminar discontinuity will produce a single repeating reflection whereas an inclusion cluster type defect will often produce a multiple echo cluster.
2. A shallow lamination will also produce multiple echoes which should not be confused with the multiple echo cluster which indicates inclusion type defects.
17.4.4.3 Inclusion cluster discontinuity Inclusion cluster discontinuity is a discontinuity producing an indication with an energy ratio greater than –12dB but which is not a laminar type defect. If, however, movement of the probe in transverse direction causes loss of discontinuity indication the discontinuity shall be classified as an inclusion stringer discontinuity.
17.4.4.4 Inclusion stringer discontinuity Inclusion stringer discontinuity is a discontinuity producing a linear indication of the inclusion cluster type for which any movement of the probe transverse to the direction of rolling causes a loss of indication.
17.4.5 Record of results The record of results shall provide the following information:-
− Identification of the testing authority
− Identity of the testing officer
− Description of test equipment and settings used
− Identification of the plate under examination
− Reference number of this Specification Supe
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− Surface condition of the plate at the time of test
− A plan showing location, outline, area, depth and classification [including energy difference] of all discontinuities of area exceeding 300mm2
− Date of examination.
18 S21 Structural steelwork fabrication for overbridges This Specification sets out the requirements for the fabrication of steel girders for overbridges. This Specification does not apply to the fabrication of steel girders for rail underbridges (refer to Specification S20).
All aspects of the fabrication of steel girders for overbridges shall comply with the requirements of the RTA QA Specifications B200 “Fabrication of Major Steel Structural Members” and B204 ”Welding of Bridges and other Road Structures”.
The supply of fastenings shall comply with the requirements of the RTA QA Specification B240 “Supply of Bolts, Nuts, Screws and Washers”, current version.
19 S22 Miscellaneous steelwork This Specification shall apply to the fabrication, protective treatment, supply and delivery of:
− over head wiring structures (OHWS)
− steel walkways, refuges, working platforms, access stairs and ladders to OHWS
− safety cages, walkways on signal gantries, switch platforms and mounting platforms
− supports for cable trays and service bridges
− handrails, anti-throw barriers, pedestrian balustrades and safety screens
− crash beams and warning frames
− other minor steel items.
All steel components and fasteners shall conform with the requirements of RTA QA Specification B241 "Manufacture and Supply of Minor Steel Items" and RTA QA Specification B240 “Supply of Bolts, Nuts, Screws and Washers”.
Protective Coating:
− For paint coating, requirement of Section 21 “S24 Protective Paint Coating of Steelwork” shall apply.
− For galvanised coating, requirement of Section 22 “S25 Protective Galvanised Coating of Steelwork” shall apply.
Bolts in bearing shall be of such lengths that no threaded portion shall be within the thickness of the parts joined. At least one washer shall be used, placed under the bolt head or nut whichever is to be rotated. Tapered washers shall be used where the surfaces under the bolt head or nut is not perpendicular to the centre line of the bolt.
Dimensions and tolerances of the bolt and nut shall comply with AS1110 and AS1112. Diameter of holes shall be equal to the nominal diameter of the bolt shank with tolerance of plus 2 mm and minus 0 mm unless otherwise specified on the drawing.
High strength bolts shall be class 8.8 in accordance with AS1252.
High strength lock pin and collar fastening system and high strength one-piece blind bolt fastening system (for one-sided blind fastening applications) shall comply with ASTM A490. Unless nominated otherwise on the Drawings or elsewhere in the Project Documents, the finish for these fasteners shall be mechanically galvanised to the manufacturer’s standard.
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Welding shall conform to AS/NZS 1554.1 Structural steel welding - Welding of steel structures.
Welded splices shall be full penetration butt weld of SP category. Ultrasonic examination shall be carried out for all full penetration butt welds, in accordance with the recommendations of AS 1554.1. All welding procedures and test results are to be submitted to the Railcorp Representative.
20 S24 Protective paint coating of steelwork – System P This Specification sets out the details of paint coating systems, surface preparation and paint application requirements for the paint protective treatment of new structural steelwork elements.
This Specification does not apply to the protective treatment of fasteners (bolts, nuts and washers etc.), which shall be protected by hot-dip galvanizing in accordance with the requirements specified for System G (Specification S25).
The protective paint coating of steelwork shall comply with the requirements of RTA QA Specification B220 “Protective Treatment of Steelwork”, except for the paint coating system.
The paint coating system shall consist of a priming coat and one finishing coat as follows:
Priming Coat
(a) The priming coat shall be an organic zinc rich epoxy primer approved under APAS Specification Number 2916, applied to achieve a minimum dry film thickness of 75 micrometres;
(b) For primers, no liquid constituents manufactured earlier than 6 months prior to application shall be used;
(c) The priming coat shall be applied before discolouration occurs and in all cases not later than 4 hours after abrasive blast cleaning.
Finishing Coat
(a) After the priming coat has been allowed to dry, it shall be over-coated with a two-pack medium build epoxy micaceous iron oxide finish, approved under APAS Specification Number 2973, employing a 'mist' coat on the initial pass;
(b) For epoxy MIO coatings no material manufactured earlier than 12 months prior to application shall be used on the steelwork;
(c) The finishing coat shall be applied to a minimum dry film thickness of 200 micrometres. The total dry film thickness of the system shall be 275 micrometres.
Paint Plaques
(a) For each bridge span or crash beam included in the Contract, one plaque shall be provided and fixed to that span by the Contractor to record the protective coating system used on that span;
(b) Each plaque shall be of metal, manufactured by casting or other approved method, have a minimum size of 300 mm x 150 mm, be hot-dip galvanized to a minimum zinc thickness of 105 micrometres and be fastened to a vertical surface of the steelwork in a non-highly stressed and readily visible position, approved by the Superintendent. Four brass bolts of minimum diameter 5 mm, with nuts, shall be used for the fastening, each bolt passing through a plaque corner area which has been locally thickened on the back so that most of the attached plaque's back face will stand clear of the surface of the steelwork;
(c) Each plaque shall record, in raised letters and numerals, which are clear and at least 12 mm high, the following information:
− Paint Manufacturer's Name Supe
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21 S25 Protective galvanised coating of steelwork – System G
21.1 Scope This Specification sets out details of galvanised coating systems, surface preparation and galvanising application requirements for the protective treatment of structural steelwork elements.
Protective galvanised coating of steel bridge girders is to comply with the requirements specified in this Section.
Protective galvanised coating of miscellaneous steelwork is to comply with the requirements of RTA QA Specification B220 “Protective Treatment of Bridge Steelwork“ and AS 4680 - Hot-dipped galvanized (zinc) coatings on fabricated ferrous articles.
Fasteners such as high strength and commercial bolts, nuts and washers shall be hot-dip galvanized in accordance with the requirements of AS 1214 - Hot-dipped galvanized coatings on threaded fasteners (ISO metric coarse thread series). For bolts to be fastened to steel bridge girders, the additional requirements in Section 22.3 also apply.
21.2 General Hot-dip galvanizing of steel bridge girders shall be executed generally in accordance with the recommendations of:
− Australian Standard AS/NZS 2312, "Guide to the Protection of Structural Steel Against Atmospheric Corrosion by the use of Protective Coatings.", Section 4, "Surface Preparation Treatments" and Section 5, "Metallic Coatings for Corrosion Protection".
− Australian Standards AS/NZS 4680, "Hot-dip Galvanized (Zinc) Coatings on Fabricated Ferrous Articles" and
− AS 1627, "Metal Finishing – Preparation and Pretreatment of Surfaces."
Prior to the commencement of galvanizing of bridge girders a site conference shall be arranged between the Contractor, the galvanizer and the RailCorp Representative, to ensure that all parties are familiar with the requirements of the Specification. Minutes of this conference shall be taken by the RailCorp Representative and distributed to all parties concerned prior to commencement of the work.
21.3 Bolts Threaded elements shall be centrifuged on withdrawal from the molten zinc bath and nuts shall be retapped and their threads oiled for corrosion protection.
Galvanized fasteners shall be test assembled as specified in AS 1214, then lubricated by the manufacturer ready for use using an approved anti-corrosion coating.
21.4 Surface preparation Prior to galvanizing, all surfaces of steelwork shall be prepared by either of the following procedures:
− Abrasive blast cleaning, in accordance with AS 1627.4, to Class 2 ½, with a profile height not less than 30 nor more than 60 micrometers followed by removal of dust and debris by vacuuming or other means
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− Pickling, in accordance with AS 1627.5, followed by draining, thoroughly rinsing and drying the steelwork
If pickling is proposed, the Contractor shall submit to the RailCorp Representative for approval full details of the process, such as the composition of the pickling liquid and inhibitor.
(Whichever surface preparation is used, a preliminary cleaning shall be carried out by washing with fresh water or solvent cleaning and mechanical removal to remove all dirt, oil and grease, existing paint, salt deposits, weld slag and dags and weld spatter, and any foreign matter which is not readily removable by the surface preparation proper or which may contaminate the treating agent or have a detrimental effect on the galvanizing coat.
21.5 Hot-dip galvanizing (a) For hot-dip galvanizing fabricated steelwork the size of the galvanizing bath shall, preferably, allow the steelwork assembly or sub-assembly units to be fully immersed in a single dip, avoiding the necessity for double-end dipping.
(b) The material used for galvanizing shall be zinc metal specially manufactured for this purpose and shall be at least 99.5 percent pure.
(c) The temperature of the galvanizing bath before dipping shall not fall below the range 470 degrees Celsius to 480 degrees Celsius, subject to adjustment to suit the size of the fabricated unit to be dipped as approved by the RailCorp Representative.
(d) As well as safety precautions, the Contractor shall take all precautions to avoid distortion of the fabricated units during galvanizing. He shall be liable to rectify or bear the rectification cost for any avoidable distortions resulting from incorrect procedure. The Contractor shall draw attention to any design features which may lead to difficulties during galvanizing before galvanizing commences.
(e) After hot-dip galvanizing the mass of covering zinc on all steelwork surfaces shall average not less than 900gm/square metre (130 micrometers thickness) and at no point shall the mass fall below 750gm/square metre (105 micrometers thickness).
21.6 Testing and acceptance (a) Measurement of zinc coating shall be carried out using an approved thickness gauge in the manner described in AS 1580 - Paints and related materials - Methods of test, Method 108.1 - Determination of dry film thickness on metallic substrates - Non-destructive methods. Pencil type instruments are not acceptable. Readings shall be taken peripherally 100 mm from each end, in the approximate centre of the member, and at other points agreed on beforehand with the RailCorp Representative at the site conference and averaged to give a single figure.
(b) Where a single measurement is below 105 micrometers a square of 100 mm sides shall be drawn around the point. Ten measurements shall be carried out in this square area. If the average value of the ten measurements is not less than 105 micrometers the work is acceptable on that area. If "deficient" areas, showing an average value of less than 105 micrometers when examined as specified, total 5 percent or more, of the total surface of the member, the member shall be liable to rejection by the RailCorp Representative. On flame cut edges a thickness of 84 micrometers will be acceptable, in place of 105 micrometers.
(c) Adhesion shall be checked in accordance with the method described in AS 1580.408.2 Method 408.2: Adhesion - Knife test. If the coating flakes off in the form of a layer or skin to expose the base metal in advance of the knife, the member shall be rejected.
(d) The finish shall be uniform in appearance and colour. Surfaces shall have a smooth, even finish free of blisters, flux spots, inclusions, dross and acid or black spots. Lumps, globules and deposits of zinc which will interfere with the intended use of the member shall not be permitted.
(e) Galvanized surfaces which will have faying surfaces in friction-grip type bolted joints shall either be sufficiently rough to have a minimum co-efficient of friction of 0.35 or they shall be made so by grit blasting, wire brushing or needle gunning. The Contractor shall provide adequate and Su
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representative test results to show, to the RailCorp Representative's satisfaction, that the minimum co-efficient of friction requirement has been met.
(f) If galvanized bearing surfaces should be unsatisfactory for their function, due to warping or uneven coating, the RailCorp Representative may direct that they be remachined. Where the remachining removes all the galvanizing from any areas, such areas shall be cleaned by abrasive blasting followed by a priming protective coat comprising an Inorganic Zinc Silicate paint, APAS 2908, with a minimum dry film thickness of 75 micrometers, applied in accordance with the manufacturer's recommendations. The priming coat shall be applied before discolouration occurs and in all cases not later than 4 hours after abrasive blast cleaning.
21.7 Repairs to galvanizing coating (a) Where any part of a galvanizing coat has been damaged during handling, welding operations, transport or erection, such part of the coating shall be repaired after the assembly or erection of the steelwork in accordance with the procedure given below. The extent of the Contractor's responsibility to carry out galvanizing coat repairs shall depend on the requirements of the particular Contract.
(b) If the Contract includes the delivery by the Contractor of the fabricated steelwork to and its erection at the site, the whole of the galvanizing coat repairs shall be performed by the Contractor. Otherwise, the Contractor shall carry out only such repairs as will remedy all damage and complete his work to the point of handing over to the Principal, to the satisfaction of the RailCorp Representative, and remedy any faults which subsequently appear until expiry of the Defects Liability Period. Any repairs required to remedy damage resulting from work performed after the handing over shall be carried out by the Principal.
(c) Damaged galvanizing coatings shall be repaired by surface preparation and the application of priming paint patch coats which shall cover the whole of the affected areas and overlap some way into the surrounding sound galvanized areas as specified below.
21.8 Surface preparation for repairs (a) The areas to be patch coated shall be cleaned of all dirt, oil and grease, existing paint, salt deposits, weld slag and dags and weld spatter, and any foreign matter which may contaminate the surface or have a detrimental effect on the repair coating. In addition, any zinc corrosion products shall be scrubbed off using nylon pads and hot clean water. Burrs and sharp edges shall be removed by grinding.
(b) After cleaning, the preferred method of preparation of galvanized surfaces and bare steel surfaces to be patch-painted, is abrasive blast cleaning, as detailed in (i) below. For small areas up to and including 200 sq cm abrasive blast cleaning, as detailed in (i) below, or mechanical cleaning, as detailed in (ii) below, shall be used. For all areas above 200 sq cm and where Inorganic Zinc Silicate Primer is used, abrasive blast cleaning, as detailed in (i) below shall be used.
(i) Abrasive blast cleaning shall be carried out in accordance with AS1627.4, "Abrasive Blast Cleaning of Steel Surfaces", to a minimum of Class 2½ so that the profile height shall be not less than 30 and not more than 60 micrometers. In addition, a strip 75 mm wide of sound galvanized coating immediately surrounding the damaged coating shall be given a light "brush" or "matt" blasting to form a feathered edge. Dust and debris produced shall be removed by vacuuming or other means.
(ii) Mechanical cleaning shall be carried out with a flailing tool or by grinder, then finishing with a flailing tool. All corrosion product and millscale shall be removed to expose bright steel or galvanizing over the whole surface. Maximum profile height on the prepared surface is to be achieved with the flailing tool, by frequently grinding the ends of the flailing wires perpendicular to the longitudinal axis of the wires. In addition, a strip 30 mm wide of sound galvanized coating immediately surrounding the damaged coating shall be mechanically cleaned with the flailing tool to form a feathered edge. Dust and debris produced shall be removed by vacuuming or other means.
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(c) Priming paint patch coating shall be applied before discolouration of the surface occurs and in no instance later than 4 hours after abrasive blast cleaning.
21.9 Priming paint patch coating Patch coating shall not be carried out if the relative humidity is greater than 85 percent, the temperature is below 10 degrees Celsius, or in unsuitable weather conditions, such as extremely high winds, heavy rain or high temperatures.
Coatings shall be applied in accordance with the manufacturer's instructions as to mixing procedures, recoat times, pot life, thinning rates and application techniques. Paint shall be applied by spray except that brushing will be permitted for some patching work only, as specified below. Thickness shall be measured by an approved type thickness gauge.
The priming paint shall be either of the systems specified hereunder.
− A two-pack epoxy resin-based zinc-rich primer, APAS 0014/1 and APAS 2916, applied by brush or spray to a minimum 125 micrometre total dry film thickness (including the thickness of the galvanizing coat remaining in the case of the feathered edges), and shall be allowed to dry not less than 16 hours. This system is suitable for patching small areas. No single area shall be over 200 sq. cm. Total of all areas shall not be over 500 sq. cm.
− An Inorganic Zinc Silicate primer, APAS 2908, applied by spray to a minimum 125 micrometre total dry film thickness (including the thickness of the galvanizing coat remaining in the case of the feathered edges), and shall be allowed to dry overnight. This system is suitable for large areas or for numerous medium-sized areas. Preparation shall be in accordance with clause 21.7 (b)(i).
21.10 Change of camber due to galvanizing The potential effect of the galvanising on the design camber in structural members is to be taken into account during fabrication
21.11 Protective coating system identification For each bridge span included in the Contract, one plaque shall be provided and fixed to that span by the Contractor to record the protective coating system used on that span.
Each plaque shall be of metal, manufactured by casting or other approved method, have a minimum size of 300 mm x 150 mm, be hot-dip galvanized to a minimum zinc thickness of 105 micrometers and be fastened to a vertical surface of the steelwork in a non-highly stressed and readily visible position, approved by the RailCorp Representative. Four brass bolts of minimum diameter 5 mm, with nuts, shall be used for the fastening, each bolt passing through a plaque corner area which has been locally thickened on the back so that most of the attached plaque's back face will stand clear of the surface of the steelwork.
Each plaque shall record, in raised letters and numerals, which are clear and at least 12 mm high, the following information:
− Galvanizer's Name
− Year of Galvanizing.
22 S26 Erection of structural steelwork This Specification sets out the requirements for the erection of structural steelwork in bridges or associated structures.
Erection of steelwork shall conform with the requirements of RTA QA Specification B260 "Erection of Structural Steelwork”.
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23 S27 Erection of minor steelwork This Specification sets out the requirements for the erection of steel and aluminium barrier railing, light standards and nameplates and other minor steelwork items.
All aspects of the erection of minor steelwork shall comply with the requirements of the RTA QA Specification B264 “Erection of Barrier Railing and Minor Components”.
24 S30 Pot bearings This Specification applies to the design, fabrication, testing, protective treatment, supply and installation of structural steel and stainless steel pot bearings and associated attachment plates.
All aspects of the design, fabrication, testing, protective treatment, supply and installation of structural steel pot bearings and attachment plates shall comply with the requirements of the RTA QA Specification B282 “Pot Bearings – Structural Steel”;
All aspects of the design, fabrication, testing, protective treatment, supply and installation of structural steel pot bearings and attachment plates shall comply with the requirements of the RTA QA Specification B283 “Pot Bearings – Stainless Steel”.
Installation of pot bearings shall comply with the requirements of the RTA QA Specification B284 “Installation of Bridge Bearings”.
25 S31 Elastomeric bearings This Specification sets out the requirements for the supply of;
− unreinforced elastomeric bearing pads and strips
− laminated elastomeric bearings.
All aspects of the supply of unreinforced elastomeric bearing pads and strips shall comply with the requirements of the RTA QA Specification B280 “Unreinforced Elastomeric Bearing Pads and Strips”.
All aspects of the supply of laminated elastomeric bearings shall comply with the requirements of the RTA QA Specification B281 “Laminated Elastomeric Bearings”.
The following test data shall be used for strips where applicable:
26 S32 Installation of bearings This Specification sets out the requirements for the installation of bearings for bridges and other structures.
All aspects of the installation of bearings shall comply with the requirements of the RTA QA Specification B284 “Installation of Bridge Bearings”.
Notwithstanding the requirement shown in Clause 5.3 and 5.4 of RTA B284, the installation of bearing pads and strips for underbridges shall be in accordance with the details shown on the drawings.
27 S36 Concrete work – Minor work This Specification sets out the requirements for the;
− Supply, placing and curing of concrete for drainage structures, footings and plinths, footways and any other concrete work not specified elsewhere and;
− Supply and placing of mortar for filling gaps and distributing loads between components, and grout for grout filled revetment mattresses.
All aspects of the supply, placing and curing of minor concrete works shall comply with the requirements of the RTA QA Specification R53 “Concrete (for General Use) Mortar and Grout”.
28 S38 Ground anchors This Specification sets out the requirements for the supply and installation of ground anchors.
The supply and installation of ground rock anchors shall conform to the requirements of RTA QA Specification B114 “Ground Anchors”.
Concrete works associated with the installation of ground anchors shall conform to the requirements of Section S10 “Concrete Works”.
Ground anchors shall have a design life of 100 years.
The design of ground anchors shall include mitigation against the effects of stray currents.
Ground anchors shall not extend under private property without the approval of the Chief Engineer Civil.
Where the anchors are applied directly to rock, the exposed rock face shall be inspected by a qualified and experienced geotechnical engineer, prior to the setting out of the rock anchors. The number and distribution of the anchors may be varied to suit the geological conditions.
Anchor heads shall be protected so as not to be an obstruction. They shall be recessed or protected by a continuous smooth surface of shotcrete or concrete.
The designer shall specify requirements for testing.
The designer shall specify requirements for long term monitoring, if any.
All testing of anchorage components shall be undertaken at a laboratory NATA registered for the relevant tests.
29 S39 Shotcrete batter protection This Specification sets out the requirements for the supply and application of structural shotcrete for permanent works, excluding linings for tunnels and shafts. Su
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All aspects of shotcreting shall comply with the requirements of the RTA QA Specification B82 “Shotcrete Work”.
30 S40 Scour protection
30.1 General This Specification covers the supply of materials, preparation of base and construction of structures and surfaces required for creek bed and bank scour protection including inlet and outlet of culverts.
Slope and scour protection shall conform to the principles and details shown on the Drawings prepared for the particular installation.
Alternative protection systems include the following:
− rock filled gabions and mattresses
− grouted fabric mattresses
− dumped stone riprap
− grouted or ungrouted stone or concrete pitching
− soil - cement bagging.
30.2 Rock Filled Gabions and Mattresses The supply and installation of rock filled gabions and mattresses shall be in accordance with RTA QA Specification R55 “Rock Filled Gabions and Mattressess”.
30.3 Grouted Fabric Mattresses Grouted fabric mattress shall consist of "Fabriform" proprietary multiple panels of double-layer, open selvedge fabric joined in a mat configuration. The two fabric layers shall each be no lighter than 8 x 8 count/centimetre (20 x 20 count/inch), 840 denier tire cord nylon, of which at least 50 percent by weight shall be bulked continuous multifilament tire cord nylon. The fabric shall have a tensile strength of not less than 35 kN per metre. The double-layer fabric shall be woven together on spaced centres in such a manner as to provide Filter Points for the relief of hydro-static uplift pressure. Filter Points shall be spaced at 200 millimetres nominal.
Individual mill width panels shall be cut to suitable length and the two layers of fabric separately joined edge to edge by means of nylon thread. The tensile strength of stitched joints shall be not less than 18 kilonewtons per metre.
Grout shall consist of a mixture of Portland cement, fine aggregate, and water so proportioned and mixed as to provide a pumpable slurry. Pozzolan and grout fluidifier conforming to these specifications may be used at the option of the Contractor. The mix shall exhibit a compressive strength of 15 MPa at 28 days.
The surfaces to be protected shall be prepared and graded to such an extent that they are normally stable in the absence of erosive forces. A fabric envelope in a mat configuration shall be positioned over these surfaces in its design location and anchored at the top and bottom of the slope as shown on the Drawings. Grout shall be pumped into the space between the layers of fabric and the mattress filled to form a stable mat of suitable weight and configuration.
30.4 Dumped Stone Riprap Dumped stone riprap shall consist of hard, dense, durable stone placed on the bed or banks in such a manner as to ensure that the completed layer is stable, has a reasonably uniform surface and has the larger rock fragments uniformly distributed within the riprap.
Bedding material consisting of sandy gravel shall be placed beneath the riprap where existing materials are finer than the bedding grade specified in the table below. Su
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Sizing of dumped stone riprap and bedding shall comply with the gradation by weight or size specified in the following table:
Velocity through opening (m/sec)
1.5 to 2.5
2.5 to 3.0
3.0 to 3.5
3.5 to 4.0
4.0 to 4.5
RIPRAP
Over 90% larger kg - 2 5 10 20
Over 50% larger kg 5 10 20 40 80
Thickness mm 300 300 400 500 600
BEDDING
Over 10% ret'd mm 19 19 37.5 37.5 53
Under 50% pass mm 9.5 9.5 19 19 19
Over 10% pass mm 2.36 2.36 4.75 4.75 4.75
Thickness mm 200 200 200 200 200
30.5 Stone or Concrete Pitching Before any stone pitching or concrete block pitching is placed the bed or bank shall be neatly shaped and compacted to the satisfaction of the RailCorp Representative.
Pitching shall be laid on a sand bed 75 millimetres thick with non-woven polyester geotextile between the sand bed and the pitching. Filter fabric shall be lapped 300 millimetres at all joints.
Stone pitching shall consist of approximately rectangular blocks of sound durable stone, having a minimum dimension of at least 250 millimetres and a volume of at least 0.03 cubic metres. As an alternative, blocks conforming to the above dimensions may be precast from 20MPa concrete.
The stone or concrete blocks shall be placed in courses and bedded normal to the slope with the larger blocks at the bottom of the slope, firmly bedded against the bed pitching or trench cut at least 500 millimetres into natural ground or 150 millimetres into rock. The blocks shall be laid with staggered joints, so that the distance between blocks is not more than 20 millimetres and so that each block is supported by the embankment and not by adjacent blocks.
The finished pitching shall present an even, tight and reasonably smooth surface of the required contour, care being taken to keep earth from filling the spaces between the stones.
Where grouted pitching is specified the spaces between the stones shall be completely filled with grout from bottom to top and the surface swept with a stiff broom. Grout shall consist of one part of Portland cement and three parts of sand, thoroughly mixed with water to produce uniform grout having a thick, creamy consistency.
Tapered wood blocks or other means shall be used to form weep holes in end joints between stones on a grid one metre by one metre. The wood blocks shall be removed after the mortar has set and the holes trimmed. Weep holes shall continue for the full thickness of the wall through to the filter fabric.
Pitching shall not be grouted at temperatures below 5 degrees Celsius. In hot, dry weather the grouted work shall be protected from the sun and kept moist for at least three days after grouting.
30.6 Soil-Cement Bagging Materials for bagged soil-cement bank protection shall be thoroughly mixed dry in the proportion of 1 part cement to 4 parts sand or loam by volume unless other proportions are specified on the Drawings. The sand or loam shall be subject to the approval of the RailCorp Representative, but generally shall be granular or finely divided friable material capable of being easily and intimately mixed with Portland cement. Su
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Hessian bags, having internal seams, or only one external side seam, and having dimensions approximately 600 x 300 x 100 millimetres shall be filled with dry mixture to about 80 percent of their volume and tied about 75 millimetres from the top. After laying, the tied end of each bag shall be folded under the bag to provide a neat vertical joint with the adjacent bag. If bags having an external side seam are used, the seam shall be placed against the embankment.
The bottom layers of bags shall be bedded in a trench cut at least 500 millimetres into natural ground, or 150 millimetres into rock. The bags shall be placed close together on the prepared slope of the embankment, the joints between successive courses being staggered. During placing of the bags the slope shall be checked with a guide line stretched from the top to the bottom of the embankment. As each row of bags is placed any backfill necessary to make good any irregularities in the embankment behind the bags shall be well tamped. The bags shall then be thoroughly wetted and compacted by methods approved by the RailCorp Representative. Minor irregularities in the finished surface shall be removed by tamping the face of the bags. At each end of the bagged area, alternate bags shall be keyed into the embankment by placing them at right angles to the face of the embankment. The above procedure shall be repeated until the bagging of the embankment is completed. Prior to ceasing work each day, the finished surface of the bagged area completed that day shall be well watered again to assist the hydration process.
The finished bagging shall present an even and reasonably smooth surface of the required contour.
31 S41 Demolition of existing structures This Specification sets out the requirements for the demolition of an existing structure and the disposal of resulting materials and components which may or may not be contaminated.
All aspects of the demolition of an existing structure shall comply with the requirements of the RTA QA Specification B341 “Demolition of Existing Structure”.
Other relevant documents are:
− AS 2601 – Demolition of Structures
− AS 2436 – Guide to Noise Control on Construction, Maintenance and Demolition Sites
− AS/NZS 3012 - Electrical Installation: Construction and Demolition Sites
All demolition work is to be undertaken and supervised by appropriately qualified and certified personnel in accordance with Workcover NSW requirements.
Prior to commencing demolition, the Contractor will be required to submit a demolition plan, outlining:
− the proposed methodology;
− proposed measures to ensure the safety and health of personnel (including where applicable, public safety) and protection of the environment;
− the proposed means of disposal of all released materials.
Where nominated in the scope of work, the Contractor is to engage at his cost an appropriately qualified archivist or archaeologist to undertake archival recording. This may include excavations, photographs and the preparation of a report.
Hearing protection and noise control are to be implemented and to conform to AS 2436.
Where required by the relevant Authorities, all mechanical equipment is to be fitted with appropriate silencing or noise suppressing accessories. Equipment operators are to be supervised to ensure that such accessories are correctly and consistently used.
Dust emission shall be minimised during the demolition work. If necessary, the Contractor is to provide dust-proof screens and covers and spray surfaces with water as required.
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Unless otherwise specified in the Scope of Work, the Contractor is to remove all released and demolished materials from the RailCorp property and dispose in accordance with relevant environmental and other regulations.
The Contractor is to meet the costs for all transport from site and tipping fees.
32 S45 Reinforced soil retaining walls This Specification sets out the requirements for the construction of Reinforced Soil Walls (RSWs).
All aspects of the construction of Reinforced Soil Walls shall comply with the requirements of the RTA QA Specification R58 “Construction of Reinforced Soil Walls”.
Concrete test panels and colour control of concrete where required shall be provided in accordance with AS3610, to suit the class of finish defined in RTA QA Specification B80.
33 S46 Soil nailing The supply and installation of soil nails shall be in accordance with RTA QA Specification R64 “Soil Nailing”.
34 S48 Bridge deck waterproofing Work covered by this Section includes the supply and installation of waterproofing to bridge decks.
Materials to be used are as shown on the Drawings. The Contractor shall submit details of any alternative materials to the RailCorp Representative for approval, 14 days prior to the proposed commencement of construction of the waterproofing. Submission of details of alternative materials shall constitute a “Hold Point”.
The Contractor shall submit full details to the RailCorp Representative for approval for fixing of the prescribed waterproofing materials to the bridge deck. This approval shall constitute a “Hold Point”.
Where proprietary membranes are prescribed, they are to be installed in accordance with the Manufacturer’s instructions.
Membranes should be folded up over the inner face of the kerbs and suitably fastened to the kerbs, to provide a continuous waterproofing over the deck.
Upon completion of the works, the Contractor shall supply an original copy of Warranty certificates for waterproofing membranes and materials used in the construction.
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This specification specifies the production and supply requirements of hot rolled structural steel plate for use in bridges and special structures.
Unless otherwise specified herein the relevant sections of the latest edition amendment or suppression AS / NZS 3678 shall apply.
DESIGNATION
Grades shall be designated in accordance with AS / NZS 3678 except that the Australian Standard designation (ie. AS / NZS 3678) shall be replaced with the NVR designation (ie NVR). Grade / Thickness availability shall be as shown in Table 1, with the respective mechanical and chemical property requirements as detailed in AS / NZS 3678, for the corresponding grades, as applicable.
Grade Thickness
NRV 250 10 - 150
NVR 250L15 10 - 150
NVR 350 10 – 80
NVR350L15 10 – 80
NVR400L15 10 – 50
Table 1
FREEDOM FROM DEFECTS
General
The plate shall be free from defects detrimental to its use for the applications specified in Clause 1.
Notwithstanding that plate has been accepted previously, if subsequent processing reveals that it contains defects found to be detrimental, the plate shall be deemed not to comply with this specification provided that it has not been improved improperly treated after delivery.
Removal of Surface Defects
Injurious surface imperfections shall be removed by mechanical means provided that no region of the plate thickness is reduced below the specified thickness of the plate and the direction of any final grinding is in longitudinal direction of the plate.
Welding shall not be used in the repair of surface defects
ULTRASONIC TESTING
All impact tested grades shall be ordered ultrasonically tested in accordance with AS1710 Level 2.
On request, all NVR grades may be ordered with ultrasonic inspection to AS1710 as per BSL – IM Price Schedule.
PLATE SURFACE INSPECTION / QUALITY
All NVR grades shall be off-line inspected by BSL - Plate Finishing Department to ensure critical surface suitable for the stated end use (Clause 1).
Off-line inspection shall only be conducted on plates that have been abrasively cleaned to a suitable class of blast. Plates shall be repaired as required.
On request, all NVR grades may be ordered in the blasted and primed condition as per BSL – ISD Price schedule.
