Specification for Air Cooled Heat Exchangers

PREPARED

BY NA PTT PUBLIC COMPANY LIMITED

CHECKED BY

ONSHORE COMPRESSOR STATION 4 PROJECT

APPROVED BY

CERTIFIED

(PTT) NA

REV.NO.

DATE

REVISED BY

APPROVED BY

DESCRIPTION

D1 18-Feb-08 NA ISSUED FOR ITB D2 22-Jun-08 NA REVISION ISSUED FOR ITB

SPECIFICATION FOR

AIR COOLED HEAT EXCHANGER

SPC-0804.02-20.22 REV.D2

TOTAL 20 PAGES

AREA CODE OF SITE LOCATION

GENERAL AREA: 010

.

PTT PLC. CONTRACT NO.

PTT PLC. PROJECT NO.

0804.02

GENERAL REQUIREMENT FOR AIR COOLED HEAT EXCHANGER

2.

PTT PUBLIC COMPANY LIMITED ENGINEERING SPECIFICATION

SPC-0804.02-20.22 PAGE: 2 OF 20 REV: D2

CONTENTS

SECTION

1.0 SCOPE ................................................................................................ 3

2.0 CODES SPECIFICATIONS AND STANDARDS............................................ 3

3.0 DEFINITIONS ....................................................................................... 4

4.0 PROPOSALS ........................................................................................ 5

5.0 DOCUMENTATION................................................................................ 5

6.0 DESIGN ............................................................................................... 6

7.0 MATERIALS ....................................................................................... 15

8. 0 FABRICATION .................................................................................... 16

9. 0 INSPECTION, EXAMINATION AND TEST................................................ 16

10. 0 PREPARATION FOR SHIPMENT............................................................. 17

11.0 SUPPLEMENTAL REQUIREMENTS ......................................................... 18

ATTACHMENT 1 : PIPING AND PIPING LOADS ................................................ 18

ATTACHMENT 2 : PIPING AND HEADER CONFIGURATION................................ 20


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INTRODUCTION SPC-0804.02-30.01 is based on API 661, 4th edition, November 1997. The item numbers used in this specification amend, supplement and delete various clauses/paragraphs of API Standard 661. Clauses (paragraphs) in API Standard 661 which are not mentioned in this specification remain applicable as written. This specification shall be used in conjunction with the data/requisition sheet relevant to the equipment its serve. The equipment (including auxiliaries) covered by API 661 Standard and SPC-0804.02-20.22 shall be designed and constructed for 20 years minimum service life and at least 5 years of uninterrupted operation. In all case, the CONTRACTOR/VENDOR shall inform PTT of any deviation from the requirements of API 661 standard and SPC-0804.02-20.22. 1.0 SCOPE (Add) This Engineering Standard covers minimum technical requirements for the Design, Fabrication, Material Supply, Testing and Inspection of Air Cooled Heat Exchangers. CONTRACTOR shall be responsible for the Design, Supply of Materials, Manufacture and Testing of the Exchanger and its components. CONTRACTORS shall responsibility to obtain all necessary approvals and to comply with all applicable local regulations. Changes of any kind proposed by Local Authorities shall not be implemented without prior written agreement by PTT/CONSULTANT. Where the Mechanical Design data is provided by PTT/CONSULTANT the CONTRACTOR is responsible for checking, approving and guaranteeing the data provided. Any conflicting requirements shall be referred to PTT/CONSULTANT for clarification before proceeding with the design and/or fabrication of the affected part. The CONTRACTOR shall comply with all applicable local rules and regulations, state and national codes as noted in section 2, and insurance requirements. The air-cooled heat exchanger shall be forced draft fans. Sub equipment, sub-assembly, instrument, device and material, which are supplied by the CONTRACTOR, shall be in accordance with PTT ‘s project vendor list. 2.0 CODES SPECIFICATIONS AND STANDARDS 2.1 In addition to the contents of this Engineering Standard, Air cooled Exchangers shall comply with the following as applicable.


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2.2 American Society of Mechanical Engineers Codes ASME, Section II Part D Materials Properties ASME, Section VIII DIV.1 Boiler and Pressure Vessel Code - Unfired Pressure Vessels ASME, Section VIII DIV.2 Boiler and Pressure Vessel Code - Alternative Rules ASME, Section IX Boiler and Pressure Vessel Code - Welding Qualifications ASME, B16.47 Large Diameter Steel Flanges ASME B16.5 Pipe Flanges and Flanged Fittings 2.3 American Petroleum Institute API 661 Aircooled Exchangers for General Refinery Service. 2.4 E.E.M.U.A. Publications Publication 132 Electric Motors. Publication 140 Noise Procedure Specification. Publication 141 Guide to Use of Specification 140. Publication 143 Recommendations for Tube End Welding. 2.5 National Association of Corrosion Engineers NACE MR-0175 Sulphide Stress Cracking Resistant Metallic Materials for Oilfield Equipment. 2.6 PTT/CONSULTANT Engineering Standards.

SPC-0804.02-20.02 Quality Requirement for Pressure Vessel SPC-0804.02-20.03 Marking for Vessels and Heat Exchangers. SPC-0804.02-30.00 General requirements for Machinery SPC-0804.02-40.05 Wind and Earthquake Loading. SPC-0804.02-40.06 Design Loading for Structures. SPC-0804.02-40.07 Structural Steelwork Design. SPC-0804.02-60.01 Instrumentation General Specification. SPC-0804.02-70.01 Electrical Standard. SPC-0804.02-70.02 Electrical Equipment. SPC-0804.02-70.09 Motors. SPC-0804.02-91.01 Equipment Noise Specification. SPC-0804.02-93.01 Hot Insulation for Piping and Equipment. SPC-0804.02-93.06 Painting SPC-0804.02-99.00.05 Basic Engineering Design Data PR-0804.02-10-03 Design Gulidlines

3.0 DEFINITIONS 3.2 (Add) Bare and finned surface shall be net effective. 3.5 (Add) considering as ineffective the portion within the tube sheets and that made inaccessible to cooling air by the tube supports


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4.0 PROPOSALS 4.1.1 (Add) When the thermal design is supplied by PTT/CONSULTANT the required design information will be transmitted within the PROJECT SPECIFICATION. 4.2.1 (Clar) The CONTRACTOR/VENDOR’S shall provide the Thermal Design data and specification sheet to PTT/CONSULTANT for each process case. 4.2.2 (Add) The Setting Plan and Plot Plan dimensions shall be attached. 4.2.3 (Clar) Electric motors shall be mounted shaft up. 4.2.5 (Clar) Any requirement for provision of exchangers as shop assembled modules will be stated in the PROJECT SPECIFICATION. Unless stated otherwise units may be designed for field erection, in which case individual bays shall be designed, shop fabricated and shipped with the minimum number of loose structural pieces match marked for bolted field assembly. 4.2.8 (Clar) Noise data shall be supplied as stated in the Equipment Standard SPC-0804.02-91.01. 4.2.9 (Clar) Every fans that install into the heat Exchanger shall be submitted Fan Performance curve. 4.2.13 (New) CONTRACTOR shall provide the Allowable Loads and movements to PTT/CONSULTANT as detailed in Attachment 1 of this standard. Submittal of this information is mandatory. 4.2.14 (New) The CONTRACTOR shall specify the exchangers louvers manufacture. All louvers materials need to confirm their suitability for the Design Temperature and also whether parallel or opposed type blade action is to be used 5.0 DOCUMENTATION 5.1.1 (Add) The requirements for drawings and engineering data shall be defined in the PROJECT SPECIFICATION. 5.1.5 (Clar) All proposed welding procedures and qualifications shall be submitted for approval by PTT/CONSULTANT prior to the start of fabrication. 5.1.6 (Clar) All information for installation, operation and maintenance of the exchanger shall be a matter of agreement between PTT/Consultant and the vendor. 5.2.1h (Clar) Completed noise data sheets are required by PTT and to be complying to the Engineering Specification SPC-0804.02-91.01. 5.3.1 (New) The following information together with a full definition of the fabricated item shall be clearly shown on the CONTRACTOR drawings:

- Design Criteria.


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- Materials of Construction. - Nozzle Designation. - Hydro test Pressure. - Name Plate Location. - Actual Weight for each item.

6.0 DESIGN 6.1.1.1 (Add) Maximum Tube Bundle weight shall be 15 tonnes unless approved otherwise by PTT/CONSULTANT. 6.1.1.2 (Add) The CONTRACTOR/VENDOR shall supply the data required by Attachment 1 of this standard when the lateral bundle movement deviates from that shown in API 661 Paragraph 6.1.1.2 or the PROJECT SPECIFICATION. 6.1.1.4 (Add) Tube supports shall be install directly on the tube or fin root. Supports resulting in loads on fin tips are not permitted. (Add) Pressed aluminium boxes shall be considered as standard for tube support elements. Zinc or zinc alloy supports are prohibited for tube bundles.. Alternative support methods shall approval by PTT/CONSULTANT. (Mod) Tube supports shall be spaced not more than 1220mm(48 inches) apart for non-ferrous tubes. 6.1.1.7 (Mod) The last pass of multi-pass condensers shall be sloped 10mm/m minimum. 6.1.1.8 (Add) An effective means must be provided to minimize air by-passing at the unfinned ends of the tubes and between the outer tube rows and bundle frames. 6.1.1.13 (New) Low friction pads shall be provided at each header support point when specified. The materials of Low friction pads shall be stainless steel on stainless steel surface. 6.1.1.14 (New) For forced draft exchangers the top of finned tube bundles shall be protected by an 8 BWG (Min.) steel wire mesh 50 mm x 50 mm. For induced draft exchangers, the top of finned tube bundles shall be similarly protected immediately beneath the removable fan guards. 6.1.2.4 (Add) Steam Coils should be a single row of straight finned tubes and loped 20mm/m toward the outlet header. 6.1.2.5 (Add) Steam Coil design conditions will be specified in the PROJECT SPECIFICATION.


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Standard header size should be 3" nominal pipe fabricated of SA-10 Grade B Carbon Steel material. Nozzle size and rating for all coil connections should be 3"NB – 150 lb raised face (or higher rating as required). Prime tube size should be 25.4mm, 12BWG fabricated from SA-214 Welded Grade Carbon Steel. Fins for steam coil tubes shall be aluminium with a standard outer diameter of 57.2 mm (for 25.4mm tubes) and a maximum density of 433 fins per meter, embedded type. Tube length shall be maximized consistent with the main coil tubing dimensions. 6.1.3.4 (Mod) The Design Temperatures for pressure parts, as listed on the Air cooled Exchanger specification sheet, shall be used as the basis for fin type selection. 6.1.6.1.2 (Clar) When the design is given to the PROJECT SPECIFICATION the CONTRACTOR shall confirm that the tube bundle configuration is suitable for the header compartment and tube metal temperatures shown. When the design is not given in the PROJECT SPECIFICATION it is the responsibility of the CONTRACTOR to investigate all design and operating conditions, temperature differentials, or temperature shocks specified in the PROJECT SPECIFICATION to determine that his proposed design is adequate. Unless otherwise specified the maximum process operating temperature shall be taken to be equal to the mechanical design temperature. 6.1.6.1.3 (Clar) Calculations for split headers shall include consideration of minimum design air temperature with fans operating at design pitch. Both design and turn- down process flows shall be taken into account. The greatest absolute expansion of the tube bundle shall be based on the design temperature, maximum process fluid inlet temperature, whichever is greater. 6.1.6.1.6 (Add) Where the minimum thickness of header components is given in the PROJECT SPECIFICATION, CONTRACTOR may increase this thickness where rationalization of plate selection results in economies. The Tubesheet thickness shall allow for 'cyclic service' when this is specified in the PROJECT SPECIFICATION. 6.1.6.1.6 (Mod) Where the stated corrosion allowance is more than that included in API-661 the difference shall be added to minimum nominal thickness of Header Components. 6.1.6.1.9 (Subs) Headers shall be the plug type.


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6.1.6.1.10 (New) Tubes shall be welded to the Tubesheet when specified, and normally where the design pressure is 30 bar(g) or greater. Tubesheets shall be provided with expansion groove/s whenever tubes are welded to the tubesheet (see 8.3.4.3). 6.1.6.3.4 (New) Plug type headers shall be designed in accordance with ASME VIII Div 1, App. 13 and transition type nozzles in accordance with App. 13.12. Nozzle reinforcement shall be by area replacement in accordance with para UG-37. 6.1.6.3.5 (New) Box headers with gasket plugs are acceptable up to 175 bar(g) design pressure. Otherwise PTT/CONSULTANT approval is required. 6.1.8.1 (Clar) Tube access plug gaskets shall be solid metal type compatible with header materials. Other gasket types proposed shall be subject to PTT/CONSULTANT approval. 6.1.9.8 (Clar) Flanges shall be of the forged welding neck type in accordance with ASME B16.5. Transition pieces should be forged or hot formed from seamless pipe. 6.1.9.8f (New) Nozzles shall not project past the inside surface of the header box. Nozzles shall be designed to avoid impingement on tube ends, restriction to flow, and uneven flow distribution. 6.1.9.12 (Clar) Threaded connections shall not be used in hydrogen service (i.e. when the hydrogen partial pressure exceeds 7.0 bar(a)). In these services, use 25mm LWN flanged nozzles for vents, drains, pressure and temperature connections. Flange ratings shall be for main nozzles. 6.1.9.13 (Clar) Thermowell Connections, when required, will be specified in the PROJECT SPECIFICATION. 6.1.9.14 (Clar) Pressure Gauge connections when required will be specified in the PROJECT SPECIFICATION. 6.1.9.16 (Add) Chemical cleaning connections, when specified, shall be 50mm connections installed in inlet and outlet nozzles and 100mm or larger in piping. For bundles in series or series-parallel arrangements, one chemical cleaning connection shall be provided in the inlet nozzle and one in the outlet nozzle of each series group. 6.1.9.18 (Add) Couplings shall be plugged with 150 mm long round bar stock of material comparable to the couplings. 6.1.9.20 (Clar) 25mm diameter flanged c/w blind vent and 40mm diameter flanged c/w blind drain connections shall be provided in each header. 6.1.9.23 (New) All flanged connections below 50mm shall be adequately braced or self reinforced by using LFWN nozzles.


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6.1.9.24 (New) Branch pipe which connected to heat exchanger nozzle shall be design by U- loop configuration, header pipe shall be placed lower than the heat exchanger ,see detail in Attachment 2. 6.1.10 (Mod) Design of exchanger shall be suitable for 1.5 x nozzle loads and moments specified in this para. (See also Attachment 1). 6.1.11.2 (Clar) For design by the CONTRACTOR the maximum tube length will be stated in the PROJECT SPECIFICATION. All units common to a particular piperack shall employ tubes in the same length unless otherwise approved by PTT/CONSULTANT. 6.1.11.7 (Add) Fin material shall be extruded aluminium. CONTRACTOR shall guarantee that fins will not suffer permanent harmful distortion when subjected to either maximum or minimum design temperatures with the fans out of service and not suffer permanent harmful from the effect of environmental around the operating area. Extruded aluminium fins shall be formed from a 4.32 mm thick aluminium sheet extruded to give a nominal fin out side diameter is 31.75 mm. greater than the prime tube o.d. unless otherwise approved by PTT/CONSULTANT. 6.2.1.1 (Add) When the Thermal Design is not given by PTT/CONSULTANT and the exchanger is mounted at grade, adjacent to re-circulation units or above a solid floor, CONTRACTOR shall take into account the available area for inlet air flow and make allowance for any additional pressure losses which may result. 6.2.1.2 (Clar) CONTRACTOR shall review the specified control system and may propose alternatives if economically attractive. CONTRACTOR shall state any special controls or operational procedures that are considered necessary to perform the process function or to prevent mechanical damage to the exchanger. Internal re-circulation shall not be used. When winterizing is required, the following shall be specified: a) Louvres plus steam coil b) External air re-circulation plus steam coil (for more severe cases). When a bay contains several services each shall be provided with louvres, operable from grade or remote control panel, to enable independent control of each service. 6.2.1.4 (Add) All Air cooled Exchanger components which may be exposed to high temperatures shall be capable of withstanding the following maximum inlet temperatures with fans out of service over a prolonged period of time (i.e., at least 48 hours). 1. Maximum process inlet temperature shown on individual item specification sheet less 28�C (power failure). 2. Steam out service when specified.


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6.2.1.5 (New) CONTRACTOR shall duplicate mechanical equipment, where possible at no extra cost, to minimise spare parts. 6.2.2.1 (Add) Equipment Noise Specification shall comply with engineering standard SPC-0804.02-90.01. Noise data that meet the requirements of engineering standard must be submitted with the proposal. Noise data must include noise from fan, drive, motor and any reverberation effects from the structure at the design condition. 6.2.2.3 (Sub) Noise tests shall be in accordance with EEMUA-140 and -141.

6.2.3.2 (Add) Fans shall have a minimum of 4 blades except that for fans 1.83m (6ft.) diameter or less, 3 blades may be acceptable subject to PTT/CONSULTANT approval. 6.2.3.10 (Mod) This paragraph shall apply to fans 1219 mm. (4 ft) in diameter or greater. 6.2.3.14 (Add) Air flow control shall be done by Variable speed drive (VSD). Number of fan which utilized VSD will be indicated in the data sheet. At least 1/3 of driver shall be control by Variable speed drive (VSD). CONTRACTOR shall confirm that fans are suitable for use over the whole speed range. Fans that have “critical speeds” within the required speed range are not acceptable. The fan “critical speed” shall be taken in to account for the fan support structure design. 6.2.3.17 (New) The design of the fan ring shall comply with the fan manufacturers requirements. Inlet cone or bell shall be furnished with the fan. The fan ring and cone, or bell, shall be one piece or welded. No flanged joint between ring and cone, or bell, is permissible. Where the fan ring itself is fabricated in sections (e.g. two half circles) then the above shall apply to each section. 6.2.3.18 (New) Fan hubs shall be examined for hairline cracks using magnetic particle or dye penetrant according to hub materials. 6.2.3.19 (New) All part of Fan shall be of heavy duty type, including the following items : - Fan hub - Fan blabe and blade shaft - Bearing,shaft - ect. Size (diameter) of Hub tube / Fan Blade shaft shall be greater than 2.75 inch. 6.2.4 (Add) Upper and lower fan bearing housing shall be installed separately to


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each other. Each housing shall be installed rigidly and directly to the structural main beam. Bearing manufacturer shall be one of the following: Dodge - - USA ,FAG - - Germany, NSK - - Japan. Bearing lock (grub) screws shall be provided to secure shaft with inner sleeve of each bearing. Drilled or slotted shall be provided on shaft surface given lock (grub) screw sit in the slotted. 6.2.5 (Add) Automated & Centralized greasing system shall be provided to lubricate fan Cooler and motor components. The system shall be made from stainless steel 316L including (but not limit to) grease header/tubing and container. (Add) The system shall be dual-line system, electric motor driven grease pumps shall be provided. For the large quantity of fan coolers, the system shall be separate in many independent systems, the physical location of each fan cooler shall also taken into account. Tube fitting shall be “Swagewlok”. (Add) Additional Manual g reas ing points and lubrication drain points for fan bearing and motor shall also be provided. These shall be accessible from outside guards to permit manual lubrication without shut down of equipment. 6.2.6.1 (Subs) Fan and belt Guards shall be removable type with locking device. removable lock. 6.2.6.2 (Subs) Fan and belt guards shall be non-sparking woven serrated wire mesh with the wire diameter shall be 4mm minimum. Expanded metal mesh is not permitted. 6.2.6.4 (Add) The openings in wire mesh of fan and belt guards shall be in the range of 650-1000 mm2. 6.2.7.1.1 (Add) All drivers, fans, bearings, transmissions, etc., shall be weatherproof for outdoor location. (Add) Electric Motors shall be used for all drivers. Electric Motor (rated) size 37 kW (50 hp) and above are required prior approval from PTT/CONSULTANT. 6.2.7.1.2 (Add) As a minimum motors shall be rated to provide 120% of the summer design fan power, including drive losses. The rating shall be exclusive of the Motor Service Factor. 6.2.7.2.1 (Mod) Electrical Motors, Motor Control and their installation shall be in accordance with PTT/CONSULTANT Engineering Standards SPC- 0804.02-70.01, SPC-0804.02-70.02 and SPC-0804.02-70.09. 6.2.7.2.2 (Subs) Electric motors arranged shaft up shall be fitted with a brass


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slinger plate or equivalent device to prevent access of rain to shaft bearing. Flange mounted motors shall not be used. 6.2.7.2.6 (Subs) Foot mounted motors only shall be used. Motor casing and its footing shall be one (same) piece design. 6.2.8.2.1 (Add) Belt Drives shall be HTD Belt drive ,and shall be anti-static and Oil Resistant type. Belt manufauturer shall be Gates or Optibelt. 6.2.8.2.8 (Mod) Belt drives shall have a minimum service factor based on the belt manufacturers recommendation for the service. In any case the minimum service factor shall be not less than 2.0 based on the driver rated power. 6.2.8.3.8 (Add) Coupling between right angle gear and motor shall be flexible disc coupling,with spacer. 6.2.8.4.1 (Clar) All belts shall be fully enclosed. Belt guards should be non-sparking and be constructed of wire mesh, with mesh size, minimum gauge or thickness, etc., as required by local regulations. Expanded metal or perforated sheet metal is not acceptable. 6.2.9.1 (Subs) Piezoelectric Accelerometer (display value in velocity) to be provided with Trip Function (Adjustable).The value and status alarm shall be shown at both LOCAL and DCS. 6.2.9.2 The accelerometer are to be provided one per motor, one per fan (low frequency response type). Accelerometer shall not be mounted directly to casing/structure, SS mounting pad shall be provided. The mounting pad shall be fully welded to casing/ structure by using appropriate welding rod. The mounting location for the accelerometer shall be carefully selected

- To represent High Vibration / Trip in case of bearing / fan damage. - For ease of maintenance.

Reference should also be made to PTT/CONSULTANT Specification SPC- 0804.02-60.01. 6.2.10.1 (Clar) Lourves are not permitted. . 6.3.1.5 (Clar) All tube bundles including induced draft items shall be removable without dismantling header platforms, motor maintenance platforms, motor/drive supports or, where possible, pipe supports. 6.3.1.7 (New) The PROJECT SPECIFICATION shall specify if grade mounting or pipe rack mounting is required and normally give support and access requirements. If this is not the case normal minimum support and access requirements are described below. 1. Grade Mounted - Provide minimum 2100 mm headroom


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clearance under the fan guard or tube bundle. 2. Pipe Rack /Elevated Mounted

a) For Induced or Forced draft unit with bottom mounted drivers a minimum vertical clear distance of 2100 mm shall be maintained between the bottom of the fan guard or tube bundle on all units and the walking surface level of the lower maintenance platforms. b) A mechanical maintenance access platform shall be provided for the full area under the Aircooled Heat Exchanger. c) The maximum distance between ladders or stairs giving access to grade from both header and mechanical access platform shall be 25m.

3. Header walkways are required at both ends of units. Each header walkway shall be connected to the other header walkway, so that the walkway shall cover all around the Aircooled Heat Exchanger. 4. Where the exchanger is provided as part of a complete package and supported on the CONTRACTORS structure, CONTRACTOR shall provide a dimensional sketch of the exchanger arrangement, including support structure and access, with the proposal for PTT/CONSULTANTS approval. See also para. 6.3.5.1. 6.3.1.8 (New) Earthing lugs shall be provided on the structure. 6.3.1.9 (New) Component parts for field assembly shall be shop fabricated and clearly piece marked. 6.3.2.1 (Subs) For fan shafts and structural parts, the maximum double amplitude of vibration shall not exceed 0.15 mm or the value of 11/(Frequency, CPS), mm, whichever is smaller. In addition the first natural frequency of the support structure shall be less than 0.8 or more than 1.2 times the rotation frequency. Field Vibration Testing shall be performed to ensure fan and structure integrity. Vibration Testing shall be performed as measured on Primary Structural Members with all fans running at Design speed and power. 6.3.2.4 (New) Bolted assemblies of the complete unit shall be protected against loosening by vibration through the use of double lock washers or Elastic Stop Nuts for all bolts. 6.3.3.1.f (Mod) Design for wind loads shall be in accordance with the PROJECT SPECIFICATION. 6.3.3.1.g (Clar) Earthquake loads shall be in accordance with the PROJECT SPECIFICATION.


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6.3.3.1.j (Clar) Design for snow and ice loads shall be in accordance with the PROJECT SPECIFICATION. 6.3.4.3 (Add) When not otherwise specified in the PROJECT SPECIFICATION, CONTRACTOR shall ensure that units have structurally independent bays that can be separated. 6.3.4.5 (Add) Externally re-circulated type Forced Draft units shall employ a bypass louvre in the side or top re-circulation plenum. 6.3.4.6 (Mod) Minimum thickness of steel sheet material used in construction of plenums and fan rings shall be 5/32 inch. Plenum and fan ring shall be provided with rigid stiffeners. 6.3.5.1 (Clar) When not specified in the PROJECT SPECIFICATION platform arrangements and the method of unit support proposed by the CONTRACTOR shall be clearly stated in the proposal, using drawings as necessary. (Add) Ladders leading from the platform below air cooled heat exchanger to the header walkways shall be provided. 6.3.5.2 (Add) The whole area below the air cooled heat exchanger shall be provided with platform of grating type. Grating shall be in accordance with SPC-0804.02-40.07. (Add) Stairways leading from Grade Level to the platform below air cooled heat exchanger shall be provided. 6.3.5.5.2 (Clar) Safety gates shall be provided across ladder openings. 6.3.5.8 (New) Header walkways shall be provided with half standard handrails on the inner side next to the exchanger. The design shall prevent open sides without obstructing access to the header. 6.3.6.7 (New) For modules, lifting lugs shall be provided on the structure for lifting the module complete with tube bundle(s). When specified, a lifting frame shall be provided suitable for lifting both the complete module or a tube bundle. Lifting lug shall be provided for motor lifting, fan shaft/hub/blade assembly lifting. Passage way (checkered plate, suitable motor transportation by trolley) shall be provided from each motor location to Maintenance lift locations. Maintenance lifts (Electric Hoists) shall be provided to lift the motor/fan assembly between platform and grade. 6.3.7 (New) When exchanger operating temperature exceeds 65�C mesh guards for personnel protection shall be provided at headers adjacent to walkways. Design and layout shall allow for this.


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7.0 MATERIALS 7.1 (Clar) For header box materials and other associated pressure parts (excluding tubes) the requirements of this section of API 661 shall be supplemented by the relevant specifications referred to in the PROJECT SPECIFICATION. 7.1.1 (Mod) All material shall be new, of highest quality and selected and applied in accordance with good engineering and construction practice. (Add) Parts of fans and transmissions which cannot be protected against corrosion, shall be made of non- corrosive material. 7.1.2 (Add) Carbon steels used in the fabrication of pressure parts shall be killed steels. The use of rimmed steel is not permitted. All attachments to pressure parts shall be of the same material specification as the part to which they are attached. 7.1.3 (Mod) Cast iron headers are not acceptable. 7.1.7 (Mod) Side frames and support beams which are part of the tube bundle and inaccessible for maintenance must be finish coated. Tube bundles shall be stainless or high alloy steel. 7.1.8 (Clar) Structural steel and fan ring and air plenum shall be hot dip galvanized steel in accordance with the PROJECT SPECIFICATION, except that where tube bundles are wholly or partly of stainless or high alloy steel, all structure and plenums beside or above the tube bundles must be painted with zinc free paint. 7.1.9 (Mod) Hot-dip galvanising shall conform with the PROJECT SPECIFICATION. No further welding, forming or other operation injurious to the galvanising shall be performed after the galvanising. All connections shall be made by bolting. 7.1.11 (New) All materials shall be identifiable in the finished fabrication by means of cast or heat marks transferred prior to cutting of components. These cast or heat marks must be traceable to mill test certificates presented by the fabricator in the "Manufacturer's Data Report" for the vessel in question. 7.1.12 (New) Heat Exchanger tubes shall be made from seamless pipe. Carbon steel tubes in hydrogen or wet H2S service shall be "killed". 7.1.13 (New) Unless otherwise specified, welded austenitic stainless steel tubes shall be cold drawn to a minimum reduction of 15% in wall thickness prior to a final full solution anneal. 7.2.2 (Mod) Welded header pass partitions and stiffeners shall be of the same material as the header plate unless otherwise approved by PTT/CONSULTANT. 7.3.1 (Add) Only aluminium alloys which are resistant to sea atmosphere shall be


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used. (Add) Material selection and fin design for tubes must guarantee a strong and durable connection between fin and tube. 7.3.2 (Add) Wood or plastic coated wood or plastic is not acceptable for blades. 7.3.6 (Add) For carbon steel headers the solid metal gaskets for the tube access plugs shall be of soft iron, with 90 BHN maximum. 8. 0 FABRICATION 8.2.1 (Add) Welded tube to tubesheet joints shall satisfy ASME code and project requirements (e.g. hardness limits). Weld overlays and suitable weld consumables shall be applied to avoid the need for PWHT. Where PWHT is considered the only option full details shall be submitted for approval by PTT/CONSULTANT. 8.3.1.2 (Mod) Table 5, Special Close Fit shall be used for all tubes of work hardening materials. 8.3.3.4 (New) Tube holes in tube sheets shall have a surface finish equal to that of drilled and reamed holes. No spiral grooves are permitted. Tube holes shall be deburred on both sides. 8.3.4.1 (Add) Unless otherwise specified welded tube-to-tubesheet joints shall be strength welded. (Add) Strength welded tube to tube sheet joints shall be used for pressures above 30 Barg. or lethal service, or clad tubesheets, or for temperatures above 300�C. 8.3.4.3 (Mod) Tube end welding to tubesheets shall be in accordance with EEMUA- 143. (See also 8.2.1 above). The welds shall be gas leak tested followed by careful light expansion of the tube into a single expansion groove which shall comply with para 8.3.1 through 8.3.3 of API 661. Weld procedure qualification (WPQ) shall include a pull out test. 8.5 (Add) Production drawing (shop drawing) of fan shaft, driver pulley and driven pulley shall be submitted to PTT. Location plan of the bearing hold down bolt hole shall be submitted. 9. 0 INSPECTION, EXAMINATION AND TEST 9.1 (New) All inspection and examinations shall be made by CONTRACTOR as required by the PROJECT SPECIFICATION, this


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Standard and all Codes, Specifications, Standards referenced in para 2, plus CONTRACTORS practices for quality control. 9.2.3 (Clar) Non-Destructive Examination of header main seams shall be specified by CONTRACTOR and shall be consistent with the joint efficiencies used in the design. As a minimum spot radiography shall be applied to welds of tubesheet and plugsheet to top and bottom plates, end closure welds, and any welds within plates forming the exterior of the box (excluding welds for nozzle attachment). 9.2.10 (Add) When any set-on connection covers a main longitudinal header seam the longitudinal weld seam shall be fully radiographed or ultrasonically examined for a minimum distance of 50 mm on either side of the nozzle cut-out. 9.3.3 (Add) The minimum hydrotest temperature may be 10�C, provided the null ductility transition temperature for the materials can be shown to be -10�C or lower. 9.3.4 Water used for hydrostatic testing units with austenitic stainless steel materials shall not contain more than 30 parts per million of chlorides. 9.3.7 (Clar) Special tests, such as submerged bundle leakage testing, shall only be required when stated in the PROJECT SPECIFICATION, except that gas leak testing is required for welded tube to tubesheet joints (see 8.3.4.3). 9.4 (Clar) When specified in the PROJECT SPECIFICATION, for shop assembled units, each fan-driver combination shall be run-in for a period not less than 1 hour to ensure the integrity of the drive train. Where auto-variable pitch fans, or variable speed motors, are provided their operation shall be checked over their full control range during the run-in period. Requirements for noise and/or vibration testing during the run test will be specified in the requisition. 9.5.3 (Add) The nameplate shall be in accordance with PROJECT SPECIFICATION. 10. 0 PREPARATION FOR SHIPMENT 10.1 (New) VENDOR shall advise shipping dimensions and weights as required by PROJECT SPECIFICATION. 10.1.3 (Subs) Flange openings shall be protected with wooden covers. Threaded openings shall have a bar stock plug 150 mm. long, of material comparable to that of the threaded opening. 10.2.1 (Mod) Surface preparation shall be comply with the requirement of the Project Painting Engineering Standard. 10.2.4 (Mod) All equipment shall be protected in accordance with the Project Painting Engineering Standard. The following should be noted:


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The rear face of carbon steel and low alloy tube sheets, tube bundle frames and other items which may be inaccessible after assembly shall be finish coated before assembly. 11.0 SUPPLEMENTAL REQUIREMENTS 11.1 (Mod) The requirements are applicable when the design pressure is 100 bar(g) and higher and when the tubesheet exceeds 50 mm. thickness. 11.2.3 (Mod) See paragraph 8.3.4.1, seal welding is not permitted unless specified by PTT/CONSULTANT. ATTACHMENT 1 : PIPING AND PIPING LOADS (Addition to Paragraph 6.1.10 API Standard 661). 1. VENDOR TO CONFIRM: 1.1. For all cases the permissible “ Fz ” loads shall be adequate for the following:

a) Frictional force to move the Header or Bundle as a result of thermal expansion of the Piping Header. b) The elastic restraint to movement of the exchanger tubes. c) Any loads imposed by the exchanger design.

1.2. Low Friction plates shall be provided unless specifically otherwise noted in the requisition. The plates shall be made from stainless steel on stainless steel.

1.3. The VENDORS design shall be suitable to withstand nozzle loads and moments of 1.5 times the values given in API 661 Para 6.1.10 as a minimum.

2.0 BUNDLE MOVEMENT - DETAILS TO BE PROVIDED BY VENDOR 4.1. Permissible header movement is based on (Indicate one):

a) Movement of Tubes and Headers relative to the Bundle Sideframes b) Movement of the complete Bundle relative to the Plenum and Substructure.

4.2. (Inlet) (Outlet) (Neither) Header is restrained against movement in the x- direction. 4.3. Permissible header movement in the z-direction, either side of bundle centre line is: 4.4. Total weight of all components that move to permit movement in z-direction is:


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SPC-0804.02-20.22 PAGE: 19 OF 20 REV: D2

a) Dry weight Kg b) Operating weight Kg

4.5. Co-efficient of friction for movement in z-direction with low friction plates (e.g. Stainless Steel on Stainless Steel) is: 4.6. If Tubes and Headers move relative to the Bundle Sideframe the following data shall be provided:

1. Tube material ASTM 2. Outside diameter Wall thickness 3. Number of tubes 4. Distance from centre line of header nozzle to first tube support (approximate tube bending length):

a) Inlet header mm b) Outlet header mm


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SPC-0804.02-20.22 PAGE: 20 OF 20 REV: D2

Header Pipe

Header box of Heat exchanger

Min

imum

5.0

met

er

Branch pipe

Heat exchanger Nozzle

Branch pipe

ATTACHMENT 2 : PIPING AND HEADER CONFIGURATION

Header pipe shall be at least 5.0 meters below header of air cooled heat exchanger, see figure below. Typically, header pipe and their support are located same level as the walkway underneath the fan cooler. Branch pipe shall be U-loop configuration.

Date post:	02-Oct-2014
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Specification for Air Cooled Heat Exchangers

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