N839EX PRA005 B HDPE Duct Welding

Ref : N839EX-PRA 005 - Rev.B Quality Management System certified by Page 1/17

DELAWARE DEPARTMENT OF TRANSPORTATION

INDIAN RIVER INLET BRIDGE

Cable Stays

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HDPE Duct Welding – working procedure

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N839EX-PRA 005 – B

INDIAN RIVER INLET BRIDGE – Stay Cables

HDPE Duct Welding – Working Procedure


REV. PRELIMINARY NOTE This document is the exclusive property of FREYSSINET.

It is confidential and may not be used, reproduced or communicated either in whole or in part, in any form or manner without the prior written agreement of FREYSSINET.

This document shall not be distributed to third parties except under the terms of the contract. INTERNAL FREYSSINET REVISION STATUS

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B 12/05/10 US units ASE SJE EMR

A 26/01/10 First issue NVT ASE SJE

Rev. Date Modification Designed by Checked by Approved by

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CONTENTS

1 SCOPE ......................................................................................................................4

2 ABREVIATIONS ....................................................................................................4

3 RESOURCES...........................................................................................................5 3.1 PLANT AND EQUIPMENT ....................................................................5 3.2 MATERIALS ..........................................................................................5

4 PROCEDURE ..........................................................................................................6 4.1 GENERAL LAYOUT ..............................................................................6

4.1.1 Main Sheath ................................................................................................6 4.1.2 Expansion Duct ...........................................................................................7

4.2 WELDING OPERATIONS .....................................................................8 4.3 FABRICATION PROCEDURE...............................................................9

4.3.1 Fabrication instructions...............................................................................9 4.3.2 Fabrication process......................................................................................9 4.3.3 Thermal expansion correction & length tolerances ......................................10 4.3.4 Fabrication inspection ...............................................................................10 4.3.5 Finishing works.........................................................................................11

5 RISK ASSESSMENT ............................................................................................12

APPENDIX 1 – SITE WELDING PROCEDURE.....................................................13

APPENDIX 2 – TIME AND PRESSURE TABLE ....................................................16




REV.

1 SCOPE

The purpose of this procedure is to describe the different operations to be carried out in order to prepare the stay cable HDPE sheaths to installation. All quality control operations including control checks, inspections and recordings are described in the Inspection and Test Plan (ITP).

2 ABREVIATIONS

HDPE HIGH DENSITY POLYETHYLENE

LH1 MAIN DUCT

LH2-1 INTERNAL PART OF THE EXPANSION DUCT

LH2-2 EXTERNAL PART OF THE EXPANSION DUCT

LH2-3 REDUCED PART OF THE EXPANSION DUCT

LH2 EXPANSION DUCT COMPOSED BY LH2-1, LH2-2 AND LH2-3

LH3 PART OF DUCT INSIDE THE TT

TT TRANSITION TUBE

CG CONTROL OF GEOMETRY TEAM

SCOP STAY CABLE OPERATIONAL PLATFORM




REV.

3 RESOURCES

3.1 PLANT AND EQUIPMENT

The following equipment shall be required:

• ROTHENBERGER ROWELD P250 and P315 HDPE welding machine including

collars set : φ110 (4 5/16”), φ130 (5 2/16”), φ140 (5 8/16”), φ150 (5 14/16”), φ170 (6 11/16”), φ180 (7 1/16”), φ190 (7 8/16”), φ200 (7 14/16”), φ225 (8 14/16”), φ250 (9 13/16”) and φ280 (11”),

• Standard trolleys, • Transition Tube trolley, • Transition Tube screwing bench, • Alignment supports, • Welding container. • Weld rib plane

3.2 MATERIALS

• Clean cotton pieces of rag, • Thermometer, • Chronometer – (time measurer).

B




REV.

4 PROCEDURE

4.1 GENERAL LAYOUT

The “typical HDPE sheath or duct” that surrounds the bundle of strands on all the free length of the stay cable is referred to as the main sheath. The main sheath shall slide into a “HDPE expansion duct” of larger diameter connected to the top anchorage. The main sheath and the expansion duct are made of several parts welded / screwed together. This is detailed hereunder. Please refer to drawing N839EX_PGA005 for a better understanding.

4.1.1 Main Sheath

The main sheath shall mainly comprise 11.8 m pipe lengths (38’8”) but also particular HDPE and steel pieces, which will be detailed below. HDPE pieces are connected between each other by butt-weld connections. The connection of steel parts (Transition Tube) with HDPE parts is done by screwed connections.

Anchorage sleeve: The HDPE machinated sleeve shall be used to connect the Transition Tube to the first standard tube of the main sheath.

LH3: A part of duct is butt-welded to the lower end of the Anchorage sleeve. This over length of duct inside the Transition Tube is used to make the threading easier.

Expansion sleeve: This sleeve shall ensure a proper sliding of the main sheath and the expansion duct. It shall be butt-welded at the top end of the main sheath. It shall be used on every stays. The length of the HDPE main sheath (referred to as LH1) is calculated to allow sufficient windows at both deck and pylon working areas to allow for a proper access during the stay cable installation : 1 to 2m (3’ to 7’) from the pylon formwork tube exit and 1 to 2m (3’ to 7’) from the deck guide tube. B




REV.

4.1.2 Expansion Duct

Located at pylon end, the expansion duct ensures the transition between the main sheath and the top anchorage. It shall slide onto the main sheath and shall provide a watertight connection while permitting the free thermal expansion of the main sheath. The length of the expansion duct (referred to as LH2) shall be calculated so that :

• at minimum temperature, -6.7°C (20°F), the main sheath and the expansion duct shall overlap over 1 meter (design value).

• at maximum temperature , +37.8°C (100°F), the gap between ends of the main

sheath and the expansion duct shall be 3 meters (9’10”).

The expansion duct shall comprise several HDPE pieces, which will be detailed below. HDPE pieces are connected together by butt-weld connections. The elements composing the top part of the expansion duct have a larger diameter than the elements that compose the lower part. LH2-1: LH2-1 shall be connected to the top anchorage. It shall be made of :

- Anchorage sleeve: Machinated HDPE part butt-welded to a standard HDPE tube at the lower end and screwed to the top anchorage at the top end,

- Few meters of HDPE tube, - Upper connection sleeve: Machinated HDPE part butt welded to a

standard HDPE tube at the top end and screwed to the lower connection sleeve at the lower end.

LH2-2: LH2-2 shall be connected to the LH2-1 part. It shall be made of :

- Lower connection sleeve: Machinated HDPE part screwed to the upper connection sleeve at the top extremity and butt-welded to a HDPE tube at the lower extremity,

- Few meters of HDPE tube. LH2-3: LH2-3 shall be connected to the LH2-2 part. It shall be made of:

- Reduction sleeve: Machinated HDPE part butt-welded to a HDPE tube at the lower end and butt-welded to LH2-2 at the top end,

- Few meters (few feet) of HDPE tube.

B

B




REV. 4.2 WELDING OPERATIONS

All welds are butt-welds and are carried out with a mirror-welding machine. The welding procedure to be followed is provided by the supplier of the HDPE welding machine. Refer to appendix 1 for the welding procedure that will be used on site. This procedure shall be displayed at the welding location. The typical sequence of operations for butt-welding two tubes includes:

• Clamping of the two tubes in the machine, • Surfacing of the extremities of the tubes, • Heating by means of an electrical mirror, • Removing of the mirror, • Applying pressure.

The welding procedure shall contain all the parameters (pressure, temperature and time) to be used at each step of the welding operation. These parameters are given for each type of tubes to be used on site (appendix 2). All the welds performed on site shall be done in a sheltered area (the use of welding tent or container is compulsory). When new tubes are assembled, trolleys shall be placed under the duct to keep it from touching the ground.

Remarks:

a) Helix: The main sheath is manufactured with a double outer spiral of HDPE. At the location of the weld, the operator should process in order to :

• Keep all the filets without removing them, • Get the best alignment (no tolerance) between the filets of the two tubes (This

depends on the filet geometry).

b) Plastic bags: Some duct elements shall be delivered on site wrapped in plastic bags. In that case, plastic bags shall be removed only locally at the time of the welding. To prevent any stain, the bags shall be removed as close as possible from the duct erection phase.




REV. 4.3 FABRICATION PROCEDURE

4.3.1 Fabrication instructions The number of 11.8m long tubes (38’8”) to be assembled as well as the theoretical lengths of complementary part are calculated. A table including the length corrections regarding the real temperature on site shall allow the welding supervisor to compensate the thermal expansion of the already-welded elements.

4.3.2 Fabrication process

We note as free length the length of standard HDPE sheath between two consecutive sleeves. These free lengths shall be made of ‘n’ lengths of 11.8 m long standard tubes (38’8”) and one (1) remainder (complementary part) butt-welded together. Prior to weld each remainder, a site measurement of the assembled sheath length and, if applicable, of the last pipe to be welded shall be carried out. After each butt welding, the weld rib on the internal surface of the duct shall be removed using the weld rib plane.

Weld rib plane

From the obtained values and taking into account the effect of temperature (thermal expansion as per detailed below), the length of duct to be added is calculated and then welded.

Note 1: At the top end of the LH1, the last pipe shall be long enough to allow the main sheath to slide freely in the expansion sleeve. Usually, this part shall be made of one (1) 11.8 m long part (38’8”), if not, when LH1 is too long for instance, the last element is cut and must measure at least 4 meters (13’1”). The external part of the last weld-ribs shall be removed.

B

B

B




REV. Note 2: All the weld ribs on the inner surface of the ducts (LH1, LH2-1, LH2-2, LH2-

3 and LH3) shall be removed using the weld rib plane. Note 3: The main sheath of the first stays shall be manufactured and measured in

different parts depending on the available areas on site before there is sufficient length on the deck.

4.3.3 Thermal expansion correction & length tolerances

A temperature measurement shall be carried out on site. Temperatures are measured at one end of the already assembled duct using an electronic thermometer (or any thermometer guarantying a precise measurement). The measurement is done in four points (two outside the duct and two inside).

Mean temperature shall be obtained.

Φreal= 1/4*(Φ1+Φ2+Φ3+Φ4)

LH1 and LH2 lengths are calculated at a temperature of 18.3°C (65°F), called design temperature. The length LH1 to be welded on site is given by the following formula:

( )( )143.18 103.18111 −−° °⋅°−°+= CCCTLHLH SITEonMEASUREDCSITEonMEASURED

Thermal effects are not significant for LH2. The difference between measured lengths and theoretical lengths for LH1 must be within +/- 150 mm (+/-6”). The difference between measured lengths and theoretical lengths for LH2-1, LH2-2 and LH2-3 must be within +/- 50 mm (+/-2”).

4.3.4 Fabrication inspection

The manufactured lengths shall be checked prior to incorporation into the permanent works. The measured lengths shall be recorded in the Inspection and Test Plan (ITP).

Θ1

Θ3

Θ2

Θ4

B




REV.

4.3.5 Finishing works

The finishing works shall start upon approval of the manufactured lengths. They shall consist in screwing of the Transition Tube on the Transition Tube sleeve.




REV.

5 RISK ASSESSMENT

OPERATIONS HAZARDS PRECAUTIONS COMMENTS

Handling ducts using cranes

Bodily injuries / Crushing injuries

Person in charge of handling to use appropriate slings – No

lifting above personnel.

Facing of the ducts Cut injuries Operators to be kept away from the rotating tool while facing.

Use of the HDPE welding machine

Heat injuries

The person in charge shall follow the instruction manual – Use of

gloves is compulsory when handling the heating plate.

Heating plate to be stored in the correct holder when not in use.

Use of the HDPE welding machine

Risks of fire Heating plate to be kept away from combustible material.

Fire extinguisher to be installed in

the welding container.




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APPENDIX 1 – SITE WELDING PROCEDURE




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REV.

APPENDIX 2 – TIME AND PRESSURE TABLE




REV.

4 5/16 5 2/16 5 8/16 5 14/16 6 11/16 7 1/16 7 8/16 7 14/16 8 14/169 13/16 11

15/64 15/64 15/64 15/64 15/64 15/64 15/64 1/4 9/32 19/64 11/32

3 1/16 3 10/16 3 15/16 4 3/16 4 13/16 5 1/16 5 6/16 6 1/16 7 9/16 9 1/16 11 6/16

PN eq (PSI) 84.1 71.1 65.3 60.9 52.2 49.3 46.4 47.9 46.4 198.7 255.2

71.1 84.1 88.5 94.3 108.8 114.6 120.4 133.4 161.0 198.7 255.2

1

3/64 3/64 3/64 3/64 3/64 3/64 3/64 3/64 1/16 1/16 1/16

7.3 7.3 8.7 8.7 10.2 11.6 11.6 13.1 16.0 20.3 26.1

2

61 60 60 60 60 59 59 64 71 77 87

3

5 5 5 5 5 5 5 5 6 6 6

4

7 7 8 7 7 7 7 7 8 9 9

71.1 84.1 88.5 94.3 108.8 114.6 120.4 133.4 161.0 198.7 255.2

5

8.7 8.6 8.8 8.8 8.6 8.6 8.6 9.2 10.1 10.7 11.8

t OD

OD (in)

t (in) A (in²)

P1 (PSI)

h (in)

P2 (PSI)

P3 (PSI)

B

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N839EX PRA005 B HDPE Duct Welding

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