Production welds shall be made in accordance with previously defined and qualified procedures of Clause 5.3(a), (b), (c) or (d), and within the limits of essential variables.
NOTE: It is recommended that gas tungsten arc welding or gas welding be used for butt welds on pipe of outside diameter 42.2 mm and less.
11.2 WELDING EQUIPMENT
Welding equipment shall be of a size and type suitable for the work. It shall be maintained in a condition that will ensure the production of satisfactory welds, the continuity of operation and the safety of personnel.
11.3 WELDER AND WELDING PROCEDURE
All welds shall be made by qualified welders or operators using a qualified welding procedure.
11.4 SUPERVISION OF WELDING
Welding shall be carried out under the supervision of an approved person who has had appropriate experience and training in the supervision of welding of pipelines and the use of ancillary equipment.
NOTE: AS 1796 provides rules for certification of welding supervisors.
11.5 SAFETY IN WELDING 11.5.1 General
All welding operations shall comply with the Australian Standards relevant to safety in welding.
11.5.2 Welding site
A thorough check shall be made in and around the welding site to ensure there are no substances that could constitute a risk of fire or explosion.
11.6 STORAGE AND HANDLING OF ELECTRODES, FILLER RODS AND FLUXES
Electrodes, filler rods and fluxes shall be stored and handled in accordance with Clause 2.2.3, in such a manner that will prevent damage or deterioration.
Consumables in opened containers shall be protected from deterioration.
Damaged material shall not be used.
11.7 WELDING IN ADVERSE CLIMATE CONDITIONS
Welding shall not be carried out under climatic conditions that contribute to persistent defects.
Where a gas-shielded arc-welding process is used and winds or draughts could impair the quality of the weld, welding habitats or windshields should be used.
11.8 PREPARATION FOR WELDING 11.8.1 Edge preparation
Surfaces and edges to be welded shall be smooth, uniform and free from cracks, fins, tears, and other defects that could affect the soundness of the weld. Surfaces to be welded and surfaces adjacent to the weld shall be free from paint, scale, slag, moisture, rust, grease, or other foreign matter.
11.8.2 Internal cleaning
The internal surface of the pipe shall be free of loose debris. It should be swabbed if necessary.
11.9 METHOD OF MAKING THE WELD PREPARATION
The weld preparation shall be made in the manner specified in the qualified welding procedure specification.
11.10 ACCURACY OF ALIGNMENT
Components shall be assembled to provide alignment within the limits of Clause 15.4.3.
11.11 LINE-UP CLAMP
Line-up clamps shall have the following attributes:
(a) Provide rounding of pipe ends (removal of ovaling does not expand pipe diameters).
(b) Accommodate dimensional tolerances in abutting pipes.
(c) Provide even distribution of ‘high-low’.
(d) Have appropriate gap setting.
(e) Provide access for welding operation.
(f) They shall not damage pipe coating (both internal and external) (g) They shall not contaminate the weld (pick up impurities).
NOTE: Line-up clamps require specific settings and maintenance.
The line-up clamp shall be released only after the length of root pass is equal to or greater than that specified in the qualified welding procedure specification.
11.12 TACK WELDS
Tack welds shall only be used as a means of alignment during welding when tack welding is specified in the qualified welding procedure. Tack welds shall be deposited only in the weld groove and, where the tack weld is to be incorporated into the finished weld, full fusion at the root shall be obtained. The length of individual tack welds shall not be less than 25 mm or 20% of the outside diameter of the pipe, whichever is the lesser. Tack welds that are unsound shall be ground out.
11.13 WORKING CLEARANCE
There shall be safe access and clearance for welding.
11.14 PLACEMENT OF WELD PASSES
Consecutive or adjacent weld passes shall not be started at the same circumferential position.
Accessed by GHD PTY LTD on 05 Aug 2009
11.15 ARC STRIKE AND ARC BURN
An arc shall be struck only on the fusion faces or the surfaces of the parent material that will be fused into the weld. An arc burn that results from an inadvertent arc strike shall be removed in accordance with Clause 24 or 25. The work return clamp shall make good electrical contact with no evidence of arcing.
11.16 CLEANING
Each pass of weld metal shall be cleaned in the manner specified in the qualified welding procedure.
11.17 PEENING
Peening shall not be carried out on the root pass or the capping pass or passes. On filler passes, peening shall be carried out when specified in the qualified welding procedure.
11.18 INSERT PATCHING
Insert patching shall not be carried out.
11.19 PREHEAT AND INTERPASS TEMPERATURE 11.19.1 General
The preheat and interpass temperature shall be that specified in the qualified welding procedure. Both parts of the parent metal shall be at the required temperature at the time that welding is commenced.
11.19.2 Application of preheat and interpass temperature
The specified preheat and interpass temperatures shall be maintained during all stages of welding including tack welding.
11.19.3 Extent of heating
The full thickness of both parts of the parent metal shall be heated to the required temperature. The width of the heated band on either side of the centre-line of the weld shall be not less than 75 mm or three times the width of the weld, whichever is the greater.
11.19.4 Monitoring of preheat and interpass temperature
The temperature shall be monitored at positions that are not less than 25 mm from the weld position by the use of temperature-indicating crayons or paint, thermocouples, pyrometers, or other appropriate methods.
11.19.5 Condensation
Where preheating is specified in the qualified welding procedure, and where a gas flame is used for preheating, no condensation or moisture shall remain. Where the metal temperature is less than 100°C, the flame should not be directed into the weld preparation.
11.20 POST-WELD HEAT TREATMENT
Where specified in the qualified welding procedure, post-weld heat treatment shall be carried out.
11.21 IDENTIFICATION OF A PRODUCTION WELD A production weld shall be identified in an approved manner.