The best way to answer this is to refer you to ASME Boiler and Pressure Vessel Code, Section IX. This section contains all of the necessary essential variables for qualification of a welding procedure specification (WPS) and welder qualification according to the desired welding process(es).
Now, regarding preheat and post weld heat treatment requirements these are usually spelled out in a code of construction document or by specific requirements of the designer that exceed code of construction requirements.
Welding consumables are normally specified by the designer or owner and selection depends on the material being joined to the above mentioned plate along with service conditions. Once can use welding consumables that are similar in chemical composition and strength properties to the base plate or use higher or lower strength consumables depending on what material is being joined to the Grade 22 plate.
Thanks for your feedback. I know that the question sounds basic stuff. To be more specific, I'm looking for a suitable welding procedure for A387gr22 material for welding the cracks in the turbine exhaust cylinder. We've been using the repair welding procedure supplied by the manufacturer which is pretty basic and the cracks are re-appearing on regular intervals. While we are yet to conduct RCA, I'd also like to know whether there are any alternative welding procedures for A387gr22 material in such services or any similar experiences to share.
This is the provided information about welding
*****
Welding procedure: GTAW
Filler Material: TGS-2CM
Amp: 60-120Amp
Pre-heat: More than 150deg C
Post heat: After keeping 10min at 300-350deg C, welded portion should be covered with glass cloth and cooled slowly
(Temperature should be controlled by thermal choke)
*****
Are the repairs cracking, or are the repairs holding and cracks occuring elsewhere on the part?
Finding the root cause may(likely will) suggest refinements that could be made to the repair procedure. Finish your RCA and provide your findings along with a photo of the failure.
Armed with this additional information, a solution to the problem may be obvious to you, or to someone else reading the forum.
David Benson
Benson's Mobile Welding & Fabrication
The procedure provided will not nearly fully relieve welding residual stress. It appears that cracking results from fatigue, more than likely exacerbated by the high residual stress. Where do the cracks initiate? Do cracks originate in the HAZ near the toe of the weld? Do you grind flush after welding? How thick is the casing?
