Q. Show the procedure of Welding of vessels?

Welding of vessels, including pressure retaining parts and attachments thereto, shall be performed utilizing Welding Procedures, Welders and Welding Operators that have been qualified in accordance with Section IX of the ASME Boiler and Pressure Vessel Code.

Where possible, all longitudinal and circumferential seams in shells, all seams in heads and nozzle to shell or nozzle to head joints shall be full penetration double butt welds of the "V", "U", "J" or "Bevel" type. Lap welds are not permitted. Double butt welds shall be back-gouged prior to welding of the second side of the joint.

For small diameter vessels or nozzle butt welds where access is restricted, prior approval is required for one sided welding procedures.
The GMAW welding process shall be used for root pass welding only and shall be removed by back-gouging and back-welding where access permits.

The use of the FCAW welding process for pressure retaining parts of vessels, including attachments thereto, requires prior approval. The Vendor shall not assume approval for the purposes of the bidding process.
Only Low Hydrogen welding consumables, processes and welding procedures shall be used for welding of pressure retaining parts or attachments thereto.

The Vendor shall submit all proposed Welding Procedure Specifications, complete with the applicable Procedure Qualification Records, for review and approval, prior to starting fabrication.