Clad Steel Welding
Clad Steel Welding
(OP)
I have a vessel constructed of A516 gr 70 clad with 316L Stainless Steel in accordance with ASME section VIII and my question is related to the welding of clad material. I do not have very much experience with this type of material and need to find out if the carbon steel side or the stainless steel (clad) side should be welded first? Also, if any problems may be caused by the wrong side being welded first? Are there any documents from AWS, ASME, or other organizations that discuss which side of the plate should be welded first?





RE: Clad Steel Welding
RE: Clad Steel Welding
RE: Clad Steel Welding
Also see SecIX for your procedure requirments.
RE: Clad Steel Welding
UG-99(g)(3)"all welded seams which will be hidden by assembly be given a visual examination for workmanship prior to assembly" - I do not understand the point you were trying to make with this reference?
UCL-31 - Joints in Integral or Weld Metal Overlay Cladding and Applied Linings it states as follows:
"(b) When a shell, head, or other pressure part is welded to form a corner joint, as in Fig. UW-13.2, the weld shall be made between the base materials either by removing the clad material prior to welding the joint or by using weld procedures that will assure the base materials are fused. The corrosion resistance of the joint may be provided by using corrosion resistant and compatible weld filler material or may be restored by any other appropriate means." - This appears to cover corner joints to me, does this cover butt joints as well?
This discussion is continuing on this thread Thread330-61136
RE: Clad Steel Welding
UCL-31(a)this could also cover butt joints. See UCL-32,40,42,46.
RE: Clad Steel Welding
If you tried to weld the stainless first, you would not be able to weld the base metal without distorting the stainless overlay from the heat of the welding.
RE: Clad Steel Welding
To contol this it will be advisable that the base metal welding shall be carried out first and then clad restoration.
Some margin in base metal thickness also need to be kept say 0.5mm to 0.6mm while doing thickness calculation. This will be used while removing clad for base metal welding.
RE: Clad Steel Welding
RE: Clad Steel Welding
1. Remove cladding during joint preparation, then weld the backing steel (base metal) with the appropriate carbon or low-alloy steel consumable, and finally, the region where the clad was removed during joint preparation will be overlaid with the appropriate high alloy consumable
2. Weld the entire thickness of the clad plate with the appropriate full alloy consumable
Published Information Sources:
International Steel Group (formerly Bethlehem Steel) - page 7 (9 in pdf)
http://www.bethsteel.com/customers/pdfs/clad.pdf
Nickel Development Institute (NiDI), the American Iron and Steel Institute (AISI), the American Society of Metals International (ASM Int’l), and the Committee of Stainless Steel Producers - page 33…36
http://www.nidi.org/multimedia/technical_support/technical_literature_pdfs/9000_aisi_publications/9002.PDF
Special Metals (formerly Inco Internetational) - page 23
http://www.specialmetals.com/publication/tech_bulletin_welding.pdf
RE: Clad Steel Welding
I am also in process of having numerous other alloy vessels fabricated and the same process applies. (2-1/4 Chrome with 347 Stainless steel clad with Inconel 625 weld overlay and clad restoration.)
The process is;
1. Shell plates will be rolled... before the shell plates are tacked up, the cladding will be stripped back away from the groove to allow room to make the full penetration weld on the backer/base material.
2. The backer/base material (carbon steel) will be completely welded.
3. After the base material is welded out, the clad restoration welds will be made with the same metallurgy as the clad material (316L Stainless). This normally takes 2 passes to achieve the same undiluted chemistry composition of the clad material (316L).
Regardless what the backer or clad material that is used, the backer has to be welded out first before any clad restoration welds can be made. The minimum requirement for the clad thickness is typically 7/64" or 0.109".
RE: Clad Steel Welding
Strip the stainless material back at least 1/2 inch from the edge of the weld bevel and weld the carbon steel. 309SS Stainless steel should be applied first pass and then the apply the final passes of 316SS.
RE: Clad Steel Welding
RE: Clad Steel Welding
Crack due to embrittlement always the main problem.
In case of ferrite control is specified by client, then proper selection of consumable is necessary.