Welding Duplex Stainless Steel
Welding Duplex Stainless Steel
(OP)
Hi everybody:
I'm about to start construction of a Duplex stainless steel (UNS S31803) vessel, According to Section VIII div 1 and stamped.(ID=84" TTL=180")
Have you experience welding this kind of steel? which is the more recommended process? (FCAW, GTAW, SMAW, SAW, Other). Thickness is 12mm (0.472").
If someone can help me too in finding good references regarding welding quantities calculation... would be great.
You know, this welding material is so expensive, about USD 30 per pound!!
Thanks a lot!!
I'm about to start construction of a Duplex stainless steel (UNS S31803) vessel, According to Section VIII div 1 and stamped.(ID=84" TTL=180")
Have you experience welding this kind of steel? which is the more recommended process? (FCAW, GTAW, SMAW, SAW, Other). Thickness is 12mm (0.472").
If someone can help me too in finding good references regarding welding quantities calculation... would be great.
You know, this welding material is so expensive, about USD 30 per pound!!
Thanks a lot!!





RE: Welding Duplex Stainless Steel
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: Welding Duplex Stainless Steel
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: Welding Duplex Stainless Steel
Some notes for you - hope it helps
DUPLEX SS REQUIREMENTS
PQR specimens shall be toughness tested, hardness tested, and examined microstructurally. Microstructure of the weld and the HAZ shall contain between 30 and 70% ferrite. Toughness tests shall be run on the weld and HAZ, and meet an average of 20 ft-lbs over three tests with no individual sample less than 15 ft-lbs at -20?F (27.20/20.3 J at 30?C). Hardness limits shall be agreed upon before testing.
All root passes shall be made with GTAW. Root pass must be back purged.
Shops must be qualified by CLIENT to weld duplex SS.
Only GTAW, GMAW, SMAW, and SAW are Clientepted for welding duplex SS.
Heat input shall be limited to 20-63 kJ/in (0.8-2.5 kJ/mm). Interpass temperature shall be limited to 300?F (150?C) for 22% chromium duplex SS, and 250?F (120?C) for 25% chromium duplex SS.
Only neutral shielding gases are allowed. Active gases (with N2, O2, or H2 additions) are only allowed with prior written consent of CLIENT.
Production welds shall be hardness tested at the same frequency as the radiography.
Cosmetic remelting and downhill progression are prohibited.
Post weld heat treatment (pwht) is not normally needed for duplex SS. All PWHT procedures shall be approved in advance by CLIENT.
Flame cutting and flame straightening are prohibited
RE: Welding Duplex Stainless Steel
Here's also an ammendment to the heat input data
Heat input shall be limited as follows:
- For 22% chromium duplex SS:0.5 to 2.5 kJ/mm
- For 25% chromium duplex SS:0.5 to 1.5 kJ/mm
Interpass temperatures shall be limited as follows:
- For 22% chromium duplex SS: 300?F (150?C)
- For 25% chromium duplex SS: 250?F (120?C)
RE: Welding Duplex Stainless Steel
http://www.gowelding.com/met/duplex.html
http://www.outokumpu.com/applications/documents/start.asp
The second web site (Outokumpu) has several technical articles regarding welding of duplex stainless steels with recommended filler metal and welding parameters that would supplement the responses above.
RE: Welding Duplex Stainless Steel
For a duplex vessel the filler metal should be super duplex because super duplex degrades to duplex (ferrite to austenitic not sure exactly what).
Try the australian stainless steel association - www.assda.asn.au
RE: Welding Duplex Stainless Steel
RE: Welding Duplex Stainless Steel
It seems what you said is a portion of a specification? ("Clientepted" appeared when replacing ACC by CLIENT?)
May be not all of them are mandatory requirements, right? but, anyway, is a good info, thks.
RE: Welding Duplex Stainless Steel
You're in the wrong job - you should be a detective - yes its taken from a spec.
RE: Welding Duplex Stainless Steel
RE: Welding Duplex Stainless Steel
The latest pricing I've seen on 2209 FCAW is about USD20/pound
Here is a link to the Nickle Design Institute, free download for "Practical Guidelines" on 2205
http://www.nickelinstitute.org/multimedia/technical_support/technical_literature_pdfs/other/39309_IMOA_Duplex_ii.pdf
TAPPI (Tech Applications Pulp & Paper Industry) has a TIP which is very good on 2205 as well.
I would suggest purchase a Fisher Ferritescope, or similar device. I just came from a project where someone grabbed 309 and used it in a seam. It showed up immediately because the ferrite was so low. Due to the configuration, a run-off tab would not have been taken there and it would have been missed during fabrication.
Be careful with your heat on FCAW because we have had situations where microslag was introduced and the qualification coupon nearly failed the ASTM A923 Method C test (weight loss test for determining presence of detrimental intermetalic phases). Heat input was adjusted and results of the new coupons were dramatically improved
It is common to specify ASTM A923 Methods A, B, & C (do not use A to eliminate B & C testing).
Are your heads cold formed or hot formed. I would guess cold from the geometry and thickness you gave. In this case, I would recommend PT inside and out. This helps identify areas (small surface cracks) that were caused during forming and not as the results operation (process).
Please know that 2205 is not immune to SCC and there are examples of it occuring. This is why it is best to eliminate as many as of the forming cracks as possible so an inspector doesn't find something that isn't there and want a sample cut out for examination. Painful and expensive lessons.
If you need some EXCELLENT 2205 shops you can post your e-mail address and I'll send you some references and their web pages. I have no financial ties to any of them and they have done great work for this size equipment in the past.
RE: Welding Duplex Stainless Steel
you can send me further info to:
heyner_garcia@hotmail.com
thanks in advance, again...
RE: Welding Duplex Stainless Steel
What does SCC mean?
RE: Welding Duplex Stainless Steel
RE: Welding Duplex Stainless Steel
RE: Welding Duplex Stainless Steel
245 is a superaustenitic, there are about half a dozen of this type of 6% Mo alloys on the market. Good strength, easy to work with and good corrosion resistance in seawater.
The superduplex are a different animal. There are only a few on the market, and they are tricky to work with. But if you really need high strength and seawater service they can do the job.
= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm