DSS vs SDSS welding.

[S.Mohammed]

dear all,

ASME IX,B31.3.

WPS available for SA 182 F51 UNS 31803  P.10H with GMAW ER 2209-16 can be utilsed for welding SA 182 F53 UNS 32750  P 10H?( thk range is covered by WPS.).

what are the metalurgy cocern to be require?.

regards
mohd.

[pgoswami]

No,

 

31803 is DSS while 32750 SDSS. Duplex alloys are used for very demanding applications. Hence the weld metal must match or exceed the requirements of base metal properties. Hence a new PQR would  be advisable.

 

What're the  design and service requirements by the way??

 

You need to consider all of these before proceeding for any welding on DSS or SDSS.

 

Appreciate your response.

 

Thanks.

 

Pradip Goswami, P.Eng,IWE

Welding & Metallurgical Specialist

Ontario, Canada

pgos...@quickclic.net

pradip....@gmail.com

pradip_...@yahoo.ca

 

---

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of S.Mohammed
Sent: Wednesday, March 26, 2014 6:13 AM
To: material...@googlegroups.com
Subject: [MW:20411] DSS vs SDSS welding.

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[Ramin Kondori]

There must be a reason why the designer has specified SDSS 2750 (UNS 32750) and it's not a good idea to downgrade your weld metal to DSS 2205 (UNS 31803).

Best Regards

Ramin Kondori

Sr. QA/QC engineer

Yadavaran Oilfield Project

SIPC (SINOPEC)

[S.Mohammed]

dear sir,
i agree with weld.metal chemistry.

service is seawater line highly corrosive.

But as per ASME,there is same A number 8 is provided for both DSS n SDSS. And P.number also 10H and group also same 1.

its looks like a limitation of ASME or it is more libaral about metal classfication.

in what code or standard basis should i say to my construction for new WPS.

regards,

[pgoswami]

Hi Mohammed,

True both DSS (31803) and SDSS(32750) are classified under P No 10H Gr1 in ASME Sec-IX. However in QW-422,  under  ISO 15608, Group listing , DSS (31803) is Group 10.1 while  SDSS(32750) is classified as Group 10.2. The proper explanation of Gr 10.1 and 10.2 is given the attachment. Alloy 31803 and alloy 32750 is not the same. This possibly would be addressed in subsequent amendments of Sec-IX Code.

ASME Sec-IX code is applied typically for welding qualification in potable water plant to Nuclear power plant (just a statement to highlight the wide application range) . One  code can't address the concerns of all the industries. In many instances specific standard, design requirements are applicable .Duplex is one those alloys, which is fabricated to specific design requirements. Should you want to know about this read through API-RP-938Cor other related specifications for offshore oil and gas industries.

Seawater corrodes all alloys. Only a few could sustain these environments , such as DSS/SDSS, Nickel alloys and Titanium. 

In addition to ASME Sec-IX qualification tests, Hardness, Critical Pitting Temperature(CPT) to ASME G48A are mandatory. For DSS if the CPT test is typically 30 Deg C/24 hrs for SDSS it would be 40Deg C /24 hrs or more. Do you have these tests in PQR testing.

Hence should  you would decide to weld SDSS 32750 with GMAW ER 2209-16 filler ( which matches the chemistry of DSS 31803), I'm sure the service induced  failures are only a matter of time.

Perhaps you need to get the concurrence of your client before you  proceed for welding.

It would be good to hear about the outcome.

Thanks

Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Specialist
Ontario, Canada
pgos...@quickclic.net
pradip....@gmail.com
pradip_...@yahoo.ca

-----Original Message-----
From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of S.Mohammed

Sent: Wednesday, March 26, 2014 1:17 PM
To: material...@googlegroups.com
Subject: [MW:20416] RE: 20411] DSS vs SDSS welding.

dear sir,
i agree with weld.metal chemistry.

service is seawater line highly corrosive.


But as per ASME,there is same A number 8 is provided for both DSS n SDSS. And P.number also 10H and group also same 1.

its looks like a limitation of ASME or it is more liberal about metal classification.

in what code or standard basis should i say to my construction for new WPS.

regards,

*****************************************************************************************************************************************************************************************************************************

No,

31803 is DSS while 32750 SDSS. Duplex alloys are used for very demanding applications. Hence the weld metal must match or exceed the requirements of base metal properties. Hence a new PQR would  be advisable.

What're the  design and service requirements by the way??

You need to consider all of these before proceeding for any welding on DSS or SDSS.

Appreciate your response.

Thanks.

Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Specialist
Ontario, Canada
pgos...@quickclic.net
pradip....@gmail.com
pradip_...@yahoo.ca

--------------------------------------------------------------------------------
From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of S.Mohammed

Sent: Wednesday, March 26, 2014 6:13 AM

To: materials-welding@Google groups.com

Subject: [MW:20411] DSS vs SDSS welding.


dear all,

ASME IX,B31.3.

WPS available for SA 182 F51 UNS 31803  P.10H with GMAW ER 2209-16 can be utilsed for welding SA 182 F53 UNS 32750  P 10H?( thk range is covered by WPS.).

what are the metallurgy concern to be require?.

regards
mohd.


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[Ramin Kondori]

Dear Mr. Mohammed:

ASME Sec IX is not the only criteria. It only deals with weld-ability and minimum mechanical properties and it has nothing to do with corrosion resistance.That's why we use NACE as an additional requirement for such applications.

And for seawater application, SDSS and DSS are definitely different...!!!

There is no problem with weld-ability (or even mechanical properties) but corrosion resistance will drop. The weld metal will not be 2705 anymore and it means that corrosion characteristics will be different which may result in failure during corrosion tests (ASTM G48, ASTM A923 etc.). So I would forget about the idea of using 2205 for welding 2705 and making things complicated. "Keeping things as simple as possible" always works.

Best Regards

Ramin Kondori

Sr. QA/QC engineer

Yadavaran Oilfield Project

SIPC (SINOPEC)