Duplex SS -PQR Qualification 1

[4872]

Dear Friends
I was asked to prepare WPS for Duplex Stainless Steel varies from 1" to 8" x Min Thks 5mm to 38mm.
Impact Value -40 deg celcius
Process - ROOT and Hot pass - GTAW / Fill & Cap-SMAW
Pls guide me in preparing Proposed WPS complyimng to ASME Sect IX-QW-403.6 & QW-451

Thanks

 

[moltenmetal]

Others can help more, but one thing you'll need is ferrite content examination on the finished samples.

 

[metengr]

4872;
Please answer the following questions so that we can help you further;

1. Do know understand basic welding concepts?
2. Are you familar with ASME Boiler and Pressure vessel Code, Section IX?
3. Do you have a copy of Section IX?

 

[weldtek]

If you're new to duplex I suggest you do some reading. Check the web sites at Avesta and also IMOA - International Molybdenum Association.
The specs you're working to will play a large role in what testing is required, but as posted, % ferrite is standard.
Heat input is crucial in controlling resultant ferrite. I'm confused as to the thickness range you're wanting to qualify, but, most specs restrict qualified thickness well beyond those restrictions set forth in Sec IX.
This prelude is intended as information because if you qualify a duplex procedure to ASME Sec IX requirements only, I'd bet money no knowledgeable client will accept it for use on their fabrication.
Getting to your specific question, QW403.6 is simply saying that if you run a test on material with a base metal thickness of 5/8" or greater, the minimum qualified thickness is 5/8". In this case ( 5/8") max qualified thickness would be 2 x 5/8" or 1.25". That same paragraph is also saying that a test on 5/16" thick material qualifies down to 5/16", however, 3/16" would qualify down to 3/32".
When impacts are required, more than one test plate is required to cover the full range of thicknesses, however, Code rules allow one to test the thinner plate with impacts only, and test the thicker plate with bends and tensiles. Bear in mind, I'm referring to minimum Code requirements here, and not what would be required by an average client or what might be considered best practice.

 

[pradipgoswami]

Hi 4872,

Which grade of duplex S.S is to be welded? Duplex is easily weldable provided all the required precautions are excercised. The common welding precuations for welding austenitc S.S are equally applicable for duplex welding. To qualify a welding procedure in,Thicknesses 5mm to 38mm you have to weld 1 coupon.
-any coupon thickness between 19 mm to 38 mm thick coupon, will qualifies, 5mm to 2T base metal
-20mm thk coupon-qualifies, 10 to 40 mm.

ASME Sec-ix PQR would call for, 2-Transverse tensile, 4 side bends for the above thickness.Impact, WM,BM, HAX @ -40 deg celcius would be also required. Refer Sec-IX, QW-451.1 for details.

Impact would be tricky,however with good control on interpass temperature, and heat input, this is achievable. Use welding comsumabales of well known manufacturers ONLY.

In addition if there is ferrite test on the PQR it has to be done either as per ASTM-E-562 or as required by client.

I have attached some references for your information.

Thanks

Pradip

http://www.outokumpu.com/35058.epibrw

 

[MikeMet]

Go to the following IMOA website and download the Practical Guide to Fabrication of Duplex Stainless Steels. It's free and a great reference

http://www.imoa.info/moly_uses/moly_grade_stainless_steels/duplex_stainless_steel.html

 

[EdStainless]

The impacts are being used to qualify that you haven't formed detrimental secondary phases in the welding process.

You need to be careful about the direction of the impact samples.

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