UT scan or RT on Duplex stainless steel

[engrom]

Friends, I'm not expert in NDT techniques & I would think can find NDT specialists here who can advice on best methods to check wall thickness of SS/DSS pipe materials. As DSS materials could be more susceptible to weld root corrosion, can radiography be applied to initially check before we go for more advanced techniques...
Thanks in advance for ur help...

 

[SJones]

If you have a susceptibility to weld root corrosion, something has gone wrong in the materials selection process. RT may not give you the accuracy you require whereas UT, even though defect detection is hampered by the microstructure, should still function reasonably well as a thickness measuring technique.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[EdStainless]

Depends on weld geometry. In nice simple cases use UT. If more complex then RT might give you better idea, but not solid numbers.

I agree with Steve, if you are ahving weld root issues in duplex either the welding practice was very messed up or you simply have the wrong material.

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[ndeguy]

Hi engrom

For wall thickness readings of pipe call in an experienced NDT outfit and have them perform UT thickness measurements in suspect locations (bends, elbows, tees etc. This can be done very precisely (+/- 0,1mm).

For your pipe-to-pipe welds you can still use UT but you might need to grind flats on the weld cap directly over the root(or better, grind the whole cap flat) as an aid to effective coupling. Your NDT people should be able to accurate results.

For small diameter pipes (6" OD max) a pair of RT elliptical shot will give you a good visual image of the weld root condition. Again call in an experienced NDT ooutfit to meet your requirements.

Cheers

Nigel Armstrong
Karachaganak Petroleum
Kazakhstan