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R & D, - -
UCV & EGROUP, Venezuela, Joined Oct 2008, 120
AUSTENITIC SOCKET WELD UT INSPECTION
A company who I give NDT & welding consulting services, responsibly of fabrication of a gas pipeline, is asking me the possibility to perform UT in lieu of RT for a weld volumetric inspection. The joints are Socket Weld as shown ASME B31.8 Fig. 1-6(e).
The Socket Weld Joint is very similar to a lap joint, but in this case, we are dealing with pipes instead plates. The pipe thickness is ¼ inch (6.35 mm), and the socket coupling is about 3/8 inch (9.5 mm) in the portion that seems proper to place the transducer.
An additional challenge is the pipe material an AUTENITIC 304 Stainless Steel. So, we also understand that low frequency transducers are strong recommended.
I deeply appreciate if anyone has recommendations about this not common application of UT. This is valid to perform UT in lieu of RT for laps welds configurations?, what provisions should be considered?
Thank you all NDT brothers!!!
Consultant, - Trainer/Inspector
Northern NDT Ltd, United Kingdom, Joined Sep 2006, 6
Re: AUSTENITIC SOCKET WELD UT INSPECTION In Reply to Carlos Correia at 23:14 Dec-14-2009 (Opening).
The attempted application of UT for the inspection of socket welds would not be advisable for the following reasons:-
1 The weld fusion faces cannot be interogated with UT at favourable angle.
2 The items are thin and the use of low frequency probes on thin probes when attempting to quantify accurately is not realistic
3 The Austenitic makes for a very difficult inspection and if UT is used the welding process needs to be very well controlled to create a consistant metallurgical structure eg all welding position in 2G position
4 The application and prove up of the ASME code case requirements could prove costly - only to realise the inspection has little value
5 If the socket welds in question are fittings then the scan surafce will be minimal
If the NDT company you work with is able to overcome all of these issues and successfully prove up the inspection Im sure they could sell the technique worldwide
Kind Regards Charlie Jackson