RT of Socket Welds

weldweb · Sat Jun 20, 2015 1:47 pm

Is anyone familiar with the radiographic inspection of the socket welds? Could anyone give me some details about it? Thank you

Braehill · Sat Jun 20, 2015 3:59 pm

WW,
Welcome to the forum.

Your question is pretty broad, you'll need to narrow it down a bit. Do you want to know how to weld it to pass the x-ray, how the test itself is performed, what they're looking for with this equipment. There are people here who weld socket weld piping that I'm sure gets x-rayed that can answer your questions if you can be more specific.

This forum is a little more personal than most forums so if you don't mind giving us a first name or a nickname we can use in our responses so we don't have to forever refer to you as weldweb it would be appreciated.

Len

Coldman · Sat Jun 20, 2015 7:48 pm

I've seen UT of socket welds but personally haven't heard of RT on socket welds. Is it a common practice?

LtBadd · Sat Jun 20, 2015 8:43 pm

weldweb wrote:Is anyone familiar with the radiographic inspection of the socket welds? Could anyone give me some details about it? Thank you

Hello and welcome to the forum
Will this be welded to a code? If so you can only ask what that particular code says about this. For instance after a brief Google search of your question I found this, however remember this only applies to welds made to ASME B31.3

"Radiographic examination of fillet or socket welding as a method for final acceptance is not required by ASME B31.3..."

More here https://www.hera.org.nz/Story?Action=View&Story_id=1578

weldweb · Sun Jun 21, 2015 8:18 am

you are right about asme b31.3 but i know that some clients require this examination to be sure that the pipe fitter will respect the 1.5 gap. But i want to know which will be the thickness for exposure time?

LtBadd · Sun Jun 21, 2015 11:45 am

weldweb wrote:you are right about asme b31.3 but i know that some clients require this examination to be sure that the pipe fitter will respect the 1.5 gap. But i want to know which will be the thickness for exposure time?

Will you be doing the RT test?

weldweb · Sun Jun 21, 2015 2:01 pm

Not me, but i would like to know which will be the penetrate thickness, the thickness of the weld or the thickness of the weld+thickness of the pipe. Which of these are taking in account when you calculate the exposure time?
PS: i will come with more info after they will make the RT; it will be good to know for anyone

Sun Jun 21, 2015 3:05 pm

weldweb wrote:Not me, but i would like to know which will be the penetrate thickness, the thickness of the weld or the thickness of the weld+thickness of the pipe. Which of these are taking in account when you calculate the exposure time?
PS: i will come with more info after they will make the RT; it will be good to know for anyone

I'd appreciate that update, and I'm sure others will, also.

I'm familiar with RT being done on socket welds, for the reason you stated. I once had to rebuild two gas manifolds where the "fitter" didn't know about hold-back on socket welds. Cracking gave it away initially, so RT was done. I was only involved after the fact, so I didn't see films or talk to the techs.

Steve S

taz · Sun Jun 21, 2015 4:43 pm

You cannot use RT to evaluate the gap according to ASME B31.3 since the 1.5mm is before welding and not after.

Interpretation: 16-06
Subject: ASME 831.3-1996 Edition, Para. 328.5.2, Welding Requirements - Fillet and Socket Welds
Date Issued: May 20, 1997
File: 831-96-0588
Question: In accordance with ASME 831.3-1996 Edition, para. 328.5.2 and Fig. 328.5.2c, what is the
minimum gap acceptable in a socket-welded joint after welding?
Reply: The '116 in. approximate gap shown in Fig. 328.5.2c is "before welding." The Code does not
provide a gap dimension after welding.

This does not mean though that RT is not used to evaluate socket welds. One of the most comprehensive specification on socket welds that I know of is this:

http://lmse.larc.nasa.gov/admin/public_ ... 0727_H.pdf

It specifically states dimensions of the gap after welding unlike B31.3

Another specification that requires a gap after welding is Exxon Mobil GP 03-18-01 that specifically requires a gap of 1.6mm after welding.

To complicate matters even more the whole socket gap thing is under review from the ASME 31.3 committee since tests have been conducted that suggest the in-service fatigue resistance of socket fittings that were welded without any gap is improved.

All of the above is just blabbering though and unless you give more details on specific standards and specifications this is all the help I can provide.

weldweb · Mon Jun 22, 2015 1:39 pm

which examination do you think should be done first for the socket welds?
ps: thank you taz for the informations; it was very interesting; I know also that TOTAL require RT for socket welds; it seems that the "major six companies" in oil and gas industry are very careful with their refineries.

plain ol Bill · Mon Jun 22, 2015 5:06 pm

Many refineries require the use of crush washers in a socket weld fitting anymore. That insures you are putting the correct gap in before welding.
"crush washers is what I call them - not sure if that is their real name or not".

LtBadd · Mon Jun 22, 2015 7:43 pm

plain ol Bill wrote:Many refineries require the use of crush washers in a socket weld fitting anymore. That insures you are putting the correct gap in before welding.
"crush washers is what I call them - not sure if that is their real name or not".

Sounds about right...also gap a let http://www.galgage.com/measuring_gap-a-let.html
You can get them in whatever alloy you need