Welding Tips and Tricks

This question is for anyone that has done this test... or something equivalent from AWS code.

Basically, a T class weld certification is defined as: a welder’s and welding operator’s ability to weld from one side without backing and achieve complete penetration in the root pass, e.g., hollow section, pipe, and plate.

Similar to an ASME test.

The test, is done with an F4 electrode, 6" sch 80 pipe, open root, fill and cap. The welder has the option of welding the root with an F3 electrode, but it will be stated as such on the qualification card.

I've never even attempted to do an open root with a 7018... has anyone here been required to do it?

In Canada you have to re-qualify every two years ( is it the same in the US?),I want to do this test because it qualifies you for all positions on one piece of pipe doing a CJP joint.

Hi - it was a few years ago - but I did a similar test with 7018 - in the UK some pipeliners use 6010 - but almost no one else does -it's not easy even to buy 6010 - I don't know why - my test pieces covered the procedure for all positions but consisted of a vertical up & horizontal overhead - though they call it something else as in the UK at least on pressure vessels ( not sure about other stuff ) they no longer accept ASME coding or procedure & don't use the terms 1 > 6G for position - it seems to be just a ploy to make paperwork for office guys & cost working guys to keep paying out for testing.
Anyhow the original I did was in 10mm - but I later did the same test in 1/2" as it did'nt quite cover the material thickness range I encountered at the time - not sure how this equates to schedule pipe - I can look up a cross over spec - but usually pipe in the UK does not come in schedule specs ( have managed to special order some on occasion for a particular job but that was 160 )
Prep was 70 degree included angle - knife edge with 2.5mm gap ( WPS had a leeway on that but can't remember it now ! ) I started with it a bit wider as it tended to close up despite 2 heavy bridge pieces tacked on the back.
Root was done with 2.5mm electrode negative ( that was WPS spec ) keyhole had to be maintained & a small reinforcement
Subsequent runs were electrode positive - there was a difference between the two thicknesses but as far as I can remember it was 3 stringer runs followed by a weave cap - there was a maximum width on the cap & a high / low spec on the height of the cap - the WPS also had a fairly narrow window of amps for the test piece & the examiner had a clamp meter thing attached to the leads that recorded that for the whole test - so the power source was quite critical - at the time I had a large 3phase Kempi & that was fine. - To be honest I don't think since I moved workshops I still have the paperwork & it's out of date now anyway - I'm sure if I try to get re-certified they'll have changed it all again & there will be another new hurdle to jump - I'm lucky in that I usually don't need to prove a current coding - most of what I weld is not for a " critical industry " & if there is any question about insurance issues then the client usually pays the cost of a local NDT firm to come & test the repair as liability comes to them first -

Ok, you said one thing that changed my mind about thinking the test was going difficult.
You did the fitup with a knife edge.
I did end up trying some with a 2.5mm root opening and land... needless to say it's a pain in the arse.

I'm going to get rid of the land the next time I try.

Thanks!

Hi - everything I did was what the given WPS called for - it was given to me as an accepted practice for the application I was working on at that time and it was approved by the insurance body that would cover the in service item repairs - this may not be the same now or for your given WPS - it would depend on who stipulates the WPS and the industry your testing for.
The worst problem I had was finding a rod that would run well within the amp parameters given and pass metallurgy testing - went through several brands before ending up using " Filarc " - you may get lucky & pass with the first rod you try - but if not don't be afraid to try a few - sometimes makes a big difference - also just because their a big brand name or your paying good money for them it does'nt make them the best - some of the worst rods I tried came in a Lincoln box ! go figure. "Eutectic" will usually be good - but pricey & similarly will "Soudametal" - but I don't know what is available where you are.
The only real challenge is to maintain the keyhole in the root run within the amp range allowed - this is where rod choice seemed crucial - after that it's not rocket science - just ensure no undercut / good fusion on toes & no slag inclusions / porosity - ( test piece cleanliness & quality is the biggest factor there )
Good luck with the test.