Is tack welding the ends allowed on AWS test pieces

[capntom62]

I was told today that we do not allow the ends of WPS test weldments to be tack welded.
I thought and have seen the ends to be tack welded to prevent the root opening too much on a groove joint, also on Tee joints.
We are welding to AWS D17.1

Thoughts on this ?

 

[gtaw]

How else are you going to hold them in position unless someone has it in mind to build very stiff fixtures.

We routinely tack weld coupons together for qualifying WPSs and well as welders. As a matter of fact, when welding 20-inch coupons we use several tack welds along the entire length to maintain the proper alignment.

Best regards - Al

 

[Ron]

Agree with gtaw. Further, make sure the tack welds are outside the area of testing, whether mechanical or NDT. We typically have tacked the sides (ends) of the prep area for the coupons. You can also increase the size of the coupon and then cut the proper size coupon after welding....serves as both a run-off tab and tack area.

 

[kingnero]

ISO coupons have a 25mm "discard" zone at both ends, in order to accomodate tack welds and start/stop defects.
I assume ASME has a similar provision? If not, cut the pieces few inches longer as per Ron.

 

[DAVIDSTECKER]

We use what we call run off tabs that are tacked on.
This allows the welder to start off the test material and then on to the test materail

 

[gtaw]

Are those coupons castings? Is that assembly welded with or without backing? If it is welded without backing, does the welder back gouge the second side and then back weld the second side?

Interesting.

Al

Best regards - Al

 

[DAVIDSTECKER]

gtaw,
Yes those are castings, 3" thick, double bevel prep.
No backing, and yes back gouge and weld opposite side.

 

[gtaw]

Interesting. Do you mind if I as what the material specification is or the chemistry of the material?

Best regards - Al

 

[DekDee]

Is that not very expensive coupons at that thickness or is that all that is available ?
Does AWS D1.1 require stop/starts in the coupon ?

 

[gtaw]

I would not categorize this as a standard welder qualification test in accordance with AWS D1.1 for a couple of reasons; 1) the material is cast. I doubt it is a prequalified base metal, thus it would unlikely to be listed in AWS D1.1, 2) The bevels appear to be substantially more than 45 degrees which is the standard groove angle for AWS testing, 3) none of the standard AWS tests depicted in AWS D1.1 require back gouging because backing is used in all cases except for the TK&Y specifically for tubulars and must be a qualified WPS, i.e., supported by a PQR that passed visual, volumetric NDE, bend tests, and reduced section tensile testing. The TK&Y is not back gouged and back welded.

The subject of back gouging and back welding on the performance testing comes up often, yet there are no provisions in the standard AWS qualification testing regime for back gouging and back welding test coupons.


Best regards - Al

 

[DAVIDSTECKER]

The material is ASTM 757 Gr. C1Q.
We are qualifying for NAVSEA procedures.
This weld required over 24 test coupons.
2 Test blocks were submitted.
I forget the number of pass's but it was 8-9 hours of welding each sample.
3" thick qualifies us for unlimited thickness.

 

[gtaw]

My apologies, I don't know how I got on the tangent of D1.1. After going back to the beginning, I see you are qualifying to an aerospace welding standard.

Thanks for the information on the base metal. I see it is a quench and tempered cast steel with a small addition of nickel. The elongation of the material is only 20%, so make sure the bend mandrel is the appropriate diameter.

Looking at the photograph you included, it is tough to see the coupons are 3-inched thick, 3-inches wide maybe, but not 3-inches thick.

Is the welding involved for fabrication or repair of the casting?

I am very familiar with NAVSEA TP248 and fabrication per TP278. I am also familiar with AWS D17.1, so I find this exercise interesting. NAVSEA TP278 is usually referenced for anything that is considered shipboard equipment. But, D17.1 can be applicable to ground support equipment as well as flight hardware. You might consider using AWS B2.1 for the mechanics of qualifying the WPS as allowed by D17.1. B2.1 for the most part follows ASME Section IX other than the addition of base metal specification not included in ASME Section IX.

Good luck.



Best regards - Al

 

[david339933]

This entire thread is a high-jacked tangent....

 

[DAVIDSTECKER]

No worries, my train of thought often takes a dirt road.
We do both, weld repair of casting and assembly of castings.
We are mainly a marine equipment manufacturer.
This was for welding together sections of Bow Stems.
We work a lot lately with C1Q, A1Q, and WCA.
Some of these ship projects have their special versions of MIL standards so we're pretty much shackled to them.
NAVESEA reviews and approves our procedures for almost every project.

 

[DAVIDSTECKER]

gtaw,
I see that you are a member of Pat's Pub.
Any thing special I should say If I apply for membership?
Maybe we could take this conversation there.

 

[gtaw]

Not that I'm aware of.

Many on these threads take on some unusual twists and turns. Sometimes it's because we are grasping for straws due to the absence of information, in others it because we misconstrued what the poster is looking for or we misinterpret what is being asked. I often compare these conversations to the old Paul Harvey radio show because we only get bits and drabs of information. The poster only provides tidbits of information and we don't see the whole picture until days later when more information is provided. Paul's skits were always the same; he would provide some of the information, get the listener to draw a conclusion, and then after a station break lead in with, "and now for the rest of the story!" Great fun.

And now for the rest of the story. For the life of me, I don't see how AWS D17.1 ties in with the ship's hull structure! The governing documents is usually 1688 or 1689 depending on whether it is a submersible or surface ship.



Best regards - Al

 

[kingnero]

cause we're already off tangent...
Why are you placing the run on / run off tabs like that?
I'm usually putting them in the same plane as the bevel (thus in a V) (I'll get a picture next time), this way you can weld "over" the edge of the plate on the higher runs. Especially on thicker coupons like these.

 

[david339933]

I don't see how AWS D17.1 ties in with the ship's hull structure!

It doesn't....OP's question is clear and concise....but has been lost to interesting casting oblivion....

 

[gtaw]

You are right, Dave wasn't the person to post the original. No wonder I'm confused. I didn't reread all of the posts.

Best regards - Al

 

[DAVIDSTECKER]