Review Of Welder Qual (Long But Concise) 2

[tc7]

A new welder is showing a performance test from previous experience as follows:
ASME Sect IX/AWS D1.1
Pipe
6G
A53 Schedule 80; 6-inch nominal
SMAW/GTAW
Fillers: ER70-S/7018
No backing strip

Radiograph results were:
1-2 OK
2-3 OK
3-4 1F
4-5 OK
5-6 1F
6-1 1F (1F = small porosity)

Final determination by Inspector: ACCEPTED

My Section IX assesment:
1. Since QW-304 permits an alternative RT method of qualification, no other mechanical testing or visual testing is required for this welder;
2. welder may weld any and all P-1 materials (all groups) and all P numbers upto P11 plus P34 & P42;
3. welder may use any, all and only F-6 fillers for TIG root up to 2T of that deposited in qual test, on plate or pipe subject to appropriateness of the filler to base (& qualified WPS);
4. welder may use any, all and only F-4 fillers for SMAW up to 2T of that deposited in qual test, on plate or pipe, subject to appropriateness of the filler to base (& qualified WPS);
5. welder may weld any position, plate or pipe;
6. welder may weld all pipe greater than and including 2 1/2” sched 40.
7. welder may weld any thickness plate greater than ????;
8. welder may not weld plate thickness less than or equal to ?????;
9. since no solid backing was used in test, welder may weld with or w/o solid backing;
10. since no purge gas was used, welder may weld with or w/o purge gas.

My questions:
a. any and all comments on above, please!!
b. Any additional facts and observation regarding the welders test?
c. Cannot find specific Sect IX paragraphs to support 7, 8, 9, 10 above.
d. Thankyou for you help and interest.

Tom

 

[metengr]

tc7;

7. welder may weld any thickness plate greater than ????;

Review Article 3, QW-356 for Welder Performance using GTAW

Essential welding variables are what they are per this Table.

Essential welding variables for SMAW are listed in Article 3, QW- 353

To answer above, is the WPS the welder uses in production.

8. welder may not weld plate thickness less than or equal to ?????;

This is governed by the WPS the welder uses in production

9. since no solid backing was used in test, welder may weld with or w/o solid backing;

Again review Tables QW-353, QW-356 in Article 3

For GTAW, removing backing requires requal
For SMAW, removing backing requires requal

10. since no purge gas was used, welder may weld with or w/o purge gas.

Again review table QW-356 applicable to only GTAW

removing inert backing requires requal.

 

[tc7]

Hello Met-
My lack of experience with QW-353 and QW-356 is exactly what prompted me to post my questions....

QW-353 & QW-356 doesn't address qualified plate thickness ranges at all, but now I do see in QW-404.30 that plate thickness is dictated by 2t weld deposit when RT was done in lieu of bend tests.

As for my backing question, QW-353 & QW-356 kicks me into QW-402.4 which mentions "deletion of the backing"; this welder passed his testing with no backing on his GTAW root pass - since neither QW-356 or QW-402.4 mentions "addition" of a backer, can I assume this welder is permitted to GTAW WITH backing when the WPS calls for it?

The SMAW question is somewhat reversed from the above: assuming the GTAW root acted as the backing for the SMAW fill BUT since QW-353 doesn't even mention backing as an essential variable, may I assume he can weld SMAW process WITHOUT a backer if the WPS calls for it?

On purge gas: QW-356 kicks me into QW-408.8 which mentions "omission of inert gas"; since this welder passed his test without inert gas, and neither QW-356 or QW-402.8 mentions "addition" of inert gas, can we assume this welder is permitted to weld WITH inert gas when our WPS calls for it?

Since QW-353 doesn't mention inert gas at all, can I assume this welder can weld WITH and WITHOUT inert gas backing?

Well I started out with three questions, now I have four questions! Hope you can advise and thanks again.
T


P.S. Incidentally, I have to refernce 1998 Section IX since our newest verion walked away, but I don't think this will significantly affect how I am reading the above issues.

 

[metengr]

T-

this welder passed his testing with no backing on his GTAW root pass - since neither QW-356 or QW-402.4 mentions "addition" of a backer, can I assume this welder is permitted to GTAW WITH backing when the WPS calls for it?

Correct. The committee views welding w/o backing to qualify for performance is more stringent in comparison to welding w/backing.

may I assume he can weld SMAW process WITHOUT a backer if the WPS calls for it?

No. If the welder qualified w/o backing, he could weld w or w/o backing. If he qualified w/backing as above, attempting an open root butt weld with SMAW would not be permitted.

since this welder passed his test without inert gas, and neither QW-356 or QW-402.8 mentions "addition" of inert gas, can we assume this welder is permitted to weld WITH inert gas when our WPS calls for it?

Yes.

Since QW-353 doesn't mention inert gas at all, can I assume this welder can weld WITH and WITHOUT inert gas backing?

This only applies for GTAW. If the welder is welding with SMAW, this does not apply. A welder qualified by process and by weld deposit thickness. The base metal thickness is dictated by the WPS.

 

[tc7]

OK - I'm almost there!

I didn't understand your last response on the use of inert gas & SMAW. Are you saying that since this welder is only qualified to weld SMAW with backing, then the use of inert gas purge doesn't apply?

Or are you saying that Sect IX disallows inert gas purge with SMAW in all circumstances?

T

 

[metengr]

T;
The inert backing gas would only apply to using the GTAW process in an open root weld joint configuration. Again, if the welder qualified w/o backing gas it can be added w/o requal of the welder. If the welder is welding against SMAW weld metal, backing gas would not be used, only shielding gas.

I hope this helps.

 

[tc7]

Met-
I am getting lost on a single point (disregard the new welder question for this): Are you saying that your general practice is to never use inert gas purge on an open root with SMAW ~ or ~ does some paragraph in Section IX disallow inert gas purge on an open root with SMAW?

This confusion on my part is probably because we have had jobs go through our shop and we used SMAW on open root with purge gas (I don't remember if it was a Mil, AWS or an ASME job).

Thanks again for your patience.
T

 

[metengr]

T;
The SMAW or shielded metal arc welding process is self shielding because the electrode contains flux that protects the as-deposited weld metal from harmful infiltration of oxygen and nitrogen.

The GTAW process does not use flux, and requires shielding gas to protect the weld puddle. In an open root butt weld, in addition to shielding gas to protect the weld puddle, backing gas is also used to provide protection against oxidation of the base metal along the exposed open root portion on the other side of the weld joint. If you weld with GTAW over SMAW backing, there is no need to backing gas because the shielding gas covers the entire weld region.

 

[tc7]

I understand what shielding is supposed to do. I was just talking to our foreman and he said purging is required in Mil-278 piping when backing is not used, regardless of welding process. Whether that makes sense or not is anyone's guess.

So then I guess I'm all squared away with that quick lesson.
Thankyou sir, you're a gentleman and a scholar.

Best regards,
T

 

[metengr]

T;
The only reason I could think of for using shielding gas for backing is to protect the surface of the base metals at the root location, when depositing the root pass. Backing gas will only serve to prevent oxidation of the base metal(s), which may be required for very specific applications to prevent the ingress of oxide contaminants into the system.

 

[Welder4956]

1. Since QW-304 permits an alternative RT method of qualification, no other mechanical testing or visual testing is required for this welder;

Visual inspection is required per QW-302.4.

 

[tc7]

thanks Welder4956, I stand gladly corrected!