Welders Qualification Testing With Purging (ASME IX) 2

[Salmet]

Dear members, Why is a welder qualified with purging of inert gas, not allowed to weld without purging according to ASME IX QW-356 and QW 408.8? Despite practically, it is more difficult to weld with purging of inert gas than welding without purging. Thanks in advance.

 

[metengr]

Please review QW-408.8 again, if the welder has qualified with inert gas backing, they can still weld with no inert gas backing provided the weld joint is single sided, or with a backing strip or a double sided weld joint, expect for the following materials;

The above exception does not apply to
P‐No. 51 through P‐No. 53, P‐No. 61 through P‐No. 62, and
P‐No. 10I metals.

The rationale is obvious based on the above.

 

[DekDee]

metengr,
You need to change the "is single-sided, or with a backing strip" to "single-sided with a backing strip" as per QW 408.8 - makes quite a difference in the statement.
I am hoping to hear any further opinions as it is quite an interesting question,
Cheers,
DD

 

[metengr]

DekDee;
Yes, it was my error in copying, I should have simply copied directly QW-408.8.

 

[Salmet]

Metengr,

If a joint is backed up by a backing strip or double welded, mostly it is not purged and even if purged, the parameters does not remain the same as in case of joint to be welded with gas backing from one side only. The query is still there, in other words: Why a welder qualified to weld an SS 304 stainless steel by using ER 308L filler wire with purging is not allowed to weld carbon steel with ER 70S-3 with out backing. lets set aside good engineering practice etc., keeping in view practical considerations only.

 

[metengr]

Salmet;
Since I am a member of Section I standards committee not a member of Section IX standards committee, I cannot provide an answer with authority. I can speculate like anyone else on an internet forum. Here is a tip - if you want the committee to consider your query submit a request for code revision and let the committee decide if a revision is necessary.

 

[Salmet]

Metengr,

Thanks a lot for your kind input as usual. Can you please guide me how to submit a request the ASME IX commitee for any querry?

 

[metengr]

Salmet;
If you have access to the 2013 ASME Section IX code book, see below
under Introduction;
(1) Code Revisions. Code revisions are considered to accommodate technological developments, address administrative
requirements, incorporate Code Cases, or to clarify Code intent.

CODE REVISIONS OR ADDITIONS
Requests for Code revisions or additions shall provide the following:
(a) Proposed Revisions or Additions. For revisions, identify the rules of the Code that require revision and submit a copy
of the appropriate rules as they appear in the Code, marked up with the proposed revision. For additions, provide the
recommended wording referenced to the existing Code rules.
(b) Statement of Need. Provide a brief explanation of the need for the revision or addition.
(c) Background Information. Provide background information to support the revision or addition, including any data or
changes in technology that form the basis for the request that will allow the committee to adequately evaluate the
proposed revision or addition. Sketches, tables, figures, and graphs should be submitted as appropriate. When applicable,
identify any pertinent paragraph in the Code that would be affected by the revision or addition and identify paragraphs in
the Code that reference the paragraphs that are to be revised or added.

 

[metengr]

Here is the submittal address
6 SUBMITTALS
Submittals to and responses from the committees shall meet the following:
(a) Submittal. Inquiries from Code users shall be in English and preferably be submitted in typewritten form; however,
legible handwritten inquiries will also be considered. They shall include the name, address, telephone number, fax number,
and e-mail address, if available, of the inquirer and be mailed to the following address:
Secretary
ASME Boiler and Pressure Vessel Committee
Two Park Avenue
New York, NY 10016-5990

 

[steakman911]

There is no doubt that welding an open root on SS piping with GTAW and proper filler, is significantly more challenging/difficult than doing so on A106B/A333 type with an S3, S6 or even an S2 type filler metal. Rates of thermal conductivity being the main underlying issue along with ensuring your purge and if required, trailing gas shield is intact.

A very good question .. why indeed..?