D1.1 PQR in 2 positions

By ctacker (****)

Date 10-11-2007 23:26

if your welder qualifies vertical he is qualified for all positions except overhead! with the exception of slots in which he needs qualified for the position he is welding!

By CHGuilford (****)

Date 10-12-2007 14:08

To the best of my knowledge, D1.1 does not address PQR test plates welded in multiple positions. My vote is that the PQR is an interesting curiosity but is not valid per D1.1.

By 803056

Date 10-12-2007 14:28 Edited 10-12-2007 14:31

I agree with Chet.

At best, the thickness of the layers would have to be recorded so you could discriminate between those beads deposited in the vertical and horizontal positions. The sample would have to be machined to tests the vertical welds separate from the horizontal beads, i.e., four bends and 2 tensiles for the vertical weld and four more bends and two more tensiles for the horizontal welds. The thickness of the weld in the vertical would be the basis of the thickness range qualified in the vertical and the thickness of the weld deposit in the horizontal would be the basis of the thickness range qualified in the horizontal. I do not believe they could be combined.

Imagine rotating the plate from flat, to horizontal, to vertical, to overhead; four positions on one test plate! No, some how this simply doesn't make sense.

It seems to me this would be an exmple of false economy and more trouble then its worth.

Best regards - Al

By rickc

Date 10-12-2007 15:01

ctacker: Agreed. Table 4.10 is clear on that.

CHGuilford: The only hint I can find is in the Commentary. C-4.2.4 on Page 431 reads, "Each WPS shall be qualified for each position for which it will be used in fabrication." I could interpret that to mean you have to run a coupon in one position only and could reject it on the grounds that welding a PQR in multiple positions appears to be outside the scope of D1.1 but, I could see an argument in favor of what our sub-contractor has been doing. When I reject something I normally like to be very specific as to why (page, section number, etc.) because (a) it bugs me when inspectors don't do that for us and (b) I like to be right.

By pax23

Date 10-12-2007 15:40

I think this test is clearly not in compliance with the requirements of Section 4, Parts A (General Req.) and Parts C (Performance Qualification).

I agree with Rickc, it is always best to be able to cite a section supporting your conclusion. This is tough since I doubt the committee expected someone to try to perform a test like this so they would have to be swamis to anticipate this possibility and write something specifically into the code stating that you can't do this.

My best argument would be what type of test is this, 2G or 3G? By my understanding of the definitions in A3.0 and D1.1, either a 2G or 3G test has to be a complete test weldment. Now I have to read this into the definition but most of us would agree that is self evident. Now what did this gentleman do. He did neither. He did some type of fabricator or client specific type of test which would be a deviation from the code and would therefore need to be approved by the EOR. In addition to approving the test, the EVs and the ranges of this client/fabricator specific test would need to be identified.

There is also a clause in the the code, might be commentary, that uses the phrase '....specifically devised tests..." which I take as meaning they are trying to standardize the tests and avoid unnecessary variations.

There is always someone looking for an angle.

By rickc

Date 10-12-2007 21:33

Thank you, I think y'all have given me some good points to work with.

BTW, This is off topic but regarding the same piece of paper, I can't find anything in the code requiring a Maximum Interpass temperature on a WPS. There are max's listed for some materials in the footnotes on Table 3.1 and Table 4.9 but, no blanket requirement that I can find.

By pax23

Date 10-12-2007 21:39

Quite true, there are a few exceptions for specific materials but no blanket limitation unless you are dealing with a situation that requires impacts. Then Table 4.6 establishes a maximum interpass temp.

By 803056

Date 10-12-2007 23:04 Edited 10-12-2007 23:06

There are some very knowledgeable people that don't agree with me on this subject, but I view it as the preheat temperature is the minimum temperature that must be attained for welding to be initiated or continued, whereas the maximum interpass temperature is the maximum temperature at which welding can continue. That is, the weldment must be allowed to cool below the maximum interpass temperature before welding can resume.

The maximum interpass temperature may not be a variable that has to be controlled to attain or maintain the specified mechanical properties. For instance; when welding hot rolled carbon steel, the maximum interpass temperature is not usually controlled. There is little chance that the welding operation is going to exceed the temperature at which the steel is rolled and the time at temperature for the welding operation is never going to come close to the time at temperature of the manufacturing processes used to make the steel. If notch toughness is a concern, the steel has to be manufactured with notch toughness in mind and the welding process has to be controlled to ensure the notch toughness of the weld (selecting the correct filler metal) and base metal are not compromised. Interpass temperature and heat input are controlled to ensure cooling rates that will promote a fine (small) grain structure in the weld and HAZ to minimize the loss of notch toughness.

That isn't the case for other steels such as quench and tempered steels that include a quench operation after rolling and then a tempering operation to reduce the hardness of the martensite. The tempering operation gives the steel good toughness and ductility without excessive loss of strength. In that case, the interpass temperature and heat input are controlled to prevent an unacceptable reduction of the mechanical properties in the HAZ. High heat input and excessive interpass temperatures will allow the HAZ to cool too slowly to form martensite as the austenized metal in the HAZ cools below the transformation temperature. The high interpass temperature will also create a wider HAZ that is softer and has less strength than is required. Once again, the cooling rates have to be such that fine grain structures are attained to maintain the notch toughness of the base metal.

In the case of austenitic stainless steel, interpass temperature is controlled as a means to minimize the time at temperatures where sensitization can occur. Likewise interpass temperature is controlled when welding heat treatable aluminum alloys that can be overaged if held at "high" temperatures for too long a time.

Best regards - Al