First of all, thanks, Tim, for your kind words on my person.
js55 is right. American codes and standards (ASME, AWS, AISC etc.) still don't accept vibratory stress relief (VSR), so it's precluded for this particular case.
I believe it's time for AWS to nominate a committee to study carefully what VSR consist of, how it operates, pros and cons, check other countries' experience and come up with a conclusion:
a) VSR is plenty acceptable, in which case AWS should nominate another committe (could be the same) to write a draft standard on how VSR should be used. Once ready, the draft would be subjected to comments from whoever is interested.
b) VSR is not acceptable, in which case the committee should explain exactly, carefully and in all details why it isn't acceptable.
Now, speaking of Matt's problem, if I were him I'd do as I did back in my days of project engineer: organize a meeting with all parties involved. In this case, the parties would be Matt's company, his client and the valve manufacturer (if he's too far away, his nearest representative may attend).
At the meeting the problem would be deeply discussed and, if everybody acts with good sense and good will to solve it, a solution satisfactory for everybody will be found. I used to do like that back in my days of project engineer with good results.
Attention, though! It should be a personal meeting, with all persons sitting at the same table and looking one to the other's face. No internet contacts!
Giovanni S. Crisi
Sao Paulo - Brazil
Thanks for your input Professor. Very good advice, as always.
For conversation sake, do you think VSR could be a viable practice in this or similar situations?
Thanks,
Tim
Matt mentions a check valve, but he doesn't say whether it's a swing check or duo check.
Duo check valves are usually sandwiched between two flanges, and there are no welds to be done on them. So, we can assume that Matt's one is a swing valve.
Swing check valves' seat is machined, yes, but with not a great precision, as is, for example, the machining of a ball valve.
In my opinion, VSR could be safely used. If the flap moves a couple of tenths of a millimeter due to vibration, it wouldn't cause any visible harm.
Giovanni S. Crisi
Hello again Professor Crisi,
I was recently involved in a meeting where the applicability of Vibratory Stress Relief was mentioned.
The Chief Engineer for the project stated "There has never been any proof that VSR works and it should not be considered."
Well, I have to disagree with that general statement, but as VSR is not recognized by welding Codes, as far as I know, there's no sense in arguing the point.
Do you know if there has been any progress of Code recognition of VSR, as you suggested should be done earlier?
Thanks,
Tim Gary
Tim,
It's always good to hear your greetings.
The Chief Engineer is wrong. Back in 2004 I presented a paper before the 30th Brazilian Welding Conference showing the results of a research that I conducted here at Mackenzie U. in Sao Paulo, with the help of one of my pupils.
The tests were carried out on a 4 inches, Sch 40, A106 Gr.B (low carbon steel) pipe. Three pieces were welded. After welding, one of them was left untouched, the second one was submitted to PWHT as required by the Code and the third one was submitted to VSR treatment.
Mechanical tests (root and face bending, tensile, impact, hardness) on the three specimens showed that VSR treatment produced an equivalent stress relief than PWHT.
The paper is written in Portuguese, but someone in the States translated it into English. Time has passed and I don't remember exactly who. Give me a couple of days and I'll find out.
You don't need to thank me; it's always a pleasure to be of service to an AWS Forum mate.
Giovanni S. Crisi
Tim,
The translation of our article was done by The Stress Relief Engineering Company, makers of the Formula 62 equipment for vibratory stress relief.
You'll find the whole article translated into English in
www.stressreliefengr.com
Giovanni S. Crisi
Forum
