Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / General Welding Discussion / piping
- - By cryogenicshaun (**) Date 02-02-2006 12:05
our customer spec for the vessels we build call out for the piping attached after the flange to be built to b31.3. when i went to start inspection processes on the piping the boss said he didnt want to perform inspection other than a visual. i was under the impression that if yoou build to it you need to test to it. is this correct? he said the customer said to build to it but did not state that we need to test to it. when the spec calles for piping to be built in accordance with b31.3 wouldnt that mean to go with the entire process? or does inspection usually need to be put in writing also?
Parent - - By tito (**) Date 02-02-2006 12:33
I would agree with you. I doesn't matter if the customer says "build and inspect to B31.3". By stating to build to B31.3 it is implied to follow all requirements of the code, especially since it is process piping, and it is attached to a vessel.

Alternate solution: Have your boss or whoever contact the customer to clarify this. Get it IN WRITING if the customer waives inspection and testing. Until then, I wouldn't let any pipe out of the door until all tests and inspections have been completed and accepted.
Parent - - By jon20013 (*****) Date 02-02-2006 12:43
Full pen welds would require a minimum of 5% RT and pressure testing (Hydro), RT % could go higher, depending on fluid service category. May be inservice pressure test, but that really depends on fluid service category too. Agreeing with tito.
Parent - - By cryogenicshaun (**) Date 02-02-2006 13:30
i asked him to call and verify that and he doesnt want to. the fluid is liquid nitrogen so im thinking its probably going to be severe cycle due to the rapid increase and decrease of temperature.
Parent - By jon20013 (*****) Date 02-02-2006 13:49
If he doesn't want to call for a test waiver (in writing) then it seems your comapny has no option except to fulfill Code requirements. If you do not then your Company may be held liable for Contract issues and end up in a prolonged court battle. If you are the QC involved your name will be right in the middle of the issues.... Good luck, if I were you I would put my hands onto a B31.3 and really study the issue. RT + Hydro testing.
Parent - By tito (**) Date 02-02-2006 13:51
Well, since he is your boss, seems like the only thing you can do is: upon completion of job, initiate an NCR stating that proper inspection and testing was not performed or allowed to be performed because of Boss' interpretation of spec. See if he will sign off on it, accepting the piping. He probably won't so, write whatever else on the NCR explaining the situation without pointing the finger too much, but enough to explain. Then I would also write in a log or notebook or whatever, explaining EVERYTHING in detail and put it in the QC job file which hopefully is under lock and key. Make copies of everything and store in a seperate place, just in case. CYA

Ask your boss if you can call to verify this interpretation of his. If not, tell him you cannot and will not accept the responsibility of this. Before you do as stated above, tell him you are going to write an NCR on it. We are all plagued from time to time with witnessing something that is not right, and forced to turn a blind eye. But this should only happen when you superiors overide you. Then, all you can do is document and file.

This is just what I would do. Remember, CYA
Parent - - By G.S.Crisi (****) Date 02-02-2006 14:34
My opinion is the following:

1st. First thing to do is to look at the purchase order and its attached documents. If they say somewhere that the piping is to be built AND INSPECTED according to ASME B31.3, then the discussion is over: it has to be inspected and that's it.
If they say that the piping is to be built according to B31.3 but say nothing on inspection, then a good lawyer will convince the court and the judge that inspection is out of the scope of supply and the client has to pay an extra price if he wants to perform it.

2nd. I've reasoned as a lawyer till now. Let's reason now as engineers. If the piping was carrying drinking water, then I wouldn't make a point about inspection, but it's carrying liquid nitrogen, which is a quite different thing.
As an engineer, I wouldn't allow a liquid nitrogen piping to be put in operation if a proper inspection hasn't been performed, no matter who pays for it. If a drinking water weld fails, someone will get an unexpected shower; if a liquid nitrogen weld fails, someone can be killed.

3rd. I confess my ignorance: is B31.3 the right Code for liquid nitrogen, i.e., cryogenic service? Liquid oxygen, for example, doesn't fall under B31.3

Giovanni S. Crisi
Sao Paulo - Brazil



Parent - - By cryogenicshaun (**) Date 02-02-2006 19:16
what code does liquid oxygen fall under? its all considered process piping from our work scope. we do build oxygen vessels also. and yes it is cryogenic service. let me ask this, in b31.3 normal cycle, the radiography requirements are listed in "other examinations" does that mean that if piping is leak and pressure tested within code specs that radiography is not necessary? is there anyway that nde can be bypassed as long as proper leak and pressure test are done?
Parent - - By cryogenicshaun (**) Date 02-04-2006 17:30
uh oh. everybody left me here.
Parent - - By G.S.Crisi (****) Date 02-05-2006 20:03
Beg your pardon, it wasn't liquid oxygen but gaseous oxygen. Memory played me a trick.
The standard I'm talking about is Standard G.4.4: "Industrial practices for gaseous oxygen transmission and distribution piping systems", published by:
Compressed Gas Association, Inc.
500 Fifth Ave.
New York, NY 10036
Giovanni S. Crisi
Parent - - By Shane Feder (****) Date 02-06-2006 00:53
Cryogenicshaun,
I am currently working in a coal mine so do not have all my relevant codes with me however I have recently finished a B31.3 project so I remember most of the info, just not the exact details.
The only way you can bypass radiography is if your piping falls within Category D. To fall within Category D your piping must fall below a certain temperature, below a certain pressure ( I can't remember if that is design or operating) but most importantly be non hazardous to human tissue. I am quite sure liquid nitrogen will not fall in this category.
Normal Fluid Service will require 5% minimum radiography and Severe Cyclic will require 100%.
As the fabricator it is not your responsibilty to be trying to figure out how much NDT you should be doing. It is the responsibilty of the design engineer and should be reflected in the contract documents.
Hope this helps,
Regards,
Shane
Parent - By pang_cs Date 06-13-2007 09:09
Dear All,
Sorry to interrupt, By the way learning from your, can a low pressure steam and / or medium pressure steam be define into Category D per B31.3 with only insulation (part of restorative?) but to avoid hydrotesting?
Up Topic Welding Industry / General Welding Discussion / piping

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill