Hydro-static testing 6

[Johnmartyblake]

I have a question concerning welds in a hydro-static test. Simply do welded Temporary caps in a test section have to be fully welded and x-rayed.
I need to know if there is a code that states this one way or another. I have looked thru CFR 49- 192 & 195 ASME Section 9 and cannot find any thing. and before you bring up the obivious. I am working with a fab shop and refinery that are questioning my requirement that ALL welds in the test sections have to be full, complete and Xrayed. Their normal practice is to put in a bead and hotpass for all Temp. welds in a hydrotest section. FYI test pressure is 1875psi for 4 hrs.

 

[pennpiper]

John,
You wrote, "I am working with a fab shop and refinery". This suggests you should be looking at ASME B31.3.
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It has been a while since I have looked but I think B31.3 only requires a small percentage of the joints to be Xrayed, not 100 percent Xray.
I also think B31.3 does not require Xray of temperature test closer welds. You are just going to cut them off after hydrotest to make the final Installation welds. Those final installation Welds do need to be Xrayed.

Sometimes its possible to do all the right things and still get bad results

 

[DSB123]

Not only do the final installation welds need to be X-rayed but since they will not be pressure tested they must be subject to a Non-Pressure Tested Closure Weld procedure!!!

 

[LittleInch]

I've always hated and I ban the use of the word "temporary" for these exact reasons. It puts into peoples mind that somehow this item can be lower quality, lower testing, design etc = lower safety. If instead of "temporary" you call them "hydrostatic closure welds" - see the difference?

Neither the cap nor the weld know that it is "temporary", hence there is no reason why this weld, compared to the one next door to it is treated ANY DIFFERENTLY.

The reason you won't find this quite frankly sloppy and dangerous practice in the code is is because it is sloppy and dangerous. The shop may well have been getting away with it for years, but that doesn't make it right.

Simply tell the shop that a weld is a weld is a weld and treat them all the same. There is no reduction specified in any design code I've ever seen so the absence of something means it is not covered. Codes don't like telling you things you can't do because if they miss one off the list then they are in trouble. They tell you things you can do or should do. Thus your comment "I have looked thru CFR 49- 192 & 195 ASME Section 9 and cannot find any thing" is correct. Therefore their practice is NOT ALLOWED.

Sorry for shouting, but this really annoys me and poor practice in testing leads to accidents, injuries and death. Those small caps can shoot off faster than a bullet...

Rant over. Stick to your guns.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LittleInch]

Plus anyone who tells you "its only water" should read these. Especially the first one as it was a plug which blew off.

https://www.osha.gov/pls/imis/accidentsearch.accident_detail?id=14234207

https://www.cdc.gov/niosh/face/stateface/ok/99ok018.html

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[david339933]

If the code doesn't specifically state you are allowed to do something, does not mean it is prohibited.

General statement, not arguing this is acceptable.....Good engineering judgement must be used....

 

[LittleInch]

Agree - prohibited is a legal requirement (which the CFRs are). What it means if not stated is that it isn't code / regulation compliant and you can't use the design code as a back-up / defence if something goes wrong / doesn't work / fails.




Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[david339933]

Agree and disagree. Agree that the code can't be used as a defense if not stated, but doesn't necessarily mean it isn't code compliant. "The code does not address all aspects of these activities, and those aspects which are not specifically addressed should not be considered prohibited." U-1 Sec. VIII Div. 1. You can still be code compliant if you do something that the code doesn't specifically state you are allowed to do.

 

[Johnmartyblake]

Thank you all for your responses. You are correct LittleInch as I read some of the replies I realized I should have provided more information. I thought Less was better. The job I am on is a Pipeline replacement that goes into a meter site in the refinery. The Plant is footing the bill for the replacement thus we are using most of their specifications. Most of those are geared toward B31.3 but the majority of the replacement is under DOT B31.8/API 1104. There is actually only one small spool that is being done under B31.3 that is between the plant and the meter station. The largest of the "hydrostatic closure welds" are 12". Personally, I believe it is a safety issue. I don't really want to be around if a 12" X .500wt cap blows off. Again, thanks to you all for your input.

 

[LittleInch]

david,

Without laboring the point "You can still be code compliant if you do something that the code doesn't specifically state you are allowed to do. " - I disagree.

when you look at the words you quote it simply means it is not prohibited, but then you're on your own. It may very well be justifiable and be acceptable, but it is not IMHO, "code compliant".

Anyway I think we've got the main jist out there and I hope John manages to get them to do it properly. The biggest danger for a hydrotest is actually the small caps / nozzles as they can get a big velocity before the pressure in the pipe falls very rapidly. Big ends just tend to fall off and crush your foot....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BigInch]

They tell you things you can do or should do. Thus your comment "I have looked thru CFR 49- 192 & 195 ASME Section 9 and cannot find any thing" is correct. Therefore their practice is NOT ALLOWED.

I have to agree with David. "Engineering Judgement" plays its most important role. The code only requires the minimums of all things needed, as there are theoretically an infinite number of additional requirements which may be necessary at times to provide a safe design for any given specific system. Rather than attept to create a code addressing an infinite list of cases and covering an infinite^2 list of requirements for of all of them, the code provides only the collective minimum requirements for any system within its scope and defining all remaining requirements for any specific system at hand is left up to the responsible engineer.

For example B31.8

The Code sets forth engineering requirements deemed necessary for the safe design and construction of pressure piping. To the greatest possible extent, Code requirements for design are stated in terms of basic design principles and formulas. These are supplemented as necessary with specific requirements to ensure uniform application of principles and to guide selection and application of piping elements. The Code prohibits designs and practices known to be unsafe and contains warnings where caution, but not prohibition, is warranted.

The way I learned to read that is ... Codes, or the CFRs, tell you ONLY the MINIMUM of what you MUST do. You (as the responsible engineer) are perfectly free to do anything that is not mentioned in the code, as long as (presumably) you consider it necessary to meet the intent of the code, which is pretty much simply put only to provide a safe, useable and workable design. (That might even include drilling a hole in the pipe wall, or through the disk of a check valve, if you think you need to, although you won't find either of those in the codes). In fact you are REQUIRED TO DO MORE than the code requires, each and every time that you, as the responsible engineer, believes it is necessary to result in a safe and workable design.

What you must do all the time is at least what the code, or CFRs say you must do. You only have to follow their recommendations when you, as the responsible design engineer, agrees. What you must not do is anything the code says you cannot do. What you can do is ANYTHING else that you as the responsible engineer considers necesary to meet the intent of the code (ie. whatever results in a safe and workable design). What you also MUST DO is anything else you think is necessary to get to that point.

Getting back to the OP question, which appears to be in regard to "temporary" pieces of pipe and fittings that are only neeed for testing purposes and will be removed after testing is completed. There is not and answer to be found in these design codes. These design codes do not address the requirements for non-permanent portions of piping systems. We have prevoiusly discussed this topic in this forum and failed to come to a uniform agreement. Some of us considered that these temporary components should be designed exactly as permanent components, using the "test pressure" as their "design pressure". Others, of whom I was not one, considered that the temporary test components could be stressed to 100% of yield anytime they were being used. I wouldn't want to ride Chuck Yeager's Bell X-1 test airplane, if it was designed to like be at 90% yield crossing the sound barrier. Ha ha ha ha. I'd say ... At least complete the welds ... the X-ray question is up to whoever survives the test.

If a (the, any) un-hydrotested weld remains within the permanent pipe and components of a pipeline after testing and repair under B31.4 or 31.8 codes, the weld(s) must be X-rayed. Thus pipe assemblies made for repairs are pretested, temporary end caps, or other non-permanent fittings and headers, etc. are cut off and removed, then the remaining assembly is dropped in and welded into the original pipe. Those "golden" welds have not been hydrotested, so they must be X-rayed. There are (usually) only two such golden welds allowed for any given repair, one on each side of the pre-tested assembly. The pipeline codes specifically prohibit making a longer pipeline by joining pretested pipes or assemblies together by the use of un-hydrotested, X-rayed, "golden" welds.

Reaction to change doesn't stop it