Does a 600# flange need to be tested?
Does a 600# flange need to be tested?
(OP)
New 24" natural gas pipeline in WV, USA.
Inspection had me remove all 600# flanges and weld temporary test heads on prior to hydro of a section of pipeline. Design pressure is 1480psi, material is X65. Hydro pressure was 2400psi due to elevation difference. Inspection said the flanges are tested at manufacture site. I don't agree. I was under the assumption 100% of the pipeline had to be strength tested including the flanges. Please advise, Bigfaz
Inspection had me remove all 600# flanges and weld temporary test heads on prior to hydro of a section of pipeline. Design pressure is 1480psi, material is X65. Hydro pressure was 2400psi due to elevation difference. Inspection said the flanges are tested at manufacture site. I don't agree. I was under the assumption 100% of the pipeline had to be strength tested including the flanges. Please advise, Bigfaz





RE: Does a 600# flange need to be tested?
You are essentially correct, but there is something strange here. A section diagram / sketch would help showing elevations and heights, pressures etc.
What you are testing with flanges is the connecting weld, not the flange itself. The flange is not tested per se, but forged and built to standards.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Does a 600# flange need to be tested?
I always find it quit hysterical when engineers mandate that pipelines be rated to 1480, then all the devices that create the pressure are rated to 1200 psig. So all your compressors are ANSI 900? That's what you need to get to 1480 on the pipeline. If you test to the line at 2220 at the low point, then it's rated to 1300 psig. You can operate it at 10% over that or 1430. You lost 50 psig of room. You'll never miss it and save a bundle of money up front. Think about this just a couple of decades ago, the 600 class flange was rated to 1440.
I also love it when piping designers spec sch 80 6" in plant piping in order to get a full 1480 piping, then every vessel that pipe is connected to is rated at 1000 psig. Put in sch 40 rated to 1200 plus psig and save a bundle.
Technically, they are right. You could pneumatic test 1600 or so and get your full 1480
RE: Does a 600# flange need to be tested?
the elevation difference is 400', the wall thickness is .500, the test pressure is being monitored at the lowest elevation. The minimum test pressure is 2220psi. The hydro is now complete and the line dried. The flanges were welded back on and the welds x-rayed in accordance of API 1104. The flange welds were not hydro tested. Inspection removed the flanges prior to hydro because the said the flanges would not hold the test pressure. If that is so, I think engineering would have used 900# flanges. Just my thoughts. Thanks, Bigfaz
RE: Does a 600# flange need to be tested?
I kind of agree with dcasto - pipelines should be designed and rated for what they have to do - that's why pipeline design codes exist - not the max cold working pressure of the flanges. That always sounds to me like a piping engineer got hold of the design without realising the implications such as the one you have just faced. Having a desing pressure of 1360 (I get 1360 compared to dcastos 1300) would have made all those issues go away, but probably very little impact on the operation of your pipeline.
FYI ANSI B 16.5 states that the max system pressure test is 1.5 x the cold rating of the flange (2220 in your case), but higher is "the responsibility of the user"
Whilst the inspector is erring on the cautious side, the flip side of his decision is that you now have an untested weld on what sounds like a piece of pipe subjected to welding, cutting off, welding a test end, cutting that off and re-welding the final flange. I think I know what I would have done....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Does a 600# flange need to be tested?
I think LittleInch and I would have done the same thing.
RE: Does a 600# flange need to be tested?
Since RT has been acknowleged to be incapable of imaging fine, tight Lack-of-Fusion that did not trap slag, 100% RT is not particularly a good method of testing. A "Full Flange" hydro, to 1.5 times the cold MAWP of the flanges is a superb method of assuring that the line is well built. If it is indeed a hydro, vs. a pneumatic, those few more 10's of seconds of running the pump are damn cheap insurance. If everything was designed and built properly, your flanges are your limiting element. Hydroing to 1.5 x Limiting Element just makes sense.
RE: Does a 600# flange need to be tested?
RE: Does a 600# flange need to be tested?
Yes, exactly Inspection removed the flanges prior to hydro because the flanges would not hold that high test pressure. Engineering should have specified 900# flanges, or reduced the test pressure to +/- 2160 psig, OR LESS. Maybe less because it is not often on a pipeline where you must test to 1.5 times design pressure, so it really is a mystery why the test pressure was set so high. Normally 1.25 x design pressure is sufficient on most parts of a pipeline, but it depends on your Class Design Factor at the test section's location. Where on this pipeline is this, compressor station, road crossing, downtown, rural area?
Right now this seems to be a major mistake by your engineers, for which if true, you need to let them have both barrels ... of a 12ga.
Learn from the mistakes of others. You don't have time to make them all yourself.
RE: Does a 600# flange need to be tested?
However, there isn't a sane person that would accept that. If I was a DOT inspector and saw that you didn't test that flange assembly, I'd make your next few months not a very fun. It's not the fitting that's at issue, it's the weld and the bolts that are at issue.
If you can't live with less than 1480, then as stated above, put in 900 class fittings. Just like I said you'd have to do at your compressors because of the temperature derate.
RE: Does a 600# flange need to be tested?
841.3.1
Yes there are a few exceptions,
But not always are those excepted. You can only make those exceptions where
that pretty much limits it to golden welds.
Furthermore, that work must be done in the context of,
While it is possible to not do hydro/pnuematic tests on limited repair pieces, it is overwhelmingly obvious it is not allowed, or permissible, or practical to construct 500 miles of pipeline without hydrotesting, or pneumatic testing under those particular circumstances which do allow pneumatic testing.
Learn from the mistakes of others. You don't have time to make them all yourself.
RE: Does a 600# flange need to be tested?
RE: Does a 600# flange need to be tested?
If I can do it, it's practical. If I can't, it's not. If you can't do it, I'll show you how. That's practical. Lawyers get that part. See you in court.
Learn from the mistakes of others. You don't have time to make them all yourself.
RE: Does a 600# flange need to be tested?
Also, the pipe would all be hydro tested, just not the welds. Or manufactured components
RE: Does a 600# flange need to be tested?
That typifies the usual problem with agency field inspectors; they know it all, and it's often the only regulatory interface with the owner/reps, other than submitting a permit itself.
Learn from the mistakes of others. You don't have time to make them all yourself.
RE: Does a 600# flange need to be tested?
The pipe was tested at the mill. The entire purpose of a final hydro is to test the welds.
RE: Does a 600# flange need to be tested?
The entire purpose of a final hydro is to test the system in its "as installed" position, ready to accept its contents. That means everything possible connected with the system (pipe, welds, fittings, flanges, supports) should be tested.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Does a 600# flange need to be tested?
Learn from the mistakes of others. You don't have time to make them all yourself.
RE: Does a 600# flange need to be tested?
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Does a 600# flange need to be tested?
The same has been applied, in my experience, to block valve and tie-in prefabrications, beach pulls, platform risers and river crossings that had higher class location and test pressures than the mainline. After they were pretested at higher pressure (for the fabricated items DF=0.6, or riser = 0.5), were tested through again at the lower pressure consistent with the Class 1 test pressure. That, even though they were not specifically intended for "repairs".
Learn from the mistakes of others. You don't have time to make them all yourself.
RE: Does a 600# flange need to be tested?
RE: Does a 600# flange need to be tested?
Learn from the mistakes of others. You don't have time to make them all yourself.
RE: Does a 600# flange need to be tested?
What if an operator is using several lengths of pretested pipe (e.g., 40 foot “joints” or “pups”) that must be welded together for the replacement segment. Are the welds excepted as tie-in joints? (PHMSA uses the term joint to identify the connection, welds or fusions, between lengths of pipe.)
The following interpretation for 2012 discusses this situation.
Interpretation Subpart E 1
October 17, 2012
U.S. Department of Transportation
Pipeline and Hazardous Materials Safety Administration
1200 New Jersey Ave, S.E.
Washington, D.C. 20590
Mr. XXXX
Attorney at Law XXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXX
Dear Mr. Paul:
In a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA) dated December 8, 2011, you requested an interpretation concerning the requirements in 49 CFR Part 195 for pressure testing a segment of pipeline that has been replaced prior to putting that segment in service. Specifically, you asked whether post-installation pressure testing was required for a pipe replacement project involving multiple joints of pre-tested pipe. You also asked whether PHMSA could provide any relevant enforcement guidance documents on this issue.
Pressure testing a pipeline segment before placing it in service is a core requirement of the Federal pipeline safety regulations. Part 195, Subpart E governs the pressure testing of pipeline used in hazardous liquid service. 49 CFR 195.302(a) states:
(a) except as otherwise provided in this section and in § 195.305(b), no operator may operate a pipeline unless it has been pressure tested under this subpart without leakage. In addition, no operator may return to service a segment of pipeline that has been replaced, relocated, or otherwise changed until it has been pressure tested under this subpart without leakage.
The term “pipeline” is defined in § 195.2 as:
“Pipeline or pipeline system means all parts of a pipeline facility through which a hazardous liquid or carbon dioxide moves in transportation, including, but not limited to, line pipe, valves and other appurtenances connected to line pipe, pumping units, fabricated assemblies associated with pumping units, metering and delivery stations and fabricated assemblies therein, and breakout tanks.”
The term “pipe” is further defined in § 195.2 as:
“Pipe or line pipe means a tube, usually cylindrical, through which a hazardous liquid or carbon dioxide flows from one point to another.”
Under these definitions, the term pipe means that section of pipe through which a hazardous liquid will flow from point-to-point and therefore must be pressure tested from point-to-point. No distinction is made as to the length of pipe or the number of welded joints within the replaced pipe segment. Similarly, under § 195.308, a pipe tie-in segment being installed must be pressure tested either with or without the tie-in welds (which themselves require non-destructive testing). Note that the welds connecting several pipe lengths in a section to be tied-in are not tie-in welds. In general, while PHMSA has not required post-installation pressure testing when a single joint of pre-tested pipe is replaced, operators are subject to the pressure testing requirement anytime more than one pipe joint is being replaced.
Regarding your request for enforcement guidance documents, all available PHMSA enforcement guidance materials are posted on the PHMSA website for public viewing at: http://wwvv.phmsa.dot.gov/foia/e-reading-room. Once you visit the website, please click on – “III. Staff Manuals and Instructions” to view the enforcement guidance materials. While PHMSA does not have an enforcement guidance document for 49 CFR Part 195, Subpart E-Pressure Testing, we have enclosed an enforcement guidance document dealing with the pressure testing requirement for natural gas pipeline replacement projects under Part 192. While this enforcement guidance is not applicable to hazardous liquid pipelines, it is illustrative of the manner in which PHMSA applies the pressure testing requirement to pipe replacement projects. In relevant part, it states that “the entire replaced segment must be tested… except the tie-in joints” (and notes that the several pipe lengths are not tie-in joints).
Finally, if you have a scenario where you can demonstrate that conducting a post-installation pressure test on a replacement segment is impracticable, you may contact the PHMSA regional office covering the area and submit a proposed alternative in writing for its consideration such as a proposal to perform an appropriate strength test on the segment prior to installation (which PHMSA may elect to witness).
I hope that this information is helpful to you. If I can be of further assistance, please contact me at XXXXXXXXXXXXX
Sincerely,
John A. Gale
Director, Office of Standards and Rulemaking
U.S. Department of Transportation
Pipeline and Hazardous Materials Safety Administration
you must get smarter than the software you're using.
RE: Does a 600# flange need to be tested?
RE: Does a 600# flange need to be tested?
you must get smarter than the software you're using.
RE: Does a 600# flange need to be tested?
A single length of pipe may be replaced and the only requirement is NDT of the two "golden" welds.
Anything more than a single length of pipe must be hydrotested.
Is that correct ?
It does seem strange - if I have understood the interpretation above.
If I replace a section of pipeline with two pipe lengths I have to hydro the one weld connecting the two lengths but the two welds either side are just subject to NDT ??
Cheers,
DD
RE: Does a 600# flange need to be tested?
People always say, "Well in that case, where you draw the line then?"
Well now you know.
you must get smarter than the software you're using.