Hydrotest of pipeline

[Green white]

I need to hydrotest a new pipeline

the design pressure (DP) of this pipeline is 1200 psi
the Maximum Operating pressure (MOP) is 900 psi
shall I hydrotest the pipeline to 1.25 X DP (1200 X 1.25 = 1500 psi)
or
1.25 X MOP (1.25 X 900 = 1125 psi)

 

[LittleInch]

What does your design code say?

Why such a big difference between the two?

But the test pressure will set the MOP for ever more

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

 

[1503-44]

Of course test it NOW to 1500.

You or your client apparently have paid for the extra material and strength to reach 1500.
Testing to 1500 does not cost 10 cents more than testing to 1125.
But if you do not test to 1500, rerating it later to MAOP of 1200, I promise it will happen, will cost you the extra steel already plus another hydro later. At least DOUBLE the price for NOTHING.

Sorry to say, but unless you forgot to tell us something, IMO it's a nobrainer.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[goutam_freelance]

Since the pressures are on the higher side, I assume it is for power plant application, so B31.1 applies.

In that case test pressure shall be 1.5*design pressure=1800 psi, provided allowable stress is not exceeded.

I do not appreciate the fixing of design pressure at 1200 psi, when the maximum operating pressure is 900 psi.

Engineers, think what we have done to the environment !

https://www.linkedin.com/in/goutam-das-59743b30/

 

[LittleInch]

He said pipeline.

B31 4 uses MOP as the base number to provide the MINIMUM test pressure.

So it's up to the OP what he wants to do given the advice offered.

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

 

[1503-44]

Actually 900 is kind of low for a pipeline these days, or even 40yrs ago for that matter. Many pipelines are designed for 1460, some even more.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[goutam_freelance]

If it is really a pipeline then I suppose AWWA M11 will be applicable.

Then the considered test pressure is logical. However, it is to be noted that a test pressure of 125 % of design pressure is a maximum. For large diameter pipelines the maximum test pressure may be significant from a safety point of view.

Engineers, think what we have done to the environment !

https://www.linkedin.com/in/goutam-das-59743b30/

 

[1503-44]

There are many PL codes to chose from.
We just have to believe the info given is correct.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[infometrix]

For new pipelines, it is always 1.25 X DP.

thanks

 

[LittleInch]

Info - It depends on the design code of which there are many and they vary. So it is simply not correct to state "always". B 31.8 for example refers to 1.25 x MOP or 1.5 x MOP.

Others also vary.

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

 

[1503-44]

These are the minimum factors to achieve a given MAOP.

What is more common is to actually test to +/- yield stress, which qualifies the pipeline for its highest possible MAOP, as I suggested above. Why waste the material capacity already bought and paid for by not testing to yield? Pipelines last a long time and it is typically the case that they eventually wind up being tested to yield sooner or later anyway to squeeze the last drop of flow rate capacity that you can get out of them. Even still, then you loop the pipeline with another one alongside it and it's usually even a larger diameter. I worked for one company that wouldn't build any cross country pipeline with less than a 30" D. After 5yrs they changed that rule to 36". Then they started looping that one with a 42. Unused capacity is the worst sin you can commit working at a large pipeline company.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[mfgenggear]

When I was a young man , working in a sheet metal shop fabricating tube and pipe.
There was hydrostatic testing required on the individual section of various exotic pipe section for the petrol and chemical industry. I do not recall the specifications, but I tested upto 2000 psi.
With no failures.

Point is, what are the requirements , the op has to fiquire that out . We don't guess at
Testing requirements. It must be established for fit, form and function.