pipeline hydrotest 3

[rochdi82]

Gentlemen,
We are planning for the hydrotest of 36" pipeline (20Km long).
After pipeline filling we will pressurize the pipe.
I'd like to know the relation between the added water volume and pressure raise in the pipe (i.e: how much water will we need to increase pressure by 5 or 10 bars).
Please advise. Any other recommendation for this hydrotest (filling/ preessurisation/dewatering, etc.) is wellcome.
thanks for all.

 

[pierreick]

Hi,
Water is incompressible!
You need to fill your pipe and then apply pressure with a suitable hydro test pump, roughly about 12800 m3 .
You should ask yourself about the quality of water needed to perform the task , all the logistic to bring the water to site before pumping?
How do you intend to drain the water after the test? how dry should be the line after flush ? Etc.
To get a meaningful answer provide more info about the application .
Good luck
Pierre

 

[LittleInch]

BS PD 8010 has an excellent chart and calculation for this. I'm not able to access until Monday but see if you can find it.

Also has a very good section on how to do a pressure test.

Otherwise it's the bulk modulus of water minus about 1/3 to allow for the expansion of the pipe as pressure increases.

It's best to employ people that have done this before....

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

 

[LittleInch]

Water is virtually incompressible, but not 100%. Similarly the pipe is almost a fixed volume but not 100%.

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

 

[bimr]

Volume of water required to fill test section

V = L x (3.1416 X d²/4) x 12/231)
V = 0.0408 x d² x L
where
L = Length of test section, feet,
d = Inside diameter of pipe, inches,
V = Gallons required to fill @ O psig.

 

[GD2]

rochdi82,
Looks like you are totally new at pipeline hydrotest.
My advise is start at writing a Test Plan. You will get numerous information on pipeline hydrotest on the web.
You need to have a good understanding from test preparation to filling to dewatering to avoid hydraulic surging to vibration in each stage of the test.
The water fill rate may depend on many factors like water permit, temperature stabilization etc. Many test procedure specifies pressure increase at the rate of 50 kPa after the temperature stabilization period is complete which is usually achieved at 60% of the test pressure.
A pressure-volume (P-V) plot is also required if you suspect that the stress at any point in the test section will exceed the 100% SMYS. P-V plot is usually plotted at every 50 kPa pressure increment so that any deviation from the straight line proportionality can be detected.
Pumping shall continue until P-V plot reached the 0.2% offset line or the max test pressure is reached.
Make sure that P-V plotting is done during daylight hours.

GDD
Canada

 

[rochdi82]

Thanks to all,
I appreciate your contributions,
I'd actully assist to many hydrotest, but this is first time with such conditions ( pipe diameter & pipe lenght)
we've prepared test plan & WMS, but the only pending point is about the amount of water to add for pressurisation ( after pipeline filling).
we are under ASMe B31.4 & API RP1110, we can't use BS standards.
we just need to have an accurate estimation of the water quantity to add in each pressurisation stage (30%, 50%; 75% to 90% increase by 1bar/mn and then 0.5bar/mn to 100% pressure test: these are client requirements), so we can make provision for water tank and can have the appropriate pump (should be triplex plunger pump).
I thank you in advance for any further information.

 

[LittleInch]

You don't need to "use " BS standards, you just use bits of them that are not in the other codes for information.

In section 11.6.5 (so you can reference it) you get this little gem

Now this is in SI, so V is m3, P is bar, D/t is in m, but is really the ratio so both can be mm.

I just did it for you pipeline (36", 20km long) with an assumed D/t of 60 and I get about 0.21m3 / bar. That is for an water volume in the pipe of 2,900 m3.

Sounds about right to me. 21 m3 to get from 0 to 100 bar test pressure.

You won't be far away.

Just be clear that you need to measure the volume and plot the P/V graph. A deviation from a steady slope when at the top end indicates you're starting to get close to yielding the pipe....





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

 

[rochdi82]

@LittleInch : Thank you so much, for such a valuable clarification