How long should the pressure sustained during hydrotest? 2

[linmumu73]

Could somebody kindly advise me :
During hydrostatic test of water pipeline, the pipeline is filled up with water under the testing pressure of 16 bar(working pressure 10 bar).How long should this pressure sustained? The client is asking for holding the pressure for 10 hours. Is it possible to hold this? The pipeline is of socket-spigot joints and some flanged joints.
I saw some reference saying that is is about 10 to 20 min. Is it true?

Thanks!

 

[micjk]

linmumu73,
10hrs sounds a little extreme. in my experience with hydrstatic tests we normally hold for 45 mins to 1 hr. you could run into problems with temperature variations dropping or raising pressure making the test end results questionable. I am not sure if there are any ANSI codes governing this or if it is corporate inspection dept. governed.
good luck,
micjk

 

[abbver98]

In ASME B31.3 345.5.5 : pressure shall gradually increased til lesser (0.5 test pressure, 1.7 bar) is attained, then preliminary chek and examination (341.4.1(a). Pressure gradually increased in steps and holding long enough to equalize piping strains. This, til test pressure. Then reduced to design pressure before examining leakage. No precisions concerning value of pressure step.
In ASME VIII UG-101, 1st step to 0.5 design pressure and by 1/10 design pressure steps til test pressure. By each step enough time holding to allow observation ….
I don't think that with this you'll reach 1 h !!!

 

[BenjieL]

We normally do ours in about an hour tops.

 

[BobPE]

Here in the US we follow American Water Works Guidelines for potable water which state not less than 1.25 times the maximum working pressure at the highest point in the pipe for no less than 2 hours duration with test pressures not varying more than +/- 5 pisg.

Hope this helped..

BobPE

 

[DSB123]

linmumu73,
If you are talking about a "pipeline" then the British Standard BS 8010 specifies the Test pressure to be held for 24 Hrs. In general for Piping ssytem to ASME B31.3 then the norm is a pressure test of 1 hr.

Hope this helps.

 

[pmarriott]

ASME B31.3 para 345.2.2 stipulates "A leak test shall be maintained for at least 10 mins."

30 minutes is a more practical minimum though.

 

[mgp]

The new European Piping code EN 13480 specifies this in section 5:


The pressure of piping under test shall be increased to a value of approximately 50 % of the specified
test pressure. Thereafter, the pressure shall be increased in steps of approximately 10 % of the specified test
pressure until it is reached. The piping system shall be held at the test pressure for a period of at least 30 min. The
pressure shall then be reduced to the design pressure and all components and welded joints subjected to a close
visual examination of all surfaces and joints. During this examination, the piping shall show no signs of general
plastic yielding.


Hope this helps

Regards
Mogens

 

[PVRV]

linmumu73,


1) ASME B31.3 Process Piping

1.1) 345.2

345.2.2 (a) Examinations For Leaks
A leak test shall be maintained for at least 10 mint, and all joints and connections shall be examined for leaks.

--> My understanding is which ever is greater (10 mints or duration to examine all joints and connections.

1.2) Test Pressure (345.4.2)

--> My understanding it is 1.5 X the Design Pressure provided St/S does not exceed 6.5

2) ASME B31.4 Pipeline Transportation Systems for Liquid
Hydrocarbons


2.1) 437.4.1 (a)portions of piping system to be operated at a hoop stress of more than 20% of the specified minimum yield strenght of the pipe shall be subjected to any point to hydrostatic proof test equivalent to not less than 1.25 times the internal design pressure at that point for no less than 4 hours.

--> Question what if the piping system is operated at a hoop stress less than 20% of the specified minimum yield strenght of the pipe than:

2.2) 437.4.3 A 1 (one) hour hydrostatic or pnematic leak test may be used for piping systems to be operated at a hoop stress of 20% or less of the specified minimum yield strenght of the pipe.

Cheers

 

[TerryOsser]

Surely the client can determine the extent of the pressure test. Pipelines as DSB123 states is normally 24 hours. Topsides are noramlly 1 hour. Both are overridden by the client, and normally in the project Pressure Testing Spec it is written a minimum test duration, or 'until the client is satisfied that there are no leaks' which is translated as ' until he wants you to stop the test!'

 

[PVRV]

TerryOsser & DSB123,

I agree; Problem is when project specific requirements or Company General Procedures are absent from the Contract Document (inclusive of Hydrostatic Procedure). Only reference is ASME B31.3 or B31.4

Yes, it is prudent to compliment minimum requirements in several cases. For example, ASME B31.4--> API-1104 has no provision for progressive inspection; you are stuck with random RT even if the repair % is high.

Regards