Pressure test for open end piping network 1

[Merc-]

Hi everyone,

Is pressure test required for piping system which is open to atmosphere?

Sea water Intake and outfall pipelines(Around 1km in total length,HDPE-DN1000) which is submerged in a offshore trench and each spool(previously hydrotested ) is connected by bolted flanges. One end of pipeline is connected to Intake-pump-station and other end is open to sea and process fluid is sea water itself which flows towards intake-pump-station.

ASME B31.3, 345.1 (d) states "Unless specified in the engineering design, lines open to the atmosphere, such as vents or drains downstream of the last shutoff valve, need not be leak tested."

As per the above the statement, Can we consider this line is open to atmosphere? Can hydrostatic pressure test ignored considering the consequences of the leak is minor & identifying the leak is practically impossible?

 

[Dhurjati Sen]

If the code followed during construction is B31.3, then you can safely ignore hydr-test.

Unless of course, it is a client requirement.

However, a service test may be required to check the flange tightness.

DHURJATI SEN

 

[LittleInch]

So is this an inlet or an outfall? or both?

Also I don't agree that pipes submerged under water at their open end are open to "atmosphere".

If this pipe comes ashore and enters ground not normally saturated with salt water and leaks as it is under pressure from the sea depth then it can casue a lot of damage to plants and create other issues.

At 1km or even 500m you will need a higher pressure to pump it out.

This clause is usually intended for short lines open to the air either as open drains or open vents.

A bit more detail would be nice...

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