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- since 1996 -

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was founded in 1984 and develops special ultrasonic imaging systems for high-tech materials.
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Technical Discussions
PPM
PPM
10:33 Nov-29-2015
Pressure Testing

what is the minimum holding time for hydraulic line pressure test ( testing pressure is 410 bar) ??

 
 Reply 
 
Steven Doc
Other, Quality Manager
Siemens Energy, Egypt, Joined Feb 2011, 187

Steven Doc

Other, Quality Manager
Siemens Energy,
Egypt,
Joined Feb 2011
187
10:50 Nov-29-2015
Re: Pressure Testing
In Reply to PPM at 10:33 Nov-29-2015 (Opening).

Holding time is prescribed in the Code or Specification. Generally Specification as these can be more stringent. There is no such thing as a general holding time.

 
 Reply 
 
Tj
Other, Piping Inspector
Arak Supply company for Oil and Gas Companies, Philippines, Joined Oct 2015, 4

Tj

Other, Piping Inspector
Arak Supply company for Oil and Gas Companies,
Philippines,
Joined Oct 2015
4
12:33 Nov-29-2015
Re: Pressure Testing
In Reply to PPM at 10:33 Nov-29-2015 (Opening).

Hi,

For reference, in my company the minimum holding time for hydrotest of above ground piping should not be less than 30 minutes. If the line to be tested is long and has many branches then you can increase the holding time to more than 1 hour depending on the amount of time required to inspect everything.

If your line is intended for underground piping, the minimum holding time is 4 hours provided all joints are exposed for visual inspection. If the joints are backfilled then it is a 24 hour holding time.

Can you please tell me if you are a designer, supervisor, site engineer or QC personnel?

Thanks.

 
 Reply 
 
Steven Doc
Other, Quality Manager
Siemens Energy, Egypt, Joined Feb 2011, 187

Steven Doc

Other, Quality Manager
Siemens Energy,
Egypt,
Joined Feb 2011
187
12:50 Nov-29-2015
Re: Pressure Testing
In Reply to Tj at 12:33 Nov-29-2015 .

TJ, are you saying that you are inspecting the system while under test pressure? If so this is very bad practice. You should hold your test pressure for the required time and check for pressure loss on the gauge, then reduce the pressure to Operating Pressure and then inspect the system physically.

I wouldn't have any of my guys approaching a system under hydrotest, regardless of test pressure.

 
 Reply 
 
Tj
Other, Piping Inspector
Arak Supply company for Oil and Gas Companies, Philippines, Joined Oct 2015, 4

Tj

Other, Piping Inspector
Arak Supply company for Oil and Gas Companies,
Philippines,
Joined Oct 2015
4
14:02 Nov-29-2015
Re: Pressure Testing
In Reply to Steven Doc at 12:50 Nov-29-2015 .

Hi Steve. In my company, As we reach the test pressure, we practice a 10 minutes observation for the pressure gauge at the test manifold to verify if there will be a pressure drop due to leakage and during that time no one is allowed to enter the test area. The test manifold is placed at about 3 meters away from the test area.

The actual time when the test pressure is achieved shall be recorded and considered as start of the 30 minutes minimum holding time. After the 10 minutes wait, the QC inspector and the Client inspector will conduct a joint walkdown inspection of all joints and the entire line. In case of leaks, the line will be depressurized prior to any tightening or repair.

 
 Reply 
 
Steve Doc
Other, Quality Manager
Siemens Energy, Egypt, Joined Feb 2011, 187

Steve Doc

Other, Quality Manager
Siemens Energy,
Egypt,
Joined Feb 2011
187
14:09 Nov-29-2015
Re: Pressure Testing
In Reply to Tj at 14:02 Nov-29-2015 .

TJ, I have seen this happen all over the world. Extremely bad practice. The system is under excess pressure, and as such under excessive stresses. There is no estimating when a catastrophic failure would occur under these conditions. Pressure Tests are barriered off for a reason. That reason is possible sudden release of energy and projectile objects. As said previously I wouldn't have any of my team work under these conditions.

Take a look at this document, its a good safety reference for pressure testing.

http://www.hse.gov.uk/pubns/gs4.pdf

 
 Reply 
 
ndtalpha
ndtalpha
14:10 Nov-29-2015
Re: Pressure Testing
In Reply to Tj at 14:02 Nov-29-2015 .

Dear
Can you please let me know
If we conduct 24 hours which one is correct start and stop time.any code ref available.

 
 Reply 
 
Steven Doc
Other, Quality Manager
Siemens Energy, Egypt, Joined Feb 2011, 187

Steven Doc

Other, Quality Manager
Siemens Energy,
Egypt,
Joined Feb 2011
187
14:12 Nov-29-2015
Re: Pressure Testing
In Reply to ndtalpha at 14:10 Nov-29-2015 .

Start time is the time you reach prescribed test pressure after all stages of equalisation. End time is when the prescribed test pressure duration has been completed. Depressurisation process does not count as part of the test duration.

 
 Reply 
 
Tj
Other, Piping Inspector
Arak Supply company for Oil and Gas Companies, Philippines, Joined Oct 2015, 4

Tj

Other, Piping Inspector
Arak Supply company for Oil and Gas Companies,
Philippines,
Joined Oct 2015
4
14:27 Nov-29-2015
Re: Pressure Testing
In Reply to Steve Doc at 14:09 Nov-29-2015 .

Hi Steve. Thank you for pointing out this safety concern, I appreciate the article and its a good source to promote awareness on how to do hydrotesting in a much safer manner.

 
 Reply 
 
PPM
PPM
02:44 Nov-30-2015
Re: Pressure Testing
In Reply to Tj at 14:27 Nov-29-2015 .

Thanks for your advice. it is an hydraulic pipe line which goes to deck crane and engine room in a ship. do you have any idea regarding ship building/repair standard for conducting pressure test. according to B31.3 (process piping) the minimum pressure holding time is 10 min. but i want to know is there any other standards for ship building/repair.

 
 Reply 
 

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