Inline Test Method

[bevjones2009]

Hi all,

I am quite knowledgeable on inline testing with test equipment involving loads cells etc... but I am trying to rack my brains on a method I read about some years ago where the line had to have isolation valves installed and an injection point for nitrogen. The pressure would be increased and a calibrated gauge would be watched for the "Set Point" of the PSV.

I'm not interested in using this method, but it is starting to annoy me that I cannot remember the name of the method.

Can anyone help me?

Many thanks in advance.

 

[mbt22]

Pop testing?

Matt

 

[The Obturator]

Possibly.................It may have been using a ChangeOver Valve. 1 live SRV 1 Standby/Idle. Depending of the COV design, the idle SRV inlet could be pressurised by pressure entry in the space from the closed COV seat with an attached gauge.

Per ISO, only the term Safety Valve is used for all overpressure eventualities regardless of design.

 

[bevjones2009]

@mbt22 - Correct but there is a certain method name for it.

@avalveman - Yes of course there must some sort of COV to keep the system protected.

 

[zacharialamsyah]

I think the name is Trevitesting, which is applicable to Boiler's PSV. To prevent shutdown of eboiler, Trevitest can be applied even on stream condition, and applicable per API 576 and ASME Boiler Pressure Vessel Code Section VIII division 2 Article R-5 .

follow link :

http://www.furmanite.com/services/valve-repair/on-line-safety-relief-valve-testing-trevitest/

for better explanation

Regards,
Zachari Alamsyah

 

[bevjones2009]

@Zachari - No the method is different to a TreviTest, it is more like a hot float but with N².

 

[JAlton]

You may be thinking of an IN Situ Test Method that involves a bleed ring or other port (Some PRVs now have Test Ports in the Nozzle from the OEM) where an Outside N2 Source can be attached above an Isolation Valve in order to Pop Test the PRV in Place. Many companies use this device for In Situ Testing. See attached sketch.

JAC

 

[The Obturator]

JAlton - Wouldn't you compromise safety if you isolated the SV ? It would be better to use a ChangeOver Valve, as I mentioned previously, or to install a bursting disc below the SV and include a test pressure entry point in the space between valve and disc. The disc should be of a design allowing up to 4x the normal burst pressure in the reverse direction.

Regarding having an entry port in the SV nozzle. Some manufacturers have done this from pressure from the end users (or users done themselves). The problem here is later, with a full nozzle design, being difficult to realign nozzle and inlet/body access holes after maintenance.

Per ISO, only the term Safety Valve is used for all overpressure eventualities regardless of design.

 

[JAlton]

ASME SEC VIII, Div 1, Non-Mandatory Appendix M, describes the procedure for installation and use of Isolation Valves underneath a PSV. You could use a Rupture Disc, if rated as you described. A Bleed Ring is the best connection method. I do not care for the Nozzle Tap connection, I just mentioned it as an available option. You are correct that Safety may be compromised by isolation valves, but it is permissible. A changeover valve would be preferable. I was primarily responding to the issue of In-Situ Test Method other than Lift Assist Device (i.e. Trevitest).

JAC

 

[e43u8]

@jAlton,

The link you provided can't be opened...

 

[JAlton]

Sorry about the attachment. I converted it to a PDF. Hope this works.

JAC

 

[bevjones2009]

@JAlton - I would love to see that attachment but the link seems to be corrupt.

 

[e43u8]

@JAlton,

Thanks a lot...now the link has no problem to be opened...

One question about the test operation...

What is the pressure increase rate (pressure ramp up) from normal to set value?

 

[bevjones2009]

@JAlton - Thanks for the updated link, that is how I mean, whilst the PSV is still inline.

Just like testing a pilot valve without removing it from the pipeline.

 

[The Obturator]

bevjones2009 Pilot Operated SRV does not need inlet pipe isolation (and the pilot is actuated not the main valve).

Per ISO, only the term Safety Valve is used for all overpressure eventualities regardless of design.

 

[bevjones2009]

@avalveman - I know that, it was used as a for instance as they can be tested whilst still inline.