Help sourcing a PSV for a CRI package (3rd time lucky)

[cannondale]

3rd time lucky (I posted this elsewhere on the forum too)

I'm designing a system to pump mud cuttings slurry and am looking for a pressure safety valve to protect the system.
The max working pressure is 520 barg and we plan to set the PSV at 572 barg (8294 psig). The pump is a triplex, 8" stroke 5.5" plungers, with a damper on suction and discharge to get me +-3% pulsation frequency.

I've been looking at auto reseat, lever reset and pilot operated valves. is there a technical reason why i shouldn't use the auto reseat over a lever reset?

Pilot operated valves are pretty much out due to cost, but I can't help but keep looking at the auto reseat valves on a price basis.

Plus, anyone know why I can't find valves at this pressure with PED certification.

I'll have to get Gost K certification foe the valve if it doesn't have it so any experience of that too will be of interest.

Your comment greatly appreciated.

 

[dcasto]

first, you can not set the psv at 10% over unless it is a pilot operated valve.

Next, if you want economy, you will pay for it one way or another......

you have 8000 psi with some huge investment in equipment and personnel expose, whats a few bucks for the right PSV worth.

 

[cannondale]

So tell me what is the right PSV ??
It seem there's only personal opinion and little to choose technically.
The decision is far less of a cost driven one and more of an operational one.
On the cost subject, there is a sizable difference in cost, approximately: 5K (auto reseat) 15K (lever reset) 40K (pilot operated)
Pilot operated is not a consideration due to the requirement for either air or nitrogen, which isn't readily available at this site, and the cost of providing a support system if a complete none starter.

 

[micalbrch]

dcasto/cannondale: I answered this question already in another thread. The pump is a reciprocating triplex piston pumps. Although equipped with a pulsation dampener it will create some pulsations and this leads to pressure peaks. Therefore it is common practice to set the PSV higher than the pump's operating pressure. The PSV must not be set higher than the pulsation dampener pressure rating but that's another story. And the PSV does not have to be pilot operated to do so. It must be a full stroke pressure relief valve which is designed to release 3 times the stroke volume of the piston pump. One can think about a 5 or 10 % higher setting, that's true. But that should depend upon the gearload of the pump at given pressure. The main purpose of the PSV must be protection of the pressure vessel, of the pump casing, of the pipeline (if you want) - protection of everything which can burst and severely hurt people. The pump gearbox can break. That's expensive but will not create any dangerous situation.

 

[cannondale]

micalbrch:

Thanks for you posts here and on the other thread. I've not been able to resolve my issue as yet.

As you say the PSV is there to protect the personnel and equipment from failure. In this case the pump and pipeline can do 10,000 psi, so no problem there. My client has this now accepted the use of an auto reseating type valve, over a lever reset type.

Although I'm still curios as to other peoples experiences of the different configurations (pros and cons).

The common consensus is not to use a pilot operated valve due to the likelihood of the pilot tube blocking, and is generally uneconomical for a fixed pressure application.

Lever reset, direct acting valves, appear to be a good safe solution, as they need to be manually reset, following an over pressure situation. Although operationally, they could be fairly annoying when working close to the set pressure.

The jury is still out on a definitive selection. However, I'm going to use a conventional direct acting valve, that will reseat following an over pressure situation. (probably either from Anson or Weir SPM).

Thanks for the assistance, the lack of replies also alerted me to the fact there may not be too many systems like this where there's either a choice, or an alternative PSV available.