Single Trip Positioned

[kroal]

Hi everyone. I'm looking for help in translating comments for check valve.

(2) Limit Switch Tags.: 1-XZSH-11300 (Open), 1-XZSL-11300 (Closed)
(3) Seat Leakage: Tight Shut-off as per API 598.
(4) Vendor to Specify all the material to guarentee & satisfy all requirements specified in datasheet.
(5) Valve to be low delta P check Valve.
(6) Valve shall Non slam.
(7) Cyclic Operation every 24 Hour. Vendor to ensure the Design of Valve accordingly.
(8) Process Gas contains 74.76 mol% Hydrogen.Valve shall be suitable for Hydrogen service.
(9) Helium leak test required as per ISO 15848.
(10) Pressure Drop - a) 343.3 kPa with no air supply to check valve piston. b) 1 kPa with air supply to check valve piston.
(11) Actuator is pneumatically assisted/ close damper spring return.
(12) Air to actuator to allow valve to open but not prevent valve from closing.
(13) Valve shall have hardfacing Alloy #21 (Stellite) disk and body seat.
(14) Air bottle to cater for three full strikes.
(15) External Self contained Hydraulic slam retarder to prevent disc slam under rapid close operation.
(16) Power (Air/Electricity) Failure Position: Back-up Bottle air comes online; Check Non-Return Function ≤ 1 kPa ΔP on inlet side; Closing on Reverse Flow Single Trip Positioned; Check Non-Return Function ≤ 343.30 kPa ΔP on inlet side; Closing on Reverse Flow.


Ask to explaine next:
1. What is "Check Non-Return Function"?
2. What is "Single Trip Positioned"?
Thanks in advance.

 

[LittleInch]

1) sounds like they want a test to demonstrate that when held fully open, the DP is < 1kPa
2) They want the limit switch checked to show that it shows closed when it is closed.

Looks like a pretty onerous spec to me - Any pictures or diagrams?

The non slam bit always gets me - totally dependant on speed of reverse action (not specified). A fast one (< 1 second) and the non slam piston needs to be massive. Only non slam ones I've ever seen work well are the axial flow valves where you can balance the forces much better than a swing check

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[kroal]

Thank.
Unfortunately that is all information. I think it was translated from italian to english. And now I have misunderstanding during translation into russian.
Alex.

 

[gerhardl]

Careful here! Refer point 10) in requirement and 16. This is still unclear to me, but likely that they want to check the failure operation. Suggestion:

Situation 1) Control of and requirement for failure position:
- Back up bottle comes online.
- Control of (non return function): that the valves stays open when the pressure difference in the main piping line ≤ 1 kPa (which is also the allowed ΔP resistance for full flow over the valve?) on inlet side. Valve shall close if flow reverts. (But at what pressure closing shall start, and how it shall be released is not defined?!)

Situation 2) Single trip positioned (???) What does this mean? Normally I would have read this as either a) Valve released and closed, control of full tightness and limit switch signal. Valve shall close if flow reverts. (Alternativ situation 2: gone from normal situation with power, to position (at main power failure) ready to be released and operated by back-up system???)

We can guess all we want, but please check! I have experience for translations from original language to English to be strongly misleading, having to cross-check the original, when I translate to a third language.

Anyway my experience is (agree with LittleInch here!) that datasheets very often contains all information, except what you need to supply the correct product.

 

[georgeverghese]

To me, "single trip position " could be the first instance when the backup air bottle supplies air to the check valve to assist with the opening function.

 

[gerhardl]

Seems logical, georgeverghese!