Check valve

[Erkamal]

Dear Friends,

I have design one check valve for 10000 PSI .

it is really going good at high pressure. but it is failed at low pressure seat test.

I have used high compressive spring also for giving force towards to seat but still it is not working.

Any one have idea that what is going inside the valve and what should be taken care.

 

[israelkk]

What do you expect without giving your design and calculations to check?

 

[Erkamal]

Dear Sir,
In my above question ,

I said . it is working well at high pressure. only fail at low pressure seat test.

On my view , it should be work. but i can not judge that it is working well on high pressure & do not work on low pressure. so what is the possibility for failing at lower pressure.

I assume that when low pressure will also cover the seat's upper surface. seat bottom surface will be sealed with opposite sealing part.

 

[Danlap]

Hi Erkamal,

what is your definition of fail? In number please and wrt let say ISO 5208 in terms of leakage rate.
Also what type is it? Nozzle or piston/ball type check valve?
check the sealing contact between the "plug" and seat with blue pigment or something.

if you apply high compression spring then it might be possible the cracking pressure when valve required to be open then it will not open. so it is a trade off.
in general yes, high pressure testing normally work tighter compare to low pressure test for Check valve.
if required to work perfectly (zero bubble) for both occasion, maybe you should alter the design.

Kind regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[israelkk]

It either work over the whole spec or not, if not, it is not a working product. How you can be sure that if it will work in these prototypes it will work every time you manufacture from a new batch of materials even from different material manufactures. Or a new batch of seats with the deviations in material properties (hardness, surface finish, etc. Nothing is ever exactly the same. In my area of field you have to prove your design and operation by tests backed by calculations and mathmatic models and simulations that your success was not merely a luck. Without information on the type of seat, actual dimensions and shape, surface finish and many other factors no expert will give an intelligent answer. If such products are available in the market I assume you could check them.

 

[israelkk]

The word design is used too liberaly. Many think that if they created a 3D model of the products or even exact manufacturing drawing with all dimensions correctly defined including surface finish, special coatings they finished a sound design. Life shows differently. Just creating parts from models or drawing is not enough. If you cannot prove that design have to work all the time because calculations of static, dynamics, hydrodynamics and many other fields involved in the products, the word design is an empty shell word.

 

[Erkamal]

HI Israeikk,

Great thanks for your valuable replies.really countable

 

[jbeckhou]

Our design for poppet style check valve uses a peek seal between the poppet and seat. It will hold 200psi no problem, gas.

Petrotrim Services, LLC

http://www.petrotrim.com

 

[israelkk]

jbeckhou

The problem is to work both at 10000psi and low pressure. From my understanding the gas pressure assists the spring to create the seal force. Therefore, 10000psi creates enough brute force to seal (probably metal to metal seal) but when the pressure is low the part of the gas pressure force is 50 times smaller. Therefore, it can not seal. Your PEEK seal works as long as the pressure is 200 psi. Go and see what will happen if you put 10000psi.

 

[Erkamal]

HI Israelkk,

Agree with your comments. yes. Peek seal will not work at high pressure. Metal to metal seal should be.

I am working on check valve which is spring loaded and metal to metal seal. i am modifying some parts . now it is good to prevent on leakage at high pressure & little on low pressure side. now i m facing low seat pressure below 30 PSI only.

Thx to all other frds also who are guiding me .

 

[israelkk]

The problem with check valve is to assure exact return of the poppet every time, which is almost mission impossible. When you have a large force due to the 10000psi pressure it may force the poppet into place or even deform the seat for a new sealing area. However, when the pressure is low it will not. The size of the valve is an issue too. The larger the valve the more difficult to control. You didn't provide general dimensions and design. Therefore, we have difficulty to even start to help you. Another info that can help is an answer to the question if there is a similar check valve in the market that that works and who.

 

[LittleInch]

Erkamel,

other than the max pressure (10,000 psi) and min pressure (30 psi) we know nothing about your valve - drawings, size, type, sealing surfaces, tests being undertaken, leakage requirement, fluid used etc)

It is therefore very difficult to provide any advice or comment on something we can't see other than general comments.

To design something like a check valve with such a large pressure range (330:1) is expecting an awful lot. Check valves are rarely expected to seal completely and with nothing other than reverse pressure difference, there is not much you can do.

Any soft seat will be crushed at the high pressure and therefore you may just need to document what the leakage is at a low pressure.

If you supply more details we might be able to see if there is anything else to comment on...

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

 

[pennpiper]

Erkamal,
I have read all this and I still don't get it.
Why are you trying to Design your own Check Valve?
What kind of system will this Check Valve be used in?
What kind of Pump (Centrifugal or Reciprocating) will you have upstream of this Check Valve?
What is the Commodity (and state) in this Check valve?


Sometimes its possible to do all the right things and still get bad results

 

[jbeckhou]

If the seal is designed correctly, it won't crush. We have used peek seals to assist low pressure sealing in check valves and gate valves for years, API-6A, NL, P+X, 20,000 psi working pressure, up to 7" valves, PSL-3G, bubble tight. I've never seen a check valve (poppet and seat style) rated for 10k hold 30psi without some sort of seal being used. The seal is only there to help seal at low pressure, higher pressure will be metal to metal.

Your problem may not be with the design, could be machining problem, material choice or even the calculations may be incorrect.
If you provided a drawing or assy drawing, I'm sure you would receive better feedback.

Petrotrim Services, LLC

http://www.petrotrim.com

 

[Erkamal]

Hi Friend,
Thx for giving your valuable comments.

Dear JBECKHOU, i m not sure PEEK seal will work at high pressure. it will be gone after few months of use of check valve.

I have attached figure here. almost all thing improve.but i could not judge that how can prevent the leakage at low pressure. leakage is between 0 to 30psi now.

it is one inch , custom made valve.