Steam Boiler's Safety Valve Spring

[aida2011]

Hi all,

May I know is there any method to assess the condition of spring of a safety valve fixed on a steam boiler?

I saw the normal procedure is to hit the spring and listen for abnormal sound, which could be subjective, and there is one person making the claim that a good method is to put the spring on a horizontal position on a flat floor, put a ruler, and if found slight deviation, (the ruler is not parallel to the floor), the spring is to be rejected.

Thanks very much

Aida Hanani

 

[Jordan Hribar]

Unless you are an A.S.M.E. certified assembler for safety valves for air, steam, liquids and gases.
This is not an issue you should be addressing yourself.

The job of the spring is to hold the seat of the SRV down until a set (desired) pressure is reached, in which case the seat lifts and steam pressure is relieved. If this cannot be done, than the SRV must be replaced, or repaired by a certified assembler and re-stamped.

« Rien ne se perd, rien ne se crée : tout se transforme ».
— Antoine Laurent de Lavoisier (1743-1794)

 

[israelkk]

If you have an access to the required spring specifications (drawing, force vs deflection, etc.) then you need to use a force/deflection spring testing machine to check the spring. Every spring maker should have such a machine. If you have a new spring too, you can try to compare the old one to the new one using such a machine. Allow up to +/-10% deviation of the old spring compared to the new one. You should also check the old spring for wire surface defects, nicks, holes, tool marks, cracks etc., using a X10 magnifying glass.

 

[aida2011]

Dear all

I have seen an inspector of safety valve spring, in checking the spring for crack, he hit the spring with a hammer. Is this method correct?

If not correct, what are other simple methods to detect cracks in spring?

Thanks

Aida

 

[israelkk]

Magnaflux