Safety valves

[BESC5240]

Hi,

I've been searching for an official guideline (European legislation/standard) that states the period after which a safety valve has to be replaced or recalibrated.

I always tought it was good practise to check the safety valves (and the exchaust pipe) every 6 months visually and to replace the valves each 5 years (and after they have been open of course).
But I wonder if their is any official guideline on this.

I would need the European guidelines on this, however I'm also interested what is done in the rest of the world (or what officially should be done).

thanks.

[aawood1]

Hi, Under BS EN 378-2000 it just says "However Bursting dise's and other relief devices should be changed at appropriate intervals." I do not know if this comes under the requirements of the Pressure Equipment Directive (PED). I have always changed the safety valves about 42 of them on one site after 5 years, and sent the 50mm ones back to Heal to be serviced and recalibrated.
Arthur.

[Peter_1]

Besc5240, I have the 4 leaflets of the EN 378, those we used at ... you know. I then took copies of these.
I think we needed those for the first PED certification you did for Carrefour.
Have you read these already?

[Peter_1]

I went to the final works of the Bachelors in Kortrijk and Stefaan has given his 2 students a study about C02 cooling "C02, myth or the future'
They visited also a CO2 plant in Luxemburg and London.
They're planning to install one next year for Match.
I received Friday the pdf version of it.

[BESC5240]

Hi Arthur and Peter,

Thank you for your reply.
Up till now I also found this vague term "appropriate interval". I was hoping that there was a more specific figure somewhere ...

Thanks anyway.
Any other input is welcome.

[Argus]

I always tought it was good practise to check the safety valves (and the exchaust pipe) every 6 months visually and to replace the valves each 5 years (and after they have been open of course).
But I wonder if their is any official guideline on this.

I think that you have partially answered your own question, which is you change them out when ever they have operated in anger or after a certain period in service (in your case you have assessed 5 years, no doubt based on your experience and good practice where you are).
There really cannot be any definite term of years or period of time because systems and valves vary so much.

EN 378 is concerned with requirements for safety of systems, not the question of maintenance good practice. So by saying that they should be replaced or recalibrated after an “appropriate interval”, they are inviting you to make a judgement based on your experience.

You may consider checking through the Guidelines to the PED, but I’m not sure it’s covered there.

http://ec.europa.eu/enterprise/press.../index_en.html

There are unlikely to be any set tables of intervals or you would have found them by now.

Why not write a short method statement for the operating manual, probably no more than a paragraph or two; describe the type of valves and the operating pressures and list the significant events that determine when they should be changed. Include in it a short risk assessment explaining the rationale for your period of 5 years.

That way you can demonstrate a best practice approach and an evaluation of the risks together with your reasoned approach to a solution.


.

[US Iceman]

I have seen the "five year rule" also here in the US. I have not been able to find where this began or the logic behind it.

In some sense, this seems to approach the realm of urban legends. Everyone I talk to says the valves have to be changed in five years, or immediately after a discharge.

I can certainly understand the need to immediately replace a valve that has discharged, but the five year rule... no one can tell me exactly where it came from.

Several end-users here are beginning to test their old valves for relief pressure while trying to develop some statistics to support extending the five year rule. Unfortunately, the information I have seen is not very complete (this was just started in the last few years). However, the general tendency is the the five year rule may be too short!

[NH3LVR]

I thought the 5 year rule came from ASHRAE, and had been taken up by the Insurance Companies and State Boiler Codes. Will have to check with the Boss on this one.

[US Iceman]

I would like to know where it came from too. Right now I'm beginning to think it is a rumor that was passed around often enough to become a fact!

[TXiceman]

The 5 year rule in the US appears in the IIAR bulletins. ASME and other codes do not require any specific change period. Where plants here gt caught is on the PSM and RMP which will reference the IIAR as part of the requirements. That then makes it part of the PSM for that plant.

Most chemical/refiners have pretty well defined safety procedures that often go well beyond the national and Federal standards. Most of the plants use the expensive Farris, Consolidate, Anderson Greenwood type valves and rebuild and test the valves on about a 2 year program (sometimes longer). They will hardly accept a "cheap" throw away type refrigeration valve.

Do the European codes reference any of the IIAR standards. If so, the 5 year rule will creap in that way.

Ken

[Paulajayne]

Under the UK Pressure Safety Systems regulations 2000 S.I. 2000 No 128 :-

Bursting Discs exchanged every two years.
PRVs overhauled or replaced every four years.

Paula

[US Iceman]

The 5 year rule in the US appears in the IIAR bulletins. ASME and other codes do not require any specific change period. Where plants here get caught is on the PSM and RMP which will reference the IIAR as part of the requirements. That then makes it part of the PSM for that plant.

Thanks Ken. I suspected it was the IIAR bulletins, but have not really spend a great deal of time looking for it.

The last sentence in the above quote is the one I did not think of. Interestingly enough, I have heard of some valves being tested after the five year replacement that would not relieve until higher pressures were used (than the stamped set point).

Your comments on the process safety valves is similar to what I have expereinced also. This leads me to believe we in the ammonia sector have a ways to go yet.

Thanks for input.