PRV Replacement

[ammoniachick]

We were told by an out side consultant that we are required to send off our PRV's back to the manufacture as we replace them every five years. I can not find this recommendation/rule in any of the guideline books I have. Is anyone doing this?

 

[micalbrch]

Send the old ones back to the manufacturer and buy and install new ones or send the old ones back for inspection and install them again after return?

What is the purpose of the PRV and where are you from?

 

[JohnGP]

It's not what we do, but maybe what a PRV manufacturer would like to happen. Our PRVs are checked on site by a certified calibration organisation and I'm not aware of any regulation that would require sending back to the manufacturer. We also wouldn't replace unless physically damaged or couldn't be calibrated to the required set pressure.

Cheers,
John

 

[ammoniachick]

The PRV's are on Ammonia Pressure Vessels. Send the old ones back to the manufacturer and buy and install new ones

We are a small company and do not have on site calibration guys.

 

[JohnGP]

Relief valves need to be able to operate as designed whenever the requirement arises. To ensure that functionality they must be regularly checked and recalibrated, depending on local requirements for the type of equipment being protected. To be certified, any repairs and calibration must be performed by a recognised facility (the manufacturer obviously being one).

Removal, repair, calibration, and re-installation should be planned around shutdown periods for the plant. Whether or not you send the valves out for refurbishment, or have someone come in to do the work at your company, if your shutdown period is shorter than the time required to complete an overhaul, then of course you would need new replacements to be available to install immediately.

I don't know where you are, but as I said, I am unaware of any requirement to send PRVs back to the manufacturer, and can only imagine that happening if you wanted them to overhaul the valves and there was no one locally available to perform the work and recalibration. The valves themselves should last longer than 5 years (depending on the environment) but maybe some of the internal bits will require replacement during the overhaul.

Cheers,
John

 

[MJCronin]

Chick...

The requirements for relief valves in ammonia service are goverened by ANSI K61.1.

Replacement dates are affixed to the valves.

Para 5.8.15 of K61.1 gives a maximum of 5 years.

The RV manufacturers love it....

http://www.henrytech.com/Tips/HT-TT11.pdf

-MJC

 

[dcasto]

The PRV's sent back are yours and you should get a cash credit. The relif valve company just rebuilds them and sends them back out.

 

[JohnGP]

My lack of experience with ammonia shines through.......

 

[micalbrch]

dcasto is right. Why should you send back the PRVs you paid? They are yours. And then you shall pay the same amount for new ones? Scrap the old ones and buy new ones or send back the old ones but then pay less than for new/overhauled ones.

That is not of lack of experience with ammonia. That is more a bad attitude of the PRV manufacturer.

 

[JohnGP]

Oh I could see that the PRV manufacturer is onto a good deal, I just didn't realise that PRVs in ammonia service have a specified maximum service life of 5 years. That being the case though, is it allowed to overhaul and resell into the ammonia industry or elsewhere?

Or do manufacturers require the valves to be returned so that they can ensure that the valves are taken out of service after 5 years and scrapped?

 

[micalbrch]

I confess that I do not know anything about PRVs in ammnonia service. But can the manufacturer of the PRVs be held responsible for what the user's responsibility must be (= replace the PRVs after 5 years)? Hard to beleive.

 

[ammoniachick]

Thank you for all of your posts! All very valuable information!