The first step would be to check with local legislation, and I assume that you have done it already.
If the local authority allows, risk based method can be used to extend the PSV testing interval. Now you have two choices:
- The quantitative API 581 method: this one requires PSV testing data and procedure to meet with certain requirements, and most of the time the calculation is complex, confusing, and takes long time
- The qualitative risk based method proposed long time ago by BP, and since has been adopted by other companies such as Premier Oil, KNOC, Conocophillips. You should refer to BP GN31-008 for more information.
There is another sub-option of the qualitative method, which was developed by a consultant named Centrica Energy, using a different flow chart than BP but same philosophy. I'm not sure, though, where this method is actually used.
Edited by dutru, 02 February 2016 - 08:16 PM.