SRV Calc: Using Weibull Analysis to Predict Valve Replacement

The five-year replacement interval for relief valves isn’t a practice that gets much scrutiny. It’s spelled out in IIAR Bulletin 110, and a provision establishing the need for a common interval appears in the Boiler and Pressure Vessel Code, making it a generally accepted “no-brainer” for much of the industrial refrigeration industry.

At its core, that five-year estimate for optimal replacement of valves is just that, an estimate. And it’s an estimate that raises questions about how relief valve replacement intervals can impact optimal safety, efficiency and economics in any facility. Until recently, no real mechanism for quantifying those replacement intervals – and the potential benefits of extending or shortening them – has existed.

But a new analysis tool, called SRVcalc, may prove to be a powerful way to do just that, with long reaching implications for how the industry implements generally accepted practices that have been on the books for years. SRVcalc is a tool intended to statistically analyze post-mortem relief valve test data to refine the replacement interval of relief valves for a given installation.

SRVcalc is the byproduct of a research project funded by ARF and overseen by the IIAR Research Committee. The principal investigator for this project was Dr. Frederick T. Elder of Frederick T. Elder and Associates, Madison, WI. “Like all IIAR research projects, SRVcalc is intended to fill in the gaps in our knowledge base,” said Bruce Nelson, IIAR Research Committee Chair and President of Colmac Coil Manufacturing Inc. 

IIAR Premium Content. Click here to read more.