Metallography utilization process for Stainless Steel PSV Failure Assessment

Nestor Ferreira Carvalho, Marcus Vinícius Gonçalves, Roberto Egon Heinrich, Aldo Ramos Santos, Deovaldo de Moraes Junior

Abstract


To meet legal requirements aimed at the safety of people, environment and equipment, all boilers and vessels containing fluid under external or internal pressure, to operate in Brazil, should have automatic safety device against overpressure. Most companies adopt for this purpose Pressure Safety Valves, PSV calls. Where the PSV is subject to a variable back pressure over 10%of the opening pressure, balanced valves, which use abel lows for protecting the valve seat and prevent the effect of the back pressure. This article reviews the material and manufacturing details of balanced bellows PSV´s as well as the stress corrosion process associated with stainless steel and comes the cause of failure using metallography as a to confirm the mechanism of deterioration involved.

 

Keywords: Safety Valve; Bellows PSV; Stainless Steel; Metallographic; Stress Corrosion.


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