A common question we hear from many of MRC Global’s customers concerns the definition of a double block-and-bleed valve. There is confusion because there are many interpretations of the term double block-and-bleed (DBB) when describing valve functionality. It seems that almost every end user and manufacturer has a different idea of what the term means for valve selection, which can result in the wrong specifications or valve type.
As a leading valve distributor, API fugitive emission standards are something MRC Global addresses on a daily basis. Compliance with these standards and the associated EPA standards are a vital part of the valve selection and sourcing process.
In my 28 years in and around the offshore energy environment, I've learned how important a properly functioning valve network is to the safety and operational security of an offshore platform. Experience shows the best way to efficiently and safely assess the viability of the vital emergency shut off valves is with a condition monitoring system.
For many years, the gate valve has been the “go to” valve for isolation, simplicity and availability for process containment. If an application required a block valve, the gate valve was selected 90% of the time. For extreme applications, when the process conditions exceeded the gate valve’s parameters, a ball valve was used. However, we are now seeing that, in certain applications, a triple offset butterfly valve could be a better solution. The triple offset valve offers many advantages like ease of operation, commercial availability with larger sizes even in alloy materials, and a smaller envelope size and weight.