IMPORTANCE OF USING METAL SEATED BUTTERFLY VALVE IN HIGHER RATINGS

Metal seated butterfly valve are recommended to use in higher pressure rating like #300 and more rather than PTFE seated valve  .PTFE seated valves are designed for using in chemical industry and for low pressure rating and non critical applications and they are designed for class IV leakage only i..e permissible leakage as per API 598 were as metal seated valves are designed and destined to use for higher temperature ,critical application like – hydrocarbon, Sulphur fumes, steam, gases – nitrogen, oxygen, argon etc and they give stringent class VI leakage and highly preferred or can say are only recommend to use for refineries, petrochemical ,terminals , LNG,LPG etc.

As  described and explained in previous mail also PTFE seat valves are meant for low pressure rating and non-critical applications mainly for chemical , water sector  as they have leakage class IV and this amount of leakage is permitted in these non-critical sector and loss is also economical whereas metal seated valves are used for critical application and higher ratings from #150 and above were leakage rate is nonnegotiable and require only zero leakage to avoid expensive leakage loss and reaction of hazardous medium with the environment.

 So, as per our above discussion we request you to only use metal seated valves only for the Oil & Gas projects and this is not recommendation it is a requirement.