BW valves on HP ratings

[Robys]

Dear All
I'm revamping a plant where our client has all the 2" and above valves 900-1500-2500 LB with BW ends, regardless the service or the valve type. My company normally use flanged valves. What's for you the better selection?

 

[JLSeagull]

The end connections normally depend upon the service. Flanged connections are normal for mundane services including hydrocarbon and utility applications. Welded ends are common for small bore steam and for toxic gas such as acid gas.

 

[rmw]

A flange can and more likely than not during its life will leak. Especially if your plant piping is such that the connection will be under stress of some kind. A properly welded BW connections won't leak. Flanges should only be used where you have the expectation that you will have to open the connection at some time or times in the future.

rmw

 

[reverman]

another thing to consider is weight. Class 900-2500 flanges in larger sizes are extremely heavy. This leads to larger pipe hangers and such. This is also one reason you see pressure seal valves in these pressure classes.

a 6" class 2500 bolted bonnet flanged valve would have 4 flanges roughly 4.25" thick or more at least 19" in diameter.

moving to a pressure seal valve with BW ends will probably drop the weight around 1000 or more pounds.

 

[gerhardl]

Apart from possibel risk (leakage) and weight you should also consider the lifetime cost where you else are free to choose between the two types:

What is the likeliness for failure, and the cost (including down costs) for maintenance or change of a certain valve?

In all likelyhood you will probably end up with a mix of the two types, based on availabillity, local price (bid from suppliers), local working hour rates, sizes, material, service, pressure classes and cost as described above.