Large Valve Body Wall Thickness - Standard/Code 3

[Y-Shevy]

We have an enquiry for a very large axial nozzle check valve (>60in) to be manufactured from carbon steel. The customer has specified a relatively low design pressure (~8barg) which is well below the material specific ceiling pressure for a 150# valve (ASME B16.34). The customer has specified the flange geometry requirements (ASME VIII Div1 App.2) which is also based on the DP (and will dictate the hydro testing).

My question is; what standard/code to use as the basis for the body wall thickness (as the customer has not specified this information). Our default standard would be ASME B16.34 for body wall thickness requirements, however, the valve is out of scope, even so, an extrapolated wall thickness based on diameter would mean the full 150# rating would be a significant cast weight (cost). Additionally, the valve would be serioiusly over-engineered for a DP of 8barg. As this is a one off supply we are extremely unlikely to have a repeat order of this size.

Another standard we would consider is: BS EN 12516-2 (Industrial valves — Shell design strength Part 2: Calculation method for steel valve shells).
Other than BS EN 12516, are there any other resources for calculating valve body wall thicknesses for diameters well beyond the scope of ASME B16.34?
Thanks
Y

 

[bcd]

The scope of AWWA standards often go beyond NPS 60 in size. The AWWA standards usually have a Table giving minimum wall thickness by size, pressure class, and material.

Another option is MSS standards. I took a quick look at MSS SP-67, which is for butterflies since I knew the scope includes larger than NPS 60. MSS SP-67 provides an equation to calculate wall thickness for valves that are not in accordance with ASME B16.34.

SP-67 wall thickness equation is: t = (1.5 P d)/(2S - 1.2P)

t - wall thickness
P - pressure rating at temperature under consideration
S - allowable stress per ASME Boiler and Pressure Vessel Code Section I or Section VIII Division I

 

[LittleInch]

The thing to watch as a check valve is whether any forces are a square of the diameter? Not all forces in valves are due to pressure.

Any form of shock loading on this could be very significant.

That is a decent sized valve alright.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Y-Shevy]

Thank you for your responses bcd and LittleInch! I've not referenced MSS SP-67 before, but I'll get hold of a copy and have a read. I also take your point regarding the shock loading.
I will crunch a few numbers, I'm curious to see how close the wall thickness calcs compare between BS EN 12516-2 & MSS SP-67.
Cheers
Y