B16.34 wall thickness/ B16.5 flange hub diameter

[nctexan22]

1. Table 3-B gives valve body minimum wall thicknesses based on inside diameter. I believe these values are based on a 30k min yield material. Is this true?

2. For an 8" full bore 2500# valve, B16.5 table F22 gives a hub diameter "x" of 12.00". With an 8" thru bore, the wall thickness between the body and the flanges, due to the "hub diameter" will be sub minimum (1.97" vs. required 2.83"). Increasing the "hub diameter" in order to meet the 16.34 wall thickness requirement will interfere with nuts sitting on B16.5 dictated bolt circle. What am I missing here?

Thank you for any assistance.

 

[reverman]

1. See B16.34 Appendix B for method used for establishing P-T ratings

2. the 8" class 2500 full port valve is 5.75" in diameter not 8" (B16.34 appendix A). You won't find a 8" class 2500 valve with an 8" thru bore. (5.75 + 2.06*2 = 9.87")

 

[reverman]

by the way the stress constant used for wall thickness calcs is 7000 psi

 

[nctexan22]

reverman thank you for your reply. I am confused but I feel I'm going to learn something here so it's good. My valve data sheet calls for a B16.34 8" 2500# valve, with 8" RTJ flanges. The thru bore is called out to be 8", and the pipe is stated as being 8" XXS, which would correspond to pipe inside diameter of 6.875" with .875" wall thickness.

So this valve is NOT a B16.34 8" 2500# valve, which would have a inside diameter of 5.75"? In other words the data sheet is incorrect.

Another question: You have used the wall thickness equation in Table VI-1 to obtain the 2.06". Could I use the wall thickness eqn. in B-1.3, which gives 1.96?

 

[reverman]

the valve vendor has stated the thru diameter is 8"? that would be surprising API 6D (which has the largest port requirements I'm aware of) only requires 7.05" (179 mm)

The valve can have a larger diameter than 5.75" and still meet B16.34 (it could have a smaller one for that matter) since the port diameter appendix is non-mandatory. Generally though the port diameter of the valve will be in accordance with API 600 (if this is a gate, globe or swing check valve) which requires 5.75".

Also for gate, globe, and checks most companies are now designing valves to API 600 wall as well which in this case would be 62mm (2.44")

 

[nctexan22]

This is a trunnion mounted ball valve design, with a full 8" bore (8.062" to be exact). So I assume I would, in fact, use 2.83" as my min wall thickness, as provided by table 3-B in B16.34.

 

[reverman]

I apologize for some reason I thought I read gate valve in the first post. I do not have a lot of experience with ball valves and the standards that govern their design. You may want to look at API 608.

But you are correct if the valve states it meets B16.34 then it would need to meet the wall thickness requirements in Table 3-B. If it doesn't then it doesn't meet B16.34