Reduced Port with ASME B16.34

[JChanMe]

Hi Guys! I am having a hard time understanding the description in ASME B16.34.

We placed an order for 14" Cl 2500 BW gate valve, in the order, it does not specify RB or FB, now the manufacturer considered it as reduced port (12" Port), so the valve has a 14" ID on end connections and 12" ID of flow passage and they claimed they referenced Table A-1 in Nonmandatory Appendix A. But I found that section 6.1.2 specifies that the inside diameter shall not be less than 90% of the basic inside diameter. Can any body help me, please?

James Chan
FBV Inc.
Engineered Solutions

 

[bcd]

The 90% restriction in 6.1.2 of B16.34 is for establishing the minimum wall thickness of the valve body. It limits how much the wall thickness can be reduced on a 14 inch valve. For an extreme example, say you have a 14" class 2500 valve with 2 inch internals. Without the 90% restriction, you would be able to make a 14 inch valve with 2 inch wall thicknesses.

Won't mention anything comparing full versus reduced bore. Lots of debate within the valve engineering forum on that. Some opinions and some facts on FB versus RB in that forum.

Table A-1 in Appendix A is informational only. It explains how the relationship between valve size and iminimum ID were established. It has nothing to do with your situation.

 

[JChanMe]

thank you bcd for the explanation. Regarding FB and RB on gate globe and check valves, i am still not sure if it applies. If so then it is acceptable to have a 12 inches valve's flow passage with 14 inches valve's end connection, plus appying the relationship.
I have been trying to find out more about bore issues, but only API 6D has the definition and a table to establish the min bore diameter.
Can you point me to a direction regarding the FB and RB, please? Bcd
thanks.

James Chan

 

[bcd]

Reduced bore is legitimate in gate and check valves and is acceptable for some applications. You will need to determine if full bore is required in your application. For example, if a pig will be used to clean the pipeline, it will not pass through a reduced bore valve so you need full bore.

For minimum bore sizes, you can look at other gate valve standards from API. API-600 for example. It also lists the minimum bore size for a 14" class 2500. What standard was specified in the purchase order?

 

[JChanMe]

Hi bcd,

thanks for your reply. I really appreciate it. The standard specified is ASME B16.34 for design. Now everything comes down to one question: is it acceptable to use the minimum bore size of a 12" valve for a 14" valve?

James Chan