8" and Larger Globe Valve Not Allowed in Spec 1

[jskernahan]

Hi All,

I have a piping spec that does not allow 8" or larger globe valves and insists on a v-ball or gate valves as an alternative. I'm not sure the reason for this and am wondering if anyone has any insight? Below are the spec conditions:

Flange rating: 600# (max pressure: 10,210 kPag @ 38 deg C)
Code: ASME B31.3
Temp range: -45 deg C to 260 deg C
Service: Low temp sour process (NACE)
Corrosion Allowance: 3.0 mm

Thanks

 

[pennpiper]

jskernahan,
You need to do some real research on this issue.
This includes an actual quote from a Valve supplier.
Class 600 10" Globe Valve with all your other data vs. a "V"Ball or other valve fit for your service and duty.


Sometimes its possible to do all the right things and still get bad results

 

[zdas04]

Experience with large disks has not been positive. It is hard to keep a very large disk flat in throttle service, it is nearly impossible to successfully lap in the seating surfaces, and it is common for the disks to slip out of alignment with the seat.

A V-ball has none of these issues and are very stable in larger diameters.

A gate valve is not a throttling device and that advice from the standard should not be followed.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[mk3223]

My understanding is that it was difficult to manually operate large global valve which was not justified for the valve cost. Sometimes in the larger bypass valve of the control valve station, the gate valve might be used and intended for a temporary operation as the accurate modulation was not necessary.

 

[jskernahan]

Awesome, thanks guys