Pigging through valve - Unequal wall thickness
Pigging through valve - Unequal wall thickness
(OP)
All -
I'm preparing to order a through-conduit gate valve (24") to replace in a 24" line. On the downstream side the wall thickness is STD (0.375") on the upstream side of the valve the pipe is XH (0.500").
Since the bore of the line is changing, do I need to make any special considerations for the bore size of the valve?
If it makes any difference - I've researched how flexible pigs are capable of being, so normally it won't be a problem during day-to-day operations - I'm more concerned that at some points in time they will be using a more delicate smart pig for line double-isolation.
Any thoughts on this would be very much appreciated.
Thanks,
G
I'm preparing to order a through-conduit gate valve (24") to replace in a 24" line. On the downstream side the wall thickness is STD (0.375") on the upstream side of the valve the pipe is XH (0.500").
Since the bore of the line is changing, do I need to make any special considerations for the bore size of the valve?
If it makes any difference - I've researched how flexible pigs are capable of being, so normally it won't be a problem during day-to-day operations - I'm more concerned that at some points in time they will be using a more delicate smart pig for line double-isolation.
Any thoughts on this would be very much appreciated.
Thanks,
G





RE: Pigging through valve - Unequal wall thickness
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. ùGalileo Galilei, Italian Physicist
RE: Pigging through valve - Unequal wall thickness
RE: Pigging through valve - Unequal wall thickness
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. ùGalileo Galilei, Italian Physicist
RE: Pigging through valve - Unequal wall thickness
What is the ID of the current valve? Equal to the thick pipe or the thinner? Which is the direction flow? Thick to thin or vice versa?
The issue is not so much the variance in ID. This sort of change should not cause an issue, but whether the change is a step or a smooth internal angle. A step can damage the feelers on an intelligent pig.
It is a little odd to change ID at a valve, but I would go for the larger ID in the valve and machine the inner face of the thicker flange to transition smoothly between the two wall thicknesses. A slope of 1:4 is commonly quoted.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Pigging through valve - Unequal wall thickness
Their cut sheet has the nominal bore of the valve at 23-1/4"
RE: Pigging through valve - Unequal wall thickness
Where would I get the 1:4 slope value from - pig manufacturer, valve, engineering standard, rule of thumb?
Thanks
-G
RE: Pigging through valve - Unequal wall thickness
I would go for the larger ID of the valve and machine off the difference on the smaller ID (d/s)connecting flange which should have a final ID the same as the thicker wt pipe.
I doubt the valve manufacturer will offer much as this is a pipeline design issue, not a valve issue. If it was me I would say tell me what we want.....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way