what are the suitable gate valve for hot tapping?
what are the suitable gate valve for hot tapping?
(OP)
hello everyone,
my company has selected a (flexible wedge gate valve, API 600) for the hot tapping. but the contractor who is in charge for construction said it should be (thru-conduit gate valve, API 6D.)now the client wants a justification form both side for why we have selected this type of valves. size of valve is 36", and the service is crude oil.
my boss give this job to me. i have done so many research about these two type of gate valve, but i did nor reach to a good justification for using them for hot tapping.
i will be glad if anyone could help me
thank you guys
my company has selected a (flexible wedge gate valve, API 600) for the hot tapping. but the contractor who is in charge for construction said it should be (thru-conduit gate valve, API 6D.)now the client wants a justification form both side for why we have selected this type of valves. size of valve is 36", and the service is crude oil.
my boss give this job to me. i have done so many research about these two type of gate valve, but i did nor reach to a good justification for using them for hot tapping.
i will be glad if anyone could help me
thank you guys





RE: what are the suitable gate valve for hot tapping?
May want to take below criteria for this kind of consideritaon:
1. Process condition (T, P, etc.)
2. Position of the valve (is it vertical or horizontal), some company preferred to installed it horizontally to prevent it from "locked" open or closed
3. Clean process crude oil or not.
By design, don't get me wrong, both valves (Through conduit and flexible wedge gate valve) perform good tight sealing in order for someone can work safely on the downstream side.
Through Conduit Gate Valve use the force from the upstream line pressure to make it more tight sealing (shall Differential Pressure taken into consideration). However, if the process is not so clean, once the valve retracted open, it may carry dirt which on most cases will scratch the seat (which eventually resulting internal leakage shall close position next time). And also if compared with wedge gate valve, the gate is a bit heavier, in that case shall positioned horizontally for some low end manufacturer, the stem would bent (due to load). And you know the rest.
Whether you choose Through Conduit or Wedge, should take into account the design and material of the seat, gate and stem.
I would suggest Flexible Wedge or Double Expanding Gate Valve, hence you are the Valve specialist who know the process and design condition.
RE: what are the suitable gate valve for hot tapping?
If my assumption is wrong, then please advise, but the experience of the hot tap contractor should be listened to - they will have done many hot taps and had some bad experiences, so learn from them.
At the end of the day this is down to risk and cost difference between the two valves, but bear in mind that if you choose a different (cheaper) valve from that recommended by your hot tap company and it doesn't seal, any cost difference is likely to to be wiped out many times by the claim from the hot tapping company.... Your boss will promptly forget that he agreed to this and blame it all on you (!).
Because of their location (often below ground and very close to the pipeline, these valves are often just manual valves not normally operated with the process valves that open and close on regular basis ocated further downstream.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: what are the suitable gate valve for hot tapping?
prognosis: Lead or Lag
RE: what are the suitable gate valve for hot tapping?
As the hot tapping machine cutter has to pass through this valve before it reaches the EXISTING pipe, the passage for cutter has to be clear. Hence what contractor told you is right. It has to be through conduit valve (with nothing in the way of cutter).
This type of mistake happens, when MTO is prepared by an inexperienced designer (who would not write in remarks column or somewhere that this particular valve is for hot tapping), then person preparing the material requisition would simply refer MTO; take valve datasheet and place the order. If the valve happens to be full bore ball valve, or through conduit in the piping material class, day is saved else this situation!