Minimum Separation between a Hot Tap and an existing weld or a bend

[RiniEIT]

Does anyone know the minimum separation distance between the edge of a pipe bend and a hot tap saddle? And also the same for between a circumferential weld and a hot tap saddle?

"The important thing is to never stop questioning" - Einstein

 

[LittleInch]

IMHO, this is no different than minimum distance between circumferential welds. This has been discussed many times before and the general consensus is 2 times the HAZ, but there are lots of opinions and few hard facts.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RiniEIT]

Thanks.

One more thing, can a saddle be located on a small bend such as a 1 or 2 degree overbend or sagbend on large mainline pipe, lets say NPS 42 or 48 in size? I would think not but not sure if there are any exceptions or allowances. I'm trying to locate an NPS 4 hot tap saddle onto NPS 48 mainline pipe with a slight bend in it. Before I decide to shift my design up or downstream to avoid this bend, I'm just wondering if it can be done.

"The important thing is to never stop questioning" - Einstein

 

[pennpiper]

Newq2Pipe,
You are asking questions on a Forum that you should be addressing to your Hot Tap Specialist Contractor.

They are in the business of doing this type of dangerous work and should know all the answers. Of course they will need to make a site visit and evaluate all the safety concerns before they can make a final decision.

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

 

[BigInch]

1-2[&deg] bend isn't anything to worry about, if that bend is over the length of a whole joint of pipeline, but if it is 1[&deg] over the length of 1/4 diameter, it's a lot more.

If you need a straight edge to see it, don't worry.

 

[LittleInch]

Radius of the bend is thekey issue.

If this is a saddle type then it might depend on the length of the saddle, but for a 4" on a 48" assuming this is a cold bend, then I agree you shouldn't see it, but then the actual bent part of the pipe for a one to two degree bend won't be very long so why does it need to be exactly there??

It sounds like it could be done, but if you can avoid it then it is good to do so.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RiniEIT]

Gents, thanks for your input.

The reinforcement length of the saddle will be 306mm. From what I know, sag bends or over bends tend to span 1 degree per pipe diameter. So the length of a 1 degree cold bend on an NPS 48 mainline pipe will run for 1219mm.

I am vouching for moving the saddle away from the bend but the client coordinated the field survey efforts and the survey company only swept an area of pipe containing 2 to 4 degree sag and over bends. The reason for all the existing bends is to achieve underground clearance from an existing highway, located a bit further downstream.

I will go ahead and call a hot-tap company and see what they say. I should've thought of that sooner. Stay tuned.

"The important thing is to never stop questioning" - Einstein