expansion loop guide

guys

can anyone tell me what is the minimum distance for the closest guide to the expansion loop? considering the loop is not anchored in the middle and the loop is free to move in direction perpendicular to run on the piperack. do we have any criterion for that distance?

Not anchored in the loop leg?


Guide is required for loops to be effective in reducing EXP stress.
I have seen in some books, the min length marked in the below image as 40D etc... However it is difficult to follow and its based on judgement on the load on the first guide, EXP stress and the displacement in OPE case.
However max length would be dictated by the optimum spacing between pipes,EXP stress and stress in SUS+U1 (Seismic) case.



You want the loop to move as far as possible in perpendicular direction to reduce guide load?

40D is excessive (e.g.foar a 10" line, 40*10=400inch (10160mm)

General rule is first support before and first after the loop to be guide.

You already have some contraints as number of lines that have loops at that location (grouped loops), distance between the beams.

Regards,

Dan
then what if the first support is so close to the elbow at the loop?

What do you mean?

Dan,
I also felt the same, 40D is difficult to follow.
bobby,
you can have the first support from loop as rest and the next as rest+guide. Any problem?

Gents

I agree with you guys. I think normally you put it at a decent distance from the loop and that depends on the perpendicular run of the loop, pipe size and some other factors. actually that was a question I had been asked during an interview and I didn't know the answer. I reckon there is no special rule for that, since I have not found any answer for that.