Dear All,

I am doing Under ground piping stress analysis for FRP piping. Iam getting failure on Elbows. I tried with increasing the thickness on elbows (2.2 times the pipe thk). Then also getting the same failure on Elbows. This is for under ground piping of 400ND.
Please suggest. I kept the pipe under 1.9M depth. Friction-0.5, Soil density-0.00185. here Laminated joints are used. Is there any other factor to conttrol?

1. How would we represent the thrust block while modelling. Is the same anchoring the elbow on both side. ? What are all the changes we need to do? please explain.
2. I heard that, for Laminates pipes in Underground piping, we should not give thrust block..Why? Then How to do analysis?
3. How would we decide the max restaints loads for larger pipe dia (ex. 1800ND,1400ND etc). From what size we need to consider Saddle support.
Kindly reply me for the above queries. Thankx in advance.

Dear All,

How can we do the underground piping analysis for FRP Piping which is varying the burial depth along its travel. And also, How can we give the thrust block for Underground GRP/FRP Pipes of 2 Nos going parallel to each other.We need to give the Anchor/thrust block for both pipes simultaneously.

Please advice your valuable reply.
Thanks

Hi,
Hope these few points will help you
1.We can give thrust block for GRP piping and normally you cannot support the GRP on elbows.
2.The load on thrust blocks will be reaction force due to sudden opening or closure of value.
3.Better to do surge analyis if there is a possibility of surge.

Please note that are laminated joints in Underground piping which are not supposed to give thrust block.

1: Modelling trust blocks on FRP pipe is the same as for steel pipe.
2: Laminated pipes has the same behaviour as welded steel pipe. The connections between the pipes are axially restraint.
3: If you are dealing with that size of pipe you will have a lot of other things to worry about. You never must consider saddles. It's your own free choice.

I have made some comparison between steel and FRP piping. Don't forget that FRP has completely other material behavour. Make sure you first understand steel pipe stress analysis and FRP material behaviour before you start doing FRP pipe stress analysis.

Mr.Corne,

Will you agree this statement mentioned in this topic by satpiping


"
Please note that are laminated joints in Underground piping which are not supposed to give thrust block."