Hi Pipers,
Well I am doing stress analysis of 24" pipeline having 90deg temp. Now the moments and forces which are coming on the thrust block is around 45 tonnes. Can somebody suggest me how to reduce these forces provided that you don't have a loop option.
Or there is no option but to design the thrust block for that much load?
Regards
Bikram

Is the pipeline buried ? 45T is a huge load, which assuming it's axial, must be due to full restraint. Can you add some flexibility ?

Sorry guys , the load are coming around 450 tonnes.
Any solutions to this?
Regards
Bikram

yes you can install thrust block and anchor flange for calculation.. but what happen to you piping system? will it not buckle? 450tonnes is pretty big will civil guys not protest?

If you want.. fixed it in the middle and install resting at both ends -IMO-

Regards!

Hi Bom,
"fixed it in the middle and install resting at both ends "-Can you please elaborate on that, Since it is a burried pipeline.
Regards
Bikram

hi piper,

oppsss! Sorry i was out of topic.

Regards!

Two opposing inline axial restraints have been discussed numerous times in this forum. A recent one was http://www.coade.com/ubbthreads/ubbthrea...=true#Post16839

This is very basic strength of materials, Delta= P*L/(A*E), solve for P.

If your load is due to thermal expansion, then you must quantify some "give" in the soil, supports, etc...

Now if this is a pressure times area load as in unrestrained pipe (Bell & Spigot, or Dresser coupling) then you have quite an adventure ahead of you.

But Bob,
Do you think we can do something in this case , as we don't have a supporting arrangement where we can play . Can you please explain what you said about the soil"you must quantify some "give" in the soil".
Thanks for the concern.
Regards
Bikram Jeet Singh

Not an uncommon problem. I here comments like "I'll have to pour enough concrete to fill a house to hold that load". But one insight was this - that concrete will not immediately carry the thrust load as minor gaps will have to close first. This small motion will reduce the resulting thrust load. The reduced thrust load will reduce the amount of concrete. It's just being practical, which may be hard to do if you only see CAESAR II results.
So, turn your anchor into six rigid restraints and vary a gap on the axial restraint to see it's effect on the load. But keep an eye on how that gap changes things on the sensitive side of the "anchor".

Hi Dave,
Well Thanks for the reply. But tell me how to achieve practically this at site. I mean what can I do to achieve these gaps and absorb the loads while laying the piplines.Since the pipeline is in a trench and soil around , is this the way soil forces acts on the pipeline.
Regards
Bikram

Bikram,

I have no practical experience to give you on anchor sizing for buried lines. I can tell you a lot about analysis though - you will probably see a great drop in axial load if you loosen up on that axial restraint provided by the anchor. It's up to you and your fellow engineers on the job to marry the real world uncertainties with the ideal analysis.

You keep getting advice, and ignoring it. If you only want someone to say, "That's OK, it will work!" please specify such in your initial post. You will have a very short thread.

How are you going to resist these thrust forces in the real world? By building a foundation.

Who designs foundations? Normally, civil engineers.

Have you talked to your project's civil engineer? What does he say? If your soil can handle 1000 psf, then he is going to need a 30' x 30' bearing area. That's a whole lot of concrete. And, since you're unlikely to bury your pipe 15' below grade, he's going to have to design a foundation with a high aspect ratio, which is not going to endear you to him.

450 tonnes is a whole lot for a 24" pipe at 90 F. For a 3/8 wall pipe, this is a design axial stress of over 100,000 psi. What is your pipe material?

I suggest you put away the computer software and do some pencil and paper calculations for a few hours, until your understanding of your piping system is deeper than just knowing what the highest number in your computer output is. Then go back to the software and find a solution to your problem.