Above ground Pipeline 1

[vijaydere]

Good Morning,

I am analysing Above ground pipeline which is 6 Km long.

my question is whether I need to model it completely and analyse as a normal piping system, or
is there any virtual anchor possible in above ground potion so that we can ignore the rest of the part as we do in underground pipeline?

Thanks
Vijay.

 

[LittleInch]

Yes you need to model the whole section. AG piping normally needs expansion loops or offsets to reduce stresses. Pipe is not constrained like it is when buried so can bend and bow. Pipe will eventually lock up but this is usually s lot further than when buried, but depends a lot on what your supports are and friction factor used.

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

 

[KevinNZ]

You could design a standard straight run with support spacing to cope with gravity, wind, EQ etc. Then only model the pipe at the expansion loops to few supports way from the loop. At ends of the model place an anchor with the displacement calculated from the length of pipe back to the actual anchor. But when you design the actual anchor you will need manually work out the anchor loads from all the attached pipe.

I would model the whole 6km. It does not take long to enter all the nodes.

 

[vijaydere]

Thanks to both of you for sharing your thoughts.

Regards,
Vijay.

 

[LittleInch]

To increase length between expansion loops what sometimes happens is you analyse a straight run with a free end, run your cases and then work out where the lock up starts ( no movement of the pipe on the supports) for the smallest distance. This then becomes your midpoint between expansion loops or bends.

If you try to run pipe for too long in theory it will create compressive stress. In practice there will be some part of the piping not the same as the other, either in x, y or z or strength and then all that stress will feed into a single location from either side and either buckle or bend the pipe or mash buckle the pipe. You will spend longer going round repairing it and putting it back on the supports than any minor saving in expansion loops.

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

 

[C2it]

IF you have several roughly equal lengths between line-stops or "anchor bays" beware that a stress calc may show nearly zero axial load due to equal and opposite loads from either side of the restraint. Whilst that is the theoretical 'normal' case, massive differential axial loads can be developed when a thermal change occurs along the pipe, through line filling or initial flow for example.