Hi Bhargava ,


I the absence of the model its very difficult to give a specific solution to this problem. Firstly my understanding is that cold spring is used to reduce loads on the terminal points and not as a solution to reduce large displacements. So consider review your decision seeking other opinions . It seems a vertical leg is causing this problem?. A layout and supporting solution is best advised.


To answer your queries please note that by using cold spring you cannot take credit for expansion stresses as per code bcos these are stress ranges and not absolute stresses.Be carefull to check your loads in cold case bcos there are possibilities that the terminal loads could overshoot the allowables in the ambient conditions itself.

1) The maximum limit of displacements in operating state assuming that the code stress check is satisfied is governed by pipe spacing and supporting considerations. We limit the axial displacement of pipes into an expansion loop to 100mm.The transverse movements to 25 mm. But these are not hard and fast rules.

Please note while giving the cold pull the length should be 2/3 rd the actual length to meet code requirements.

2)Since you have a Spring Hanger coming into the picture you have to use the Alpha Tolerance method.This is basically to define the load cases to meet code requirements by segregating the external spring forces from the cold spring forces in the load case F.The cold spring forces are defined as another temperature field using alpha tolerances as you have seen in page 6-6 of Technical Reference Manual.

3)Giving cold spring at locations close to Spring Hanger will definitely affect the hanger design since weight loads are affected .Also note stakes during the the fabrication stage becomes still higher.

4)Though I am not experienced here , Guess you have to fabricate the pipe and then position it and then place the hanger. A second opinion is invaluable.


Hope this is usefull.Feel free to contact me.

Shivaprakash C Rao
www.edeleanu.com.sg

shivaprakashcrao@hotmail.com