Dear all,

Regarding this discussion, I have recently analysed well head (christmas tree) lines considering 50mm displacement upwards as well as downwards. It eventually gave "for operating case with upward displacement, lift off in first support" and "for operating case with downward displacement, heavy load developed downwards in first support and failed with code compliance".

In this case, i suggested spring support in first support location and designed the system with a spring. now, the stresses, loads on supports & terminals, displacements all were satisfactory and i prepared the report.

But then, it was strictly told by the client that no spring support will be used in this project. so, i redesigned the system with no rest but guides only (i prepared support detail for first support location with a maintenance rest support which will be located with 60mm gap below the line. so that during downward displacement the line will not press down the rest support and create more load and stress). since the horizontal length of line was less than 6mtr, maximum sagging (displacemnt) was 6mm with no rest. so i decided this is ok. i found the loads also within limit. now i have prepared the report.

But, i still wanted to know from you experienced engineers if the design i have done with no rest but only guides arrangement (note that i have given maintenance rest support which is in no effect during operation and sustained after installation)is desirable when i cant go for spring support. Please advise me on this. I have to release the report only after your replies.

(note that the max stress ratio is 37% and that is in sus case. the stresses in other cases are low. the max deflection in sus case is 6.2mm and the max vertical load is 3.5KN on terminals. the line is 4" dia, A333 gr6, 43C operating temperature, 30mm insulation)

thank you all in advance.