Constant Spring Hanger Vertical Angle Greater Than 4 Degree

[adam08285]

Guys,


According to MSS SP 69,

"If horizontal pipe movement results in a vertical angle of the hanger rod greater than 4 degrees, common practise is to either offset the pipe attachment or structural attachment by the amount of anticipated rod swing or provide a traveling device for horizontal movement. In special cases, vertical angles greater than 4 degrees may be used provided the resulting horizontal force and vertical deflection are considered in the piping and support design. "

From above requirement, the maximum degree angle should be only 4 degree.

My questions is as follows:
1) If we had applied attachment offset but the vertical angle is still greater than 4, is it still acceptable?
2) In special cases, can anybody explain what we are going to do with horizontal force and vertical deflection in piping and support design if angle is greater than 4 degree?
Is it related to stress analysis?

 

[XL83NL]

I believe the 4deg is a value set, below which horizontal have no foreseen detrimental impact on the working. If you're unsure, make a free body diagram to determine the impact.

How much are u off? I've had one situation where there was a possibility to go beyond four deg in the hot condition and we followed the mfr recommendation to stay below this value.

 

[adam08285]

In my case, the horizontal movemnt is the 158mm and offset about 79mm.the vertical angle obtained is 4.4.according to mfr, their spring design can cater up to 5 degree.

I am curious about the last sentence of the mentioned requiremnt mss sp 69 above.do we need to check anything related to stress?