MECHPIPENEER
Petroleum
Hello Folks,
I am trying to better understand how friction at pipe supports contributes to pipe stress due to thermal expansion/contraction on long runs of pipe supported in a rack. I have conceptualized a hypothetical scenario as follows to aid in my understanding:
- A straight run of pipe of OD 'D', thickness 't', and length 'U' anchored at one end (infinite capacity anchor) and fully free to displace axially at the other end
- The pipe is supported on a rack with spans of length 'L', the pipe is free to displace axially along the rack, however there is an axial friction resistance at each rack support of 'Ff'
Does friction due to thermal exp/contraction accumulate from the total qty of pipe supports to produce an axial force = U/L*Ff between the anchor and first support? Or does the disproportionately larger thermal pipe displacements at the supports furthest from the anchor result in friction accumulating and dissipating in a staggered manner between the supports back to the anchor resulting in a lower axial force?
In the end can a pipe as described above be infinitely long without exceeding allowable stress due to thermal exp/contraction or is there a limit to how long the pipe can be due to the accumulation of friction at the supports? I am working to B31.3 and B31.4.
Thanks in advance!
I am trying to better understand how friction at pipe supports contributes to pipe stress due to thermal expansion/contraction on long runs of pipe supported in a rack. I have conceptualized a hypothetical scenario as follows to aid in my understanding:
- A straight run of pipe of OD 'D', thickness 't', and length 'U' anchored at one end (infinite capacity anchor) and fully free to displace axially at the other end
- The pipe is supported on a rack with spans of length 'L', the pipe is free to displace axially along the rack, however there is an axial friction resistance at each rack support of 'Ff'
Does friction due to thermal exp/contraction accumulate from the total qty of pipe supports to produce an axial force = U/L*Ff between the anchor and first support? Or does the disproportionately larger thermal pipe displacements at the supports furthest from the anchor result in friction accumulating and dissipating in a staggered manner between the supports back to the anchor resulting in a lower axial force?
In the end can a pipe as described above be infinitely long without exceeding allowable stress due to thermal exp/contraction or is there a limit to how long the pipe can be due to the accumulation of friction at the supports? I am working to B31.3 and B31.4.
Thanks in advance!