midstreamab
Mechanical
- Nov 20, 2018
- 2
Previous thread for background:
Link
Question:
Does anybody have any experience pre-heating HDD sections to mitigate excessively high longitudinal stress after installation during winter pipeline construction?
I don’t see how the pipe heating procedure would apply to HDD sections as they are not considered “locked-in” or “restrained” after pullback due to the enlarged borehole (min. 1.5 times the pipe size). To me, that combined stress formula/model is only applicable to sections restrained by compacted backfill.
Our client is insisting we pre-heat bare pipe to a miniumum of 0 degC (uninsulated 20", FBE coated) prior to HDD/HDB pullback and I can't understand the need for it.
Reference: CSA-Z662-15, Section 4.7.2 (Combined hoop and longitudinal stresses).
Link
Question:
Does anybody have any experience pre-heating HDD sections to mitigate excessively high longitudinal stress after installation during winter pipeline construction?
I don’t see how the pipe heating procedure would apply to HDD sections as they are not considered “locked-in” or “restrained” after pullback due to the enlarged borehole (min. 1.5 times the pipe size). To me, that combined stress formula/model is only applicable to sections restrained by compacted backfill.
Our client is insisting we pre-heat bare pipe to a miniumum of 0 degC (uninsulated 20", FBE coated) prior to HDD/HDB pullback and I can't understand the need for it.
Reference: CSA-Z662-15, Section 4.7.2 (Combined hoop and longitudinal stresses).
