The following procedures should be followed when during the pipe pull-back operation:
- Avoid supporting pipe on surface that may cause abrasion during pullback
- Minimize back tension on pipe, to prevent escalating effects at pulling end
- Avoid pulling around sharp bends (tighter than allowable bending radius), to avoid pipe collapse (kinking).
Thus, it is important to minimize bending of the pipe as it enters
the bore hole, and to ensure low friction on the portion of the pipe
outside the hole. This may be accomplished by the use of appropriate
lifting equipment and roller stands to reduce friction. Due to the
potentially high tensile load at the pipe exit, it is especially
important to avoid sharp bends at this point.
HDPE pipe has a very tight safe bend radius. This feature allows pipe
to be strung on the ground in configurations impossible to do safely
for other types of pipe. Instead of blocking cross streets the pipe is
often laid down by simply bending it around the corner. For example a
12" HDPE pipe may be safely bent to a radius of only 28 ft, which allows
this pipe to be placed in a typical cul-de-sac without fittings. In
addition, HDPE pipe will almost always have a tighter bend radius than
the drill stem being used for installation. This provides an extra
safety factor against damaging the pipe by bending in the bore.