Clarification on 6″ Bumper (REPD) Clearance Requirement

9/22/14 – PHMSA has issued a memo clarifying the 6″ clearance rule in 178.345-8(d)(1). Basically, everything attached to the piping is considered “the piping” and the bumper needs to be designed so that it can deflect forward 6″ without striking the piping. If the piping is situation such that it is not in the direct path of the bumper, then the 6″ can be measured from the rearmost face. If the bumper would strike the piping when deflecting forward, then that 6″ must be measured from the forward most face of the bumper. View the official version here.