Pipeline Mechanic
The Pipeline Mechanic domain tests field judgment for handling, aligning, joining, coating, lowering-in, and pressure-testing transmission pipe. Questions are practical: which lift, which clamp, which test step, and what fails if the step is skipped.
Handling and alignment
Pipe is lifted with certified slings and a spreader bar to protect the coating; sidebooms carry the load and tag lines control rotation. Keep personnel out of the swing radius and never straddle a suspended joint. A spreader bar also prevents sling legs from crushing the pipe end. Line-up clamps pull ends into round and match the bore; hi-lo gauges measure internal mismatch. Excessive clamp force can ovalize pipe and cause weld cracks. For internal clamps, verify the pig or clamp is removed before tie-in.
Coating, lowering-in, and testing
Field coating must overlap the factory coating and be holiday-free; inspect before lowering. Missing padding and coating holidays are common causes of later corrosion and mechanical damage. Lowering-in uses matched sidebooms, controlled spacing, and ditch checks for rocks, water, and bedding. On slopes, lowering-in crews control pipe movement with hold-back equipment. Tie-ins are made in bell holes with adequate slope and support. Hydrostatic testing holds the section at a specified pressure for a specified time; vents are opened and pigs tracked.
Worked example
Find the weight of a 40-ft joint of 12-in OD, 0.375-in wall steel pipe. Use W = 10.68t(D − t) = 10.68 × 0.375 × (12 − 0.375) = 46.5 lb/ft. 46.5 × 40 = 1,860 lb, about 0.93 ton. Add coating and fittings before choosing slings. For a two-leg sling at 60° from horizontal, each leg carries the vertical load share divided by sin 60°, not simply half the weight.
Traps
Using nominal size instead of OD; ignoring coating weight; treating sling tension as equal to load share; over-tightening line-up clamps; lowering before holiday inspection; and entering an unprotected trench.