Pipe Joining, Fusion, and Pressure Testing
What the exam tests
This domain tests joining methods and pressure testing: butt fusion, socket fusion, electrofusion, mechanical fittings, and hydrostatic testing. Expect sequence questions, temperature and pressure limits, and test acceptance criteria.
Core rules
- Butt fusion: clean the pipe, face both ends, align, heat at the specified temperature and time, join under controlled pressure, and cool before handling.
- Socket fusion is for smaller pipe; electrofusion uses the fitting's coil and a controlled power unit.
- Pressure-test with water, not air, unless the standard allows otherwise; air stores dangerous energy.
- Test at 1.5 times operating pressure, typically with a 100-psi minimum, not exceeding pipe rating; hold and inspect for loss.
- Test before backfilling and again after backfill if required; record gauge readings and temperature.
Worked example
A loop operates at 50 psi. 1.5 × 50 = 75 psi, below the 100-psi minimum, so test at 100 psi. A 2-in DR11 PE3608 line rated 200 psi at 73°F can accept 100 psi. Hold the test for the specified period, compensate for temperature change, and check all fused joints before covering.
Traps
Testing a joint before it cools; using air because it is faster; placing the gauge at the high point; ignoring sunlight heating; failing to re-test after repairs.