NCCER Pipelayer flashcards
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31 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Competent person
- A person who can identify existing and predictable hazards in the excavation and who is authorized to take prompt corrective action to eliminate them.
- Trench exit distance
- In a trench 4 ft or deeper, a ladder or ramp is required, and a worker travels no more than 25 ft to the nearest exit.
- Spoil setback
- Spoil, equipment, and materials are kept at least 2 ft back from the trench edge to reduce surcharge loading and keep access open.
- Confined space entry
- Manhole and vault entry requires a permit, atmospheric testing, ventilation, an attendant, and a retrieval system before a worker enters.
- Utility tolerance zone
- The area around marked underground utilities where excavation is done by hand rather than machine, following the locate call and local rules.
- Pipe roll hazard
- Round pipe on a slope or in storage can roll; workers never stand in the roll path, and pipe is blocked or chocked.
- Daily trench inspection
- The competent person inspects trench walls, shoring, ladders, water, and utilities before entry, after rain, and after any hazard change.
- PVC push joint
- A gasketed bell-and-spigot joint where the spigot and gasket are lubricated and the pipe is pushed home to the witness mark.
- Ductile iron push-on joint
- A joint with a rubber gasket seated in the bell groove; the pipe is pushed to the witness mark with a bar or jack, not struck.
- HDPE fusion joint
- A heat-fused joint made by butt fusion, electrofusion, or mechanical fitting; the bead is inspected and the joint cools before handling.
- CMP band joint
- A coupling or band centered on the joint of corrugated metal pipe, with bolts torqued to the specified value.
- Vitrified clay handling
- Brittle clay pipe is joined with flexible compression couplings or gaskets and is lifted with slings, not chains or hooks.
- Transition adapter
- A manufactured fitting used to join pipe of dissimilar materials; mortar or tape is never used as a substitute for the adapter.
- Pipe marking
- Markings identify material, size class, and standard, such as ASTM D3034 for PVC sewer, AWWA C151 for ductile iron, and ASTM C76 for concrete.
- Fittings list
- Common fittings are bends, tees, wyes, reducers, and adapters, selected to match the pipe material and the required line change.
- Trench definition
- An excavation deeper than it is wide with a maximum bottom width of 15 ft; wider excavations follow excavation rather than trench rules.
- Type A slope
- Type A soil may be sloped at 3/4:1 horizontal to vertical, as determined by the competent person and the tabulated data.
- Type B slope
- Type B soil is sloped at 1:1 horizontal to vertical, or is supported with an approved protective system.
- Type C slope
- Type C soil is sloped at 1-1/2:1 horizontal to vertical or supported; it cannot be benched.
- Tabulated data
- Manufacturer or engineer data that gives the spacing, depth limits, and soil classifications for a shoring or shielding system; kept on site.
- Trench shield rule
- Workers stay inside the shield, the shield is never dragged with workers inside, and the bottom stays within 2 ft of the trench bottom unless data allows.
- Water control
- Pumps and ditching remove water; a worker does not work in water above the bottom of the protective system's lower member.
- Air monitoring
- Testing for a hazardous atmosphere is required before entry where one may exist and is repeated as conditions change.
- Grade definition
- Grade is the vertical drop per unit of horizontal run, set with a laser or optical level and controlled by the pipe invert elevation.
- Laser setup check
- The laser is set on the pipe grade line, and the target reading is checked against a known benchmark before laying begins.
- Bedding and bell hole
- The bedding is shaped to support the pipe barrel, and the bell hole is dug so the bell does not carry the pipe's weight.
- Laying direction
- Pipe is laid upgrade with the bell facing upgrade, so the spigot enters the bell on the push, and full insertion is checked.
- Alignment check
- A laser, stringline, or offset line checks line; the pipe is brought to line before the joint is fully seated and backfill begins.
- Haunch backfill
- The initial backfill around the lower quarter of the pipe is the most critical for support and is placed in lifts and compacted to specification.
- Deflection test
- A mandrel or go/no-go gauge checks flexible pipe deflection after backfill and before acceptance of the line.
- Leakage test
- Infiltration, exfiltration, or low-pressure air testing verifies joint tightness, with the method and allowable rate specified before acceptance.