NCCER Pipeline Mech flashcards
NCCER Pipeline Mech · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Nominal pipe size
- A standardized size label for pipe that is close to, but not exactly, the outside diameter in inches. Wall thickness is set separately by schedule number.
- Schedule number
- A pipe wall thickness designation. For the same nominal pipe size, a higher schedule number means a thicker wall and a smaller inside diameter.
- API 5L line pipe
- The specification covering seamless and welded steel pipe for pipeline transportation systems, defining dimensions, grades, and minimum mechanical properties.
- Pipe grade X65
- A line pipe grade whose minimum yield strength is 65,000 psi. The number after X in a grade designation gives minimum yield strength in ksi.
- Barlow's formula
- Relates internal pressure to pipe geometry: P equals 2 times allowable stress times wall thickness divided by outside diameter. Used to check pressure capacity.
- Design factor
- A multiplier applied to specified minimum yield strength to set allowable operating stress. Its value depends on location class and applicable code.
- Maximum allowable operating pressure
- The highest pressure a pipeline section may legally operate at, calculated from pipe strength, wall thickness, design factor, and temperature derating.
- Hydrostatic test
- A pressure test using water to verify pipeline strength and leak tightness, usually held at a pressure above the maximum allowable operating pressure.
- Root gap
- The spacing left between pipe ends at the joint before welding the root pass. It must match the welding procedure to ensure full root penetration.
- Bevel angle
- The angled cut on a pipe end that forms the weld groove. It is specified by the welding procedure and checked with a bevel gauge.
- Line-up clamp
- A tool that holds two pipe ends aligned and round during fit-up and root welding, correcting high-low mismatch before the joint is tacked.
- High-low mismatch
- The offset between the inside or outside surfaces of two joined pipe ends. Excessive mismatch concentrates stress and must be corrected before welding.
- Welding procedure specification
- A written document giving the qualified variables, filler metal, preheat, and technique for a weld so that joints meet code requirements.
- Preheat
- Heating the pipe before welding to slow cooling and reduce hydrogen cracking risk. Minimum preheat depends on steel grade, thickness, and carbon equivalent.
- Star tightening pattern
- A bolt tightening sequence that alternates across the flange in stages, equalizing gasket load and preventing uneven compression or leakage.
- Spiral wound gasket
- A gasket of alternating metal and filler windings with a centering ring, used on high-pressure flanges where tight sealing and resilience are needed.
- Cold field bend
- A bend made in the field without heating the pipe. Code limits the radius, ovality, and wall thinning that result from the bending operation.
- Ovality
- The degree to which a pipe cross section departs from round after bending or handling. It is measured and limited by specification.
- Holiday detection
- A test that finds breaks or thin spots in pipeline coating by applying high voltage and observing a spark or alarm at the defect.
- Cathodic protection
- A method that applies direct current or sacrificial anodes to make the pipe a cathode, preventing corrosion of exposed steel.
- Pipe-to-soil potential
- A voltage measured between buried pipe and a reference electrode. A common criterion is minus 0.85 volts or more negative for coated steel.
- Lowering-in
- The operation of placing welded pipe into the trench using sideboom tractors, controlled so bending and span stresses stay within allowable limits.
- Sideboom tractor
- A tracked machine with a side-mounted boom and counterweight used to lift and hold pipe during stringing, welding, and lowering-in operations.
- Trench protective system
- Sloping, shoring, or shielding used to prevent cave-in in an excavation. Selection depends on soil type, depth, and water conditions.
- Competent person
- A person capable of identifying excavation hazards and authorized to take prompt corrective action, including ordering work stopped when conditions are unsafe.
- Gauging pig
- An instrumented or plate-equipped pig run through a pipeline to confirm the bore is round and clear of dents or obstructions before other operations.
- Smart pig
- An in-line inspection tool using magnetic flux leakage or ultrasonic sensors to measure metal loss and record pipeline geometry for integrity assessment.
- Pipeline pig
- A device driven through a pipeline by product flow for cleaning, gauging, separation, or inspection. It is launched and received at pig traps.
- Hot work permit
- A written authorization for welding, cutting, or grinding, requiring gas testing, fire watch, and isolation of flammables before work begins.
- Gas testing
- Measuring flammable gas, oxygen, and toxic gas levels in a work area before and during confined space or hot work to confirm safe conditions.
- Pipeline isolation
- Closing and locking out valves, then draining or purging a section so work can proceed without product flow or pressure in the work area.
- Torque wrench
- A calibrated tool that applies a measured rotational force to a fastener. Values come from project specification or manufacturer data, not guesswork.