Exploratory research on infrared imaging for inspection of electrofusion joints in polyethylene gas pipe. Final report, July 1990-July 1992

Technical Report · Sun Nov 01 04:00:00 EST 1992

OSTI ID:6936265

Kim, L J; Grigory, S C

The main thrust of the study was on the use of infrared imaging as an nondestructive examination (NDE) method for electrofusion fittings. However, a cursory study of ultrasonics, X-ray, acoustic emissions and wire resistivity as NDE methods was also considered. The concept of infrared (IR) imaging as an NDE technique involved observing the surface of the fitting during the fusion process to detect distortions in the heat pattern caused by subsurface defects. If defects could be detected in this manner, the distorted pattern would be recorded on infrared sensitive film. The thermal conductivity of the PE was too low and only large defects could be detected in this manner. Ultrasonic waves are reflected by the EF heating wires and these signals mask reflections from defects. X-ray of fittings on pipe must be made double wall (source on one side of the pipe and film on the other) and the dense wires likewise will mask defects in the less dense PE. Also, X-ray is incapable of detecting delaminations at the fusion line. A measure of the change in resistivity of the heating wires during fusion is a good NDE method used by at least one manufacturer but the technique is insensitive and only large defects are detected. Acoustic emissions as an NDE method shows promise. The limited experiments performed indicate that no sound is emitted from melting and fusion of PE but that sounds are emitted when defects are formed.

• Research Organization: Southwest Research Inst., San Antonio, TX (United States)
• OSTI ID: 6936265
• Report Number(s): PB-93-157261/XAB; CNN: GRI-5090-260-2001
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
032000* -- Natural Gas-- Transport
Handling
& Storage
36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
ALGORITHMS
ALLOCATIONS
BENCH-SCALE EXPERIMENTS
COHERENT SCATTERING
DEFECTS
DETECTION
DIFFRACTION
DISTRIBUTION
ENERGY
FABRICATION
HEAT
HEATING
INSPECTION
JOINING
JOINTS
MATHEMATICAL LOGIC
MELTING
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PATTERN RECOGNITION
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PIPE FITTINGS
PIPE JOINTS
PIPES
POLYETHYLENES
POLYMERS
POLYOLEFINS
SCATTERING
SIGNALS
SOUND WAVES
SYSTEMS ANALYSIS
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES
ULTRASONIC WAVES
WIRES
X-RAY DIFFRACTION