Life prediction of butt heat fusion joints in polyethylene gas-pipe materials. Final report, April 1989-March 1991
A fracture mechanics methodology was developed that permits quantifying the influence of a crack-like defect in a butt fusion joint on its life expectancy. Load-point displacement histories were measured for three-point-bend fracture specimens with centrally located notched joints that were dead loaded at ambient and elevated temperatures. A validated nonlinear viscoelastic fracture mechanics model was developed to deduce the crack length histories from the load-point displacement records. The time of initiation of crack growth and the rate of crack growth were correlated with the stress intensity factor for combinations of initial crack lengths, applied loads, and test temperatures. Master curves for the initiation time and the rate of crack growth were obtained by translating bidirectionally the elevated temperature data to a reference temperature using independently determined horizontal and vertical shift functions. These correlations were used to predict the life expectancy of butt fusion joints in pressurized SDRII pipes as a function of the size of the crack and the internal pressure. These results were employed to establish the critical defect size for a 50-year design life of the joint.
- Research Organization:
- Ohio State Univ., Columbus, OH (United States). Dept. of Engineering Mechanics
- OSTI ID:
- 5790447
- Report Number(s):
- PB-92-137637/XAB; CNN: GRI-5088-271-1739
- Resource Relation:
- Other Information: See also PB90-217332. Sponsored by Gas Research Inst., Chicago, IL
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
NATURAL GAS DISTRIBUTION SYSTEMS
PIPE JOINTS
FRACTURE MECHANICS
SERVICE LIFE
POLYETHYLENES
CRACK PROPAGATION
CRACKS
DEFECTS
MATHEMATICAL MODELS
STRESS INTENSITY FACTORS
TEMPERATURE DEPENDENCE
JOINTS
MECHANICS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERS
POLYOLEFINS
032000* - Natural Gas- Transport
Handling
& Storage
360603 - Materials- Properties