- Author
- Cassady, M. J. | Epstein, M. M. | Lustiger, A. | Markham, R. L. | Uralil, F. S.
- Title
- Evaluation of Polybutylene as a Gas Piping Material. Topical Report. January 1976-September 1980.
- Coporate
- Battelle Columbus Labs., Columbus, OH
- Sponsor
- Gas Research Institute, Chicago, IL
- Report
- GRI-80/0009, April 1982, 89 p.
- Distribution
- Available from National Technical Information Service
- Contract
- 5014-352-0152
- Keywords
- polybutylene | plastic pipes | cracking (fracturing) | test methods | outdoor storage | chemiluminescence
- Identifiers
- gas pipes; service life; fracture tests; accelerated tests; stress cracking tests
- Abstract
- Gold polybutylene pipe was evaluated for natural gas distribution applications. Measurements were made of true stress-true strain tensile properties in the axial direction; fracture toughness parameter, Kc; cleavage fracture behavior; rapid crack extension properties; rotary fatigue behavior; sustained pressure properties with methane and with a pipeline condensate; and resistance to outdoor weathering. Changes induced by outdoor weathering were monitored by visual observation, infrared spectroscopy, chemiluminescence, scanning electron microscopy, molecular weight measurements, stress crack resistance measurements, and rotary fatigue tests. In sustained pressure tests with methane, the material was found to fail by means of a weeping mechanism that has been associated with microcracks on the inner pipe wall surface. Failures with condensate involved propagating cracks. Measurements of fracture properties suggest a low Kc, low specific surface energy for crack propagation, and a susceptibility to rapid crack extension. Data for polyethylene piping materials exhibiting a broad range of these properties are included for purposes of comparison. The yellow pigmented pipe was degraded seriously by outdoor weathering. Rotary fatigue measurements suggest that long outdoor storage would adversely influence secondary loading resistance and perhaps socket-joint quality.