Technical Reference on Saddle Heat Fusion Joining of Polyethylene Gas Pipes. Volume 2. Topical Report, July 1989-January 1992.

摘要

Natural gas is transported to residential and commercial buildings by service connections that are supplied by main lines. Polyethylene (PE) is commonly used for such gas distribution piping where pressures do not exceed 100 psi. Plastic pipe is now used for more than 90 percent of utility installations. The widespread use of polyethylene can be attributed to its good resistance to cracking and chemical inertness. The report contains guidelines on heat fusion of PE gas pipes to aid the gas industry. The approach in the study was to determine how the strength of saddle joints depends on the manner in which the joints are made. In particular, the effect on the strength of the bond as the joining conditions deviate from the prescribed ones was investigated. References to joint strength in the study are synonymous with strength of the fused interface or bond strength. The variables that were studied were type of resin, heater temperature, heating time, and joining force. The effects of wall thickness and ambient temperature were not directly investigated. Wind effects were not investigated at all. The effect of misalignment was not considered. Many laboratory tests on saddle heat fused joints were conducted. The test data were correlated using a formulated model. Nomographs were developed for selecting combinations of heater temperature, heating time, and joining force to ensure the structural integrity of the saddle joints.