Study of the behavior of gas distribution equipment in hydrogen service. Phase II. Project 65022 final report, April 26, 1979-June 26, 1980

The hydrogen permeability of three different types of commercially available polyethylene natural gas pipe was determined. The collected data show that the polyethylene pipe is 5 to 6 times more permeable to hydrogen than to methane. Ring tensile tests were conducted on permeability-exposed and as-received samples. Comparisons of apparent strength between exposed and as-received specimens show little difference of any statistical significance. Ring tensile tests of exposed pipe samples, after testing to failure, show more elongation than as-received samples. Hydrogen-methane gas leakage experiments were conducted. The results show there is no selective leakage of hydrogen via Poiseuille, turbulent or orifice flow (through leaks) during the distribution of blends of hydrogen and methane. The leak rates increase with increasing pressure and decreasing specific gravity. Analytical studies show that approximately 13.7 x 10/sup 6/ SCF of natural gas are lost annually by permeation in the 154,000 miles of installed plastic pipe in the US; if hydrogen were distributed, 67.4 x 10/sup 6/ SCF would be lost. The unaccounted-for gas loss in the US is about 236 x 10/sup 9/ SCF annually; if hydrogen were distributed, the unaccounted-for gas loss could be 693 x 10/sup 9/ SCF. Permeation losses are less than 0.02%more » of the unaccounted-for gas losses. 13 references, 23 figures, 14 tables.« less