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Plastic Pipe Fittings Standards Promote Sound Connection of Gas Lines

“Thousands of miles of plastic gas distribution piping are installed in the U.S. every year,” said Consultant Raymond Henrich, a retired senior research scientist with Reliant Energy Minnegasco, Minn., and chairman of ASTM Subcommittee F17.60 on Gas. “Reliable joints between pipes are essential for these installations to operate safely. Natural gas pipe joints must resist leaking and pull apart when subjected to seasonal temperature changes, earthquakes, floods, and other natural and man-made assaults on their integrity.”

The potential for danger from escaping natural gas requires that all joints are sound. To describe and test products for joining plastic gas pipe, two ASTM specifications approved in 1999 complete a set of four critical standards on gas pipe fittings:

  • F 1948, Standard Specification for Metallic Mechanical Fittings for Use on Outside Diameter Controlled Thermoplastic Gas Distribution Pipe and Tubing;
  • F 1973, Standard Specification for Factory Assembled Anodeless Risers and Transition Fittings in Polyethylene (PE) Fuel Gas Distribution Systems;
  • F 1924, Standard Specification for Plastic Mechanical Fittings for Use on Outside Diameter Controlled Polyethylene Gas Distribution Pipe and Tubing; and
  • F 1588, Standard Test Method for Constant Tensile Load Joint Test (CTLJT).

Henrich said the four standards will serve as uniform communication tools between gas pipe fittings manufacturers, users, and state and federal regulatory authorities. Use of these standards will enable utilities to evaluate new and existing products, and guide manufacturers to improve existing products and exploit new materials and technologies while improving performance, containing costs, and maintaining safety.

The standards were developed by task groups of Subcommittee F17.60 on Gas in Committee F-17 on Plastic Piping Systems, who represent gas utility companies, fitting and pipe manufacturers, independent test laboratories and consultants, trade groups, and federal and state regulatory agencies. “For about 13 years,” described Henrich, “more than 50 people worked on numerous drafts of each standard before the final consensus versions were approved. Performance requirements and, whenever appropriate, the test procedures have been standardized in the three fittings standards.”

Standard F 1948, Specification for Metallic Mechanical Fittings for Use on Outside Diameter Controlled Thermoplastic Gas Distribution Pipe and Tubing, covers requirements and test methods for the qualification of metallic mechanical fittings for use with outside diameter-controlled thermoplastic gas distribution pipe and tubing as specified in ASTM D 2513, Specification for Thermoplastic Gas Pressure Pipe, Tubing and Fittings.

Standard F 1973, Specification for Factory Assembled Anodeless Risers and Transition Fittings in Polyethylene (PE) Fuel Gas Distribution Systems, covers requirements and test methods for the qualification of factory-assembled anodeless risers and transition fittings, in sizes through NPS 8, for use in polyethylene (PE) gas distribution systems.

Standard F 1924, Specification for Plastic Mechanical Fittings for Use on Outside Diameter Controlled Polyethylene Gas Distribution Pipe and Tubing describes requirements and test methods for the qualification of plastic-bodied mechanical fittings for use with outside diameter controlled polyethylene (PE) gas distribu-tion pipe, nominal 2 pipe size (IPS) and smaller complying with ASTM D 2513, Specification for Thermoplastic Gas Pressure Pipe, Tubing and Fittings. In addition, it specifies general requirements of the material from which these fittings are made.

Standard F 1588, Test Method for Constant Tensile Load Joint Test (CTLJT) presents the constant tensile load joint test (CTLJT), designed to demonstrate that a joint in a plastic piping system is resistant to the effects of long-term creep. The joint is subjected to internal pressure criteria at a sustained axial tensile load for a specified period and must meet requirements.

“In my 20 years of ASTM membership, these standards stand out as fine examples of how all interests work together to reach a consensus to produce very useful, much needed standards.” ASTM standards are available through Customer Service (610/ 832-9585; e-mail: service@astm.org), or the Web site (www.astm. org).

For further technical information, contact Raymond Henrich, 2030 Ordway, Golden Valley, MN 55422 (612/588-5826). Committee
F-17 meets during ASTM Committee Week, Apr. 10-13, in Toronto, Ontario, Canada. For meeting or membership information, contact F-17 Staff Manager Pat Picariello, ASTM (610/832-9720). //