Composite Pipe (14.6)

Criticality: High
Progress: Not Addressed
Score: 40
DOT Relevance: §192.51 – §192.65

Description of Key Area

Although Subpart B (Materials) of 49 CFR 192 “prescribes minimum requirements for the selection and qualification of pipe and components for use in pipelines,” composite pipes are not used at this time in the United States for natural gas applications. Studies are ongoing as to whether composite pipes could be a candidate for hydrogen applications.

Discussion of Criticality

Composite pipe materials are not currently referenced in 49 CFR192. There are two rationales for composite pipe applications: the avoidance of metallic material limitations at higher pressures and the potential for reduced installation cost through longer pipe segments relative to steel pipe.

Discussion of Progress

Although composite materials are widely used today for many applications, their adequacy for use as hydrogen pipe must assessed. Composite pipe is used in natural gas applications in Europe. One example of this is reinforced thermoplastic pipe (RTP) developed by Soluforce under the brand name of PipeLife. For hydrogen applications, composite pipe materials must be adequate to prevent or minimize leakage or permeation of hydrogen. TransCanada Pipeline has an ongoing project using composite pipe in natural gas service in Canada with test loop in operation.

Research must be conducted into materials to be used for composite pipe for hydrogen applications. In Europe, reinforced thermoplastic pipe (RTP) is used for gas transportation applications. This pipe was designed according to ISO 9080 and ASTM 2992. This type of pipe must be tested for hydrogen applications. Research has been conducted in the United States on fiber reinforced plastic (FRP) pipe and the implications for its use for hydrogen applications.

The areas of greatest concern relative to composite pipe include joining methods (e.g., mechanical and fusion), exterior mechanical damage tolerance, design analysis methods, permeation, and composite structural integrity.

During a presentation at the Materials and Components for the Hydrogen Economy Codes and Standards Workshop in Augusta, Georgia on August 29^th to 30^th, 2005, ASME has identified the subject of composite pipes as a “knowledge gap.”

SNL is conducting hydrogen compatible materials studies. The focus is on material data for applications that involve the storage, distribution, and consumption of high-pressure hydrogen gas. Pertinent data include hydrogen-affected mechanical properties (yield, tensile strength, ductility, fracture toughness, threshold stress-intensity factor, fatigue crack growth rate, fatigue crack growth threshold, and impact fracture energy).

ASME B31.12 will include the use of composite pipe and plastic pipe when research shows that it is a viable alternative to metallic pipe.

Recommendations

Potential composite pipe materials and structures, including potential joining methodologies, should be researched and tested. Research should include topics regarding permeation and rapid purge methods. Operator qualifications for composite pipe should be determined. Composite pipe standards should be established and incorporated by reference into the federal code.