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Luxfer position concerning life extension of DOT CFFC carbon composite cylinders

August 12, 2009

Luxfer position concerning life extension of DOT CFFC carbon composite cylinders

Luxfer Gas Cylinders periodically receives inquiries about the possibility of extending the service life of composite cylinders manufactured and approved for a 15-year service life under U.S. Department of Transportation (DOT) standard DOT-CFFC, including Luxfer cylinders manufactured under DOT special permit 10915 (SP10915).

For more than a decade, Luxfer has actively researched this matter and participated in detailed deliberations involving DOT, the Compressed Gas Association (CGA) and other cylinder manufacturers to obtain a service-life extension. However, DOT declined to approve life extension for these cylinders. Consequently, Luxfer decided not to pursue this effort further and to take a different approach to providing cylinders with longer service life.

Background

In 1996, DOT issued its CCFC-1 standard that established basic requirements for design, manufacture and performance of cylinders consisting of seamless aluminum liners over-wrapped with structural layers of filament-wound carbon fiber and epoxy composite material. At that time, DOT offered the possibility of extending the 15-year service life of such cylinders “up to a total service life of 30 years.” To obtain an extension, a cylinder manufacturer was required to submit for DOT approval a “Service Life Extension Plan” that would meet certain criteria. Soon after CCFC-1 was issued, Luxfer and other U.S. cylinder manufacturers individually submitted such life-extension plans to DOT. However, DOT accepted none of these plans and declined to extend cylinder service life.

In response, cylinder manufacturers attempted an industry-wide approach to obtain DOT approval under the auspices of a special CGA task group, but the service life was not extended.

Luxfer’s longer-life composite cylinder

In 2006, Luxfer began developing a new, more robust cylinder designed for a service life longer than 15 years. This new cylinder was based on ISO 11119, an international design standard. In August 2008, DOT granted Luxfer special permit 14232 (SP14232), which authorizes the manufacture of these cylinders for use in the United States.

While cylinders made under SP14232 are designed for service lives as long as 30 years, the special permit explicitly sets forth certain testing and validation requirements that must be met before the service life of any cylinder may be extended beyond 15 years. As of the issue date of this bulletin, no cylinder manufactured under SP14232 has thus far been approved for a service life longer than 15 years since these cylinders have not yet reached the age at which their service life will be eligible for extension.

For more information, please use the DOT links below or contact Luxfer Gas Cylinders at 951-341-2348 or lifesupport@luxfer.net.

U.S. Department of Transportation special permits search
DOT-CFFC (Basic requirements for fully-wrapped carbon fiber reinforced aluminum-lined)

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