Typical flaws that can occur in high-pressure seamless gas cylinders during service are: corrosion pits, line corrosion, gouges, local thin areas of corrosion, and cracks. The required periodic inspection of seamless cylinders requires that “critical flaw sizes” be established. To establish “critical flaw sizes” an assessment of typical flaws that occur in seamless cylinders was carried out using the analytical procedures described in the API Recommended Practice 579 “Fitness-for-Service.” To verify the API 579 analysis procedures, a number of hydrostatic tests were conducted on selected cylinders with various sizes of flaws to determine the burst pressure of cylinder containing flaws. These results showed that the analysis conducted according to API 579 reliably estimated the actual measured burst pressure of the cylinders for all flaw sizes and types. After the API 579 analysis procedures were verified by these experiments to reliably estimate the burst pressure of cylinders with various types of flaws, the “critical flaw sizes” to cause failure of the cylinders at selected pressures were determined by analysis. This paper presents the results of the analytical and experimental work that was performed on the assessment procedures to establish the “critical flaw sizes” in high-pressure gas cylinders.

U. S. Code of Federal Regulations, 1999, Title 49-Transportation, Part 178 Specifications for Packaging Subpart C—Specifications for Cylinders, Office of the Federal Register, National Archives and Records Administration, Washington, DC.
CGA Pamphlet C-6 Standards for Visual Inspection of Steel Compressed Gas Cylinders, 1993, Compressed Gas Association, Inc., Arlington, VA, 7th Edition.
CGA Pamphlet C-1 Methods for Hydrostatic Testing of Compressed Gas Cylinders, 1996, Compressed Gas Association, Inc., Arlington, VA, 7th Edition.
API 579, 2000, “Recommended Practice for Fitness-for-Service,” American Petroleum Institute, Washington D.C., First Edition.
Exemption DOT-E-9421 (Seventh Revision), 2000, U.S. Dept. of Transportation, Washington, DC.
You do not currently have access to this content.