This part of ISO/TR 12391 applies to seamless refillable cylinders of all sizes from 0,5 l up to and including 150 l water capacity produced of steel with tensile strength (Rm) greater than 1 100 MPa. It can also be applied to cylinders produced from steels used at lower tensile strengths. In particular, it provides the technical rationale and background to guide future alterations of existing ISO standards or for developing advanced design standards. This part of ISO/TR 12391 is a summary and compilation of the test results obtained during the development of the “flawed-cylinder cyclical burst test”. The test is an alternate test method to the flawed-cylinder burst test with monotonic pressurization and is used to evaluate the fracture performance of steel cylinders which are used to transport high-pressure compressed gases. The concept and development of the flawed-cylinder cyclical burst test is described in ISO/TR 12391-1. The details of the test method and the criteria for acceptable fracture performance of steel cylinders are given in 9.2.5.3.2 of ISO 9809-2:2000. In this part of ISO/TR 12391, test results are reported for more than one hundred flawed-cylinder cyclical burst tests that were conducted on seamless steel cylinders that ranged in tensile strength from 750 MPa to 1 210 MPa. The test method is intended to be used both for the selection of materials and to establish design parameters in the development of new cylinders as well as for an efficient quality control test to be used during the production of cylinders.