ISO 9809-4:2014 pdf download.Gas cylinders-Refillable seamles ssteel gas cylinders -Design, construction and testing-Part 4: Stainless steel cylinders with an Rmvalue of less than 1 100 MPa.
6.3 Heat treatment
6.3.1 The cylinder manufacturer shall certify the heat treatment process applied to the finished cylinders.
6.3.2 The finished cylinders made from the lerritic or martensitic steel categories shall be quenched and tempered, except if they are cold worked (see 6.4).
6.3.3 For the ferritic and martensitic steels, the heat treatment process shall achieve the required mechanical properties.
6.3.4 The actual temperature to which a type of steel is subjected to obtain a given tensile strength shall not deviate by more than 30°C from the temperature specified by the cylinder manufacturer.
6.4 Cold working or cryoforming
Cold working orcryoforming is used to enhance the finished mechanical properties in certain stainless steel materials.
For cylinders that are subjected to cold working or to the cryoforming process, all the heat treatment requirements refer to the cylinder preform operations. Cold worked or cryoformed cylinders shall not be subfrcted to any subsequent heat treatment.
6.5 Failure to meet test requirements
In the event of failure to meet the test requirements, retesting or reheat treatment and retesting shall be carried out as follows to the satisfaction of the inspector:
a) If there is evidence of a fault in carrying out a test, or an error of measurement, a further test shall be performed. If the result of this testis satisfactory, the first test shall be ignored.
b) If the test has been carried out in a satisfactory manner, the cause of test failure shall be identified.
1) If the failure is considered to be due to the heat treatment applied, the manufacturer can subject all the cylinders implicated by the failure to a further heat treatment, e.g. if the failure is in a test representing the prototype or batch cylinders. Test failure shall require reheat treatment of all the represented cylinders prior to retesting.
6.3.1 The cylinder manufacturer shall certify the heat treatment process applied to the finished cylinders.
6.3.2 The finished cylinders made from the lerritic or martensitic steel categories shall be quenched and tempered, except if they are cold worked (see 6.4).
6.3.3 For the ferritic and martensitic steels, the heat treatment process shall achieve the required mechanical properties.
6.3.4 The actual temperature to which a type of steel is subjected to obtain a given tensile strength shall not deviate by more than 30°C from the temperature specified by the cylinder manufacturer.
6.4 Cold working or cryoforming
Cold working orcryoforming is used to enhance the finished mechanical properties in certain stainless steel materials.
For cylinders that are subjected to cold working or to the cryoforming process, all the heat treatment requirements refer to the cylinder preform operations. Cold worked or cryoformed cylinders shall not be subfrcted to any subsequent heat treatment.
6.5 Failure to meet test requirements
In the event of failure to meet the test requirements, retesting or reheat treatment and retesting shall be carried out as follows to the satisfaction of the inspector:
a) If there is evidence of a fault in carrying out a test, or an error of measurement, a further test shall be performed. If the result of this testis satisfactory, the first test shall be ignored.
b) If the test has been carried out in a satisfactory manner, the cause of test failure shall be identified.
1) If the failure is considered to be due to the heat treatment applied, the manufacturer can subject all the cylinders implicated by the failure to a further heat treatment, e.g. if the failure is in a test representing the prototype or batch cylinders. Test failure shall require reheat treatment of all the represented cylinders prior to retesting.
