This part of ISO 6259 specifies a method of determining the tensile properties of polyolefin (polyethylene, crosslinked polyethylene, polypropylene and polybutene) pipes, and in particular the following properties: — the stress at yield; — the elongation at break. NOTES 1 The properties of butt fusion welds may be assessed by using machined test pieces of the types specified in this document. 2 The general method of test for the determination of the tensile properties of thermoplastics pipes is given in ISO 6259-1. This part of ISO 6259 also gives, for information purposes only, the corresponding basic specifications in annexes A to D.