IEC 60793-1-33:2017 contains descriptions of the five main test methods for the determination of stress corrosion susceptibility parameters. The object of this document is to establish uniform requirements for the mechanical characteristic of stress corrosion susceptibility for silica-based fibres. Dynamic fatigue and static fatigue tests are used to determine the (dynamic) <em>n</em><sub>d</sub> value and (static) <em>n</em><sub>s</sub> value of stress corrosion susceptibility parameters. Currently, only the <em>n</em><sub>d</sub>-value is assessed against specification. Measured values greater than 18 per this procedure reflect the <em>n</em><sub>d</sub>-value of silica, which is approximately 20. Higher values will not translate to demonstrable enhanced fatigue resistance. Silica fibre mechanical tests determine the fracture stress and fatigue properties under conditions that model the practical applications as closely as possible. The following test methods are used for determining stress corrosion susceptibility: A: Dynamic <em>n</em><sub>d</sub> value by axial tension; B: Dynamic <em>n</em><sub>d</sub> value by two-point bending; C: Static <em>n</em><sub>s</sub> value by axial tension; D: Static <em>n</em><sub>s</sub> value by two-point bending; E: Static <em>n</em><sub>s</sub> value by uniform bending. These methods are appropriate for category A1, A2 and A3 multimode, class B single-mode fibres and class C intraconnecting single-mode fibres. These tests provide values of the stress corrosion parameter, n, that can be used for reliability calculations according to IEC TR 62048. Information common to all methods is contained in Clauses 1 to 10, and information pertaining to each individual test method appears in Annexes A, B, C, D, and E. Annexes F and G offer considerations for dynamic and static stress corrosion susceptibility parameter calculations, respectively; Annex H offers considerations on the different stress corrosion susceptibility parame ...