BS EN ISO 8659:2020 pdf – Thermoplastics valves – Fatigue strength – Test method

BS EN ISO 8659:2020 pdf – Thermoplastics valves – Fatigue strength – Test method.
1 Scope This document specifies the endurance test necessary to confirm the ability of hand-operated plastics valves to withstand prolonged use, with repeated opening and closure. It does not specify the ability of valves to withstand adverse conditions, in particular those of chemically aggressive fluid media and/or environments, or excessive fluid velocities and cavitation. NOTE Concerning the chemical aggression of the materials, a classification table is reported in ISO/TR 10358 [1] . This document includes values of the parameters necessary for the proper performance of the endurance test, with the reservation that the parameters are different in particular product standards (see 5.1). 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 161-1, Thermoplastics pipes for the conveyance of fluids — Nominal outside diameters and nominal pressures — Part 1: Metric series ISO 16135, Industrial valves — Ball valves of thermoplastics materials ISO 16136, Industrial valves — Butterfly valves of thermoplastics materials ISO 16138, Industrial valves — Diaphragm valves of thermoplastics materials ISO 16139, Industrial valves — Gate valves of thermoplastics materials ISO 21787, Industrial valves — Globe valves of thermoplastics materials 3? Terms? and? definitions For the purposes of this document, the terms and definitions given in ISO 161-1 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https://www.iso.org/obp — IEC Electropedia: available at http://www.electropedia.org/
f) the fluid used for the test, and its temperature, pressure and velocity; g) the ambient temperature. 5.2 Endurance test The endurance test, using water, air or gas as the fluid medium, at the temperature, pressure and velocity specified in the particular product standard, shall be carried out, at the ambient temperature specified in the product standard, as follows: a) Open the valve — for multiple-turn valves to the fully open position at a hand-wheel speed of 40 r/min ± 10 r/min for valves of nominal size up to DN 50 and 20 r/min ± 10 r/min for valves of nominal size greater than DN 50. — for quarter-turn valves, the opening time shall be not less than 2 s for valves of nominal size up to DN 50 and not less than 4 s for valves of nominal size greater than DN 50. The valve shall be left in the open position for at least 5 s, but not longer than 20 s. During opening and closing, there shall be no visible leakage at any seal. b) Close the valve — for multiple-turn valves at a hand-wheel speed of 40 r/min ± 10 r/min. — for quarter-turn valves, the closing time shall be not less than 1 s. Closing shall be performed using the torque specified in the particular product standard. During opening and closing, there shall be no visible leakage at any seal. c) After the valve has been closed, an internal pressure shall be applied as specified in the particular product standard. The valve shall be left in the closed position for at least 5 s, but no longer than 20 s. d) The valve shall be opened as described in 5.2 a). e) The test procedure described in 5.2 a) to d) shall be repeated for as many cycles as required by the particular product standard. 6 Test report The test report shall include at least the following information: a) a reference to this document, i.e. ISO 8659, and to the product standard; b) a complete identification of the valve, giving the following information:
NOTE The opening torque is generally higher in ball, butterfly and gate valves as it is influenced by the wear between obturator and seats and by the maximum pressure difference between upstream and downstream side of the valve; the opening torque is lower in diaphragm and globe valves as the upstream pressure, acting on obturator, reduces the effort exerted to operate the valve. c) a description of the test conditions; d) the number of specimens tested; e) whether the valve complied with the test requirements [if the valve failed (leakage or fracture) indicate under what conditions it failed]; f) any operation not laid down in this document, or other occurrences which may have affected the test results; g) the date of the test.