Classification system and qualification procedures for type testing of valves
1 Scope This part of ISO 15848 specifies testing procedures, for evaluation of external leakage of valve stem seals (or shaft) and body joints of isolating valves and control valves intended for application in volatile air pollutants and hazardous fluids. End connection joints, vacuum application, effects of corrosion and radiation are excluded from this part of ISO 15848. This part of ISO 15848 concerns classification system and qualification procedures for type testing of valves.
2 Normative references The following referenced documents are indispensable for the application 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 5208, Industrial valves — Pressure testing of valves
3 Terms and definitions For the purposes of this document, the following terms and definitions apply.
3.1 body seals any seal in pressure containing part except stem (or shaft) seals
3.2 Class a convenient round number used to designate pressure-temperature ratings NOTE It is designated by the word “Class” followed by the appropriate reference number from the following series: Class 125, Class 150, Class 250, Class 300, Class 600, Class 900, Class 1 500, Class 2 500.
3.3 concentration ratio of test fluid volume to the gas mixture volume measured at the leak source(s) of the test valve NOTE The concentration is expressed in ppmv (parts per million volume), which is a unit deprecated by ISO (1 ppmv = 1 ml/m3 = 1 cm3/m3). ISO 15848-1:2006(E) 2 © ISO 2006 – All rights reserved
3.4 control valve power operated device which changes the fluid flow rate in a process control system and which consists of a valve connected to an actuator that is capable of changing the position of a closure member in the valve in response to a signal from the controlling system
3.5 fugitive emission any chemical or mixture of chemicals, in any physical form, which represents an unanticipated or spurious leak from equipment on an industrial site
3.6 leakage loss of the test fluid through the stem (or shaft) seal or body seal(s) of a test valve under the specified test conditions and which is expressed as a concentration or a leak rate
3.7 leak rate mass flow rate of the test fluid, expressed in mg·s−1 per meter of the perimeter of the stem
3.8 local leakage measurement of the test fluid leakage using a probe at the leak source point
3.9 mechanical cycle of control valves for linear/rotary control valves, test cycles performed at 50 % of stroke/angle with an amplitude of ± 10 % of full stroke/angle
3.10 mechanical cycle of isolating valves motion of a valve obturator moving from the fully closed position to the fully open position, and returning to the fully closed position
3.11 nominal size DN alphanumeric designation of size for components of a pipework system, which is used for reference purposes and which comprises the letters DN followed by a dimensionless whole number which is directly related to physical size, in millimetres, of the bore or outside diameter of the end connections NOTE 1 The nominal diameter is designated by the letters DN followed by a number from the following series: 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150, 200, 250, 300, 350, 400, etc. NOTE 2 The number following the letters DN does not represent a measurable value and should not be used for calculation purposes except where specified in the relevant standard.
3.12 nominal pressure PN numerical designation which is a convenient rounded number for reference purposes NOTE 1 All equipment of the same nominal size (DN) designated by the same PN number has the compatible mating dimensions. NOTE 2 The maximum allowable working pressure depends upon materials, design and working temperatures and should be selected from the pressure/temperature rating tables in the appropriate standards. NOTE 3 The nominal pressure is designated by the letters PN followed by the appropriate reference number from the following series: 2,5, 6, 10, 16, 20, 25, 40, 50, etc.
3.13 isolating valve valve intended for use principally in the closed or open position which may be power actuated or manually operated
3.14 performance class level of the performance of a test valve defined by the criteria specified in Clause 6
3.15 room temperature temperature in the range of − 29 °C to + 40 °C
3.16 stem shaft valve component extending into the valve shell to transmit the linear/rotary motion from the actuating device to the valve obturator
3.17 stem seal shaft seal component(s) installed around the valve stem (or shaft) to avoid leakage of internal fluids to atmosphere
3.18 test pressure pressure used for testing the valve which, unless otherwise specified, shall be the rated pressure specified at the test temperature and the shell material of a test valve in the relevant standards
3.19 test temperature fluid temperature selected for the test from Table 3 as measured inside the test valve
3.20 thermal cycle change of the temperature from the room temperature to the specified test temperature and return to the room temperature
3.21 total leakage collection of leakage of the test fluid at the leak source using an encapsulation method
3.22 type test a test conducted to establish the performance class of a valve
