GB 12241-89 General Requirements for Safety Valves (2)
Safety valves are used to limit the internal pressure of an equipment or system, usually by automatically relieving built-up pressure. GB 12241-89 provides general requirements for safety valves. It applies to safety valves (which include reheat bypass valves) of nominal sizes between DN15 and DN350, designed for use with fluids at temperatures between -20°C and +400°C.
The general requirements of GB 12241-89 include material requirements; pressure-temperature rating and seat tightness requirements; flow characteristic requirements; lift and blow-down requirements; testing and marking requirements; quality assurance requirements; personnel safety requirements; and calibration and maintenance requirements.
With regards to material requirements, the safety valve materials should be chosen according to the specifications set out in GB 150, and have adequate mechanical properties to meet the requirements of GB/T 699.
The pressure-temperature rating and seat tightness requirements refer to the minimum and maximum pressure at a given temperature at which the safety valve must be able to adequately open and close. This is stated in terms of a minimum and maximum allowable seat diameter, minimum and maximum allowable lift, and a multi-position opening and closing pressure drop performance.
The flow characteristic requirements refer to the mass flow rate, maximum flow rate and minimum flow rate of the safety valve, normally expressed in terms of mass flow rate, in words or in symbols.
The lift and blow-down requirements refer to the safety valve’s pressure differences from the full overall lift to the empty overall lift and from the closed state to the start of the blow-down.
The testing and marking requirements refer to proof tests and performance tests during manufacturing, followed by permanent marking applied to the safety valve.
The quality assurance requirements refer to the quality management system to ensure the safety valves meet the required design, safety, reliability and performance requirements.
The personnel safety requirements refer to protecting personnel from potential harm by preventing contact with the safety valve and its components, as well as avoiding release of potentially dangerous particles or substances when the safety valve is opened or closed.
The calibration and maintenance requirements refer to all maintenance activities that are necessary to ensure that the safety valve stays in proper working order. Calibration should be performed regularly to ensure accurate readings and performance.
In general, GB 12241-89 provides general requirements for safety valves to ensure that they are able to operate reliably and safely. Proper installation, operation, maintenance and calibration are essential for the safety valves to perform as intended.
