In-line testing of pressure safety valves

A method for use in a system for in-line testing and calibration of pressure safety valves (PSV), the system including:

• a first pressure safety valve (PSV) with an inlet, outlet and valve seat working against an adjustable spring which is controlling when said first PSV opens;
• a first isolation valve at the inlet of the first PSV;
• a second isolation valve at the outlet of the first PSV;
• a first bleed valve at the inlet of the first PSV between the first isolation valve and said first PSV;
• a second bleed valve at the outlet of the first PSV between said first PSV and the second isolation valve;
• a first Safety Controller (SC) with a processor or controller, data storage unit, and communication means for sending and receiving signals from/to the first SC and an external safety system, the first SC further including a calibration medium input connected to a source of a calibration fluid and a ventilation port;
• a first fluid line connecting the first SC to the first bleed valve;
• a second fluid line connecting the first SC to the second bleed valve, wherein the first SC is adapted to connect any of the first and second fluid lines to any of the calibration medium input and the ventilation port or close off any of the fluid lines;
• the first SC further including means for regulating and measuring pressure and fluid flow in each fluid line;
• a first Abnormal Condition Detector (ACD) unit connected to the first PSV for detecting leak sounds;
• second and third ACD units connected to each isolation valve, for detecting sound and valve position;
• fourth and fifth ACD units connected to each bleed valve, for detecting sound, valve position and flow, wherein the ACD units are connected to the first SC for transferring leak and position data to the first SC, the method comprising:
• verifying the positions of the first and second isolation valves, and the first and second bleed valves,
• testing tightness of the first and second isolation valves, by supplying calibration fluid from the SC through the first and second bleed valves, and either detecting possible leak sound from said isolation valves by the second and third ACD units, or measuring the amount of calibration medium needed to keep the pressure between the isolation valve and the PSV stable and comparing this volume with a previous volume measurement,
• determining the opening/lifting pressure of the PSV by closing the isolation valves and opening the bleed valves to let out any overpressure from the inlet or outlet of the PSV, the SC then supplying calibration fluid to the inlet of the PSV through the first bleed valve ramping up the pressure until the PSV starts opening, this opening being detected by the first ACD unit,
• in case no opening of the PSV is detected, determining if the PSV is stuck or clogged by elevating the pressure to a pre-set safe test level above the set pressure of the PSV and detecting any leaks to determine if the PSV needs to be replaced or repaired,
• determining if the PSV is tight enough to remain in service by applying calibration fluid to the input side of the PSV at a standard pressure level and the first ACD unit either listening for leak sounds or measuring pressure build up at the output side of the PSV,
• recording and storing test parameters relating to the condition of the PSV and the isolation valves.