Function Test Methods For The Wellhead Safety Control Systems
Wellhead safety control system is a kind of device composed of the hydraulic or pneumatic flow control loop, equipped with pressure and temperature sensing etc., it is a control system used to control the surface safety valve and subsurface safety valve. With the control function of fire automatic protection, production pipeline overpressure or undervoltage,manual shutdown emergency,remote shutdown emergency. Today we are going to learn the function test method of the control system.
1.Local control function test
It should be able to achieve the function of various relief valve for opening/closing on the operation panel, the test method is as follows:
A) Manual push the start button of the valves or turn on the handle button,then the safety valve will open automatically.
B) Manual push the close button of the valves or turn off the handle button, then the safety valve will shut down automatically.
Repeat the above steps, tested three times, the safety valve will be qualified for opening and closing each time.The system response time should comply with the requirements of table 1 below.
Sr NO. | Description | Pneumatic SSV | Hydraulic SSV | ||
Closing time,included safety valve/Sec. | Response time of the system/Sec. | Closing time,included safety valve/Sec. | Response time of the system/Sec. | ||
1 | Local control closing time of SSV | ≤12 | ≤3 | ≤8 | ≤3 |
2 | Remote control closing time of SSV | ||||
3 | Remote ESD closing time of SSV | ||||
4 | Fusible plug melting closing time of SSV | ||||
5 | Pilot valve overpressure closing time of SSV | ||||
6 | Pilot valve undervoltage closing time of SSV | ||||
7 | SSSV delay closing time | 10~120 | |||
The test position of the shut off response time (simulating the position of the SSV) to control cabinet should not be less than 10 m. | |||||
Table 1
2. Remote Control Function Test
The remote control room (simulated) should be able to achieve the function of safety valve remote shut down function, test method is as follows:
A) The relief valve shall be fully opened.
B) For the remote control operation, cut off solenoid valve power supply, the relief valve automatically shut down.
Repeat the above steps, tested three times, the safety valve will be qualified for opening and closing each time.The system response time should comply with the requirements of table 1 .
3. Fusible Plug Melting &Shut-off Function Test
Simulated hot melting of the fusible plug, in order to realize the shutdown sequence of SSV and SCSSV ,test method are as follows:
A) Fusible plug melting test: heating the fusible plug to melting temperature, and observe whether fusible plug will be melted.
B) Shut off function test:replace the fusible plug with the ball valve on the fusible plug circuit of the wellhead safety control system ,turn on the safety valve,then turn on the ball valve (simulating the circuit unloading after melting),the safety valve automatically shut down.
Repeat the above steps, tested three times, the safety valve will be qualified for opening and closing each time.The system response time should comply with the requirements of table 1
4. Over-pressure or under-voltage shut-off function test of the Pilot Valve
When received the pressure signals ,the High Pressure Pilot Valve and Low Pressure Pilot Valve should be able to achieve the function of safety valve shut-off function, test method is as follows:
A) Pilot Valve Over-Pressure Shut-off Function Test
To set the high pressure pilot valve pressure as the well control high pressure , turn on the safety valve,gradually pressurizing the pressure to ultrahigh pressure status of the high pressure pilot valve port.
Repeat the above steps, tested three times, each time the relief valve can automatically shut down for qualified, the system response time should comply with the requirements of table 1.
B) Pilot Valve Under-Voltage Shut-off Function Test
To set the low pressure pilot valve pressure as the well control low pressure ,firstly increase the pressure to normal work pressure range of the low pressure pilot valve induction port,and turn on the safety valve.Gradually decrease the pressure to under-voltage status of the low pressure pilot valve induction port,the safety valve shall be shut-off automatically.
Repeat the above steps, tested three times, each time the relief valve can automatically shut down for qualified, the system response time should comply with the requirements of table 1.
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