WHCP placed close to the wellhead contains all the components integrated within WHCP to serve as control functions to operate the well. Wellhead control panels are utilized to monitor the conditions of the flow and initiate an immediate shutdown of the pump.
Generally speaking, four kinds of sensors for shutting are utilized for sending a signal to the WHCP
- Process and ESD shutdown pilot relays
- Fusible plugs on fire loop systems
- Low- and high-pressure sensors on the flowline
- Sand probes within the flowline
- Relays for Process Shutdown:
The control system for the pneumatic wellhead requires pressurization to function. By using a pilot relay, the device shutdown interface can be achieve. If you have the case of a “pilot controlled three-way valve or relay,” this relay pilot is small.
The relay consists on the opposite side of the block of a three-way and bleeds valve, along with a pneumatic piston or tension pilot. The relay is position within a control box of the wellhead. The pilot relay has to reset itself automatically when the device that shuts down the process is activate or brought back to normal.
A three-way pilot valve permits the free movement of the tension pneumatic by transmitting a signal via an external device or the platform shutdown system. The relay switches stop the supply pressure and exhaust all downstream pressure of the holding when the signal from the remote device has been remove.
Manual Reset Relays:
A signal for a shutdown to the control system for the wellhead from the platform or plant ESD usually is due to a potentially risky or harmful condition that can occur in the vicinity of the wellhead.
It is essential that the manual reset pilot relay is utilize in the design of the shut-off system. The knob is at the one side of the reset manual pilot relay, and the tension pilot is locate on the other side of the three-way valve. When the knob is turn and the valve is release, the three-way valve is turn on and closes its ground-safety valve.
It is a requirement that the system needs to be in motion and shut down whenever the shutdown signal goes off. The removal of the potentially dangerous or harmful situation will not make the device reset automatically and won’t open the valve for safety on the surface.
Low- and high-pressure sensors
The pressure of the flow line in the well that runs downstream of the choke is control through high – and low-pressure sensors. Both the final section of the flowline as well as the downstream equipment are covered by the high integrity protection systems. The flowline breaking or leak can be detect using sensors that are low pressure. Pressure sensor specifications to be use for platforms offshore are define within API RP 14C Section A1.
The pressure sensors are usually connect together. A holding circuit’s supply pressure is link to the pilot’s intake. The low-pressure connection for the pilot connects to the low-pressure pilot’s intake connection.
Sand probes are utilize on flowlines in which it is possible to suffer erosion due to the flow of water. In these situations, the sand passage can cause erosion to the probe, and the probe will be activate.
The number of sensor failures involving sand could be helpful in evaluating the wear of the flowline once properly placed within the flowline. Therefore, it is crucial to record with care the dates and numbers of occurrence of sand sensor failures.
Sand probes must be place into a straight pipe that is at least ten feet downstream from the choke on the well or any other change in pipe direction. The pipe that runs downstream of the probe needs to be straight for a further four feet.