PressureGuard Module One - Introduction

Contents SCH Actuator Design Philosophy Key Features Control System - Standard Components Standard Control Components Components Overview Reservoir Handpump HP Gauge Pressure Regulator LP Accumulator Manual Reset Valve Home

Contents Control System - Shutdown Components Shutdown Devices Pressurematic Pilot SP Pressure Pilot Pilot Accessories Control System - Operation Manual Operation / Arming Actuator Supply Regulation Remote Arming Remote Shutdown Home

SCH Actuator Design Philosophy Self-Contained Hydraulic (SCH) actuators are most commonly used for applications in which automatic valve control is required but there is no external power source available to power the actuator. The most common specific application is for ensuring valve shutdown on wellheads where an actuator power source is either unreliable or non existent. The basic design philosophy for a SCH actuator is that a hydraulic handpump is used to pump hydraulic fluid under pressure into an actuator’s hydraulic cylinder which is used to compress the actuator’s spring as well as to move the mainline valve to its normal operating position. In the event of a situation in which automatic valve operation is required, a control component is used to vent the hydraulic fluid from the actuator’s cylinder which allows the compressed spring to move the valve to its fail-safe position. Home

Key Features Suitable for remote, unmanned, unpowered and critical service Adaptable to either quarter-turn or linear operated valves Field-proven in extreme climatic conditions Standard hydraulic model for all valve sizes and configurations Eliminates requirement for plant air, fuel gas, electricity or expensive nitrogen backup systems Modular design to simply maintenance High Pressure, zero leakage control Home

Control System - Standard Components All SCH actuator control systems are supplied with a basic manifolded control system which provides one-way local control via the handpump. In addition to reliable and leak free mainline valve automation, the manifold based control system enables quick and simple maintenance. Home

Control System - Components Overview The standard SCH control system shown below is supplied as standard with the following control components: LP Pressure Gauge HP Pressure Gauge HP Relief Valve Handpump Assembly Pressure Regulator Reservoir Actuator LP Relief Valve LP Accumulator Manual Reset Valve Home

Control Components - Reservoir Contains hydraulic fluid for actuator and controls. Reservoir is non-pressurized (closed loop option available) Houses both HP and LP relief valves Fitted with hydraulic level indicator Fitted with drain plug Fitted with suction screen Simple to remove for inspection and maintenance of internal components Home

Control Components - Handpump Used to pressurize the hydraulic fluid, thereby compressing the actuator’s spring and moving the mainline valve to it’s normal operating position. Positive displacement Weatherproof boot Chrome plated ram Replaceable discharge filter and check valve Anodized aluminum handpump handle Home

Control Components - HP Gauge Monitors the hydraulic pressure in the high pressure line which also indicates the supply pressure available to the actuator. Stainless steel body Liquid filled Brass Bordon tube Fitted with snubber Home

Control Components - Pressure Regulator Used to reduce to the hydraulic pressure in the high pressure actuator supply circuit (typically 1,000 to 1,200 psig) to a low pressure (typically 100 psig) allowing low pressure control components in the control circuit to be used downstream of the regulator. ENP brass body Home

Control Components - LP Gauge Monitors hydraulic pressure in the low pressure control circuit. Stainless steel body Liquid filled Brass Bordon tube Fitted with snubber Home

Control Components - LP Accumulator Prevents cyclic transfer, due to temperature changes, of hydraulic fluid from the high pressure actuator supply circuit to the low pressure control circuit and thereby prevents temperature induced creep of the actuator. Eliminates temperature induced actuator movement for -46°C to 77°C ambient temperature environments Home

Control Components - Manual Reset Valve Used to provide a local manual reset facility following mainline valve shutdown. High flow rates to provide fast mainline valve shutdown Normally closed, manual reset, pilot operated relay Home

Control Components - Shutdown Devices The standard SCH control system always requires at least one additional control component to initiate valve shutdown. This type of component is used to initiate the depressurization of the system allowing the spring in the actuator to move the mainline valve to its failed position. Most common of these shutdown devices are pressure pilot valves, solenoid valves and manual ball valves. Manual Reset The picture shows a Pressurematic Pilot fitted with a manual reset valve (P-MR type) being used as the shutdown device. Pressurematic Pilot Home

Control Components - Pressurematic Pilot All Pressurematic pilot valves provide high and low pipeline pressure sensing on gas or liquid pipelines and can be fitted with either an automatic or manual reset facility. P-AR Pressurematic Pilot (Automatic Reset) P-MR Pressurematic Pilot (Manual Reset) Home

Control Components - SP Pressure Pilot SP Pressure Pilot valves provide either high or low pipeline pressure sensing on gas or liquid pipelines and can be fitted with either an automatic or manual reset facility. SP Pressure Pilot for sensing low (falling) pipeline pressure SP Pressure Pilot for sensing high (rising) pipeline pressure SP Pressure Pilot for sensing high (rising) pipeline pressure c/w manual reset valve Home

Control Components - Pilot Accessories In addition to pilot valves, Bettis Canada manufacture both ISO Test Valves and Flow Tees to assist with installation and calibration. Both components are available in a range of materials and trims to cover all types of pipeline media. ISO Test Valve Flow Tees Home

Operation - Manual Operation / Arming The HP Pressure Gauge measures the fluid pressure in the HP Actuator Circuit and therefore the pressure being supplied to the actuator from the handpump. 2 During manual arming of the system, both the shutdown control component (shown here as a solenoid valve) and the Manual Reset Valve in the LP Control Circuit are in the closed position; continued operation of the handpump will pressurize the circuit until the LP Pressure Regulator’s set-point is reached. The HP Relief Valve limits the maximum pressure (typically 1200 psig) that can be generated by the handpump in the HP Actuator Circuit. The LP Accumulator prevents cyclic transfer, due to temperature changes, of hydraulic fluid from the high pressure actuator supply circuit to the low pressure control circuit and thereby prevents temperature induced creep of the actuator. The LP Pressure Gauge measures the fluid pressure in the LP Control Circuit. Raising the handpump handle sucks fluid from the reservoir though an integral check valve. On the down-stroke the fluid is forced under pressure through a filter and another check valve into the HP Actuator Circuit (shown in red). The LP Relief Valve prevents potential over-pressurization in the LP Control Circuit which could be caused by thermal fluid expansion. 1 The Manual Reset Valve is armed by pulling its toggle to the manual position. The LP Pressure Regulator limits the maximum pressure that is supplied (typically 100 psig) to the LP Control Circuit (shown in green). When the LP Control Circuit has been fully pressurized to the LP Pressure Regulator’s set-point no more fluid can pass though the regulator. Continued handpump operation forces more fluid into the HP Actuator Circuit thereby increasing the pressure in the circuit. The increasing pressure pressurizes the actuator’s hydraulic cylinder thereby compressing its spring and stroking the mainline valve to its normal (here shown as open) operating position. Home

Operation - Actuator Supply Regulation When the pressure in the HP Actuator Circuit reaches the set-point of the HP Relief Valve it will open, releasing fluid back to the Reservoir until the pressure falls below its set- point. Continued operation of the handpump will simply cause the HP Relief Valve to continue to vent fluid back to the reservoir. Continued operation of the handpump after the actuator has stroked the mainline valve to its normal operating position (shown here as open) will increase the pressure in the HP Actuator Circuit. Home

Operation - Remote Arming 1 Once the shutdown device is in the open position, it allows a pilot signal to travel to the Manual Reset Valve. When the Manual Reset Valve senses the pilot signal, its spool moves slightly allowing the toggle to move to the remotely armed position. Once the Manual Reset Valve is in the remotely armed position, loss of the pilot signal to it will result in mainline valve shutdown. To initiate remote arming of the system, the Manual Reset Valve has to be manually armed and the system pressurized via the handpump. After the system has been pressurized, the shutdown device (here shown as a solenoid valve) has to be in the open position (its normal operating position). Here the solenoid valve has been energized to move it to the open position. Home

Operation - Remote Shutdown As the LP Control Circuit begins to depressurize, the LP Pressure Regulator senses the pressure drop and attempts to maintain the pressure in the circuit by allowing fluid to pass though it from the HP Actuator Circuit. Due the loss of fluid though the LP Pressure Regulator from the HP Actuator Circuit, it begins to depressurize. During a failure condition, the shutdown control component will move to the closed position (here, the solenoid valve has been de-energized). In the closed position, the shutdown device allows the fluid in the Manual Reset Valve pilot line to be vented back to the reservoir, thereby depressurizing the line and allowing the Manual Reset Valve to move to the open position. Following the mainline valve shutdown, all fluid is returned back to the reservoir and both the HP Actuator and LP Control circuits become fully depressurized. As the HP Actuator Circuit depressurizes and the pressure from the actuator’s hydraulic cylinder is removed, the spring causes the mainline valve to be stroked to its failed position (here shown as closed). In the open position, the Manual Reset Valve allows fluid from the LP Control Circuit to be vented back to the reservoir. Home

End of Module One Home