Production Safety Controls

In some respects, virtually all automatic control equipment is also safety-control equipment: automatic control equipment nearly always is made to be “fail safe”-i.e., upon loss of power from the controlling energy medium, the controls return to the position that will result in the safest condition. Technical Data used in the field explained in diploma in petroleum engineering. Some automation controls, however, primarily perform safety functions rather than normal operational functions. These include high- /low-pressure safety shut-in valves, excess-flow valves, pressure and temperature switches, and pump-off controls.

High- /low-pressure safety shut-in valves and excess flow valves are both fluid-controlled valves of the type that is actuated by line fluid. This valve type was discussed briefly in the section on automatic control valves. The use of an excess-flow valve or low-pressure control with a safety shut-in valve primarily safeguards against a flow line break and the resultant loss of oil and surface property damage. High-pressure control with a safety shut-in valve guards against pressures in excess of the allowable limit building up in the flow line. Either of these two kinds of valves normally would be installed at the wellhead. Some more details of diploma in petroleum engineering are as under.

Another means of protecting against excessive flow line pressures and/or flow line breaks is the use of a pressure switch and an automatic control valve. Pressure switches are available that produce either an electric or pneumatic signal, as required, to actuate the automatic control valve. On rod-pumped wells, the control signal from the pressure switch also must shut down the pumping unit-i.e., turn off the switch on an electric motor or ground the magneto on an internal-combustion engine.

On rod-pumped wells that have no tendency to “head” or flow when the pumping unit is shut down, the automatic control valve may be omitted. A “pressure switch” in the sense it is used here consists primarily of a pressure-sensing element, limit pressure contact(s), and an electrical, mechanical, or pneumatic means to transmit the control signal to the object( s) controlled by the pressure switch. The pressure sensing element is commonly a bourdon tube, though some requirements could necessitate the use of a helical-, spiral-, diaphragm-, piston-, or bellows-type pressure-sensing element. In electrical control systems, the displacement of the pressure-sensing element is made to “make” or “break” an electrical switch, normally a mercury or micro switch, when the line pressure reaches the preset pressure limit(s). In pneumatic control systems, reaching the preset pressure limit(s) may actuate a pneumatic transmitter, relay, or slide valve. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join diploma in petroleum technology.

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