Pipelines & Pipeline Safety - AUTOMATIC RESET PDF Print E-mail
Written by Norrie   
Thursday, 29 April 2010 19:53
Article Index
Pipelines & Pipeline Safety
TRANSMISSION OF FLUIDS
JOINING OF PIPELINES
PIPELINE SUPPORTS
PIPELINE ANCHOR POINTS
EXPANSION LOOPS (or BENDS)
PIPELINE SAFETY
'SHAFER' AUTOMATIC LINE-BREAK VALVE
LINE BREAK - SHAFER VALVE CLOSES
AUTOMATIC RESET
RE-OPEN THE SHAFER VALVE
PIPELINE SPHERING
All Pages

FIGURE: 10 - AUTOMATIC RESET

Due to the D.P., valve V.3-A will open allowing the 'Y' section pressure to pass to the check valve 'V.5'. If tank G.1. pressure is lower than the 'Y' section of pipeline, V.5. will open to add pressure to G.1.

Meanwhile, the pressure of the 'X' section of piping will fall to zero due to the line break and/or a de-pressuring operation.

Tank G.2. will also depressurize through the orifice 'RO'. and valve V.4. The DP across the orifice will fall to zero and the diaphragm will return to the bottom of its casing by the action of the spring.

The control arm will return to its original, horizontal position. Poppet valve P.2. will spring back to close off the power gas supply and vent tank H.1. to atmosphere.

At this point, the Shafer valves are closed, the damaged section of pipeline is isolated and the control system of the Shafer is stabilized as in Diagram 1.

Work can now begin on the repair of the pipeline.


Figure: 10



Last Updated on Thursday, 29 April 2010 19:56