PIGGING OF HIGH VELOCITY GAS PIPELINE
VKV LLP pigged 36”HVJ pipeline network in 2005. The total length of the pipeline was 700km.
Number of segments: 8
Average velocity of gas: 34km/hr i.e. 9.44 m/s
Pigs to be run
ii. 2nd Run BIDI Gauge pig
iii. 3rd Run BIDI Brush
iv. 4th Run BIDI Magnetic pig with brushes
v. 5th Run BIDI Magnetic pig
Before the beginning of the operation the following problems were identified and necessary action was taken:
| Phenomenon | Implication | Modification / Action |
| High Speed Travel | (i) Disc Burnout | (a) Installation of Bypass port reduced speed to 32 km/hr |
| (ii) Mechanical failure of bodies | (b) Polyurethane compound was modified to prevent Burnout of Disc. Modification was successful so we were able to run the same discs for 2 runs | |
| (iii) Movement of Tracking teams | (c) All pig body components were tested for Impact strength | |
| (d) Fasteners installed on Pigs has twin Lock nuts and cashed Pins to prevent opening during the Pig Run | ||
| (e) Pig Tracking Teams were stationed and not moving |
However during the operation the problems encountered were different. As per the procedure for pig receiving the Flow Tee valve would be closed prior to pig receipt and flow would be diverted through pig receiver by pass line. Gas compressors were designed to run at a minimum pressure and flow rate. During the first foam pig run the flow tee valve was closed and the flow was directed through the pig receiver bypass valve. This was done at the last segment Vijapur where the gas compressor was located. The compressor stalled. To prevent this the Flow Tee valve was opened which lead to the Foam Pig being sucked into the branch line. Now to over come this the outer coating of foam pg was reinforced. The Bypass valve of Pig Receiver was kept completely opened. The Flow Tee valve was kept completely opened, the Pig would stop momentarily at the Flow Tee the valve would then be closed. Prior to complete closing the pig would move into receiver and reopen the valve.
