pdprao
Mechanical
- Dec 29, 2002
- 33
A Natural Gas Pipe line is constructed with several( 24 Nos) 18"NB 6D hot induction bends for thermal expansion loops . The Induction bends are tested with gauge plates at the time of manufacture of bends at shops. The gauging checks at shop used pig with two gauge plates mounted on the tool separated by distance of 300mm with plate size of 95% of Nominal ID of Line Pipe used for bends .
After construction of Pipe line with the above hot induction bends , the line is pigged with gauging Pig . Length of Gauging pig used is 500mm along , with single gauge plate with 4 Nos of PU cups arrangement.
The aluminium gauge plate is found to have some damage after site pigging test over 30 to 40 deg circumferential sector of gauge plate, to the extent of 1.5 to 2.5mm deep cut/ scoring marks with metal removed from gauge plate. Now the issues need to be reviewed are as below.
1) Whether Pig length of 500 mm used during site pigging with single gauge plate mounted at one end of pig (leading side ) make a difference as compared to 300mm gauge pig successfully used at shops for manufacturing of bends ? Whether the damage could be attributed to this reason of Pig Length.
2) Actually HSAW Pipes are used for Hot induction Bends manufacture( In-place of LSAW). Relatively poor Ovality control of HSAW pipes could be any factor for the problem of gauging defects compared to LSAW Pipes.
After construction of Pipe line with the above hot induction bends , the line is pigged with gauging Pig . Length of Gauging pig used is 500mm along , with single gauge plate with 4 Nos of PU cups arrangement.
The aluminium gauge plate is found to have some damage after site pigging test over 30 to 40 deg circumferential sector of gauge plate, to the extent of 1.5 to 2.5mm deep cut/ scoring marks with metal removed from gauge plate. Now the issues need to be reviewed are as below.
1) Whether Pig length of 500 mm used during site pigging with single gauge plate mounted at one end of pig (leading side ) make a difference as compared to 300mm gauge pig successfully used at shops for manufacturing of bends ? Whether the damage could be attributed to this reason of Pig Length.
2) Actually HSAW Pipes are used for Hot induction Bends manufacture( In-place of LSAW). Relatively poor Ovality control of HSAW pipes could be any factor for the problem of gauging defects compared to LSAW Pipes.
