rQuestionEngineering
Mechanical
- Aug 30, 2012
- 204
During suction pipe strain verification , movement of 0.10mm was noted at 75% of the torque value .
It was decided to torque the discharge side and the movement reverted back to below 0.05mm at 100% .
Subsequently , we continue to torque the suction to 100% .
Overall movement was within tolerance.
Can anyone tell if the above procedure is correct ?
Some expert told me that it is not correct even though the overall strain is within limit. It is required to fully torque one pipe before moving to another pipe.
I am confused and need to separate the myths and facts.
API 686 is not clear to me.
====================================
4.8 PipeStrainMeasurement
4.8.1 An alignment bracket shall be installed on the cou-
pling hub or shaft of the machine being checked for pipe
strain.
4.8.2 Indicators shall be mounted on the coupling hub to
measure vertical and horizontal movement on the opposite
machine as the pipe flange bolts are being tightened using a
torque wrench.
4.8.3 Bolt-up of the piping flanges to the machinery
flanges shall proceed with the largest flanges first. Bolt-up
must be completed in a continuous
effort without disturbing
the location of the dial indicators.
4.8.4 Initial tightening of the flange bolts shall be sn(u1g0
percent of total torque). Flange bolts
shall then be tightened
to 30 percent of total torque. The
flange bolts shall then be
tightened to 100 percent of total final torque. Piping bolt
torque values shalbl e specified by the piping engineering de-
signer or the machinery manufacturer taking into account
whether bolt threads are lubricated or nonlubricated.
4.8.5 The maximum shaft movement in either the vertical
or horizontal directions after the flange is tightened shall be
50 micrometers (0.002 inch) or less. If the shaft movement is
more than 50 micrometers (0.002 inch), the piping flange
shall be loosened from
the machinery and corrections made
to the piping or supports. The flange gasket shall then be re-
placed and the procedure repeated. For
special purpose ma-
chinery or when specified, machine shaft movement during
piping bolt-up shall be recorded on the Piping Alignment
Data Sheet shownin Figure B-4.
Note: Movement greater than 50 micrometers (0.002 inch) is permissible
during the tightening procedure.
It was decided to torque the discharge side and the movement reverted back to below 0.05mm at 100% .
Subsequently , we continue to torque the suction to 100% .
Overall movement was within tolerance.
Can anyone tell if the above procedure is correct ?
Some expert told me that it is not correct even though the overall strain is within limit. It is required to fully torque one pipe before moving to another pipe.
I am confused and need to separate the myths and facts.
API 686 is not clear to me.
====================================
4.8 PipeStrainMeasurement
4.8.1 An alignment bracket shall be installed on the cou-
pling hub or shaft of the machine being checked for pipe
strain.
4.8.2 Indicators shall be mounted on the coupling hub to
measure vertical and horizontal movement on the opposite
machine as the pipe flange bolts are being tightened using a
torque wrench.
4.8.3 Bolt-up of the piping flanges to the machinery
flanges shall proceed with the largest flanges first. Bolt-up
must be completed in a continuous
effort without disturbing
the location of the dial indicators.
4.8.4 Initial tightening of the flange bolts shall be sn(u1g0
percent of total torque). Flange bolts
shall then be tightened
to 30 percent of total torque. The
flange bolts shall then be
tightened to 100 percent of total final torque. Piping bolt
torque values shalbl e specified by the piping engineering de-
signer or the machinery manufacturer taking into account
whether bolt threads are lubricated or nonlubricated.
4.8.5 The maximum shaft movement in either the vertical
or horizontal directions after the flange is tightened shall be
50 micrometers (0.002 inch) or less. If the shaft movement is
more than 50 micrometers (0.002 inch), the piping flange
shall be loosened from
the machinery and corrections made
to the piping or supports. The flange gasket shall then be re-
placed and the procedure repeated. For
special purpose ma-
chinery or when specified, machine shaft movement during
piping bolt-up shall be recorded on the Piping Alignment
Data Sheet shownin Figure B-4.
Note: Movement greater than 50 micrometers (0.002 inch) is permissible
during the tightening procedure.
