ak1965
Mechanical
- Jul 28, 2007
- 158
We are planning to weld a 4" weldolet of A 105 specifications to A213 P 11 High Pressure Steam Piping that is in service by taking a hot tapping.
1. We shall first weld the 4" weldolet to 6 " pipe that is carrying steam @ pressure 47 kg/cm^2 and 400 deg.C. while the 6" pipe is in service
2. Nex step would be to take a hot tapping from the 6" pipe thorugh this weldolet.
3. My query is that can i weld weldolet to the pipe in running condition. I suspect during welding, due to molten pool the actual sound wall thickness will reduce for the time being, making the pipe vulnerable for failure during the welding.
4.As per ASME Section II stress table, The maximum allowable stress would be around 1037 kg/cm^2 for F 11 material at 398.8 deg C.
5. Where as the actual hoop stress generated in 6" pipe (7.11 mm thk) considering the available sound wall around 3 mm (we presume 4 mm on outer side shall remain in molten state during welding).
6. Considering above I am skeptic that during welding due to execcsive hooop stress (1206 kg/cm^2),the pipe may fail and steam jet may come out in an uncontrolled manner.
We are planning to simulate the condition in our workshop.
Please opine for this unique problem.This is urgent please.
.
1. We shall first weld the 4" weldolet to 6 " pipe that is carrying steam @ pressure 47 kg/cm^2 and 400 deg.C. while the 6" pipe is in service
2. Nex step would be to take a hot tapping from the 6" pipe thorugh this weldolet.
3. My query is that can i weld weldolet to the pipe in running condition. I suspect during welding, due to molten pool the actual sound wall thickness will reduce for the time being, making the pipe vulnerable for failure during the welding.
4.As per ASME Section II stress table, The maximum allowable stress would be around 1037 kg/cm^2 for F 11 material at 398.8 deg C.
5. Where as the actual hoop stress generated in 6" pipe (7.11 mm thk) considering the available sound wall around 3 mm (we presume 4 mm on outer side shall remain in molten state during welding).
6. Considering above I am skeptic that during welding due to execcsive hooop stress (1206 kg/cm^2),the pipe may fail and steam jet may come out in an uncontrolled manner.
We are planning to simulate the condition in our workshop.
Please opine for this unique problem.This is urgent please.
.