Pressing of pipes
Pressing of pipes
(OP)
After joining 2-3 pipes with butt joint, straighness of the centre line is deviated due to the thermal stresses and fitup face out.
To bring back the component to a straight pipe, mechanical pressing is done using hydralic press, supporting the component as a simply supported beam and the load from centre. Plastic deformation is obtained with max deforming force of 500 tons. Is the same process acceptable to creep strength materials like Grade 91/92 ? What is the max thickness of the pipe that can be straightess corrected with this available pressing force
To bring back the component to a straight pipe, mechanical pressing is done using hydralic press, supporting the component as a simply supported beam and the load from centre. Plastic deformation is obtained with max deforming force of 500 tons. Is the same process acceptable to creep strength materials like Grade 91/92 ? What is the max thickness of the pipe that can be straightess corrected with this available pressing force





RE: Pressing of pipes
RE: Pressing of pipes
RE: Pressing of pipes
I came to know that many world class manufacturers does it without bow correction(what we call for straightening the header ) How can it be done. The tolerance for straightness is +-9 from the mean theoritical central line.
RE: Pressing of pipes
RE: Pressing of pipes
The reasons are
1. There is some amount of face out
2. Root welding is given priority while fitup. A uniform root gap of 2-2.5 is maintained. So the small amount of Faceout reflects as a Bow
3. Furnace is optimised with accumulating a number of headers. In furnace itself some bow is induced.