petro84
Mechanical
- Feb 7, 2012
- 19
Hi Dear Friends
As I know there are several methods for manufacturing longitudinally welded pipe like: U.O.E,U.O.C, continuous forming and Press Brake. All of these methods cause plastic cold forming.In ASME B31.4 it is written it is forbidden to use material with increased yield strength due to cold forming. As you know cold forming can increase yield Strength up to 15% .But refer to specification of Pipe manufacturing like API 5l, there is no mandatory requirements for doing heat treatment on manufactured pipes. In some instances it will be done but in others no. Also as you know when for example you use U.O.E which E stands for Expansion as final manufacturing Process your pipe shows greater yield strength on external Pressure but lower than plate material Yield Strength on internal Pressure and U.O.C which C stands for Compression shows greater yield strength on internal Pressure and adversely lower than plate material yield Strength on external Pressure. Now here are my Questions:
1) in standards Like ASME B31.3 it is Mandatory to do heat treatment on components after Cold forming like bending that exceeds specific fiber elongation. Does this requirement applies to Production of Pipe too ?
2) if answer to first question is No, why there is no correction factor for yield strength after cold forming during Pipe Manufacturing ?
3) As Stated in ASME B31.4 using increased yield strength due to cold forming is prohibited but in reverse condition like Internal Pressure on U.O.E pipe; there is no correction factor for decreasing Yield strength due to cold forming ?
you can read follwing documents if description of my question seems to be not clear:
Also see attached page from API 5l.
Best Regards
As I know there are several methods for manufacturing longitudinally welded pipe like: U.O.E,U.O.C, continuous forming and Press Brake. All of these methods cause plastic cold forming.In ASME B31.4 it is written it is forbidden to use material with increased yield strength due to cold forming. As you know cold forming can increase yield Strength up to 15% .But refer to specification of Pipe manufacturing like API 5l, there is no mandatory requirements for doing heat treatment on manufactured pipes. In some instances it will be done but in others no. Also as you know when for example you use U.O.E which E stands for Expansion as final manufacturing Process your pipe shows greater yield strength on external Pressure but lower than plate material Yield Strength on internal Pressure and U.O.C which C stands for Compression shows greater yield strength on internal Pressure and adversely lower than plate material yield Strength on external Pressure. Now here are my Questions:
1) in standards Like ASME B31.3 it is Mandatory to do heat treatment on components after Cold forming like bending that exceeds specific fiber elongation. Does this requirement applies to Production of Pipe too ?
2) if answer to first question is No, why there is no correction factor for yield strength after cold forming during Pipe Manufacturing ?
3) As Stated in ASME B31.4 using increased yield strength due to cold forming is prohibited but in reverse condition like Internal Pressure on U.O.E pipe; there is no correction factor for decreasing Yield strength due to cold forming ?
you can read follwing documents if description of my question seems to be not clear:
Also see attached page from API 5l.
Best Regards
