Rolled Shell Plate Extreme Fibre Elongation vs Plate rolling Direction

[DK44]

Dears.
ASME Sec VIII Div 1 provides rues for Extreme Fibre Elongation for formed Shells.

1. When Plates for Shells are cold formed by rolling along the longitudinal direction of plate rolling (ie. along the grain orientation), this phenomenon is quite understandable. But if the Plate is rolled in the transverse direction of Plate rolling, this phenomenon does not appear to be more appropriate as the grains do not tend to expand longitudinally and instead they may tend to open or tear (Lamellar tear) .

2. Does the code rules for extreme fibre elongation imply indirectly the plate rolling direction? Incidentally, code does not specify any limitation / recommendation for the direction of Plate Shell rolling.

3. Is it always preferable to roll the Plate in the Longitudinal diction rather than in transverse direction of plate rolling.

4. However, Tensile (as well as Impact) tests of Plates are always performed in the Transverse direction of plate rolling meting the Specification minimum values.

 

[JStephen]

You're assuming the code is checking for adequacy in one direction but is then inadequate in the other direction.
I think the intent is to check for adequacy in either direction, and you may have some bonus adequacy in the longitudinal direction.
I think you have similar requirements for formed heads, which of course are formed in both directions.
If I remember right, one of the distinctions between the vessel-grade steels (A516) and structural steels (A36) is greater uniformity in the transverse direction.

 

[r6155]

@ DK44
What is your question?

Regards

 

[DK44]

Thank you JStephen.

Dear r6155.
1. My question is that whether Cold rolling of Shell Plate in the longitudinal direction(parallel to grain orientation) has a relation to Code provision of Extreme Fibre elongation requirements (which is more pronounced in the longitudinal direction.

2. For Cold formed Dished Heads, the extreme fibre elongation is also more pronounced in the longitudinal direction.

3. Of course, the tensile and impact properties are ensured as per Specification, in the Transverse direction of Grain Orientation of Rolled Plates.

 

[r6155]

No limitation of direction for rolling of plates in ASME VIII Div 1

Particular attention should be given to cut edges and other parts of rolled plate which would disclose the
existence of serious laminations,

You can specify UT of plates and “Through thickness tensile test”

Laminations (lamellar tearing) in welds can be reduced by preheat before welding, also before flame cutting.

Regards