How many time can roll a same plate for shell

[jayager]

thread794-231004

Hi please guide me how many times can roll a same plate?
Shell thickness : 12.7mm
Shell ID : 500mm

If ASME states about the times of rolling. Please provide the code.

 

[abuanaselmasry]

What do you mean by re-rolling? Do you mean the plate is rolled, then flatten, then rolled again?, or you mean that the plate is rolled to a diameter, and then due to some some reasons the rolled shell is resent back to the roller for rectifying the rolling, or to roll it to smaller diameter? Maybe the reason is the ovality or fit-up tolerance to the second course or whatever issues.

Regards,
M.Salaheldin
Static Equipment Mechanical Design Engineer

 

[metengr]

One can roll a plate as many times as needed provided the end result meets Code requirements for any thermal treatment and tolerances.

 

[jayager]

If once rolled,then flatten, then rolled again may cause any strength impact on the Plate.
To rectify the ovality.

 

[r6155]

Why not use NPS 20 instead of plate?

Regards
r6155

 

[abuanaselmasry]

We need to understand that Rolling is a plastic deformation we are applying to the material. This means that the material started to be work hardened. i.e the hardness will increase and the yield strength will as well increase. Again flattening will harden it more, and the second rolling is third cycle of hardening the plate. In your case the thickness is small, but still the diameter of rolling is small as well. I'm not Metallurgist, but you maybe need to heat treat the plate to acceptable ISR (intermediate stress relief) cycle. If the material is sensitives to heat treatment (like quenched materials) then, you maybe also need to simulate the heat cycle on a test coupon to assure the S value is still within code limits.

But, I don't think that you need to flatten the plate. Re-rolling can be done on the already rejected rolled cylinder. Sometimes we do the same when rolling large diameters with high thickness. It happens some times that the first rolled course, after welding, goes behind the acceptable limits. We have never flatten it before. we re-roll the same even after welding.

Regards,
M.Salaheldin
Static Equipment Mechanical Design Engineer

 

[r6155]

More information: material, welding process, longitudinal dimension of shell, dimensional deviations, etc
Please, can you explain the problem?

Regards
r6155