Assessing annular plate thickness of an old angle.

[carthago]

Could you please give more light on annular plate thickness.
I am actually looking for a clearer interpretation of API 653.

I mean assuming the remaining tank life is known or fixed.
And the annular plate thickness is less the the original thickness less corrosion allowance...HOW TO PROCEED FURTHER

tHANKS

 

[JoeTank]

You always have three options in API-653...
Repair the tank by replacing the annular ring or repair the appropriate areas.
Rerate the tank by lowering the product level to accomdate the thin annular ring.
Retire the tank.

Joe Tank

 

[carthago]

Thanks JoeTank...

But before going to the above..I thought that one can also determine if there is enough remaining corrosion thickness left over to the next inspection to operate the equipment without jeopardizing its integriy.

Actually my question is what is the minimum acceptable annular bottom thickness including remaining thickness, according to API 653.

For instance API 579 which is a complementary standard to API 653 (and also some others( has three assessement levels .
Level 1 is for items with a STRAIGHT relation Pressure versus thickness.
Level 2 is for other items like flanges , BOTTOM PLATE, Tubesheets,etc..
Level 3 is complicated = finite elements.
This API 597 gives a lot of tips and formula on how to accept, de-rate or reject an items by conducting an assessment with level 2 for instance.
My problem is I do not know how to handle An annular plate with level II !!

 

[JoeTank]

cartargo
Minimum annular bottom plate thickness is determined per API-653, Section 4.4.8.

Joe Tank