BlackOilsandBitumen
Chemical
So I have just jacked my tank at great expense to replace annular plates as it was condemned by my API inspector due to insufficient thickness in the critical zone (tomb stone repairs are not permited due to elevated temperature service).
The concern in this case in the critical zone (near shell to floor weld) was around structual integrity not leakage. The tank was condemned due to localised areas below 3.5mm, at the time I argueed that much like with shell plate defect assesment the stresses would equal out over a given critical length and that an average could be taken however this is not covered or allowed in API 653 for floor assesment.
After seeing the underfloor corrosion on the plates that have been removed I am now absolutly convinced that this repair was not neccessary as there was only some pitting in isolated areas and that given that the tank was constructed in 1953 assuming linar corrosion leakage would not have occured before next inspection and structural failure was in no way a realistic concern.
The concern in this case in the critical zone (near shell to floor weld) was around structual integrity not leakage. The tank was condemned due to localised areas below 3.5mm, at the time I argueed that much like with shell plate defect assesment the stresses would equal out over a given critical length and that an average could be taken however this is not covered or allowed in API 653 for floor assesment.
After seeing the underfloor corrosion on the plates that have been removed I am now absolutly convinced that this repair was not neccessary as there was only some pitting in isolated areas and that given that the tank was constructed in 1953 assuming linar corrosion leakage would not have occured before next inspection and structural failure was in no way a realistic concern.
