Andres Romero
Petroleum
- Jan 3, 2022
- 14
Colleagues, I wanted to tell you how you evaluate the casing of a tank according to API 653. We have some differences of opinions.
To evaluate a corroded area, we determine the current thickness as stated in paragraph 4.3.2 of API 653.
We calculate the minimum allowable thickness (tmin) as stated in paragraph 4.3.3.1 of API 653. (Evaluation for a complete ring)
The discussion is as follows:
There are people who say to evaluate the complete ring according to the 3 criteria in paragraph e) 4.3.2.1 (For corroded areas).
Criteria to continue in operation.
e) The criteria for continued operation are as follows:
i) the value t1 shall be greater than or equal to tmin (see 4.3.3 or 4.3.4), subject to verification of all other loadings
listed in 4.3.3.5;
ii) the value t2 shall be greater than or equal to 60 % of tmin; and
iii) any corrosion allowance required for service until the time of the next inspection shall be added to tmin and
60% of tmin.
Other people say to evaluate the casing according to the tmin of paragraph 4.3.3.1 for a complete ring, since there is not a corroded area, but rather generalized corrosion throughout the ring due to the stored product.
What do you think?
To evaluate a corroded area, we determine the current thickness as stated in paragraph 4.3.2 of API 653.
We calculate the minimum allowable thickness (tmin) as stated in paragraph 4.3.3.1 of API 653. (Evaluation for a complete ring)
The discussion is as follows:
There are people who say to evaluate the complete ring according to the 3 criteria in paragraph e) 4.3.2.1 (For corroded areas).
Criteria to continue in operation.
e) The criteria for continued operation are as follows:
i) the value t1 shall be greater than or equal to tmin (see 4.3.3 or 4.3.4), subject to verification of all other loadings
listed in 4.3.3.5;
ii) the value t2 shall be greater than or equal to 60 % of tmin; and
iii) any corrosion allowance required for service until the time of the next inspection shall be added to tmin and
60% of tmin.
Other people say to evaluate the casing according to the tmin of paragraph 4.3.3.1 for a complete ring, since there is not a corroded area, but rather generalized corrosion throughout the ring due to the stored product.
What do you think?
