API 653 Sec - 5 (Brittle Fracture Considerations)

Question 1

If a tank shell thickness is no greater than………, the risk of failure due to brittle fracture is minimal

Answer 1

0.5 in (12.7 mm)

Question 2

No known tank failures due to brittle fracture have occurred at shell metal temperatures of …………

Answer 2

60 °F or above.

Question 3

Industry experience and laboratory tests have shown that a membrane stress in tank shell plates of ……………. is required to cause failure due to brittle fracture

Answer 3

at least 7 ksi or ≥ 7 ksi

Question 4

For unknown material and unheated tanks, the shell metal temperature shall equal the ……………..

Answer 4

design metal temperature

Question 5

The evaluation of brittle fracture assessment shall be based on the most severe combination of ………..

Answer 5

temp. & liquid level

Question 6

The owner can also make a more rigorous analysis to determine the risk of failure due to brittle fracture by
performing a ………………… based on established principles and practices

Answer 6

fracture mechanics analysis

Question 7

The service can be considered more severe and create a greater risk of brittle fracture if ………….

Answer 7

decreased in temperature

Increased in specific gravity (thus increased stresses)

Question 8

Tank shell thickness ½” and shell metal temperatures at 60°F and above

Answer 8

0.5 in (12.7 mm)