API 650 SUG I tanks stiffeners

Crack treatment of API 650 SUG I tanks weld area: find out the crack tip with ray or ultrasonic flaw detection, drill cut-off holes at both ends of the crack with the cut-off method, the hole depth is slightly greater than the crack depth, or groove (crack stop groove) is made by angle grinder at both ends of the crack, shovel and grind the whole crack, and grind it into a suitable groove; use radiographic inspection and dye detection to verify that the crack has been completely excavated, and finally repair welding.

Service Conditions and Hydrogen-induced Cracking
When the service conditions might include the presence of hydrogen sulfide or other conditions that may promote hydrogen-induced cracking effects, particularly near the bottom of the API 650 SUG I tanks shell at the shell-to-bottom connections, care shall be taken to ensure that the materials and details of construction of the tank are adequate to resist hydrogen- induced cracking. The Purchaser shall consider restricting the sulphur content of the material to be stored through thickness testing of the steel, laboratory surveillance tests, and the use of internal tank coatings to reduce the possibility of hydrogen-induced cracking.

The vent pipe mouth should be 4m or more above the ground. The nominal diameter of the API 650 SUG I tanks API 650 petroleum storage tank vent pipe should be no less than 50mm and a flame arrestor should be installed.