Welded API standard 650 flat-bottom tanks
Treatment of API standard 650 flat-bottom tanks welding defects:
1. Lack of fusion: once found, it should be shoveled and grinded off before re welding.
2. Incomplete penetration: over standard defects shall be removed and re welded. When welding on both sides, the shallow side of the groove can be grinded and shoveled to expose the welding root on one side, and then the welding is repaired.
3. Slag inclusion: over standard defects shall be removed and re welded.
4. Crater: weld to full after grinding.
5. Air hole: if the internal air hole exceeds the standard, it shall be welded again after being removed by grinding shovel, and the surface air hole shall be removed by grinding wheel and then repaired.
API 620 crude oil tank piping materials made according to ASTM A333 and A350 may be used at API standard 650 flat-bottom tanks design metal temperatures no lower than the impact test temperature required by the ASTM specification for the applicable material grade without additional impact tests. For temperatures below those allowed by the ASTM specification, the following paragraph shall apply.
Test welds of each API 650 tank nozzle and manway reinforcing pad (or each section of multiple piece pad) using dry air and apply a soap solution test in the presence of Purchaser's Inspector before hydro testing the API standard 650 flat-bottom tanks tank. Tap one inch NPT test hole in each pad or section.