API Std 650 aboveground oil storage tanks weld metal

The hardness of the welds contacting these environments, including the heat-affected zones, shall be considered. The weld metal and adjacent heat-affected zone often contain a zone of hardness that is well in excess of a value of 22 on the Rockwell C scale and could be expected to be more susceptible to cracking than would unwelded metal. Any hardness criteria shall be a matter of agreement between the Purchaser and the API Std 650 aboveground oil storage tanks manufacturer and shall be based on an evaluation of the expected hydrogen sulfide concentration in the product, the possibility of moisture being present on the inside metal surface, and the strength and hardness characteristics of base metal and weld metal.

Large net shell API 650 tanks or net shell of tank API Std 650 aboveground oil storage tanks is a tank top for the surface grid structure and the physical structure form of truss structures, thin shell structure is reasonable, mainly for the top using triangle net shell, socket type net shell or meridian reticulated shell technology for the design of API Std 650 aboveground oil storage tanks large-scale tank top, its great spanning capacity and uniform stress, good rigidity, less material, convenient assembly, safe and reliable.

Treatment of API Std 650 aboveground oil storage 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.