API 650 floating-roof tanks bottoms
Preheating should be performed by heating and maintaining this heat in appreciable lengths of the joint to be welded, preferably using a strip burner with a mild flame rather than a harsh flame such as that from a cutting torch. Electrical strip heaters are available and have been found to be satisfactory. The preheat of 300°F should be checked with a temperature-sensitive crayon, or similarly accurate means, so that the steel 4 in. (or four times the API 650 floating-roof tanks plate thickness, whichever is greater) on each side of the joint will be maintained at the minimum preheat temperature. Ring burners or heaters are recommended for nozzle and manway welds. At no time during the welding should the base metal fall below a temperature of 300°F.
API 650 petroleum storage tank pipeline stress and product pressure, tank pressure, uniform or non-uniform temperature difference between the tank wall and the tank bottom, which cause the radial displacement and longitudinal rotation of the API 650 floating-roof tanks tank wall at the opening to affect the oil tank wall The impact is obvious. Therefore, the design must ensure that the load applied by the external pipeline on the opening of the tank wall is within the safety limit. If the stress of the API 650 floating-roof tanks connecting piping is not handled properly, the wall of the API 650 petroleum storage tank may deform or even rupture, causing a major accident.
In order to prevent the deformation of the bottom of metal vertical API 650 floating-roof tanks during welding, comprehensive control measures such as strict control of assembly geometry size, reasonable welding procedure, process control of welding deformation and rigid fixation are adopted during assembly welding. The specific methods are as follows:1. Strictly control welding groove forming of API 650 floating-roof tanks.2. Strictly control the size of tank welding seam assembly.3. Define the welding sequence of tank bottom plate.4. Reasonable distribution of welders.
