A study of the thermal zones in the repair of corrosion damage to the external surfaces of pipelines welding

The study was carried out to study the temperature gradient distribution in the cross section of the oil pipeline wall section during the repair of corrosion damage to the outer surface of oil pipelines by welding. As a result of the studies it was found that in a certain range of values of linear energy in the heated section of the pipe wall it is possible to obtain a zone of guaranteed strength properties, the metal in which has a margin of temporary resistance to rupture. Also, the dependence describing the temperature change of the inner surface of the pipe wall at different values of the linear energy and the residual thickness in the repair area by welding is obtained.
Materials and methods
Analytical studies, numerical and field experiments.
Results
Studies have shown that the use of deposition modes with a value of linear energy up to 7000 j/cm can significantly reduce the heating of the metal pipe wall in the repair of corrosion damage to the outer surface of the pipe, which will provide a zone of guaranteed strength properties. At the same time, the thickness of the zone of guaranteed strength properties is directly proportional to the speed of movement of the point source of heat and is inversely proportional to the effective thermal power and running energy as a whole. Therefore the repair of corrosion damage to the external surfaces of the pipes it is necessary to apply less heat stressed methods of surfacing, which allows to perform welding operations when the value of heat input of no more than 7,000 joules/cm.
Conclusions
1. Discovered in the research area of guaranteed strength properties that can be stored in the heated metal stock according to the temporary tear resistance. 2. To obtain a zone of guaranteed strength properties, welding must be performed at values of linear energy up to 7000 j/cm. 3. The thickness of the zone of guaranteed strength properties is directly proportional to the speed of movement of the point heat source (welding speed) and inversely proportional to the running energy.