Key points of pipe fitting processing (II)
Key points of pipe fitting processing (II)
The brief introduction of key points of pipe fitting processing
4.The welding method:
The welding methods of pipe fittings are commonly used by manual arc welding, gas shielded welding and automatic welding.
The manufacturer shall prepare the welding procedure specification to guide the welding work, and shall conduct the welding procedure evaluation according to the requirements of the corresponding specification, so as to verify the correctness of the welding procedure specification and evaluate the welder's welding ability.
Welders engaged in pipe welding operations shall be determined by the quality and technical supervision departments of examination and obtain a corresponding qualification certificate shall not engage in relevant steel welding work (according to the regulation of some industries, used for welding pipe fittings to get industry rules in some sectors of welder and welding procedure qualification examination, such as Marine welding pipe fittings to obtain corresponding class welder test and welding procedure qualification).
5.Heat Treatment:
Heat treatment process is an important part of pipe fitting manufacturing. Through the heat treatment steps of heating, heat preservation and cooling, the work hardening, residual stress and metal deformation defects generated in the forming process are eliminated, so as to change the metal structure and properties of the pipe fittings after forming and restore to the state before deformation or improve its performance. The commonly used heat treatment equipment is reflector furnace, electric furnace, etc. The common control mode is that the thermocouple in the furnace is connected to the control device of the temperature and time automatic recorder by the sensor. The heat treatment requirements are different in different pipe fitting product standards. Not all deformed pipe fittings need to be heat treatment. Usually, when the final forming temperature of low carbon steel pipes is not less than 723 ("recrystallization temperature"), heat treatment is not necessary, because the final structure state of low carbon steel pipe fittingbbbbbbb` is basically normalized at this temperature, below this temperature or above 980 ("recrystallization temperature"). Alloy steel or stainless steel pipe fittings should be heat treated regardless of cold or hot forming. The routine inspection of heat treatment is usually completed by hardness test.
6.Surface Treatment:
The surface treatment of pipe fittings is usually carried out by sandblasting, shot blasting, grinding, pickling and other methods, so as to remove the corrosion and scratches on the surface of products, so as to make the products reach a smooth surface and meet the requirements of subsequent processing and inspection. The surface hardness of pipe fitting treated with shot blasting will increase slightly.
To be continued
