Pipeline engineering can provide powerful basic conditions for the transportation of chemical raw materials in petrochemical enterprises, and also help to ensure the smooth progress of petrochemical life activities. However, due to the particularity of the chemical industry structure, various accidents will inevitably occur in the pipeline transportation stage, which greatly reduces the safety of oil and natural gas pipeline transportation.
1 make good preparations before welding construction of petrochemical pipeline engineering.
1. 1 Prepare materials.
In order to ensure the smooth development of welding operation, it is necessary to ensure that welding materials meet the requirements of relevant standards in China. Different pipeline lines have different requirements for welding materials. Therefore, in the preparation process, the quality of covered electrode and welding wire must be guaranteed to be qualified, and there is a nationally recognized quality certificate. In addition, there should be no obvious crack or shedding on the coating of covered electrode, and the packaging of the coating covered electrode and welding wire should be intact and free of moisture [1]; Before using covered electrode and welding wire, the rust and oil stain on the surface of covered electrode and welding wire should be removed to avoid adverse effects on welding operation.
1.2 Prepare the equipment.
In order to ensure the orderly development of welding operations, it is necessary to prepare the equipment in advance. First of all, all kinds of equipment needed for on-site welding operation must be carefully checked, and instruments and meters should be preliminarily debugged to ensure that they are in good condition; Secondly, ensure that the equipment meets the specific requirements of the welding operation site, such as the verification results of various instruments and meters are qualified and the equipment is in good condition; The adjustment characteristics and dynamic characteristics of the equipment are good; Indicating standards and correctness of voltmeter and ammeter, reliable process parameters, etc. Therefore, the equipment quality inspector must carefully check each piece of equipment to avoid equipment failure during welding operation and affect welding quality.
1.3 personnel preparation.
In the transportation field of oil and natural gas energy, pipelines play a very important role. The welding operation of pipeline engineering is a professional activity. Only by strictly following the standards can we effectively play the role of petrochemical pipelines. Therefore, strengthening the professional audit of pipeline welding construction personnel is also an essential preparation work before welding construction of petrochemical pipeline engineering, which has a great influence on welding quality. Before the actual pipeline welding construction, welders must undergo relevant training, such as basic welding knowledge training and operation skills training, and can only take up their posts after passing the examination.
2 petrochemical pipeline engineering welding operation steps and control points
Pipeline engineering can provide strong basic conditions for the transportation of chemical raw materials in petrochemical enterprises. Strengthening the construction of petrochemical pipelines is conducive to reducing the transportation cost of chemical raw materials in petrochemical enterprises and promoting the optimal allocation of resources [2]. After making the above preparations, the pipeline engineering construction unit must organize on-site personnel to carefully analyze the structural characteristics, chemical pipeline materials and on-site construction environment of the pipeline engineering, and draw up a set of feasible, scientific and reasonable welding operation scheme in time to provide data support for the actual welding operation.
2. 1 Operation steps and control points of tack welding
For petrochemical pipeline engineering, it has the characteristics of long transportation distance, wide distribution range and complex internal and external structure. Therefore, safety accidents often occur in the pipeline use stage due to various factors, which greatly reduces and improves the risk factor of chemical product supply and transportation system. In the construction of pipeline engineering, tack welding is a common welding method, and the welding process and welding material used are the same as the root bead. Welders must have a welder's license and have some work experience. The control points of tack welding include: firstly, the optimal weld length is10 mm ~15 mm; Secondly, the thickness is preferably 2 mm to 4 mm, and the thickness should not exceed two thirds of the wall thickness of the pipeline; Thirdly, there should be no cracks or other defects in the weld seam of tack welding; Finally, the left and right ends of the positioning weld should be polished into a gentle slope shape.
2.2 Operation steps and control points of stainless steel pipeline welding
As one of the important components in the industrial field, petrochemical industry occupies a very important position in China's national economic system. The development of petrochemical industry affects the social and economic development of China. Stainless steel pipeline welding is a common welding method in pipeline engineering construction. Its operation steps and control points include: on the basis of ensuring good penetration and fusion, welding with small or no swing, short arc and small line energy; Its control points include: it is best to use multi-layer and multi-pass welding; The interlayer temperature shall not exceed 100℃; After each pass is completed, the defects on the surface of the pass shall be eliminated, and the welding slag shall be thoroughly removed.
2.3 Operation steps and control points of dissimilar steel pipe welding
When welding dissimilar steel pipes, the welding materials must be reasonably selected according to the actual situation, such as chromium-molybdenum heat-resistant steel with different steel grades or dissimilar steel composed of carbon steel and chromium-molybdenum heat-resistant steel [3]. If preheating is needed, the preheating temperature should be determined by electric heating method according to the materials with high hardening tendency. The preheating should be carried out slowly and evenly on both sides of the groove, and the preheating range on each side should exceed 3 times the wall thickness.
3 Conclusion
Welding operation plays a very important role in petrochemical pipeline engineering construction, and improving pipeline welding quality is the key to improve chemical operation efficiency. Therefore, petrochemical enterprises must deeply analyze the structural characteristics of pipeline engineering and chemical pipeline materials, formulate a set of systematic, perfect and scientific welding construction scheme, and provide guarantee for improving the overall level of petrochemical production.
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