Discussion on manufacturing process of pressure vessel

Pressure vessel is an important equipment in petrochemical industry. The workload of manufacturing pressure vessel is heavy, which has higher requirements for the manufacturing process. In the process of preparing industrial equipment, the pressure vessel should be manufactured according to the specification requirements, appropriate quality control measures should be taken to improve the production efficiency of the pressure vessel, and the possible quality defects should be handled in time to meet the safety requirements in the operation process of the pressure vessel. This paper discusses the manufacturing process of pressure vessel, analyzes the manufacturing process of pressure vessel and gives the corresponding manufacturing measures.

Introduction

The quality control measures of pressure vessel include design, manufacture and installation, of which the most critical part is the quality control in the manufacturing process. Pressure vessel is an important special equipment in petrochemical production. Its quality is directly related to the overall quality of industrial production and the safety of people’s life and property. In order to control the quality of pressure vessels from the manufacturing process, we need to grasp every manufacturing detail and control the production quality of every link, so as to ensure the quality of products.

Manufacturing characteristics of pressure vessel

Diverse structure and variety

Different fields have different functions for pressure vessels, which makes the categories of pressure vessels diverse. In addition, the use environment and functional requirements of pressure vessels in the same field are also different, which brings diverse challenges to the manufacturing process of pressure vessels. The manufacturing of pressure vessels must be combined with the specific situation of the use site, The suitable container structure, variety and design parameters are selected according to the specific situation. Taking the heat exchange pressure vessel which is widely used in engineering as the analysis object, the main function of the heat exchange pressure vessel is to exchange heat and ensure the normal heat transmission of each part of the system. According to the different media and functions of each part of heat exchange pressure vessel, it can be divided into heat exchanger, cooler, condenser and so on.

High safety requirements

Most of the environments that need to use pressure vessels are severe. Generally, pressure vessels work in high temperature, high pressure and strong corrosive environment. At the same time, the liquid inside the pressure vessel is basically flammable and explosive. It can be seen that in the manufacturing process of pressure vessel, strict quality control is needed to ensure the safety and reliability of use, and all parameters in the manufacturing process must strictly comply with the specifications and standards.

Pressure vessel manufacturing involves a wide range of fields

The manufacturing process of pressure vessels involves a wide range of fields, from mechanical manufacturing to non-destructive testing, and then to anti-corrosion protection. It can be seen that in the manufacturing process of pressure vessels, it is particularly important to control the quality of products.

Manufacturing process of pressure vessel

Safety requirements

Ensuring the safety of pressure vessels is of great significance to the production process of the whole chemical industry. In manufacturing, it is necessary to strictly follow the safety standards to ensure that the specifications are implemented in place. Most pressure vessels will carry flammable and explosive materials in high temperature and vacuum environment. In the manufacturing process, the quality and safety must be strictly controlled, and the production quality must be strictly controlled according to the specification requirements. Especially in the manufacturing process of products, the production safety of pressure vessels must be paid attention to, so as to ensure the safety of manufactured products and avoid possible safety accidents.

Material selection

The selection of appropriate materials is an important prerequisite to ensure the smooth progress of pressure vessel manufacturing. The quality of materials is directly related to the safety degree of pressure vessel manufacturing. As the first link of pressure vessel manufacturing, the selection of pressure vessel materials must be from the perspective of overall safety and reasonable application. The selection of materials not only affects the manufacturing process of pressure vessels, but also controls the quality level of vessels. There are three main bases for selecting materials for pressure vessels:

  • (1) Select materials according to the design drawings;
  • (2) Analyze the chemical properties and physical properties of materials to select the appropriate manufacturing materials under reasonable cost control;
  • (3) Ensure the reasonable manufacturing performance of materials, require the material performance to meet the standard, strictly prohibit the use of substandard materials;
  • (4) Choose the appropriate way of using materials to avoid affecting the manufacturing quality of pressure vessels.

Welding process

The most important part of the pressure vessel manufacturing process is welding, welding can make the pressure vessel manufacturing components reasonable connection, standardize the use of technology, hire professional welding technical staff, reasonable use of welding materials, control process error. The requirements of welding technology for manufacturing pressure vessels are extremely strict, and the level and quality of technical personnel must be guaranteed. The technical personnel must follow the standard requirements and strictly implement the welding operation; In the welding process, effective management and supervision methods are adopted to implement the whole welding process.

NDT process

In manufacturing pressure vessels, the final process is to carry out nondestructive testing on the finished products, check whether there are damaged parts in the finished vessels, and judge whether the finished products are qualified. At present, the commonly used non-destructive testing processes are ut testing and RT testing, which can comprehensively test the working performance of pressure vessels.

Pressure vessel manufacturing quality control measures

Welding quality control

As welding is the most important part of manufacturing pressure vessel, the quality control of welding process is very important for the whole manufacturing work. Combined with the characteristics and specific process of welding, we must carry out quality control from four aspects: welding materials, welding process, weld repair and airport supervision. First of all, the selection of welding materials must consider the characteristics of the base metal, try to use welding materials with similar mechanical properties and chemical composition. For different welding materials, attention should be paid to control the strength requirements to ensure that the plastic deformation of the container does not exceed the limit; On the other hand, when purchasing welding materials, it is necessary to ensure that they have a complete factory certificate. The manufacturer should do a good job in sampling inspection to ensure that the welding materials are classified and stored, and the ambient humidity and temperature are controlled in an appropriate range; Secondly, in terms of welding process, ensure that the welding method is reasonable and effective. In view of the current gas welding, arc welding, automatic welding and protective welding, carry out the appropriate welding method for different applicable occasions. In addition, pay attention to the process evaluation procedure after welding, and evaluate the welding results; Thirdly, in terms of weld repair control, strictly control the quality of the weld. Once the weld is unqualified, timely repair the weld. According to the repair site data, the quality of the weld should be controlled. The data should be backed up in time to complete the heat treatment of the pressure vessel. After the repair, the second round of heat treatment should be carried out again; Finally, the welding site supervision and inspection work needs to timely check whether the welding equipment is in normal use, ensure that the welding size and form are consistent with the design drawing, timely preheat, ensure that the welding meets the relevant regulations of the process, and timely check the weld temperature.

Control and evaluate the appearance and geometric dimension

The direct factor of the pressure vessel quality is the appearance and geometric size of the pressure vessel. Undercut and other conditions will appear for the poorly handled vessels, resulting in stress concentration. In addition, the unqualified geometry will affect the manufacturing process of the whole pressure vessel. There are two aspects to control the appearance and geometry of pressure vessel. The first is the surface quality of the welded joint. The technical requirements for the surface quality of the fillet weld are extremely high. Improper welding treatment will cause serious quality problems at the fillet weld. The quality of the fillet weld will be checked to see if it meets the specification requirements. On the other hand, because the fillet weld joint is a weak point under stress, it is necessary to focus on the quality of the welded joint, Timely feedback processing; Secondly, the size of welding base metal should be checked in time to check whether there is mechanical damage, so as to ensure that the component welding error does not exceed the limit.

Pay attention to heat treatment after welding

After the completion of welding work, the post weld heat treatment is needed to improve the performance of welding structure and eliminate the thermal stress of welding joint in time. The main work of post weld heat treatment is focused on the welding joint and the overall structural performance. According to the relevant specifications and standards, confirm which places need to do welding heat treatment well. After the heat treatment, the quality of the welding head should be tested to judge whether the heat treatment is qualified.

Conclusion

To sum up, in the manufacturing process of pressure vessels, many manufacturing processes and quality control measures need to be observed by engineering personnel, clear manufacturing quality objectives, take reasonable quality control strategies, optimize the manufacturing process, and strictly control the operation in accordance with the specifications, so as to ensure that all aspects of the performance of pressure vessels meet the standards.

Author: Yang Xiao

Source: Network Arrangement – China Pressure Vessels Manufacturer  www.secmachinery.com

www.secmachinery.com is one of the leading china filtration equipment & sanitary stainless steel pressure vessels manufacturer, with professional factory. We focus on the sanitary pressure vessels, filtration equipment research and development, manufacturing, sales and service since the company been established. Our products is widely used on bio-pharmaceutical, food and beverage, fine chemical industry. 

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@secmachinery.com

Reference:

  • [1] Huang Xiaolian. Strengthening process control to ensure manufacturing quality of pressure vessel products [J]. Chemical engineering and equipment, 2010 (10): 101-103
  • [2] Miao Chunsheng, Cui Jianguo, Ma Xin. Investigation on manufacturing process of pressure vessel and Discussion on some problems [J]. Pressure vessel, 2008 (11): 56-57
  • [3] GB 150.1 ~ GB 150.4-2011 pressure vessels
  • [4] TSG 21-2016 Supervision Regulation on safety technology of fixed pressure follower
  • [5] Nb / T 47013-2015 nondestructive testing of pressure equipment

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