How To Choose A Riveting And Welding Unit With Pressure Vessel Design Qualifications? Brush Question APP

How to choose a riveting and welding unit with pressure vessel design qualifications? brush question APP

For pressure vessels, once an accident occurs, it will be classified as a major accident. If the accident is minor, it will cause production to stop, and if it is serious, it will cause personal injury. Many people do not know that the "Special Equipment Safety Supervision Regulations" formulated by the country have already made clear provisions: As for the design unit of pressure vessels, they must have corresponding qualifications. For production units and professionals, they also need to hold relevant certificates before they can work. If mistakes are made during the selection of the designer or manufacturer, not only will the acceptance fail, but you may also face fines and liability.

Not everyone can get design qualifications

The state's qualification review and approval for pressure vessel design units is very strict. According to Article 11 of the "Special Equipment Safety Supervision Regulations", design units must be licensed by the Special Equipment Safety Supervision and Administration Department of the State Council before they can engage in design activities. Currently, there are more than 800 companies in China that have obtained pressure vessel design qualifications. These companies are mainly concentrated in major manufacturing provinces such as Jiangsu, Zhejiang, and Shandong.

Design qualifications are divided into different levels such as A, C, and D. Class A has the ability to design high-pressure vessels, class C is for designing gas cylinders, and class D can only design medium and low-pressure vessels. In 2024, the State Administration for Market Regulation notified 12 companies Six of the units that designed without certificates were fined 300,000 yuan and more than this amount. If the design unit you are looking for cannot produce the corresponding level of qualification certificate, then the project will have hidden dangers from the very beginning.

The design must meet five basic requirements

The 15th Regulation clearly states that the design of pressure vessels must simultaneously meet the five requirements of strength, stiffness, stability, durability and overall sealing. If the strength is not met, it will burst; if the stiffness is not met, it will deform; poor stability will lead to instability; poor durability will be prone to corrosion and perforation; poor sealing will directly lead to leakage. In 2023, due to an incorrect strength calculation in the design of a chemical plant in Shandong, the reactor exploded during the pressure test stage, and three people were seriously injured.

The design must also be equipped with a safety pressure relief device. Devices such as safety valves and bursting discs are not dispensable. Their discharge volume and opening pressure must be accurately calculated. In 2022, a company in Zhejiang failed to install a safety valve in the design. During the operation of the equipment, the pressure soared sharply and could not be released. The entire tank bulged up like a balloon. Fortunately, the operator noticed it in time and shut down the machine, so no accident occurred.

Production unit qualifications and personnel qualifications are indispensable

What is required for a special equipment manufacturing license is the unit that manufactures pressure vessels. There are currently more than 2,000 manufacturing plants holding this certificate across the country. However, nearly 5% of the companies have their qualifications revoked or suspended every year due to chaotic management and declining quality. How to choose a riveting welding unit with pressure vessel design qualification? For example, during the first quarter of 2024, three riveting and welding factories in Hebei were seized for manufacturing pressure vessels without a license, and their responsible persons were transferred to judicial authorities.

The requirements for professional technicians are more specific. Welders who weld the main welds of pressure vessels need to hold a special equipment welding operation qualification certificate . How to choose a riveting welding unit with pressure vessel design qualifications , and can only perform welding within the materials and locations permitted by the certificate. Non-destructive testing personnel must also obtain Level 2 or Level 3 certificates for RT, UT, MT, PT and other corresponding methods. In 2023, a pressure vessel factory in Sichuan hired unlicensed welders, resulting in a weld flaw detection pass rate of only 70%, and the entire batch of products was scrapped.

Qualified materials are the bottom line for safety

Article 24 of the regulations states that materials used in the manufacture of pressure vessels must comply with national standards and design requirements. There are many accidents precisely in terms of materials, that is, using Q235B instead of 16MnR, replacing hydrogen-resistant steel plates with ordinary steel plates, or purchasing so-called "cheap materials" from unknown sources. In March 2024, a pressure vessel factory in Guangdong purchased a large number of steel plates without quality certificates. After welding, large-scale cracks appeared. After testing, it was found that the carbon content seriously exceeded the standard.

It is formal production units that need to establish a material acceptance system. The quality certificate of each batch of steel must be checked . How to choose a riveting and welding unit with pressure vessel design qualifications ? The chemical composition and mechanical properties must be re-tested on a batch-by-batch basis. Qualified materials must be stamped or marked, and unqualified materials must be isolated. In 2023, a factory in Jiangsu skipped the re-inspection link to save trouble and used a batch of plates with excessive sulfur content on storage tanks. As a result, stress corrosion cracking occurred within three months of the equipment operation.

Production process supervision and inspection must be strict

The manufacturing process of pressure vessels is subject to three levels of supervision. The first is the manufacturer's own quality inspection department, which must inspect and sign after each process is completed. The second is the third-party supervision and inspection agency. At present, local special inspection institutes are responsible for factory-based supervisory inspections. Without their signature, products are not allowed to leave the factory. Thirdly, the 2024 new version of the supervision and inspection rules stipulates that each pressure vessel has at least 18 quality control points, which must be confirmed by the supervisory inspector.

The key part in production is the welding process qualification. The manufacturer must first carry out the welding process qualification test to verify that the welding parameters can ensure that the joint performance meets the standards, and then the welding process specifications can be compiled for actual production. In 2022, a container factory in Anhui skipped the process qualification and directly carried out welding. As a result, the product cracked the weld during the hydrostatic test, and the repair cost exceeded 500,000 yuan. All production records, inspection reports, certificates and other documents must be complete, and even one missing one cannot pass the factory acceptance.

You can’t afford to choose the wrong unit

In May 2024, a company in Henan invited a small riveting and welding factory that lacked qualifications to build a steam sub-cylinder. Less than a month after the equipment was installed, the girth welds on the head and cylinder cracked, and high-temperature steam spewed out. Fortunately, there was no one else around at that time. Afterwards, the regulatory authorities launched an investigation and found that the small factory did not even have the most basic welding process assessment, and the welder certificate was a fake certificate bought online for 200 yuan.

The proper approach is: first go to the official website of the State Administration for Market Regulation to find out whether the design unit and manufacturing unit are on the licensed list, then go to the site to conduct an on-site inspection to see if it has a complete quality assurance system, review whether the supervisory inspection reports of the past two years are complete, and randomly select the archives of several manufactured products. Keep in mind, between the cheaper price of a few thousand yuan and the millions of compensation required after the accident, which one will you choose?

What kind of pitfalls have you encountered while looking for a pressure vessel riveting and welding unit? You are welcome to share your own experiences in the comment area, like and forward this article to encourage more people to avoid those fatal traps.