Shandong Zhongjie Special Equipment (formerly Heze Boiler Factory Co., Ltd.) was established in 2001, located at No. 2218 Jinnan Road, Development Zone, Heze City, with a registered capital of 50 million yuan and total assets of 500 million yuan. The company has 7 business centers: boilers, deep-freezing containers, pressure vessels, central air conditioning, engineering installation, international trade, and Internet of Things. It has three factory sites on Jinnan Road, East Changjiang Road, and Bohai Road, covering a total of 200,000 square meters, with the main workshop spanning 83,000 square meters. It currently employs 710 people, including 247 engineers and technicians, and 82 intermediate-level technical personnel. In December 2016, it was recognized as a "High-tech Enterprise" by the Science and Technology Department. In June 2021, it was identified as a "Specialized and New Enterprise in Shandong Province" by the Ministry of Industry and Information Technology. In June 2022, it was recognized as a "Gazelle Enterprise in Shandong Province" and in August 2022, as a "Specialized and New Small Giant Enterprise" by the Ministry of Industry and Information Technology.
During the welding process of low-temperature liquid storage tanks, controlling the occurrence of welding cracks is crucial. The following are some methods and measures for controlling welding cracks:
Appropriate Welding Techniques: Selecting the appropriate welding process and parameters reduces welding heat input and stress. Employing low heat input methods such as pulse welding, laser welding, etc., can lower the temperature gradient and residual stress in the weld heat-affected zone.
Preheat and Post-heat Treatment: Perform an appropriate preheat before welding to enhance material toughness and reduce thermal stress. Conduct a suitable post-heat treatment, such as annealing or stress-relief heat treatment, after welding to minimize residual stress and improve weld toughness.
Choose appropriate welding materials: Select welding materials with good toughness and crack resistance to minimize the occurrence of welding cracks. Select suitable welding materials, such as low-alloy steel, stainless steel, etc., based on the storage tank's usage conditions and requirements.
Control Welding Process: Regulate parameters and operations during the welding process to minimize the risk of welding cracks. Pay attention to factors such as welding speed, current, voltage, and welding sequence to avoid overheating or rapid welding, reducing the accumulation of thermal and residual stresses.
Non-destructive Testing and Evaluation: After welding is completed, conduct non-destructive testing on the welds, such as ultrasonic testing, X-ray testing, etc., to assess welding quality and the presence of cracks. Detect and repair welding cracks promptly to ensure the integrity and safety of the weld joints.
It's important to note that controlling welding cracks is a complex process, requiring a comprehensive consideration of factors such as materials, welding techniques, and operations. When welding low-temperature liquid storage tanks, it's advisable to consult with a welding engineer or relevant institutions for guidance to ensure welding quality and the safety of the tank.

One of the common drawbacks of pressure vessels during use is corrosion. Corrosion refers to the reaction of the metal surface with chemical substances in the environment, leading to damage to the metal surface and thinning of the material. The following are common corrosion drawbacks of pressure vessels:
Pitting Corrosion: Pitting corrosion refers to localized pits or holes that appear on the surface of metal. This type of corrosion is usually caused by corrosive substances present in the local environment, such as acids, salts, etc.
Bacterial Corrosion: Bacterial corrosion is a type of corrosion caused by microorganisms. These organisms can form a biofilm inside pressure vessels and produce acidic substances, leading to corrosion on the metal surface.
Punch Corrosion: Punch corrosion refers to a penetrating corrosion phenomenon on the surface of metal. This type of corrosion usually occurs due to the damage or defect of the protective layer on the metal surface, allowing corrosive substances to directly contact the metal.
Stress Corrosion Cracking: Stress corrosion cracking occurs when a metal surface is subjected to both stress and a corrosive environment, leading to the formation and propagation of cracks. This type of corrosion is commonly found in pressure vessels operating under high stress and corrosive conditions.
Corrosion can lead to material thinning and reduced strength in pressure vessels, potentially causing severe consequences such as leaks or ruptures. Therefore, the following measures should be taken to address corrosion issues in pressure vessels:
Regularly inspect and assess the corrosion condition of pressure vessels, including methods such as visual inspections and non-destructive testing.
Implement corrosion prevention measures such as coating protection, cathodic protection, and selecting appropriate materials to minimize the occurrence and progression of corrosion.
Regularly clean and maintain pressure vessels to remove dirt and impurities that may cause corrosion.
Comply with relevant safety regulations and operational guidelines to ensure the normal and safe operation of pressure vessels.
For severely corroded pressure vessels, repair or replacement may be required to ensure their safety and reliability.

The reasons for not allowing liquid oxygen tanks to be left empty for extended periods are mainly as follows:
Evaporation loss of liquid oxygen: Liquid oxygen has a low boiling point, and prolonged storage without use will lead to continuous evaporation, resulting in a loss of liquid oxygen within the storage tank. The evaporation rate is relatively fast, with daily evaporation amounts potentially reaching several percent of the tank's capacity, leading to waste of liquid oxygen if left unused for extended periods.
Safety Risk: Liquid oxygen is a strong oxidizer with high flammability and explosive properties. Long-term empty storage of liquid oxygen tanks increases the opportunity for contact with the surrounding environment, thereby raising the risk of accidental fires and explosions.
Risk of Storage Tank Damage: Long-term emptying of liquid oxygen storage tanks can lead to internal oxidation reactions, accelerating corrosion and damage to the tank. Tank damage can affect its sealing performance and structural integrity, increasing the risk of leaks and safety accidents.
Therefore, to ensure the safe storage and effective use of liquid oxygen, the liquid oxygen tank should be regularly maintained and serviced to prevent long-term emptying. When the tank is not in use, appropriate measures should be taken, such as sealing the tank and reducing oxygen evaporation, to minimize liquid oxygen loss and safety risks.

The normal pressure range for liquid oxygen tanks typically falls between 2-5 bar. This range refers to the oxygen pressure inside the tank, which is necessary to maintain the liquid oxygen in its liquid state. The design and manufacturing of liquid oxygen tanks should comply with relevant standards and regulations to ensure the tank can safely withstand this pressure range under normal operating conditions. It is important to note that the pressure of liquid oxygen tanks can be affected by various factors, such as the temperature of the liquid oxygen, tank design, and materials. In actual use, the normal pressure range of the tank should be determined based on specific tank design and operational requirements, and operations and maintenance should follow relevant regulations and standards. Additionally, liquid oxygen tanks should be equipped with pressure control devices, such as pressure valves or pressure relief devices, to ensure the internal pressure of the tank remains within a safe range. These devices can automatically release gas when pressure exceeds the set value, ensuring the safety of the tank. Regular inspection and maintenance of these pressure control devices should be conducted when using liquid oxygen tanks to ensure their proper functioning.
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