The safety technical measures for cryogenic containers mainly include the following aspects to ensure the safety of personnel and equipment:
Material Selection & Quality Control
The selection of cryogenic container materials is the key, and it is necessary to choose the appropriate low-temperature steel according to the use temperature, such as low-carbon (carbon content less than 0.25%) carbon-manganese steel, medium nickel steel, chromium-nickel austenitic steel, etc.
Steel procurement should be selected through the internal management of the enterprise qualified suppliers, and the smelting method, chemical composition, steel internal organization, heat treatment status and other aspects of strict regulations and requirements.
Low-temperature steel and welding rods should be managed by special personnel and warehouses to avoid confusion with other steels.
Material Inspection & Re-inspection
Low-temperature steel should be re-inspected after entering the factory to ensure the quality of the material.
The steel used in low-temperature pressure vessels must be re-tested for low-temperature impact value before processing and manufacturing, and the re-inspection of the whole project includes the chemical composition of the material, the mechanical properties at room temperature, the low-temperature impact value and the re-inspection of the ultrasonic testing of the steel.
All electrodes used for low-temperature steel should be tested for the moisture content of the coating or the diffused hydrogen content of the deposited metal according to the approval.
Cryogenic Container Design & Manufacturing
Cryogenic containers should be designed in a spherical or cylindrical shape to save material and reduce cold capacity loss.
The container should be provided with a safety valve or safety diaphragm to prevent the danger of overpressure.
There should be a proper vapor space in the container, generally 5%~10%, to ensure safety.
Use & Maintenance
A use check must be carried out before use to ensure that the container is intact.
Low-temperature dewars should be placed in a special freezer for cooling, and should not be placed directly into liquid nitrogen or other low-temperature media.
The volume of the dewar must not exceed 80% of its rated capacity.
Pay attention to balance when placing and avoid shaking or tilting.
Make sure the worktop is dry to prevent slip and fall accidents.
Safety precautions
Laboratories should be equipped with safety facilities such as protective gloves, goggles, and protective clothing to protect personnel from ice temperatures.
A dedicated area for low-temperature dewars should be set up and warning signs should be set up.
Training & Emergency Measures
Operators are regularly trained on the use and safety of cryogenic containers.
Develop emergency measures, such as first aid for deep frostbite injury, including removing clothing that affects blood circulation in the injured area, and taking a warm bath.
Installation & Storage Environment
The installation site should have good ventilation conditions or be equipped with ventilation devices.
There must be sufficient water sources and fire extinguishing equipment near the site, and there must be no flammable and explosive materials within 5m around.
Liquid oxygen containers should generally be placed outdoors and equipped with facilities to dissipate static electricity.
By following the above safety technical measures, the safety and stability of the cryogenic container during use can be ensured.
