NDE REQUIREMENTS IN FABRICATION OF CRYOGENIC STORAGE TANKS

Liquefied gases are used in a wide range of applications in many industrial sectors. The transportation of gases across the world is done in liquid state. Cryogenic liquids exist at extremely low temperatures (< -196 °C in many cases) which is why specialized equipment is required for their transportation and storage. It’s vital for these tanks to be thermally insulated so as to maintain the low temperatures. The cryogenic stationary tanks are designed for long term storage of cryogenic liquefied gases under pressure. The maximum working pressure of cryogenic liquefied gas storage tanks ranges from 2 to 37 bar, depending on where the tank is to be used. The cryogenic storage tank can replace the reverse transportation of the gas cylinder, thereby saving a large amount of manpower and material resources to a large extent. Manufacturing of cryogenic tanks requires special technical and sophisticated fabrication techniques. A non-destructive technique would be a significant aid in acceptance testing of new and refurbished tanks, saving significant time and money. In Inox India Limited, Kandla various NDT methods are employed during & after the completion of the manufacturing of storage tanks to ensure they are free from detrimental flaws with consideration of low temperature service requirements. Prime methods used are Radiography Testing, Liquid Penetrant Examination, Visual Examination, Boroscopy Examination, UV light inspection, Helium Leak Testing, Ultrasonic Thickness Check and Magnetic Particle Testing. This paper discusses the various NDE requirements in manufacturing of Cryogenic Storage Tanks particularly for storage of LIN (Nitrogen), LOX (Oxygen) & LAR (Argon) as per various Construction Codes & standards and comparison of them.