A Brief Introduction to Seamless Steel Tubes for Gas Cylinder
What is a gas cylinder ?
A gas cylinder is a pressure vessel for storage and containment of gases at above atmospheric pressure. It can store both flammable gases, such as acetylene, and inert gases such as helium. High-pressure gas cylinders are also called bottles. Inside the cylinder the stored contents may be in a state of compressed gas, vapor over liquid, supercritical fluid, or dissolved in a substrate material, depending on the physical characteristics of the contents. A typical gas cylinder design is elongated, standing upright on a flattened bottom end, with the valve and fitting at the top for connecting to the receiving apparatus.
Materials of gas cylinder
Gas cylinders can be made from aluminum, steel, alloys, and composite materials. Mechanical strength, corrosion resistance, and impact resistance are critical factors in determining which material is used. Carbon fiber composite cylinders can be very light due to the high tensile strength of carbon fiber, but are more difficult to manufacture. So the alloy steel is the usually used material because of its overall mechanical property and cost. The most common standards are GB/T 18248, EN10297, JIS G3429, EN 10083-3. Though they are different standards in different countries, they have some same steel grades or equivalents. Now let’s take a look at 34CrMo4 of each standard or its equivalent to see their difference.
As you can see, there is a little difference in their chemical composition. But their mechanical properties, tolerance, testing and delivery condition may be different, so all these shall be agreed upon at the time of inquiry and place an order. Except 34CrMo4, 37Mn, 38Mn6, STH21, STH22, 42CrMo4 are also very common materials.
Because gas cylinders store gases under high pressures, it must have excellent tensile strength, corrosion resistance, and impact resistance. So finished pipe are generally tested as below to select the unqualified.
NDT (Non-destructive testing)
ET (Eddy testing)
UT (Ultrasonic testing)
Baotou Iron and Steel Group, Baotou Steel or Baogang Group is an iron and steel state-owned enterprise in Baotou, Inner Mongolia, China. It is one of the earliest iron and steel industrial bases built after the founding of the People’s Republic of China. It is one of the major rail production bases in China, one of the seamless steel tube production bases, the largest plate production base in north China, the world’s rare earth industry and the largest rare earth scientific research and production base. It has been committed to diversified development, and in addition to two major industries of steel, rare earth , it also develops mining and non – steel industries.
On the evening of February 19, 2014, Baotou Steel Group issued a notice saying that the existing rare earth, coal, molybdenum and other resources of Baotou Steel Group would be gradually injected into Baotou Steel Shares. Baotou Steel Shares will transform itself into a resource-based enterprise and become the world’s largest rare earth enterprise.
The Inner Mongolia autonomous region where Baotou Steel is located is the junction of north China and northwest China and the gateway of western development, and the border with Mongolia accounts for 68% of the total length of China-Mongolia border, occupying an important position in the country’s strategic pattern of “opening to the north”. Baiyun obo mine of baotou iron & steel group co., LTD. is a remarkable multi-metal ore of iron, rare earth, niobium and thorium, etc. It is the largest iron deposit in northwest China, ranking first in rare earth reserves and second in niobium and thorium reserves. Baotou Steel is close to the Yellow River, Shanxi and Inner Mongolia coal rich area, adjacent to Mongolia and Russia.
Baotou Steel has always been committed to the production of high-quality goods and brand building.
Its railway rails and seamless steel boiler tube have been awarded the title of “China’s Top Brand Products”.
Railway rails have also won the title of “National Customer Satisfaction Product”. Rare earth series products of “Baiyun’ebo” are well known at home and abroad.
5 varieties of the heavy and wide plates, such as A, B and D, have acquired the certificates of CCS-China, BV-Frence, ABS-American, NK-Japanese, DVN GL-German, EC and other relevant classifications.
24 varieties of hot-rolled sheet and hot-rolled (heat-treated) heavy and wide plate, including SS235, have passed the European CE certification. Seamless steel pipe is certified by API(American Petroleum Institute).
On September 1, 2019, Baotou Iron & Steel (Group) Co., Ltd. was ranked 225th among the top 500 Chinese enterprises. It ranked 99th among China’s top 500 manufacturing enterprises in 2019. On November 22, 2019, Baotou Steel was included in the list of demonstration enterprises of green design for industrial products (the first batch).