Seamless Gas Cylinder Tube

Manufacturing Process

• Rotary Piercing: A solid cylindrical billet, made from high-quality steel alloy, is heated and rotated. It is then pierced by a mandrel to create a hollow shell, the initial rough tube.
• Cold Drawing: This hollow shell is further processed through a cold drawing mill. It is drawn through a die and over a mandrel to achieve the exact required outer diameter (OD), wall thickness, and superior internal surface finish. This process also enhances the mechanical properties of the steel through work hardening.
• Heat Treatment: Subsequent heat treatment (e.g., normalizing, quenching, and tempering) is crucial to relieve stresses induced during manufacturing and to obtain the precise combination of high strength and good ductility required for pressure containment.

Characteristics and Properties

Gas cylinder tubes must adhere to stringent international standards (such as ASTM, EN, DOT, ISO). Their critical properties include:

• High Strength: Capable of withstanding internal pressures often exceeding 200 bar (2900 psi) and up to 600 bar (8700 psi) for high-pressure applications.
• Excellent Homogeneity and Consistency: The seamless structure ensures uniform mechanical and metallurgical properties throughout the entire length of the tube, eliminating the weak point of a weld seam.
• Superior Ductility and Toughness: To prevent brittle fracture and allow for some deformation under extreme conditions without rupturing.
• Precise Dimensional Tolerances: Strict control over outer diameter, wall thickness, and ovality is mandatory for subsequent processing and cylinder performance.
• Excellent Internal Surface Quality: A smooth, clean internal surface is vital to prevent crack initiation and ensure compatibility with high-purity gases.
• Material Purity: Made from specially formulated steel alloys (often Chromium-Molybdenum steels like 34CrMo4/4130X) with low sulfur and phosphorus content to enhance toughness and weldability during cylinder neck closing.