GB6653 HP325
GB6653 HP325 steel coils, sheets, and plates are specialized carbon steel products governed by the Chinese national standard GB 6653, which covers steel plates for welded gas cylinders. The grade is specifically designed for the manufacture of welded gas cylinders, such as those used for liquefied petroleum gas. The designation combines the grade prefix with the minimum yield strength requirement of 325 MPa. The material is produced with a fine-grained structure and excellent surface quality, which are critical for the deep drawing and forming processes used by cylinder manufacturers.
Chemical Composition
The reliability of HP325 begins with a strictly controlled chemical composition. The composition includes carbon up to 0.20 percent, manganese in the range 0.30-0.90 percent, silicon up to 0.05 percent, phosphorus up to 0.025 percent, and sulfur up to 0.015 percent. Low phosphorus and sulfur contents are vital to preventing cold shortness and ensuring the structural integrity of the cylinder during its 15-to-20-year service life. The steel exhibits excellent weldability and resistance to atmospheric corrosion, which are essential for gas cylinder production.
Mechanical Properties
The mechanical properties of HP325 provide a high safety factor against bursting while remaining flexible enough for the stamping process. The steel offers a stable yield strength of at least 325 MPa and a tensile strength ranging from 490 to 610 MPa. This range ensures that the cylinder can withstand high internal pressures without permanent deformation or catastrophic failure. With an elongation rate of at least 22 percent, the steel provides superior deep-drawing performance, allowing manufacturers to press the steel into cup-shaped cylinder halves without excessive wall thinning or surface cracking.
Key Applications
The most common application of HP325 is LPG cylinders, used for both domestic cooking cylinders and industrial fuel tanks. Because of its excellent weldability, HP325 is also used to create the outer shells of dissolved acetylene cylinders. The grade is used for low-pressure liquefied gas containers, including tanks for liquid ammonia, chlorine, and other industrial gases that require a reliable pressure-rated vessel, and for small to medium-sized air compressor receiver tanks, where its durability and cost-efficiency are valued.
Standards, Equivalents, and Supply
HP325 is delivered in accordance with GB6653-2008. Equivalent grades include EN10120 P265NB and JIS G3116 SG325, which can be provided for international projects. Typical supply includes thicknesses from 2.0 mm to 12 mm and widths up to 2000 mm in both coil and plate form. Every order undergoes ultrasonic testing, tensile testing, and Charpy impact testing, and third-party inspection by agencies such as SGS, BV, or Lloyd's Register is available to verify the chemical and mechanical integrity of the products.
Frequently Asked Questions
What is HP325 steel?? HP325 is a carbon steel grade governed by GB 6653 for the manufacture of welded gas cylinders. The designation combines the grade prefix with the minimum yield strength requirement of 325 MPa.
Why is HP325 preferred over HP295 for larger gas cylinders?? HP325 offers higher yield strength than HP295, allowing manufacturers to use thinner plates without compromising safety, which reduces cylinder weight and material cost.
What are the mechanical properties of HP325?? stable yield strength of at least 325 MPa, a tensile strength of 490-610 MPa, and an elongation of at least 22 percent, which supports the deep drawing of cup-shaped cylinder halves without excessive wall thinning.
What is the chemical composition of HP325?? Carbon up to 0.20 percent, manganese 0.30-0.90 percent, silicon up to 0.05 percent, phosphorus up to 0.025 percent, and sulfur up to 0.015 percent, providing excellent weldability and resistance to atmospheric corrosion.
What are the typical applications of HP325?? LPG cylinders for domestic cooking and industrial fuel, dissolved acetylene cylinder shells, low-pressure liquefied gas containers, and small to medium-sized air compressor receiver tanks.
What equivalents and supply sizes are available?? Equivalent grades include EN10120 P265NB and JIS G3116 SG325. Typical supply covers thicknesses from 2.0 mm to 12 mm and widths up to 2000 mm in coil and plate form, with ultrasonic, tensile, and Charpy testing plus third-party inspection available.
