Products Description
HP295 and HP345 are specialized GB/T 6653 steels for welded gascylinders, with HP345 offering higher strength (> 345 MPa yield) forhigh-pressure applications and HP295 (> 295 MPa yield) providingbetter ductility for standard LPG bottles. HP295 is more economicaland easier to weld, while HP345 is stronger.
As a global leading steel supply chain group with 18+ years of experience, GNEE (Tianjin) Supply Chain Group Co., Ltd. has been dedicated to providing high-quality hot-rolled steel plates for welded gas cylinders since 2008. With over 600 companies across 100+ countries, we specialize in producing and supplying HP295 and HP345 steel plates-two core grades compliant with GB/T 6653 standard.
Comparison of core performance indicators
| Item | HP295 | HP345 |
|---|---|---|
| Yield Strength (MPa) | ≥295 | ≥345 |
| Tensile Strength (MPa) | 440–560 | 510–620 |
| Elongation (≥3mm) | ≥26% | ≥20–21% |
| Chemical Composition (C, Mn) | ≤0.20% C, ≤1.00% Mn | ≤0.20% C, ≤1.50% Mn |
| Cold Bending Performance | d=2a (bend diameter = 2×plate thickness) | d=2a (bend diameter = 2×plate thickness) |
Performance Differences Analysis
Strength and Wall Thickness Design
This is the most fundamental difference between the two. Yield strength is the key basis for designing the cylinder wall thickness.
HP345: Due to its yield strength being approximately 50 MPa higher than HP295, HP345 allows for thinner cylinder walls under the same diameter and pressure. This not only reduces steel consumption but also lightens the cylinder's weight, facilitating transportation and use.
HP295: While its strength is relatively lower, it offers greater safety margin and is typically used for ordinary liquefied gas cylinders under standard pressure and where cost control is paramount.
Plasticity and Forming Process
HP295: It boasts a higher elongation (≥26%), meaning the material is "softer." For components requiring complex deformation (such as necking or stamped end caps), HP295 exhibits better ductility, reducing the risk of processing cracks.
HP345: Due to increased strength and manganese content, the material's plasticity is slightly reduced (elongation ≥20%). During processing, if the deformation is extremely large, it may be necessary to appropriately increase the fillet radius of the mold or adopt a more advanced forming process.
Welding Performance
Both are low-carbon steels (carbon content ≤ 0.20%), which is the basis for ensuring excellent weldability.
Both have very low cold cracking sensitivity during welding, requiring no complex preheating measures (at room temperature).
It should be noted that, because HP345 has higher strength, it is recommended to use welding materials of equal or slightly lower strength (such as ER50-6 grade welding wire) to ensure that the weld metal has sufficient toughness and crack resistance.
Advantages of HP295 and HP345 Welding Bottle Steel
Advantages of HP295
Superior Forming Performance
Elongation ≥26%, good plasticity, suitable for complex deformation processes such as deep drawing, necking, and end-capping stamping.
Low risk of cracking during processing, high tolerance to molds and process parameters.
Excellent Welding Performance
Low carbon design (C≤0.20%), extremely low sensitivity to cold cracking during welding.
No preheating required, simple welding material matching, suitable for large-scale automated welding production.
Economical Production Costs
Low alloy element addition (Mn≤1.00%), lower raw material costs.
Suitable for large-scale gas cylinder production with strict cost control requirements.
Wide Process Adaptability
Low requirements for production equipment; even small and medium-sized cylinder plants can maintain a stable high yield.
Mature production process, low technical threshold, easy to quickly start production.
Sufficient Safety Redundancy
Long-term market validation, widely used in household liquefied petroleum gas cylinders.
Stable and reliable performance, meeting domestic and international standard requirements for conventional gas cylinders.
Advantages of HP345
High strength, achieving lightweight design
- Yield strength ≥345MPa, approximately 50MPa higher than HP295
- Wall thickness can be reduced under the same design pressure, resulting in a 10%~15% weight reduction per cylinder
- Reduced raw material consumption and transportation costs
Stronger pressure resistance
Tensile strength 510~620MPa, higher safety margin
Suitable for cylinders and industrial high-pressure containers with higher design pressures (e.g., >3.2MPa)
Enhancing product quality
- Superior mechanical properties meet the technical requirements of export orders and high-end markets
- Facilitates product upgrades and enhances market competitiveness
- Significant potential for overall cost optimization
- Although the material unit price is slightly higher, raw material savings are achieved through wall thickness reduction
- Combined with the reduced transportation costs due to weight reduction, overall costs are controllable and even more advantageous
Suitable for harsh working conditions
More suitable for high-pressure applications such as fire extinguishers and industrial gas cylinders
Meets lightweight design requirements, offering significant advantages in areas such as CNG storage cylinders for vehicles.
When should I choose HP295 and HP345?
Recommended Scenarios for HP295
Conventional Liquefied Petroleum Gas (LPG) Cylinders: For household or commercial use, standard LPG tanks with a design pressure of approximately 2.1-3.2 MPa.
High Forming Yield: When stamping dies are in poor condition or high-volume, high-speed stamping production is required, HP295's superior plasticity helps reduce scrap rates.
Acetylene Cylinders: Acetylene cylinders have porous packing material and relatively low shell pressure; HP295's overall performance fully meets these requirements.
Recommended Scenarios for HP345
High-Pressure Welded Cylinders: Industrial cylinders with higher design pressures (e.g., close to 5 MPa or above) requiring thinner walls to reduce weight.
Lightweight Design Requirements: In scenarios sensitive to transportation costs or with strict weight restrictions (e.g., CNG storage cylinders for vehicles), HP345 can achieve lightweighting goals through thinner walls.
Fire extinguisher cylinders: Dry powder or carbon dioxide fire extinguisher cylinders need to withstand high pressure, and the high strength of HP345 is more suitable for such applications.
Conclusion
Both HP295 and HP345 are mature welded gas cylinder steels, and their safety has been rigorously verified.
If you prioritize manufacturing costs, ease of forming, and stability in mass production, HP295 is a classic choice, representing a standard of "good enough and functional."If you prioritize lightweight design, product quality enhancement, or meeting higher pressure ratings, HP345 offers greater economic benefits due to its higher strength.
Can HP345 completely replace HP295 in gas cylinder manufacturing?
No, it cannot be simply replaced. HP345 has higher strength, but its plasticity is reduced, and welding difficulty is increased. Using HP345 requires re-testing and adjustments to welding processes and stamping dies.
How significant is the weight reduction effect of HP345?
Based on the same design pressure, HP345 allows for a wall thickness reduction of approximately 10-15%, resulting in a corresponding weight reduction of 8-12%.
Why is HP295 the mainstream, while HP345 has a low market share?
The main reasons are: HP295 has sufficient performance to meet the needs of most gas cylinders; HP345 has higher requirements for welding and forming processes, increasing manufacturing costs; HP345 has a higher unit price for materials.
What are the grain size requirements for HP345?
The grain size requirement is no less than grade 9, with actual production control between grade 9.0 and 10.5. Vanadium-titanium microalloying has little effect on grain refinement; grain size is mainly controlled by controlled rolling and cooling processes.
What are the requirements for non-metallic inclusions in HP345?
According to GB/T 10561 rating, inclusions of categories A, B, C, and D are all required to be ≤ grade 2.0, and inclusions of category DS (large spherical oxide particles) are required to be ≤ grade 1.5.
