Products Description
HP345 is a high-strength welded gas cylinder steel manufactured according to the national standard GB 6653. "HP" stands for "welded cylinder," and "345" represents its minimum yield strength of 345 MPa-approximately 17% higher than the mainstream HP295.
| Performance Indicator | HP295 | HP345 | Improvement Range |
|---|---|---|---|
| Yield Strength ReL (MPa) | ≥295 | ≥345 | ↑17% |
| Tensile Strength Rm (MPa) | 440~560 | 510~620 | ↑Approx.13% |
| Elongation (Thickness ≥3mm) | ≥26% | ≥21% | Slight decrease in plasticity |
Chemical composition of HP345
| Element | Standard Limit |
|---|---|
| C (Carbon) | ≤ 0.20 |
| Si (Silicon) | ≤ 0.35 |
| Mn (Manganese) | ≤ 1.50 |
| P (Phosphorus) | ≤ 0.035 |
| S (Sulfur) | ≤ 0.035 |
| Als (Acid-soluble Aluminum) | ≥ 0.020 |
| Ti (Titanium) | ≤ 0.20 |
| V (Vanadium) | ≤ 0.12 |
| Nb (Niobium) | ≤ 0.060 |
The core composition of HP345 is: 0.17% C - 0.25% Si - 1.40% Mn, employing vanadium-titanium composite microalloying (V≤0.025%, Ti≤0.025%).
The ingenuity of this composition design lies in:
- Medium carbon + high manganese: Manganese content reaches 1.50%, the main solid solution strengthening element, laying the foundation for high strength.
- Vanadium-titanium microalloying: Forms a sufficient number of precipitate particles, producing precipitation strengthening, further improving strength without significantly affecting plasticity.
- Purity control: P≤0.025%, S≤0.012%, ensuring steel purity and meeting demanding working conditions.
Application scenarios of HP345
Typical Scenarios
Welding cylinders for media such as liquid chlorine, liquid ammonia, sulfur dioxide, ethylene oxide, methylamine, and acetylene.
Limitations of Ordinary Cylinder Steel: For these toxic and hazardous media, leakage from the cylinder can have severe consequences.
Therefore, higher requirements are placed on the material's strength reserve, fatigue resistance, and weld quality.
HP345's Solution:
Higher strength reserve, providing a greater safety margin for the cylinder.
Stricter purity control (efficient desulfurization, optimized steel purity), reducing the risk of failure caused by inclusions.
Optimized welding performance, ensuring reliable weld quality.
Typical Scenarios
- Gas cylinders for export ocean shipping
- CNG cylinders on vehicles
- Mobile pressure vessels
Limitations of Ordinary Welded Cylinder Steel: HP295 has limited strength; to meet pressure requirements, the only solution is to increase the wall thickness, leading to increased cylinder weight and transportation costs.
HP345 Solution:
17% increase in strength, allowing for a 10-15% reduction in design wall thickness
Corresponding weight reduction of 8-12%, significantly reducing transportation costs
Especially suitable for export business-HBIS Tangsteel's HP345 products have been exported in bulk to countries along the Belt and Road Initiative, such as Thailand and Pakistan.
Typical Scenarios
- Deep-drawing welded bottles
- Irregularly shaped bottles
- Products requiring high elongation
Limitations of Ordinary Welded Bottle Steel: Some downstream users have customized needs, such as deep-drawing welded bottles requiring elongation of over 35%, where ordinary HP295 struggles to balance strength and plasticity.
HP345's Solution:By optimizing composition design and cooling regime, a balance between low yield strength ratio and high elongation is achieved.
HP295 can be used for:
- Standard LPG cylinders (15kg/50kg for household use)
- Acetylene cylinders (dissolved acetylene)
- General industrial cylinders for cost-sensitive applications and those with low pressure requirements
Why is the HP345's technological advantage so significant?
Vanadium-Titanium Microalloying
The strength improvement of HP345 does not rely on increasing carbon content (carbon content ≤0.20%, comparable to HP295), but is achieved through vanadium-titanium composite microalloying.
Low Yield-to-Tension Ratio
Yield-to-Tension Ratio = Yield Strength / Tensile Strength, reflecting the safety margin of a material from yield to fracture.
HP345 achieves a yield-to-tensile ratio below 0.80 through optimized controlled rolling and cooling processes (higher final rolling and coiling temperatures, and a post-cooling mode). This means that even if the gas cylinder is accidentally overloaded, significant plastic deformation (bulging) will occur as a warning before sudden brittle fracture.
Excellent Weldability
Although HP345 has a higher carbon equivalent than HP295 (approximately 0.45% vs 0.37%), its weldability still meets the requirements for gas cylinder manufacturing through strict composition control and purity management.
Why Choose GNEE as Your Supplier?
Manufacturer Advantage: As a direct factory, we control the entire production process from smelting to final cutting.
Quality Assurance: Our products undergo rigorous testing, including ultrasonic testing, tensile tests, and impact tests.
Global Reach: We have exported HP345 and HP295 steel to over 60 countries, understanding the specific regulatory needs of different regions.
Customization: We offer customized thicknesses, widths, and lengths to minimize waste in your production line.
If you are looking for answers to the following questions:
❓ How to make gas cylinders lighter and reduce transportation costs?
❓ How to safely and reliably contain toxic/corrosive media?
❓ How to meet the personalized deep-drawing needs of high-end customers?
❓ How to create differentiated product competitiveness using high-end materials?
Then GNEE's HP345 welding cylinder steel is worth your serious consideration.
Conclusion
The HP345 is not a simple upgrade of the HP295, but a specialized solution for higher pressure, more demanding media, and lighter weight requirements. It utilizes vanadium-titanium microalloying as its core technology, achieving a new level of strength while maintaining excellent weldability and formability.
What are the weldability characteristics of HP345?
Due to its higher carbon equivalent (approximately 0.45%), HP345 has a higher weld crack susceptibility than HP295. Strict control of preheating temperature, interpass temperature, and welding heat input is necessary during welding. Low-hydrogen or ultra-low-hydrogen welding materials should be selected.
What welding methods are suitable for HP345?
It is suitable for manual arc welding, gas shielded welding, and submerged arc welding. However, low-hydrogen welding processes are recommended, and preheating treatment may be necessary.
What is the required preheating temperature for HP345 welding?
Depending on the plate thickness and welding process, the preheating temperature is generally 50~100℃. For thick plates or structures with high restraint, the preheating temperature needs to be appropriately increased.
How should welding materials for HP345 be selected?
Low-hydrogen or ultra-low-hydrogen electrodes with matching strength should be selected, such as J557 and J607RH, to ensure that the weld metal has sufficient toughness and crack resistance.
What media can HP345 gas cylinders hold?
They are mainly used to hold liquid chlorine, liquid ammonia, sulfur dioxide, ethylene oxide, methylamine, acetylene, and other media. Because these media are corrosive, toxic, or flammable and explosive, the requirements for cylinder materials and manufacturing quality are higher.
What is the working pressure of an HP345 gas cylinder?
The working pressure varies depending on the media. The specific pressure is determined by the cylinder's design pressure and the filling medium. Due to its higher strength, HP345 can withstand higher working pressures under the same wall thickness.
What is the design service life of an HP345 gas cylinder?
The general design service life is 20 years, but the specific service life is in accordance with the "Gas Cylinder Safety Technical Supervision Regulations." Because HP345 gas cylinders often hold toxic and hazardous substances, the inspection cycle and scrapping standards are more stringent.
