HP345 Gas Welded Cylinder Steel

HP345 Gas Welded Cylinder Steel is a high-strength, low-alloy steel specifically engineered for the manufacturing of welded gas cylinders under high pressure. It is important to clearly understand that HP345 Gas Welded Cylinder Steel offers an optimal balance of strength, toughness, and weldability, making it a preferred choice for LPG cylinders, industrial gas storage, and pressure vessel applications.

At GNEE Steel, we are a professional manufacturer and global supplier of gas cylinder steel plates and coils. With extensive experience in exporting HP series steels, we provide certified materials that meet international standards, ensuring safety, consistency, and long service life for pressure equipment manufacturers worldwide.

HP345 Gas Welded Cylinder Steel is produced according to the Chinese standard GB/T 6653, designed for welded gas cylinders that require high strength and excellent forming performance.

Key Features of HP345 Gas Welded Cylinder Steel

HP345 steel is characterized by its high yield strength (≥345 MPa), which allows cylinder manufacturers to reduce material thickness while maintaining pressure resistance. This leads to lighter cylinders and cost savings in transportation.

Additionally, HP345 offers excellent weldability, ensuring safe and reliable welding during cylinder fabrication. Its controlled chemical composition enhances toughness and minimizes the risk of cracking during forming and welding processes.

Gas cylinder production line in factory

The chemical composition of HP345 Gas Welded Cylinder Steel is carefully controlled to ensure strength, ductility, and weldability.

HP345 Chemical Composition Table

Why Chemical Composition Matters for HP345 Steel?

The relatively low carbon content ensures good weldability, while manganese improves strength and toughness. Strict limits on phosphorus and sulfur reduce brittleness and improve safety in high-pressure applications.

Mechanical performance is critical for ensuring the safety and durability of gas cylinders.

HP345 Mechanical Properties Table

How Do These Properties Benefit Cylinder Manufacturing?

The high yield strength allows thinner walls without compromising safety, while good elongation ensures excellent forming performance during cylinder shaping processes such as deep drawing and rolling.

HP345 Gas Welded Cylinder Steel is widely used in various pressure vessel and gas storage applications.

Common Applications of HP345 Steel

• LPG (Liquefied Petroleum Gas) cylinders
• Industrial gas cylinders (oxygen, nitrogen, argon)
• Fire extinguishers
• Small pressure vessels

 LPG cylinders ready for shipment

Its versatility makes it a popular choice for manufacturers targeting both domestic and international markets.

Understanding how HP345 compares to other grades helps buyers select the right material.

HP345 vs HP295 vs HP325

HP345 offers higher strength and better performance, making it suitable for more demanding applications where safety margins are critical.

At GNEE Steel, we deliver more than just products-we provide complete solutions tailored to your needs.

Our Core Advantages

• Stable supply of HP295, HP325, and HP345 steel
• Strict quality inspection and third-party certification
• Custom cutting, slitting, and surface processing
• Rich export experience with secure packaging
• Fast delivery and responsive technical support

Steel plates packaging and warehouse loading

We help global buyers reduce procurement risks and improve production efficiency.

In conclusion, HP345 Gas Welded Cylinder Steel stands out due to its high strength, excellent weldability, and reliable performance in high-pressure environments. It is an ideal material for modern gas cylinder manufacturing where safety, efficiency, and cost optimization are essential.

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If you are looking for a trusted supplier of HP345 Gas Welded Cylinder Steel, GNEE Steel is your reliable partner. Contact us today to get competitive pricing, technical support, and fast delivery for your projects!

What international standards does HP345 gas cylinder steel comply with?
HP345 gas cylinder steel is produced according to Chinese GB standards and can be fully aligned with international standards such as ISO 9809. GNEE provides complete MTC and supports third-party inspections like SGS, BV, and TUV to ensure global compliance.

Is the mechanical performance of HP345 gas cylinder steel stable across batches?
GNEE ensures that HP345 gas cylinder steel maintains consistent yield strength (≥345 MPa) and tensile properties through strict chemical composition control and advanced rolling processes, minimizing batch-to-batch variation.

Can HP345 gas cylinder steel be used for high-pressure applications?
Yes, HP345 gas cylinder steel is specifically designed for high-pressure gas cylinders, offering excellent strength, toughness, and safety performance under demanding conditions.

What are the chemical composition advantages of HP345 gas cylinder steel?
HP345 gas cylinder steel features optimized carbon and alloy content, ensuring a balance between strength and ductility, which is critical for safe gas cylinder manufacturing.

Does HP345 gas cylinder steel support third-party inspection?
Absolutely. GNEE supplies HP345 gas cylinder steel with full traceability and supports inspections from globally recognized agencies to meet project and tender requirements.

What is the difference between HP345 gas cylinder steel and HP295?
Compared to HP295, HP345 gas cylinder steel offers higher strength and better pressure resistance, making it more suitable for demanding applications and reducing material thickness requirements.

How does GNEE ensure the quality of HP345 gas cylinder steel?
GNEE implements strict quality control from raw materials to final inspection, including ultrasonic testing and mechanical property verification for HP345 gas cylinder steel.

By exporting semi-finished rolled cylinders instead of raw plates, we leverage our advantages to offer you a landed cost 15-20% lower than your local processing.

Relying on many first-class equipment, such as CNC Shearing machine, Press Brake machine, Straightening machine, Roll Bending machine, Flat Bar Machine, Deburring machine etc, GNEE STEEL could provide various semi-productsand extensive forming services to customers.

GNEE STEEL PROCESSING

CTL&SL

Grinding Polishing

Cutting

Beveling

Forming

Maching

Auto Welding

Heat treatment

Painting

Engineering Services

1.CTL & SL SERVICE (141 SETS)

Currently, GNEE STEEL has imported manyadvanced CTL/SL equipment from Italy and Korea and could provide customized CTL/SL services from cold rolled stainless steel and carbon steel to hot rolled stainless steel and carbon steel as well as strips and ultra-wide sheet.

CTL FACILITIES
Max Length:16500mm

Max Width:2200mm

Max Thickness:25.4mm

Max Yield Strength:1500Mpa
 

SL FACILITIES

Max Width:2200mm

Max Thickness:18mm

Max slit Quantity:31

Max Yield Strength:1200Mpa

2.CUTTING SERVICE

GNEE STEEL imported lots of advanced cutting machines from Germany, Sweden, America and Japan, including plasmas cutting machine, water jet cutting machine, laser cutting machine, flame cutting machine and saw machine. In order to meet customers' diversified needs, GNEE STEEL also adopts nest working multi-cutting methods and intensive production to improve production capacity and save costs for the customers.

Laser Cutting Machine

Max Cutting Length:40,000mm

Max Width:4,600mm
Max Thickness:100mm

Flame Cutting Machine

Max Cutting Length:40,000mm

Max Width:8,000mm
Max Thickness:500mm

Plasmas Cutting Machine

Max Cutting Length:30,000mm

Max Width:5,000mm
Max Thickness:100mm

Water-jet Cutting

Max Cutting Length:12,000mm

Max Width:4,010mm
Max Thickness:250mm

3.FORMING SERVICE

Steel Plate Roll Bending
Maximum Rolling Thickness: up to 200mm
Maximum Width: 4200mm

Automatic Bending Machine-Press Brake
Max Bending Capability:3000Ton
Max Bending Length:15,000mm

Expert in Bending High-Strength & Wear-Resistant Steels

Punching Machine

Max Width:3,070mm
Max Thickness:8mm

Max Pressure:250t

BEVELING SERVICE

GNEE STEEL beveling platform has edge milling machine, edge planer, flame / plasma groove cutting machine, flame groove cutting robot, desktop chamfering machine, gantry planerand other advanced equipment to provide customers with parts prefabrication services,daily processing of V-type, Y-type, X-type and U-type grooves, and guarantee subsequent processes such as welding and assembly of products.

Milling：
Max Cutting Length:18,000mm

Max Width:4500mm
Max Thickness:120mm

Beveling:
Max Length:16,000mm

Max Thickness:80mm

MACHINING SERVICE

GNEE STEEL owns CNC Portal-type Boring and Milling machine,CNC Floor-type Boring and Milling machine, Vertical Precision 5-axis Milling Machine, Portal-type Planer, Vertical Lathe, Cylindical Grinding machine, Hydraulic Planer and CNC Lathe and could provide fine machining of large spare parts and structural parts for customers.

Gantry Type Boring & Milling Maching Center

Max Length:48000mm

Max Width:12500mm
Max Height:8000mm

Max Diameter:10500mm

Deep-hole Drilling Equipment
Max Driling Depth:1,100mm
Max Bore Diameter:φ80mm
Max Diametar:φ4,500mm

MMulti-hole Drilling Equipment

Max Length:13,000mm
Max Width:10,000mm
Max Bore Diameter:φ105mm
Max Drilling Depth:250mm

Floor Boring And Milling Machine
Max Length:24,000mm
Max Height:8,000mm
Turntable Dimensions:9x5m

Vertical Lathe

Max Height:6,000mm

Max Diametar:φ22,00mm

Automated Edge Milling Machine

The Automated Edge Milling Machine is a leading product in heavy-duty milling equipment. It is primarily used for weld groove preparation (beveling) on large-format plates made of stainless steel, carbon steel, and special steel grades. It can process plates with a maximum thickness of up to 90mm, a length of 16 meters, and a width of 4 meters.

It is equipped with dual milling units and a fully automatic milling cutter head changing system, enabling automated 4-edge beveling. Its standout feature is the profiling technology used when milling wavy plates and irregularly shaped products, which ensures absolute consistency of the groove after milling.

Utilizing specially designed milling cutter heads, it can execute highly difficult and complex groove profiles in a single pass.

Materials: Plain carbon steel, pressure vessel steel, wear-resistant steel, high-strength steel, stainless steel, nickel-based alloys, etc.
Width: 1200 - 4200 mm
Length: 5800 - 16000 mm
Thickness: 5 - 90 mm
Weight: Up to 35 tons

This edge milling machine is the world's premier automated bevel milling equipment. With its excellent structural design and advanced data algorithms, it achieves full automation from plate detection to the actual milling process, significantly improving processing efficiency while guaranteeing high precision.

• Processing Accuracy

Length accuracy: ±1mm when L < 10m; ±2mm when L > 10m;

Width accuracy: ±1mm;

Diagonal accuracy: ±2mm;

Root face accuracy (blunt edge): ±1mm for Y-grooves; +0.5mm for X-grooves.

• Processing Efficiency

The processing efficiency is more than 10 times that of conventional edge milling or edge planing equipment.

HEAT TREATMENT

Heat Treatment Furnace
Max Furnace Size:36x12x13.5m
Max Rated Temperature:1100℃
Max Loading Capacity:800t

Heat Treatment of Pressure Vessels
Heat Treatment of Mining Equipment
Heat Treatment of Tube Sheet
Heat Treatment of Pressure Vessel Head

Case : Steel Plates Supply for 100,000m³ Full Containment Ammonia Storage Tank Project

GNEE STEEL is currently participating in the procurement phase of a 100,000m³ full containment ammonia storage tank project, supplying high-quality steel plates for critical tank components. Due to the corrosive nature of ammonia and the risk of Ammonia Stress Corrosion Cracking (SCC), the project requires strict metallurgical control of materials according to EN 10028-3 standards.

One of the most important technical requirements of this project is the strict limitation of the actual Yield Strength (Re) for all NL2 grade materials. To prevent SCC risks in ammonia storage environments, the actual yield strength must not exceed 390 MPa, regardless of the nominal values specified in the standard or plate thickness ranges. This requirement places higher demands on steelmaking process control, heat treatment stability, and material testing.

Raw high-strength steel plates ready for the 100,000 m³ full containment ammonia storage tank production

Project Materials and Technical Requirements

The project mainly uses P355NL2 and P275NL2 normalized pressure vessel steel plates, which are widely applied in low-temperature storage tanks due to their excellent toughness and weldability.

Key technical specifications include:

Material grades: P355NL2 and P275NL2 (Normalized)

Yield strength: Standard minimum / Maximum limited to 390 MPa

Hardness: ≤ 225 HBW in base material

Impact testing: Charpy-V notch test at -50°C, minimum 27J

Certification: EN 10204 3.1 certificate, with optional 3.2 certification

These strict requirements ensure that the steel plates maintain stable mechanical properties and high resistance to ammonia-induced stress corrosion during long-term operation.

Precision rolling and forming of steel plates into curved sections for the 100,000 m³ ammonia storage tank.

Project Plate Quantities and Thickness Distribution

The total steel demand for this ammonia storage tank project is several thousand tons, mainly distributed across different tank sections:

P355NL2 – Inner & Outer Tank Shell Plates

Lower shell courses: 50 mm thickness – approx. 2,000 tons

Middle shell courses: 25 mm thickness – approx. 1,400 tons

Upper shell courses: 10 mm thickness – approx. 500 tons

P275NL2 – Tank Bottom Plates

Thickness: 10–15 mm – approx. 750 tons

P275NL2 – Suspended Roof Structure

Thickness: 5–8 mm – approx. 180 tons

S275JR – Outer Roof (Ambient Structure)

Thickness: 10 mm – approx. 450 tons

To improve tank fabrication efficiency and reduce circumferential welds, the project also requires wide steel plates to minimize welding joints, which helps reduce the potential risk of SCC in ammonia service conditions.

Formed steel segments wrapped and racked for protection, ready for 100,000 m³ ammonia storage tank assembly.

GNEE STEEL provides high-precision steel plate rolling and cylinder fabrication solutions for tank manufacturers worldwide. Send us your plate specifications or fabrication drawings for a fast quotation.

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Stainless Steel Material and Surface Specifications

Special Steel / Nickel Base Alloy