P265NB Gas Cylinder Steel Material
P265NB Gas Cylinder Steel - EN 10120 Full Data & Equivalent Grades
Comprehensive technical data for P265NB steel according to EN 10120, including chemical composition, mechanical and physical properties, thermal and electrical values, equivalent grades, and application guidelines for welded gas cylinders.
Welding, cold forming, deep drawing, hot forming
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P265NB Gas Cylinder Steel Introduction
P265NB is a hot‑rolled, weldable fine‑grain steel for welded gas cylinders, specified in EN 10120:2017. It offers a minimum yield strength of 265 MPa and a tensile strength range of 410–530 MPa with good formability and low‑temperature toughness. The steel is fully killed (normally with aluminium) and microalloyed, providing a fine grain structure that ensures reliable performance in high‑pressure gas containment. Typical delivery conditions are normalising rolled or thermomechanical rolled, available as coils, sheets, and plates. P265NB is widely used for industrial gas cylinders, fire extinguisher bodies, and other welded pressure vessels where a ductile, cost‑effective steel with proven weldability is required.
- Excellent weldability with common methods (MAG, TIG, submerged arc)
- Charpy impact energy guaranteed at –20 °C
- Low carbon equivalent for improved cracking resistance
P265NB Gas Cylinder Steel Chemical Composition
The chemical composition of P265NB is controlled to ensure a fine‑grained, fully killed steel with excellent weldability and toughness. Microalloying elements (Nb, V, Ti) are limited to prevent excessive hardness in the heat‑affected zone. The carbon equivalent is kept low to avoid cold cracking. The table shows the maximum contents unless a range is given, as defined in EN 10120:2017.
- Aluminium is added for deoxidation and grain refinement.
- Combined Cr+Mo+Ni+Cu ≤ 0.70 % and each ≤ 0.30 %.
| Element | Content (max or range) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.20 % | |
| Silicon (Si) | ≤ 0.35 % | |
| Manganese (Mn) | 0.50 – 1.40 % | |
| Phosphorus (P) | ≤ 0.025 % | |
| Sulfur (S) | ≤ 0.015 % | |
| Aluminium (total Al) | ≥ 0.020 % | Fully killed, fine‑grain practice |
| Niobium (Nb) | ≤ 0.05 % | |
| Vanadium (V) | ≤ 0.05 % | |
| Titanium (Ti) | ≤ 0.04 % | |
| Chromium (Cr) | ≤ 0.30 % | |
| Nickel (Ni) | ≤ 0.30 % | |
| Molybdenum (Mo) | ≤ 0.10 % | |
| Copper (Cu) | ≤ 0.30 % | |
| Carbon Equivalent (CEV) | ≤ 0.43 % | CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
P265NB Gas Cylinder Steel Thermal and Electrical Physical Properties
The physical properties are typical for low‑alloy carbon steels and are valid at room temperature unless otherwise stated. They can vary slightly with the exact chemical composition and heat treatment condition but are suitable for general design calculations.
- Density used for weight estimation.
- Thermal expansion influences welding distortion and service conditions under temperature fluctuations.
| Property | Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Elastic modulus (E) | 210 | GPa | At 20 °C, longitudinal |
| Shear modulus (G) | 80 | GPa | Calculated from E and Poisson's ratio |
| Poisson's ratio (ν) | 0.3 | – | In the elastic range |
| Thermal expansion coefficient (α) | 11.5 × 10⁻⁶ | /K | 20–100 °C |
| Thermal expansion coefficient (α) | 12.5 × 10⁻⁶ | /K | 20–200 °C |
| Thermal expansion coefficient (α) | 13.0 × 10⁻⁶ | /K | 20–300 °C |
| Thermal conductivity (λ) | 46 | W/(m·K) | At 20 °C |
| Thermal conductivity (λ) | 45 | W/(m·K) | At 100 °C |
| Specific heat capacity | 460 | J/(kg·K) | At 20 °C |
| Electrical resistivity (ρₑ) | 0.22 | μΩ·m | At 20 °C |
P265NB Gas Cylinder Steel Mechanical Properties
Mechanical properties are determined on transverse test pieces unless otherwise specified. The minimum values refer to the after‑delivery condition (normalising rolled or thermomechanical rolled). The Charpy V‑notch impact test is performed at –20 °C. Elongation is measured with L₀ = 5.65√S₀ (proportional gauge length).
- Yield strength decreases with increasing thickness.
- Impact values are guaranteed for thicknesses ≥ 6 mm.
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Yield strength (ReH) | ≥ 265 | MPa | Thickness ≤ 16 mm, transverse |
| Yield strength (ReH) | ≥ 255 | MPa | Thickness 16–40 mm, transverse |
| Tensile strength (Rm) | 410 – 530 | MPa | All thicknesses, transverse |
| Elongation (A, L₀=5.65√S₀) | ≥ 22 | % | Thickness ≤ 16 mm, transverse |
| Elongation (A, L₀=5.65√S₀) | ≥ 21 | % | Thickness 16–40 mm, transverse |
| Charpy impact energy (KV₂) | ≥ 27 | J | At –20 °C, transverse, thickness ≥ 6 mm |
| Bending test (bend angle 180°) | No cracks | Mandrel diameter: 3 × thickness (t ≤ 25 mm) |
P265NB Gas Cylinder Steel Fully Equivalent Material Standards and Substitute Designations
| Country / Region | Standard | Grade / Designation | Remarks |
|---|---|---|---|
| Europe | EN 10120 | P265NB | Original base standard |
| International | ISO 4978:2017 | PL265 | Equivalent grade for welded gas cylinders |
| China | GB/T 6653:2017 | HP265 | Closest Chinese equivalent; small composition differences possible |
| Germany (withdrawn) | DIN 17155 | HII | Historical predecessor, not fully identical |
P265NB Gas Cylinder Steel Application Introduction
P265NB is specifically designed for the manufacture of welded gas cylinders and other pressure‑retaining components. Its balanced carbon‑manganese composition with microalloying gives a good combination of strength, ductility, and toughness after welding. The steel is suitable for deep drawing, cold stamping, and hot forming of cylinder halves before welding. It can be joined by all common fusion welding processes. Post‑weld heat treatment (stress relief) is often applied to finished cylinders.
- Typical service temperatures down to –20 °C.
- Can be hot‑dip galvanised or coated for corrosion protection.
Product Applications: Welded steel gas cylinders for oxygen, nitrogen, argon, acetylene, CO₂, hydrogen mixtures, Fire extinguisher bodies (portable and wheeled), Compressed natural gas (CNG) cylinder type 1 (all‑metal), LPG bottles (selected designs), Pressure accumulators and receivers
Processed into products: Cylinder shell (deep‑drawn or rolled‑and‑welded), Cylinder base and foot ring, Cylinder collar and valve boss, Welded stiffener rings (if used), End closures (heads) for horizontal cylinders
Application industries: Industrial gas manufacturing and distribution, Fire protection equipment, Automotive alternative fuel systems (CNG cylinders), Welding and cutting equipment, Medical gas supply
P265NB Gas Cylinder Steel Similar / Comparable Steel Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10120 | P245NB | Lower strength; min. yield 245 MPa, tensile 370–490 MPa |
| Europe | EN 10120 | P310NB | Higher strength; min. yield 310 MPa, tensile 440–560 MPa |
| Europe | EN 10120 | P355NB | Highest strength in the series; min. yield 355 MPa |
| International | ISO 4978 | PL245 | Similar to P245NB |
| International | ISO 4978 | PL290 | Intermediate strength, comparable to P310NB |
| International | ISO 4978 | PL360 | Higher strength, comparable to P355NB |
Notes:
Fabrication guidelines: Preheating is generally not required for P265NB when welding at ambient temperature, provided the hydrogen content of the consumables is low and the heat input is controlled. For stress relief after welding, temperatures around 580–620 °C are typical. Quality certificates according to EN 10204 type 3.1 should be supplied, confirming chemical analysis and mechanical test results. For cryogenic applications below –20 °C, alternative grades or additional impact testing should be agreed.
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