What Is P245NB Steel?
P245NB is a non-alloy European quality steel specified in EN 10120 for the manufacture of low-pressure welded gas cylinders and LPG vessels, with the material number 1.0111. In the designation, P indicates pressure vessel application, 245 is the minimum yield strength of 245 MPa, N marks the normalized delivery condition, and B is the quality level. The steel offers an ideal combination of strength, ductility, and weldability, which directly affects the safety, performance, and service life of welded gas cylinders.
Key Technical Properties
The main technical properties of P245NB are a minimum yield strength of 245 MPa, a tensile strength of 360-450 MPa, and good elongation for deep-drawing operations such as the manufacture of LPG cylinder bodies, tops, and bottoms. The chemical composition is controlled for weldability, with a low carbon content, silicon about 0.25% maximum, phosphorus 0.025% maximum, and sulfur 0.015% maximum as typical listed values; the exact limits should be confirmed against the applicable edition of EN 10120 and the mill certificate. The delivery condition is typically normalized (N), as hot rolled (AR), or normalized and tempered, which produces a fine, uniform grain structure.
Why P245NB Suits Gas Cylinder Manufacturing
The low carbon content of P245NB reduces the risk of hardening and cracking during welding, because less carbon is available to form brittle carbides at grain boundaries, and it supports a wide range of welding techniques including arc, gas, and laser welding. The minimum yield strength of 245 MPa provides sufficient resistance to internal pressure without over-engineering the wall thickness, while the ductility allows the steel to deform plastically under overpressure or impact instead of fracturing suddenly. The ferrite-pearlite microstructure and the refined grain structure give good toughness, so cylinders can be transported and stored in cold environments without brittle failure, and the surface can be painted, galvanized, or otherwise treated to resist corrosion.
How to Select and Specify P245NB
When selecting P245NB for gas cylinders, confirm that the material complies with EN 10120 (material number 1.0111) and that the chemical and mechanical properties match the grade. Choose the grade for low-pressure service where the 245 MPa yield level provides adequate strength without over-engineering. Prefer material with a low carbon equivalent and low phosphorus and sulfur to avoid weld cracking and ensure stable seam performance. Check the formability, thickness uniformity, and surface quality needed for deep drawing and pressure containment, and ensure the material is certified for gas cylinder production and meets the applicable national or regional pressure vessel safety regulations. For tighter dimensional control, thickness tolerances in accordance with EN 10051:2010 can be specified at fractions of the standard tolerance.
Frequently Asked Questions
What Chinese grade corresponds to P245NB? There is no direct Chinese equivalent. HP295 (GB 6653, steel plate for welded gas cylinders) is similar in application, but its chemical composition and performance requirements differ, so direct substitution requires engineering verification.
What is the thickness tolerance of P245NB? The standard thickness tolerance conforms to EN 10051:2010, and tighter tolerances such as 75%, 66%, 60%, 50%, or 33% of the standard tolerance can be agreed.
How is the weldability of P245NB evaluated? P245NB is weldable with conventional methods such as arc, gas, and laser welding, and the low-carbon design keeps the heat-affected zone tough; an approved welding procedure specification should be used for series production.
Does P245NB perform well at low temperatures? The steel has good low-temperature toughness and is not prone to brittle fracture in normal cold-environment service, which supports safe transport and storage of gas cylinders.
Can P245NB be deep drawn? Yes, its high elongation and uniform structure enable deep drawing and forming of cylinder bodies, tops, and bottoms without fracture.
Is P245NB corrosion resistant? P245NB itself is a non-alloy steel, but it can be painted, galvanized, or surface treated to protect against corrosion from the stored gas and the external environment.
What delivery conditions are available? P245NB is typically supplied normalized, as hot rolled, or normalized and tempered, depending on the required grain structure and mechanical properties.
