16Mn Seamless Steel Pipe

Pressure And Structural Use

16mn seamless pipe offers high strength and weldability for pressure vessels, boilers, and industrial piping applications.

16Mn Steel Pipe Seamless Structural Tube Low Alloy Pipe Pressure Vessel Steel +2 More

16Mn Seamless Steel Pipe

Pressure And Structural Use

16mn seamless pipe offers high strength and weldability for pressure vessels, boilers, and industrial piping applications.

16Mn Steel Pipe Seamless Structural Tube Low Alloy Pipe Pressure Vessel Steel +2 More

16Mn Seamless Pipe, also known as Q345 in modern Chinese standards (GB/T 1591-2008), is a high-strength low-alloy structural steel pipe designed for excellent mechanical properties, weldability, and corrosion resistance. With a carbon content of 0.12-0.20% and alloying elements like manganese (0.7-1.0%), silicon, and traces of vanadium, niobium, and titanium, it is ideal for boiler pipeline protection in medium and low-pressure boilers, pressure vessels, oil tanks, and industrial piping systems. Its seamless construction ensures durability and reliability in demanding applications like shipbuilding, bridges, and mechanical structures.

The 16Mn Seamless Pipe is manufactured through hot-rolling or cold-drawing processes, typically delivered in a hot-rolled or normalized state to optimize mechanical properties. The manganese content enhances strength and toughness, while micro-alloying elements like Ti, Nb, and V refine grain structure, improving low-temperature performance and weldability. Available in sizes from 10mm to 1200mm OD, with wall thicknesses from 2mm to 80mm, and lengths up to 12 meters or customized, it meets diverse project requirements. Its yield strength of 345 MPa (hence the Q345 designation) makes it suitable for structural and pressure vessel applications.

The Seamless Alloy Pipes undergo rigorous testing, including tensile, flattening, flaring, and hydrostatic tests, to ensure compliance with standards like GB/T 8162, GB/T 8163, and GB 6479. With a tensile strength of 470-630 MPa and yield strength of 345 MPa (for thicknesses ≤16mm), the 16Mn pipe offers robust resistance to mechanical stress and moderate corrosion. Surface treatments such as black varnish, galvanizing, or 3LPE coatings enhance corrosion resistance, while plain or beveled ends facilitate integration into industrial piping systems. Due to its slight hardening tendency, preheating (150-200°C) is recommended for welding on thick or rigid structures to prevent cold cracking.

Compared to grades like 15CrMoG or ASTM A335 P11, the 16Mn Seamless Pipe has lower alloy content, making it more cost-effective for applications not requiring extreme high-temperature resistance (typically up to 350°C for pressure vessels). Unlike 12Cr1MoVG, which includes vanadium for enhanced creep resistance, 16Mn prioritizes weldability and toughness, making it versatile for structural uses. Its modern equivalent, Q345, includes grades A, B, C, D, and E, with improved low-temperature impact toughness (tested at +20°C to -40°C), making it a preferred choice for diverse applications like cranes, mining equipment, and pressure vessels.

16Mn Seamless Steel Pipe

Wall Thickness (W.T.) Tolerance of 12Cr1MoVG Seamless Pipe
Wall Thickness (S)		Tolerance
< 3.5 mm		+15% (min +0.48 mm)
		−10% (min −0.32 mm)
3.5 – 20 mm		+15%, −10%
> 20 mm	OD < 219 mm	±10%
> 20 mm	OD ≥ 219 mm	+12.5%, −10%

Comparison of 16Mn with Other Pipe Grades
Feature	16Mn (Q345)	15CrMoG	ASTM A335 P11
Material Type	Low Alloy Steel	Alloy Steel	Alloy Steel
Carbon Content	0.12-0.20%	0.12-0.18%	0.05-0.15%
Manganese Content	0.70-1.00%	0.40-0.70%	0.30-0.60%
Chromium Content	≤0.30%	0.80-1.10%	1.00-1.50%
Temperature Range	Up to 350°C	Up to 550°C	Up to 550°C
Corrosion Resistance	Moderate (With coatings)	Excellent (With coatings)	Good (With coatings)
Applications	Pressure Vessels, Boilers, Structures	Boilers, Petrochemical	Boilers, Refineries
Tensile Strength (MPa)	470-630	440-640	415 (min)
Yield Strength (MPa)	345 (min)	235 (min)	205 (min)
Key Advantage	High strength, weldability	Balanced high-temp strength	Cost-effective high-temp

Chemical Composition of 16Mn Seamless Steel Pipe
Element	Composition (%)
Carbon (C)	0.12-0.20
Silicon (Si)	0.20-0.55
Manganese (Mn)	0.70-1.00
Phosphorus (P)	≤0.045
Sulfur (S)	≤0.045
Chromium (Cr)	≤0.30
Nickel (Ni)	≤0.30
Vanadium (V)	≤0.08

Mechanical Properties of16Mn Seamless Steel Pipe
Property	Value
Tensile Strength (MPa)	470-630
Yield Strength, min (MPa)	345 (≤16mm)
Elongation, min (%)	21
Impact Toughness (J)	≥34 (at 0°C, Q345B)

International Equivalents for S355J0 (1.0553) / 16Mn
EU EN	USA	Germany DIN / WNr	Japan JIS	France AFNOR	UK BS	Old EN	Italy UNI	Belgium NBN	Spain UNE	China GB	Finland SFS	Austria ÖNORM	Norway NS	ISO	Portugal NP	India IS
S355J0 (1.0553)	A441 A633	St52-3U	SS490B	E36-3	50C	Fe510C	Fe510C	AE355C	AE355C	16Mn	Fe52C	St510C	NS12153	E355C Fe510C	FE510-C	Fe570HT

16Mn is a Chinese-grade carbon–manganese low-alloy structural steel, with ~0.12–0.20% C and 1.20–1.60% Mn, offering a balance of strength (~343 MPa yield) and weldability :contentReference[oaicite:1]{index=1}.

Tensile strength: ~470–660 MPa, yield ≥275–345 MPa, elongation ≥21%. Wall thickness tolerances are ±10–15% depending on pipe size :contentReference[oaicite:2]{index=2}.

Although generally weldable without preheat, 16Mn’s higher hardening tendency means preheating is recommended for thicker or highly constrained sections—especially in cold conditions—to avoid cracking :contentReference[oaicite:3]{index=3}.

Use low-hydrogen electrodes such as E7015/E7016/E7018 for SMAW. For MIG/TIG/SAW, ER70S‑6 or H08Mn variants are recommended :contentReference[oaicite:4]{index=4}.

Can be annealed, quenched & tempered, normalized or heat-treated depending on requirements. Surface hardness control is often applied to enhance toughness :contentReference[oaicite:5]{index=5}.

Widely used in construction, machinery, pipelines (oil & gas, water), vehicle chassis, and medium/low pressure vessels :contentReference[oaicite:6]{index=6}.

Chemically similar to Q345 but lacks micro-alloying (Ti, Nb, V). Q345 offers improved low-temperature toughness and higher allowable stress :contentReference[oaicite:7]{index=7}.

Yes. 16Mn provides higher tensile and yield strength than regular carbon steel, making it ideal for high-stress structures and heavy-load applications.

Yes. 16Mn has good weldability and can be welded using conventional methods without requiring special preheat, except for thick or rigid sections.

Yes. 16Mn offers excellent formability and can be processed through hot rolling, cold drawing, bending, and other fabrication techniques.

16Mn demonstrates excellent toughness, allowing it to absorb impact and resist fracture or deformation under heavy or sudden loads.

While not stainless, 16Mn shows good resistance to atmospheric corrosion, making it suitable for outdoor and mild marine environments.

The chemical element of Q345 steel is basically the same as that of 16Mn steel. The difference lies in the addition of Ti, Nb and V micro alloying elements, which can refine grain, improve toughness, and finally improve the mechanical properties of steel. In other words, the comprehensive mechanical properties of Q345 steel are better than that of 16Mn steel, especially its low temperature performance and allowable stress.

16Mn Seamless Steel Pipe Industry Applications

16Mn is a versatile low‑alloy structural steel with high strength, toughness, weldability, and cost-efficiency, making it a top choice across diverse industrial sectors.

Construction Structures

Used in stairs, handrails, pillars and general steelwork in buildings, offering reliable load-bearing capacity and weldability.

Bridge Engineering

Ideal for bridge bearings, beams and tie rods with high tensile strength and weight saving benefits.

Automobile Manufacturing

Used in chassis, suspension and drivetrain parts, balancing lightweight design with high strength and impact resistance.

Machinery & Equipment

Ideal for gear shafts and frames due to strong fatigue and wear resistance.

Petrochemical & Chemical

Widely used in pipelines and structural components for oil, gas and chemical plants with good corrosion and weld properties.

Mining & Water Projects

Used in mining supports, underground piping and water infrastructure, offering high strength and long service span.

16Mn Seamless Steel Pipe

16Mn Seamless Steel Pipe