GB/T 5310 Seamless Steel Tubes and Pipes

For High Pressure Boiler – Current Standard: GB/T 5310-2023

Grades 20G, 25MnG, 15MoG, 15CrMoG, 12Cr2MoG, 12Cr1MoVG

Hot rolled, Cold drawn, or Hot expanded – Heat treated condition

Product Overview

GB/T 5310 is the Chinese national standard for seamless steel tubes and pipes used in the manufacture of high pressure boilers and high temperature pressure equipment. These tubes are specifically designed for service where temperatures reach 450°C to 650°C and working pressures exceed 9.8 MPa.

Key applications include:

Superheater tubes
Reheater tubes
Economizer tubes
Water wall tubes
Boiler headers and steam pipelines

Standard Update – Important:

Previous standard: GB/T 5310-2017 (effective 2018-09-01, expired 2024-04-01)
Current standard: GB/T 5310-2023 (effective 2024-04-01)
Key change: Hot expansion process now fully recognized in the seamless tube manufacturing system

Available Grades:

Carbon steel: 20G (most popular), 25MnG
Molybdenum alloy: 15MoG
Chrome-molybdenum alloy: 15CrMoG, 12Cr2MoG, 12Cr1MoVG

✅ GB/T 5310-2023 compliant – Current standard (effective April 1, 2024)
✅ High pressure capability – Working pressure >9.8 MPa
✅ High temperature service – Up to 650°C
✅ Seamless construction – Pressure integrity assured
✅ Multiple manufacturing methods – Hot rolled, cold drawn, or hot expanded
✅ Heat treated – Normalized, normalized + tempered, or quenched + tempered
✅ 100% hydrostatic tested – Guaranteed pressure integrity
✅ EN 10204 Type 3.1 MTC provided with full traceability
✅ Factory direct | Global shipping

Key Specifications

Parameter	Details
Standard	GB/T 5310-2023 (supersedes GB/T 5310-2017)
Product Type	Seamless Steel Tube and Pipe for High Pressure Boiler
Steel Grades	20G, 25MnG, 15MoG, 15CrMoG, 12Cr2MoG, 12Cr1MoVG
Manufacturing Methods	Hot rolled, Cold drawn (rolled), Hot expanded
OD Range (Hot rolled)	22mm – 530mm
OD Range (Cold drawn)	10mm – 108mm
OD Range (Hot expanded)	Up to 820mm (by agreement)
Wall Thickness (Hot rolled)	2.0mm – 70mm
Wall Thickness (Cold drawn)	2.0mm – 13.0mm
Length	4m – 12m (fixed or random)
Delivery Condition	Normalized, normalized + tempered, quenched + tempered
Surface Finish	Black / Bare / Oiled
End Finish	Plain / Beveled

Steel Grade Overview

Grade	Type	Max Temp (°C)	Yield Strength (MPa)	Tensile (MPa)	Typical Application
20G	Carbon steel	450	≥245	410-550	Economizer, water wall, low temp superheater
25MnG	Carbon steel (Mn)	450	≥240	≥415	Higher strength carbon boiler tubes
15MoG	Mo-alloy	500	≥270	450-600	Medium temperature service
15CrMoG	1Cr-0.5Mo	550	≥235	440-640	High temperature superheater
12Cr2MoG	2.25Cr-1Mo	550	≥280	450-600	High pressure, high temperature
12Cr1MoVG	1Cr-1Mo-V	580	≥255	470-640	Advanced high temperature

💡 20G is the most popular grade – widely used for general high pressure boiler service.

Chemical Composition – GB/T 5310 Grades

Grade	C (%)	Mn (%)	Si (%)	Cr (%)	Mo (%)	V (%)	P,S max
20G	0.17-0.24	0.35-0.65	0.17-0.37	—	—	—	0.030
25MnG	0.22-0.30	0.70-1.00	0.17-0.37	—	—	—	0.030
15MoG	0.12-0.20	0.40-0.80	0.17-0.37	—	0.25-0.35	—	0.030
15CrMoG	0.12-0.18	0.40-0.70	0.17-0.37	0.80-1.10	0.40-0.55	—	0.030
12Cr2MoG	0.08-0.15	0.40-0.70	≤0.50	2.00-2.50	0.90-1.20	—	0.030
12Cr1MoVG	0.08-0.15	0.40-0.70	0.17-0.37	0.90-1.20	0.25-0.35	0.15-0.30	0.030

💡 Low phosphorus and sulfur (≤0.030%) ensures excellent toughness and weldability.

Mechanical Properties – GB/T 5310 Grades

Grade	Tensile Strength (MPa)	Yield Strength (MPa) min	Elongation (%) min
20G	410 – 550	≥245	≥24
25MnG	≥415	≥240	≥22
15MoG	450 – 600	≥270	≥22
15CrMoG	440 – 640	≥235	≥21
12Cr2MoG	450 – 600	≥280	≥20
12Cr1MoVG	470 – 640	≥255	≥21

💡 20G offers excellent balance of strength (≥245 MPa yield) and ductility (≥24% elongation) – the workhorse grade for high pressure boilers.

Grade Selection Guide – High Pressure Boiler Application

Boiler Section	Operating Temp	Recommended Grade	Key Property
Economizer	≤400°C	20G	Corrosion resistance
Water Wall	≤400°C	20G	Thermal fatigue resistance
Low Temp Superheater	≤450°C	20G	Creep strength
Medium Temp Superheater	450-500°C	15MoG	Mo-alloy creep resistance
High Temp Superheater	500-550°C	15CrMoG	Cr-Mo oxidation resistance
Reheater	550-580°C	12Cr1MoVG	V-alloy high temp strength
High Pressure Header	≤550°C	12Cr2MoG	Heavy wall capability

💡 20G is suitable for temperatures up to 450°C. For service above 450°C, alloy grades (15CrMoG, 12Cr1MoVG) must be used .

Manufacturing Methods – GB/T 5310-2023

Method	Description	OD Range	Typical Applications
Hot rolled	Rolled at high temperature	22-530mm	Standard boiler tubes
Cold drawn (rolled)	Cold worked for precision	10-108mm	Small diameter, precision tubes
Hot expanded	Expanded by heating	Up to 820mm	Large diameter boiler components

💡 The 2023 standard officially recognizes hot expansion as a seamless tube manufacturing method.

Available Sizes – GB/T 5310 Boiler Tubes

Hot Rolled Tubes:

OD (mm)	WT Range (mm)	Typical Grade	Application
22 – 60	2.0 – 8.0	20G	Small boiler tubes
60 – 114	3.0 – 12.0	20G, 15CrMoG	General boiler
114 – 219	5.0 – 20.0	20G, 12Cr1MoVG	Main steam – most common
219 – 325	6.0 – 30.0	12Cr1MoVG, 12Cr2MoG	Headers, large tubes
325 – 426	8.0 – 40.0	12Cr2MoG	Superlarge headers
426 – 530	10.0 – 70.0	By agreement	Special applications

Cold Drawn (Rolled) Tubes:

OD (mm)	WT Range (mm)	Typical Grade	Application
10 – 25	1.5 – 4.0	20G	Small diameter
25 – 50	2.0 – 6.0	20G, 15CrMoG	Precision tubes
50 – 76	2.5 – 10.0	15CrMoG	Superheater elements
76 – 108	3.0 – 13.0	12Cr1MoVG	High strength small bore

💡 Most popular size: 114.3mm to 219.1mm OD for main steam lines and headers.

Quality Assurance & Testing

Test	Method	Coverage	Requirement
Hydrostatic Test	Water pressure	100%	Mandatory
Ultrasonic Testing (UT)	Non-destructive	By agreement	Optional
Eddy Current (ET)	Non-destructive	By agreement	Optional
Tensile Test	EN ISO 6892-1	Per lot	All grades
High Temperature Creep Test	GB/T standard	Per lot	For alloy grades
Flattening Test	Ductility	Per lot	All grades
Flaring Test	Tube end expansion	Per lot	All grades
Microstructure Examination	Metallographic	Per lot	Grain size, decarburization
Dimensional Inspection	Micrometer	100%	All grades

💡 100% hydrostatic testing is mandatory for all high pressure boiler tubes.

Heat Treatment Requirements

Grade	Required Heat Treatment	Purpose
20G, 25MnG	Normalized	Uniform grain structure, good strength
15MoG, 15CrMoG	Normalized + Tempered	Improved toughness
12Cr2MoG	Normalized + Tempered	High temperature strength
12Cr1MoVG	Normalized + Tempered	Creep resistance at high temp

💡 Microstructure and grain size requirements are specified – fine grain structure (≥5) is required for all grades.

Applications – High Pressure Boiler Tubes

Industry	Application	Recommended Grade	Service Temp/Pressure
Power Generation	Superheater tubes	15CrMoG, 12Cr1MoVG	450-580°C
Power Generation	Reheater tubes	15CrMoG, 12Cr1MoVG	450-580°C
Power Generation	Economizer tubes	20G	≤400°C
Power Generation	Water wall tubes	20G	≤400°C
Power Generation	Boiler headers	12Cr2MoG, 12Cr1MoVG	High pressure
Industrial Boilers	Steam boiler tubes	20G	450°C
HRSG	Heat recovery tubes	15CrMoG	500°C
Petrochemical	High temp transfer lines	12Cr1MoVG	Up to 580°C

💡 Working conditions: Temperature 450-650°C, pressure >9.8 MPa.

Why Choose Our GB/T 5310 High Pressure Boiler Tubes?

Advantage	Description
Current standard	GB/T 5310-2023 – fully compliant with latest requirements
Full grade range	20G to 12Cr1MoVG – one-stop sourcing
20G in stock	Most popular grade – ready to ship
Multiple manufacturing methods	Hot rolled, cold drawn, hot expanded – all recognized
100% hydrostatic tested	Mandatory per standard – guaranteed integrity
Heat treated	Normalized or normalized + tempered – proper microstructure
High temperature performance	Creep strength data available for alloy grades
Full traceability	EN 10204 3.1 MTC with heat number
Global export	Shipped to power plants and boiler manufacturers worldwide

Contact for Quote

Please provide the following details:

Grade : 20G / 25MnG / 15MoG / 15CrMoG / 12Cr2MoG / 12Cr1MoVG
OD (mm) : _______
WT (mm) : _______
Length (m) : _______
Quantity : _______ (pieces / meters / tons)
Manufacturing : Hot rolled / Cold drawn / Hot expanded
Application : Superheater / Reheater / Economizer / Water wall / Header
Service Temperature : _______ °C
Inspection : Standard / Third-party (SGS/BV/TUV)

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