Difference between TC1 and TC2 of P265GH seamless steel tube

The European standard EN10216-2, "Technical conditions for delivery of seamless steel pipes for pressure applications - Part 2: Alloy and non-alloy steel pipes specifying high-temperature properties," is the core standard for the production of high-pressure seamless steel pipes. It covers multiple grades including P195GH, P235GH, P265GH, 20MnNb6, 10CrMo5-5, 13CrMo4-5, 16Mo3, 10CrMo9-10, X10CrMoVNb9-1, 15NiCuMoNb5-6-4, and X20CrMoV11-1, and is widely used in high-temperature and high-pressure equipment such as power plant boilers, petrochemical reactors, and heat exchangers. Among these, P265GH high-pressure seamless steel pipes have become the mainstream choice due to their excellent high-temperature stability, but the subdivisions TC1 and TC2 often cause confusion in selection. This article will systematically analyze, based on standards and specifications, what P265GH is, its chemical composition, and its mechanical properties, with a focus on clarifying the differences between P265GH TC1 and TC2.
 
I. What kind of seamless steel pipe is P265GH?
P265GH is a non-alloy seamless steel pipe material for high-temperature pressure applications, as specified in European standard EN10216-2. In its name, "P" represents pressure vessel steel, "265" indicates a minimum yield strength of not less than 265 MPa, "G" represents a fine-grained structure, and "H" indicates suitability for high-temperature environments. This material, through microalloying (Nb, V, Ti) and normalizing treatment, maintains stable strength and weldability at high temperatures of 100-400℃. Its resistance to hydrogen-induced cracking (HIC) meets the NACE TM0284 standard, with a corrosion rate ≤0.04mm/a. It is a high-pressure steel that balances economy and reliability.
 
II. Standards and Manufacturing Processes for P265GH Seamless Steel Pipes
(I) Core Standards
Strictly adheres to EN10216-2 "Technical conditions for delivery of seamless steel tubes for pressure applications - Part 2: Alloy and non-alloy steel tubes with specified high-temperature properties," clearly requiring specifications for chemical composition, mechanical properties, and non-destructive testing. A quality certificate in EN10204 3.1/3.2 format must be provided upon delivery. (II) Key Production Processes
 
Bill Preparation: Low-sulfur and phosphorus continuously cast billets are selected, and the chemical composition must meet the standard preset range;
Hot Rolling: A piercing + continuous rolling process is adopted, controlling the final rolling temperature ≥850℃;
Heat Treatment: The core is normalizing treatment (880-940℃, holding for 1-2 min/mm, air cooling), which can refine the grains and improve the uniformity of mechanical properties by 30%;
Finishing and Inspection: Includes straightening, non-destructive testing, dimensional inspection, etc., with different testing requirements corresponding to different TC grades.
 

III. Chemical Composition and Analysis of European Standard High-Pressure Seamless Steel Pipe P265GH
According to EN10216-2 standard, the chemical composition (smelting analysis) of P265GH material must meet the following requirements, with each element playing a key regulatory role in performance:

Element	Content Range (%)	Standard Limit Basis	Function Analysis
C	≤0.20	EN10216-2	Increasing strength, but if too high, reduces weldability and toughness.
Si	≤0.40	EN10216-2	Deoxidizer, improves flowability, and controls high-temperature oxidation.
Mn	≤1.40	EN10216-2	Solid solution strengthening improves hardenability and inhibits the harmful effects of sulfur.
P	≤0.025	EN10216-2	Harmful elements must be strictly controlled to prevent cold brittleness.
S	≤0.020	EN10216-2	Harmful elements must be strictly controlled to prevent thermal brittleness.
Cr	≤0.30	EN10216-2	Adding a small amount enhances antioxidant properties
Mo	≤0.08	EN10216-2	Enhanced high-temperature durability
Ni	≤0.30	EN10216-2	Improve low-temperature toughness
Al	≥0.020	EN10216-2	Refining grains and improving toughness
Cr+Cu+Mo+Ni	≤0.70	EN10216-2	Comprehensive control of total alloy content to ensure weldability

 
Calculations show its carbon equivalent is approximately 0.32%, meeting the requirement of welding without preheating and suitable for the manufacturing needs of most high-pressure equipment.
 
 
IV. Mechanical Performance Requirements and Analysis of European Standard P265GH High-Strength Seamless Steel Pipes
The EN10216-2 standard clearly specifies the mechanical properties of P265GH seamless steel pipes, with different wall thicknesses corresponding to different indicators. The core parameters are as follows:
 

Performance items	Test Standards	Thickness range	Indicator Requirements	Performance Analysis
Yield strength (σs)	EN10002-1	t≤16mm	≥265MPa	The core indicator for maintaining structural stability under high-temperature conditions is ≥245MPa at 200℃.
Yield strength (σs)	EN10002-1	16<t≤40mm	≥255MPa	The increased wall thickness resulted in a slight decrease in strength, but it still meets the requirements for high-pressure operating conditions.
Tensile strength (σb)	EN10002-1	All thicknesses	430-580MPa	It balances strength and plasticity within a reasonable range, making it easy to process and shape.
Elongation (δ5)	EN10002-1	All thicknesses	≥23%	Ensure the bending, welding and other forming requirements during pipeline installation.
Impact energy (KV2)	EN10045-1	0℃	≥27J	Resisting low-temperature impact loads and preventing brittle fracture
Hardness (HBW)	EN10109-1	All thicknesses	120-160	The low hardness characteristic facilitates machining and reduces manufacturing costs.

 
 
V. What are the differences between TC1 and TC2 of seamless steel pipes made of P265GH according to European standards?
The core difference between P265GH TC1 and TC2 stems from the different testing categories specified in the EN10216-2 standard, rather than differences in chemical composition or basic mechanical properties (their chemical composition and mechanical properties are completely identical). The specific differences are as follows:
 

Comparison Dimensions	TC1	TC2	Standard basis
Non-destructive testing requirements	Only longitudinal defect detection is required at both ends of the steel pipe.	100% longitudinal defect inspection is required for the entire steel pipe.	Clause 9.3 of EN10216-2
Precision of detection method	Routine ultrasound examination (UT)	High-precision ultrasonic testing, some of which require supplementary radiographic (RT) testing.	EN10228-1/2
Defect Judgment Standards	Slight dispersion defects are permissible	Linear defects are strictly prohibited, and the size limits for dispersed defects are even more stringent.	EN10216-2 Annex B
Applicable Scenarios	Under typical high-pressure conditions, such as low-pressure piping in industrial boilers	High-risk working conditions such as nuclear-grade equipment and transportation of highly toxic media.	Clause 4.2 of EN10216-2
Cost level	The testing cost is lower, and the overall price is 10%-15% lower than TC2.	The testing process is complex and costly.	Industry practice data

 
 
VI. Main Application Areas and Case Studies of P265GH Seamless Steel Pipes
(I) Core Application Areas
Energy & Power: Boiler drums, superheater pipes, and nuclear power auxiliary pressure vessels;
Petrochemicals: Hydrogenation reactor tube bundles, solvent recovery tower pressure pipelines, and catalytic converter delivery pipes;
Industrial Equipment: Heat exchanger shells, high-pressure gas storage tanks, and main pipelines for central heating systems.
 
(II) Typical Application Cases
In the construction of the containment steel lining at the CGN Guangdong Taipingling Nuclear Power Plant (China's first ecological nuclear power demonstration project), P265GH pressure pipelines (TC2 type) were selected. These pipelines needed to withstand temperatures of 350℃ and pressures of 4MPa. Through 100% ultrasonic and radiographic testing, the welded joint tensile strength reached 450MPa, meeting nuclear safety requirements. The project won the first prize in the 2023 National Excellent Welding Engineering Awards.
 
VII. Professionalism Creates Quality, Service Creates Value! We strictly adhere to the EN10216-2 standard, establishing a comprehensive quality control system from billet screening to finished product inspection. Equipped with globally advanced non-destructive testing equipment, we achieve 100% defect screening at the TC2 level. Each batch of products comes with a 3.2-level quality certificate, clearly indicating chemical composition, mechanical properties, and test results. We can customize TC1/TC2 type steel pipes according to project requirements, providing value-added services such as cutting, beveling, and anti-corrosion coating, safeguarding engineering projects in power plants, petrochemicals, nuclear power, and other fields.