All You Need to Know About SA 387 Grade 22 Class 2

2026-06-19 | More News

1. What is SA387 Grade 22 Class 2 Plate?

SA387 Grade 22 Class 2 is a chromium-molybdenum (2.25Cr-1Mo) alloy steel plate standardized under ASTM A387 / ASME SA387 — the globally recognized specification for alloy steel pressure vessel plates intended for elevated-temperature service. It falls under the Class 2 strength level, delivered in normalized and tempered (N+T) heat treatment conditions to deliver higher mechanical performance than Class 1.

As a boiler-quality (BQ) pressure vessel steel, it is engineered for long-term operation under high pressure and high temperature (HPHT) conditions, with verified creep resistance and hydrogen attack compatibility per API 941 Nelson Curve guidelines. It is one of the most widely specified Cr-Mo grades for critical refining and power generation equipment.

2. Chemical Composition of SA387 Gr22 CL2

The precise alloying balance of chromium and molybdenum defines the material’s high-temperature performance. Below are the mandatory melt analysis ranges per the SA387 standard, with product analysis tolerances for finished plate verification.

Element	Heat Analysis (wt.%)	Product Analysis (wt.%)	Core Metallurgical Function
Carbon (C)	0.05 – 0.15	0.04 – 0.15	Matrix strength and hardenability control
Manganese (Mn)	0.30 – 0.60	0.25 – 0.66	Deoxidation and tensile strength enhancement
Silicon (Si)	≤ 0.50	≤ 0.50	Deoxidation and high-temperature oxidation resistance
Phosphorus (P)	≤ 0.035	≤ 0.035	Impurity, limited to preserve low-temperature toughness
Sulfur (S)	≤ 0.035	≤ 0.035	Impurities limited to improve weldability and reduce hot cracking risk
Chromium (Cr)	2.00 – 2.50	1.88 – 2.62	High-temperature oxidation resistance and carbide stabilization
Molybdenum (Mo)	0.90 – 1.10	0.85 – 1.15	Creep strength improvement and high-temperature hydrogen attack resistance

3. SA387 Gr22 CL2 Mechanical Properties

Mechanical Property	Requirement for SA387 Gr22 CL2
Tensile Strength	515 – 690 MPa (75 – 100 ksi)
0.2% Offset Yield Strength, Minimum	310 MPa (45 ksi)
Elongation (50mm Gauge Length), Minimum	18%
Reduction of Area (Flat Specimen), Minimum	40%
Typical Brinell Hardness	163 – 220 HBW
Sour Service Hardness Limit	≤ 22 HRC (after PWHT)

Full property compliance is guaranteed for plate thickness ≤ 50mm. Heavy-gauge plates (50–150mm) follow supplementary through-thickness testing requirements.

4. Core Advantages of SA387 Gr22 CL2 steel

4.1 Creep & Strength Retention

At continuous operating temperatures up to 595°C (1100°F), the material maintains stable creep strength and structural integrity, with design allowable stress values defined in ASME BPVC Section II, Part D. Its 2.25Cr-1Mo alloy system resists microstructure degradation under long-term thermal loading, outperforming lower-grade Cr-Mo steels such as Grade 11.

4.2 Hydrogen Attack & Sour Service Resistance

Aligned with API 941 Nelson Curve limits, SA387 Gr22 CL2 exhibits excellent resistance to high-temperature hydrogen attack (HTHA) in hydroprocessing environments. With controlled hardness of ≤22 HRC and proper post-weld heat treatment, it is suitable for mild to moderate sour (H₂S) service per NACE MR0103 requirements, making it a standard for refinery hydrocracking reactors.

4.3 Fabrication & Weldability

The material supports standard pressure vessel fabrication processes, including flame cutting, cold forming, and submerged arc welding. Key fabrication requirements:

Preheating temperature: ≥150°C to avoid cold cracking
Recommended welding consumables: AWS A5.5 E8018-B2 (SMAW), AWS A5.23 flux-wire combinations (SAW)
Mandatory post-weld heat treatment (PWHT) at 675–705°C to restore toughness and relieve residual stress

4.4 Quality Assurance Requirements

Industrial-grade supply typically includes 100% ultrasonic examination (UT) per ASME SA435 / SA578 standards, with full Mill Test Reports (MTR) documenting chemistry, mechanical properties, heat treatment records, and NDE results.

5. Primary Industrial Applications of SA387 Gr22 CL2

SA387 Grade 22 Class 2 is specified for HPHT equipment across core industrial sectors:

Power Generation: Boiler steam drums, superheater headers, high-pressure steam piping in thermal and nuclear conventional islands
Petroleum Refining: Hydrocracker reactors, hydrodesulfurization (HDS) vessels, high-pressure separators, furnace tubes
Petrochemical: High-temperature process vessels, heat exchanger tube sheets, reactor shells for ammonia and methanol production
Oil & Gas: Sour service processing equipment, high-pressure wellhead components

6. Global Equivalent Grade Cross-Reference

Below are internationally standardized equivalent grades with matching 2.25 Cr-1M. o performance characteristics:

Standard System	Equivalent Grade
USA (ASTM/ASME)	A387 / SA387 Grade 22 Class 2
European (EN 10028-2)	10CrMo9-10
German (DIN 17155)	10CrMo9-10
British (BS 1501)	622-515B
French (AFNOR)	12CD9-10
Russian (GOST)	10Kh2M
Chinese (GB 713)	12Cr2Mo1R

We supply ASME SA387 Grade 22 Class 2 plates in standard mill dimensions and precision flame-cut custom profiles, with thickness ranging from 5 mm to 150mm. All plates are delivered with full EN 10204 3.1 Mill Test Reports and support supplementary ultrasonic inspection, NACE MR0103 sour service testing, and post-weld heat treatment guidance.

If you are sourcing 2.25Cr-1Mo steel plates for refinery, power boiler or petrochemical projects, you can reach out to our technical sales team for project-specific pricing, accurate lead times and free material specification verification.

Frequently Asked Questions

Q: What is the maximum service temperature of SA387 Grade 22 Class 2?

A: For long-term continuous service under creep design limits, the material is typically rated up to 595°C (1100°F). Short-term peak temperatures up to 600°C are acceptable under reduced stress conditions, per ASME pressure vessel code design tables.

Q: What is the difference between SA387 Grade 22 Class 1 and Class 2?

A: The two classes differ in mechanical strength and heat treatment requirements:

Class 1: 415–585 MPa tensile strength, ≥205 MPa yield strength, with optional heat treatment
Class 2: 515–690 MPa tensile strength, ≥310 MPa yield strength, mandatory normalized and tempered condition

Class 2 is specified for higher-pressure equipment, where higher strength allows thinner wall design.

Q: Is SA387 Gr22 CL2 suitable for high-temperature hydrogen service?

A: Yes. The 2.25Cr-1Mo composition is validated for high-temperature hydrogen service per API 941 Nelson Curve, making it the industry standard for hydroprocessing reactors operating under high hydrogen partial pressure.

Q: What is the standard supply thickness range for commercial plates?

A: Commercial supply typically covers 5mm to 150mm in thickness, with standard widths from 1000mm to 4500mm and lengths from 3000mm to 18000mm. Custom heavy-gauge and cut-to-size dimensions are available for project-specific requirements.