ASME SA387 Grade 11 Class 2 Steel Plate Specification

ASME SA387 Grade 11 Class 2 Steel Plate Specification

ASME SA387 Grade 11 Class 2 (ASTM A387 Grade 11 CL2) is a specification for chromium-molybdenum alloy steel plates intended for use in elevated temperature applications, commonly associated with pressure vessels and heat exchangers. Nominal chrome content at 1.00% to 1.50%, and Moly 0.45% to 0.65% for SA387 GRADE 11 material.

Key Properties:

Composition: ASME SA387 Grade 11 typically contains about 1% chromium and 0.5% molybdenum. This composition provides good strength and resistance to oxidation at high temperatures.

Mechanical Properties:

Yield Strength: Minimum of 205 MPa (30,000 psi)

Tensile Strength: Minimum of 415 MPa (60,000 psi)

Class 2: This classification indicates that the material has undergone additional heat treatment, enhancing its properties compared to Class 1, which may not have the same level of treatment. Class 2 is intended for applications requiring greater performance under higher stress and temperature conditions.

Applications:

ASME SA387 Grade 11 Class 2 is commonly used in:

Pressure vessels in the oil and gas industry

Boilers

Heat exchangers

Pipelines and other equipment operating at elevated temperatures

The higher content of chromium will provide excellent corrosion and oxidation resistance, so the material could be used for sour services, and to storage oil, gas, liquid for different industries.

Refered Standards for ASTM A387 Alloy Steel Plate

ASTM

A20/A20M: General requirements for pressure vessel plates.
A370: Test specification for mechanical properties of steel
A435/A435M: For straight-beam ultrasonic examination of steel plates
A577/A577M: For ultrasonic angle beam examination of steel plates
A578/A578M: For straight beam UT examination of rolled steel plates in special applications
A1017/A1017M: Specification for pressure vessle plates of alloy steel, chromium-molybdenum-tungsten

AWS Specification

A5.5/A5.5M: Low alloy steel electrodes for shield metal arc welding.
A5.23/A5.23M: Low alloy steel electrodes for fulxes for submerged arc welding.
A5.28/A5.28M: For gas shielded arc welding
A5.29/A5.29M: For flux cored arc welding.

SA387 Grade 11, 22 Chemical Composition

Except 21L, 22L and 91, each grade is available in two classes of tensile strength levels as defined in the tensile requirements tables. Grades 21L and 22L only has Class 1, and Grade 91 only has Class2.

Heat Treatment for ASME SA387 Grade 11 CL2

Chrome moly alloy steel plate under ASTM A387 shall be killed steel, with thermally treated either by annealing, normarlizing and tempering. Or in case agreed by buyer, accelerated cooling from the austenitizing temperature by air blasting or liquid quenching, followed by tempering, minimum tempering temperatures shall be as below table:

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1. What is SA387 Grade 11 Class 2?
SA387 Grade 11 Class 2 is a normalized and tempered chromium-molybdenum (1¼Cr-½Mo) alloy steel plate designed for high-temperature pressure vessels, offering higher strength than Class 1 while maintaining good weldability and creep resistance in refinery service.

2. What are the mechanical properties of SA387 Grade 11 Class 2?
In its normalized and tempered condition, SA387 Grade 11 Class 2 provides a tensile strength of 485–620 MPa (70–90 ksi) and a minimum yield strength of 275 MPa (40 ksi), making it suitable for high-stress, elevated-temperature designs.

3. How does SA387 Grade 11 Class 2 differ from Class 1?
Class 2 is normalized and tempered for higher as-supplied strength, while Class 1 is annealed for maximum formability; both share the same chemical composition but are selected based on fabrication needs and design stress requirements.

4. What is the maximum service temperature for SA387 Grade 11 Class 2?
SA387 Grade 11 Class 2 is typically used in continuous service up to about 595 °C (1100 °F), where its chromium and molybdenum content provides effective resistance to oxidation and hydrogen attack.

5. What are common applications for SA387 Grade 11 Class 2 plates?
This grade is widely used in hydrotreaters, hydrocrackers, heat exchangers, and other high-temperature pressure vessels in petrochemical refineries and power-generation facilities.

6. What welding procedures are required for SA387 Grade 11 Class 2?
Welding requires low-hydrogen electrodes, preheating (150–205 °C / 300–400 °F), and mandatory post-weld heat treatment (PWHT) around 620–690 °C (1150–1275 °F) to prevent cracking and restore corrosion resistance.

7. What is the equivalent European grade for SA387 Grade 11 Class 2?
The closest European equivalent is 13CrMo4-5 (1.7335) under EN 10028-2, which has similar composition and is commonly supplied in a normalized and tempered condition.

8. How does SA387 Grade 11 Class 2 compare to Grade 22?
Grade 11 (1.25Cr-0.5Mo) offers lower high-temperature strength and hydrogen resistance than Grade 22 (2.25Cr-1Mo), making it a cost-effective choice for moderate‑severity service in refining and chemical processes.

9. What are the Charpy impact requirements for SA387 Grade 11 Class 2?
Charpy V‑notch impact testing is often specified by purchasers; common requirements are 20 J (15 ft‑lb) minimum average at temperatures between +10 °F and –20 °F (–12 °C to –29 °C) for pressure‑vessel applications.

10. What is the difference between SA387 Grade 11 Class 2 and AISI 4130?
While both are Cr‑Mo steels, SA387 Grade 11 Class 2 is a plate product for code pressure vessels with strict toughness and testing rules, whereas AISI 4130 is a general‑purpose structural/bar alloy with different property ranges and applications.

Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.