ASTM A387 Grade 12 Class 2 Pressure Vessel Steel PLATE

ASTM A387 Grade 12 Class 2 Pressure Vessel Steel PLATE

1.Chrome Moly Plate Home Page

ASTM A387

ASTM A387 Grade 5 Class 2 | ASTM A387 Grade 9 Class 2 | ASTM A387 Grade 11 Class 2

ASTM A387 Grade 12 Class 2 | ASTM A387 Grade 22 Class 2 | ASTM A387 Grade 91 Class 2

2.A387 Grade 12 Class 2 is a high quality chrome molybdenum steel which is ideal for elevated temperature service and offers excellent anti corrosion characteristics.

3.The steel has a wide range of uses including industrial boilers and pressure vessels, especially in environments where high temperature levels are common.

4.Equivalents of ASTM A387 Grade 12 Class 2

5.Specifications of ASTM A387 Grade 12 Class 2

Chromium & Molybdenum content (according to the ASTM specification):

6.Tensile Requirements for Class 2 Plates 

7.Chemical Requirements  of ASTM A387 Grade 12 Class 2

8.Tension Test Requirements:

We shall be tested using a test specimen will confirm to the tensile requirements as outlined in Table 2.

9.Other requirements:

The following requirements and testing procedures (which are not mandatory) are considered suitable for Chrome Molybdenum steel:

Vacuum treatment

Product Analysis

Additional Tension Test

Charpy V-Notch Impact Test

Drop Weight Test

High Temperature Tension Test

Ultrasonic Examination

Magnetic Particle Examination

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1. What is the typical post-weld heat treatment (PWHT) temperature and hold time for A387 Gr.12 Cl.2?
For A387 Grade 12 Class 2, the typical recommended Post-Weld Heat Treatment (PWHT or stress relief) temperature range is 1100°F to 1250°F (595°C to 675°C). The holding time is usually a minimum of 1 hour per inch (25 mm) of thickness, with a common minimum of 1 hour total. This process is critical to relieve welding stresses, temper the heat-affected zone (HAZ), and restore corrosion resistance, ensuring the integrity of the fabricated pressure vessel component.

2. Why is preheating mandatory before welding A387 Gr.12 Cl.2 steel?
Preheating, typically in the range of 300°F to 450°F (150°C to 230°C), is mandatory for welding A387 Grade 12 Class 2 to prevent hydrogen-induced cracking (HIC), also known as cold cracking. This alloy's hardenability can lead to a brittle microstructure in the weld zone upon rapid cooling. Preheating slows the cooling rate, allowing hydrogen to diffuse out and reducing the risk of forming crack-susceptible martensite, thereby ensuring a sound, defect-free weld.

3. What is the maximum continuous service temperature for A387 Gr.12 Cl.2 plates?
The maximum recommended continuous service temperature for ASTM A387 Grade 12 Class 2 plates is generally up to 1000°F (540°C). At this elevated temperature range, the chromium content provides improved resistance to oxidation (scaling) and corrosion, while the molybdenum enhances strength and reduces creep. For service above this temperature, grades with higher chromium content (like Grade 11 or 22) are typically considered.

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.