ASTM A387 plate is chromium-molybedenum alloy steel plate intented primarily for welded boilers and pressure vessles designed for elevated temperature serivce.
Chrome moly plate under ASTM A387 in serveral grades that has different alloy contents as below, common use grades are Gr 11, 22, 5, 9 and 91.
Nominal Chromium Content, %
Nominal Molybdenum Content, %
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.
Refered Standards for ASTM A387 Alloy Steel Plate
- 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
- 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.
A387 Chrom Moly Plate Data Sheet
Table 1: For A387 Gr 11, 22, 5, 9, 91 Chrome Alloy Steel Plate
Table 2: For A387 Class 1 Chrome Alloy Steel Plates:
Table 3: For A387 Class 2 Alloy Steel Plates:
Heat Treatment for A387 Chrom Moly Alloy Steel Plate
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:
Temperature, °F [°C]
2, 12 and 11
22, 22L, 21, 21L and 9
Grade 91 alloy steel plates shall be heat treated by normalizing and tempering or by accelerated cooling by air blasting or liquid quenching, followed by tempering. Grade 91 plates need to be austenitized at 1900 to 1975°F [1040 to 1080°C] and shall be tempered at 1350 to 1470°F [730 to 800°C]
Grade 5, 9, 21, 21L, 22, 22L, and 91 plates ordered without heat treatment by above table, shall be finished in either the stress relieved or annealed condition.