ASTM A387 is the standard specification for pressure vessel plates, alloy steel, chromium-molybdenum. These Cr-Mo alloy steel plates are primarily manufactured for welded boilers and pressure vessels for elevated temperature service. Plates under this standard Hebei Metals supplies include ASTM A387 Grades 2, Grade 12, Grade 11, Grade 22, Grade 22L, Grade 21, Grade 21L, Grade 5, Grade 9, Grade 91. Each grade except Grades 21L, 22L, and 91 is available in two classes of tensile strength levels. Grade 21L and 22L are available only as Class 1 while Grade 91 is available only as Class 2. All of the plates on our inventory are sourced from several of China’s most reputed steel mills: Baosteel, Wuyang Steel, HBIS, and TISCO, etc.

1. Chemical Composition & UNS Designation

Chemical Composition of ASTM A387 Alloy Steel Plates, %
Grade	UNS	C	Mn	P	S	Si	Cr	Mo	Others
Grade 2	S50460	0.04-0.21	0.50-0.88	0.025	0.025	0.13-0.45	0.46-0.85	0.40-0.65	-
Grade 12	K11757	0.04-0.17	0.35-0.73	0.025	0.025	0.13-0.45	0.74-1.21	0.40-0.65	-
Grade 11	K11789	0.04-0.17	0.35-0.73	0.025	0.025	0.44-0.86	0.94-1.56	0.40-0.70	-
Grade 22	K21590	0.04-0.15	0.25-0.66	0.025	0.025	≤0.50	1.88-2.62	0.85-1.15	-
Grade 22L	K21590	≤0.12	0.25-0.66	0.025	0.025	≤0.50	1.88-2.62	0.85-1.15	-
Grade 21	K31545	0.04-0.15	0.25-0.66	0.025	0.025	≤0.50	2.63-3.37	0.85-1.15	-
Grade 21L	K31545	0.12	0.25-0.66	0.025	0.025	≤0.50	2.63-3.37	0.85-1.15	-
Grade 5	S50200	≤0.15	0.25-0.66	0.025	0.025	≤0.55	3.90-6.10	0.40-0.70	-
Grade 9	K90941	≤0.15	0.25-0.66	0.025	0.025	≤1.05	7.90-10.10	0.85-1.15	*A
Grade 91	K90901	0.06-0.15	0.25-0.66	0.025	0.012	0.18-0.56	7.90-9.60	0.80-1.10	*B

*All values are minimum unless a range is provided or otherwise specified and shall be based on product analysis.
*A – V:≤0.05; B – Ni:≤0.43,V:0.16-0.27,Co:0.05-0.11,N:0.025-0.080,Al:≤0.02,Ti≤0.01,Zr≤0.01.
*All values in both *A & *B shall be furnished with the unit “%”.

2. Mechanical Properties

Mechanical Properties of ASTM A387 Alloy Steel
Grade	Tensile Strength, ksi[MPa]	Yield Strength, min. ksi[MPa]	Elongation, min. %		Reduction of area, min, %
			8 inch	2 inch
Grade 2 CL 1	55-80[380-550]	33[230]	18	22	-
Grade 2 CL 2	70-90[485-620]	45[310]	18	22	-
Grade 12 CL 1	55-80[380-550]	33[230]	18	22	-
Grade 12 CL 2	65-85[450-585]	40[275]	19	22	-
Grade 11 CL1	60-85[415-585]	35[240]	19	22	-
Grade 11 CL2	75-100[515-690]	45[310]	18	22	-
Grade 22 CL1	60-85[415-585]	30[205]	-	18	45*A
Grade 22 CL2	75-100[515-690]	45[310]	-	18	45*A
Grade 22L CL1	60-85[415-585]	30[205]	-	18	45*A
Grade 21 CL1	60-85[415-585]	30[205]	-	18	45*A
Grade 21 CL2	75-100[515-690]	45[310]	-	18	45*A
Grade 21L CL1	60-85[415-585]	30[205]	-	18	45*A
Grade 5 CL1	60-85[415-585]	30[205]	-	18	45*A
Grade 5 CL2	75-100[515-690]	45[310]	-	18	45*A
Grade 9 CL1	60-85[415-585]	30[205]	-	18	45*A
Grade 9 CL2	75-100[515-690]	45[310]	-	18	45*A
Grade 91 CL2	85-110[585-760]	60[415]	-	18	-

*A denotes that the value is measured on round test specimen. In the case of flat specimen, the value shall be 40.

3. Heat Treatment

1. Except for Grade 91, all ASTM A387 plates shall be thermally treated either by annealing, normalizing and tempering, or, when permitted by the purchaser, accelerated cooling from the austenitizing temperature by air blasting or liquid quenching, followed by tempering. The minimum tempering temperatures for grades (2, 12 & 11), grades(22, 22L, 21, 21L & 9), grades 5 are respectively 1150°F[620°C], 1250°F[675°C], 1300°[705°C].
2. Grade 91 plates shall be thermally treated, either by normalizing and tempering or by accelerated cooling from the austenitizing temperature by air blasting or liquid quenching, followed by tempering. Grade 91 plates shall be austenitized at 1900 to 1975°F [1040 to 1080°C] and shall be tempered at 1350 to 1470°F [730 to 800°C].

4. Inspection and Tests

The inspection and tests that shall be alternately performed on ASTM A387 alloy steel plates include: tension test, Charpy V-Notch impact test, drop weight test, high-temperature tension test, ultrasonic examination, magnetic particles examination.

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