ASME SA-387/ ASTM A387 Gr. 11 Pressure Vessel Plates

The pressure vessel plates made of ASTM A387 Grade 11 (identical with ASME SA-387 Gr. 11) are chromium-molybdenum alloy steel plates intended primarily for welded boilers and pressure vessels designed for elevated temperature service. There are two classes available according to tensile strength levels: Class 1 and Class 2. The ASME SA-387/ ASTM A387 Gr.11 steel has the nominal composition of 1.25Cr-0.5Mo-Si with UNS designation number of K11789 and P number of 4.

Manufacture & Heat Treatment

The ASME SA-387/ ASTM A387 Gr.11 plates shall be made by a killed process. Three types of heat treatment may be furnished: (1) annealing; (2) normalizing and tempering; (3) when permitted by the purchaser, quenching and tempering. The tempering temperature shall be no less than 620°C [1150°C]. The “quenching” means accelerated cooling from the austenitizing temperature by air blasting or liquid quenching.

Chemical Composition Requirements

Element	Heat Analysis	Product Analysis
C	0.05-0.17	0.04-0.17
Mn	0.40-0.65	0.35-0.73
P	≤0.025	≤0.025
S	≤0.025	≤0.025
Si	0.50-0.80	0.44-0.86
Cr	1.00-1.50	0.94-1.56
Mo	0.45-0.65	0.40-0.70

*All composition values are in %.

Tensile Requirements

ASME SA-387/ ASTM A387 Grade 11 Class 1
Tensile Strength MPa [ksi]	415-585 [60-85]
Yield Strength MPa [ksi], min.	240 [35]
Elongation in 8", min. %	19
Elongation in 2", min. %	22
Reduction of area, min. %	-

*Class 1 plates of ASTM A387 Gr. 11 may be furnished in all types of heat treatment.

ASME SA-387/ ASTM A387 Grade 11 Class 2
Tensile Strength MPa [ksi]	450-585 [65-85]
Yield Strength MPa [ksi], min.	275 [40]
Elongation in 8", min. %	19
Elongation in 2", min. %	22
Reduction of area, min. %	-

*Class 2 plates of ASTM A387 Gr. 11 shall be furnished in heat treatment other than annealing.

ASME Codes Applicability & Maximum Use Temperatures

Code	Maxi. Use Temp. for Class 1 & 2
I	649
III Cl. 2 & 3	371
VIII Div. 1	649
III-1 Cl. 1 & MC	371
III-3 Cl. TC & SC	371
VIII-2 Cl. 1	482
VIII-2	649

Both Class 1 and Class 2 of ASME SA-387/ ASTM A387 Gr. 11 plates are permitted for use in ASME Boiler & Pressure Vessel Code Section I, III, and VIII, respectively. The maximum use temperature limits for different Construction Codes are listed in the table above.

Maximum Allowable Stresses

Temp.	S
40	118
65	118
100	118
125	118
150	118
200	118
250	118
300	118
325	118
350	118
375	118
400	118
425	116
450	114
475	101
500	72.9
525	51.7
550	36.5
575	25.2
600	17.6
625	12.4
650	8.08

*Maximum allowable stress values, S, MPa, for metal temperature, °C, not exceeding. For Class 1 of ASME SA-387 Gr. 11 plates used for Section I; III Cl. 2 & 3; and VIII-1.

Temp.	S
40	148
65	148
100	148
125	148
150	148
200	148
250	148
300	148
325	148
350	148
375	148
400	148
425	148
450	143
475	107
500	72.9
525	52.3
550	36.3
575	25.2
600	17.6
625	12.4
650	8.08

*Maximum allowable stress values, S, MPa, for metal temperature, °C, not exceeding. For Class 2 of ASME SA-387 Gr. 11 plates used for Section I; III Cl. 2 & 3; and VIII-1.

Temp.	S
40	161
65	153
100	148
125	144
150	141
175	138
200	136
225	134
250	131
275	129
300	127
325	125
350	123
375	121
400	119
425	116
450	113
475	106
500	73.7
525	52.0
550	36.3
575	25.2
600	17.6
625	12.3
650	8.12

*Maximum allowable stress values, S, MPa, for metal temperature, °C, not exceeding. For Class 1 of ASME SA-387 Gr. 11 plates used for Section VIII, Division 2.

Temp.	S
40	207
65	197
100	190
125	185
150	181
175	178
200	175
225	172
250	169
275	166
300	164
325	161
350	159
375	156
400	153
425	149
450	146
475	105
500	73.7
525	52.0
550	36.3
575	25.2
600	17.6
625	12.3
650	8.12

*Maximum allowable stress values, S, MPa, for metal temperature, °C, not exceeding. For Class 2 of ASME SA-387 Gr. 11 plates used for Section VIII, Division 2.

Design Stress Intensity

Temp.	Sm
40	138
65	138
100	138
125	138
150	138
200	135
250	131
300	127
325	126
350	123
375	121
400	118
425	116
450	114
475	106
500	97.1

*Design stress intensity, S_m, MPa, for metal temperature, °C, not exceeding. For Class 1 of ASME SA-387 Gr. 11 plates used for Section III-1, Cl. 1 & MC; III-3 Cl. TC & SC; VIII-2, Cl. 1.

Temp.	Sm
40	172
65	172
100	172
125	172
150	172
200	172
250	169
300	164
325	161
350	158
375	155
400	153
425	149
450	142
475	119
500	91.4

*Design stress intensity, S_m, MPa, for metal temperature, °C, not exceeding. For Class 2 of ASME SA-387 Gr. 11 plates used for Section III-1, Cl. 1 & MC; III-3 Cl. TC & SC; VIII-2, Cl. 1.