SA724GrA SA724GrB SA724GrC SA-724/SA-724M-2023 | Carbon-Manganese-Silicon Steel Plates | Quenched and Tempered | Welded Pressure Vessels

1. Scope

1.1 This specification covers three grades of carbon-manganese-silicon steel, designated Grade A, B, and C. Grade C may be produced with a boron addition. The plates are quenched and tempered and are intended for welded layered pressure vessels.

1.2 The maximum thickness of plates supplied under this specification is limited only by the capability of the chemical composition to meet the specified mechanical requirements. However, current practice normally limits the maximum thickness to 7/8 in. [22 mm] for Grades A and B, and to 2 in. [50 mm] for Grade C.

1.3 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.

2. Referenced Documents

2.1 ASTM Standards:

A20/A20M Specification for General Requirements for Steel Plates for Pressure Vessels

3. General Requirements and Ordering Information

3.1 Material supplied to this material specification shall conform to Specification A20/A20M. These requirements outline the testing and retesting methods and procedures, permitted variations in dimensions and weight, quality and repair of defects, marking, loading, and ordering information.

3.2 In addition to the basic requirements of this specification, certain supplementary requirements are available when additional control, testing, or examination is required to meet end use requirements. The purchaser is referred to the listed supplementary requirements in this specification and to the detailed requirements in Specification A20/A20M.

3.3 If the requirements of this specification are in conflict with the requirements of Specification A20/A20M, the requirements of this specification shall prevail.

4. Manufacture

4.1 Steelmaking Practice—The steel shall be killed and shall conform to the fine austenitic grain size requirement of Specification A20/A20M.

5. Heat Treatment

5.1 All plates shall be quenched from a temperature in the range from 1600 to 1700°F (870 to 925°C). Grade A and B shall then be tempered at not less than 1100°F (595°C). Grade C shall be tempered at a temperature not less than 1150°F (620°C). The tempering soaking time shall be not less than ½ hour.

6. Chemical Requirements

6.1 The steel shall conform to the requirements as to chemical composition prescribed in Table 1.

TABLE 1 CHEMICAL REQUIREMENTS
Element	Composition, %
Element	Grade A	Grade B	Grade C
Carbon, max:
Heat analysis	0.18	0.20	0.22
Product analysis	0.22	0.24	0.26
Manganese:
Heat analysis	1.00–1.60	1.00–1.60	1.10–1.60
Product analysis	0.92–1.72	0.92–1.72	1.02–1.72
Phosphorus, max^A	0.025	0.025	0.025
Sulfur, max^A	0.025	0.025	0.025
Silicon, max:
Heat analysis	0.55	0.50	0.20–0.25
Product analysis	0.60	0.55	0.18–0.25
Copper, max:^B
Heat analysis	0.35	0.35	0.35
Product analysis	0.38	0.38	0.38
Nickel, max:^B
Heat analysis	0.25	0.25	0.25
Product analysis	0.28	0.28	0.28
Chromium, max:^B
Heat analysis	0.25	0.25	0.25
Product analysis	0.29	0.29	0.29
Molybdenum, max:^B
Heat analysis	0.08	0.08	0.08
Product analysis	0.09	0.09	0.09
Vanadium, max:^B
Heat analysis	0.08	0.08	0.08
Product analysis	0.09	0.09	0.09
Boron, max	...	...	0.005^C
^A Applies to both heat and product analyses. ^B When analysis shows that the amount of an element is 0.02% or lower, the value may be reported as ＜0.02%. ^C If boron is less than 0.001 %, the analysis report for the element may be stated as "＜0.001." NOTE1-Where "..." appears in this table, there is no requirement.

7. Mechanical Requirements

7.1 Tension Test Requirements

7.1.1 The material as represented by the tension test specimens shall conform to the requirements given in Table 2.

TABLE 2 Tensile Requirements
Property	Grade A	Grade B	Grade C
Tensile strength, min, ksi [MPa]	90-110 [620-760]	95-115 [655-795]	90-110 [620-760]
Yield strength, min, ksi [MPa]	70 [485]	75 [515]	70 [485]
Elongation in 2 in. [50 mm], min, %^A,B	19	17	19
^A See Specification A 20/A 20M for elongation requirement adjustment. ^B See 7.1.2..

7.1.2 For nominal plate thicknesses of ¾ in. [20 mm] and under, the 1-½ in. [40 mm] wide rectangular specimen may be used for the tension test, and the elongation may be determined in a 2 in. [50 mm] gage length that includes the fracture and shows the greatest elongation.

8. Keywords

8.1 alloy steel; alloy steel plate; pressure containing parts; pressure vessel steels; steel plates; steel plates for pressure vessels

SUPPLEMENTARY REQUIREMENTS

Supplementary requirements shall not apply unless specified in the order.

A list of standardized supplementary requirements for use at the option of the purchaser are included in Specification A20/A20M. Several of those considered suitable for use with this specification are listed below by title. Other tests may be performed by agreement between the supplier and the purchaser.