ASME SA-543/SA-543M

SA543 Type B Class 2 Pressure Vessel Steel Plate Product-Performance

Technical Datasheet

Nickel-chromium-molybdenum (Ni-Cr-Mo) quenched and tempered pressure vessel steel plate, with high strength and excellent toughness. Suitable for demanding pressure vessel applications requiring high strength and good low-temperature toughness.

1. SA543 Type B Class 2 Material Identification & ASTM ASME Standards

Standards

  • ASTM A543 / ASME SA543
  • ASTM A20/A20M (General Requirements)
  • ASME BPVC Section II Part A

Alloy Type

Ni-Cr-Mo

Grade Classification

  • SA543 Type B Class 1 (lower strength)
  • SA543 Type B Class 2 (medium strength) ← This Spec
  • SA543 Type B Class 3 (higher strength)
  • SA543 Type A (lower Ni)

2. SA543 Type B Class 2 Chemical Composition & Ladle Analysis Requirements

2.1 SA543 Type B Class 2 Chemical Composition Limits

Table 2.1: SA543 Type B Class 2 Chemical Composition Requirements (ASTM A543/ASME SA543 Mass Percent)
Element Smelting Analysis Finished Product Analysis
C, ≤ 0.20 0.20
Mn, ≤ 0.40 0.40
Si 0.15-0.40 0.13-0.45
S, ≤ 0.020 0.020
P, ≤ 0.020 0.020
Cr 1.00-1.90 0.94-1.96
Mo 0.20-0.65 0.16-0.69
Ni 2.25-4.00 2.18-4.07
V, ≤ 0.03 0.03
B ...
Ti ...
Cu ...
Nb ...
Ca ...
Zr ...
Others ...

Carbon Equivalent (CE)

CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15

Typical value: 0.55-0.75 (depending on actual composition)

Note: Ni-Cr-Mo steel requires controlled welding procedures due to high hardenability; low hydrogen practice is mandatory

3. SA543 Type B Class 2 Mechanical Properties & Tensile Strength Specification

3.1 SA543 Type B Class 2 Tensile Properties

Property Standard Value Test Method Remarks
Tensile Strength Rm 795-930 MPa ASTM A370 Transverse specimen
Yield Strength ReH >=690 MPa ASTM A370 Upper yield strength
Elongation A (2in./50mm) >=14% ASTM A370 Per A20/A20M
Charpy Impact KV₂ ... — By agreement

3.2 Charpy Impact Test Requirements for SA543 Type B Class 2

Standard Grade

Impact testing not required by standard

High Strength Service

Low Temperature Service

  • Impact testing by agreement
  • Ni-Cr-Mo provides excellent low-temperature toughness
  • Typical test temperature: -40°C to -60°C
By Agreement

3.3 SA543 Type B Class 2 Hardness & Brinell Hardness Limits

  • As-supplied condition (quenched + tempered): Typically ≤270 HBW
  • NACE service environment: Weld & HAZ ≤250 HV10

4. SA543 Type B Class 2 Quenched + Tempered: Heat Treatment Guide

1

As-Rolled (AR)

Not applicable for SA543

High hardenability requires Q+T

→
2

Quenched + Tempered (Q+T)

Austenitizing: 845-915°C

Quench: Water or Oil

Tempering: 620-705°C

→
3

Simulated PWHT (SPWHT)

620-705°C × 2-4h

For property verification

Critical Control Points:
  • SA543 must be supplied in quenched + tempered condition
  • Austenitizing temperature: 845-915°C, quench in water or oil
  • Tempering temperature: 620-705°C, air cool
  • Tempering temperature must be carefully controlled to achieve required strength and toughness balance

5. SA543 Type B Class 2 Welding Procedure Specification (WPS/PQR)

5.1 SA543 Type B Class 2 Welding Procedure Specification WPS

SMAW (Shielded Metal Arc) SAW (Submerged Arc) GTAW (Gas Tungsten Arc) FCAW (Flux Cored)

5.2 SA543 Type B Class 2 Preheat & Interpass Temperature Chart

Thickness Range Min Preheat Temp Recommended Preheat Max Interpass Temp
<=13mm 150°C 150-200°C 200-250°C
>13-38mm 150°C 150-200°C
>38mm 150°C 175-225°C

5.3 Recommended Welding Consumables for SA543 Type B Class 2

Process AWS Classification Strength Match Hydrogen Control
SMAW E12018-M, E12018-M-H4 120 ksi Low Hydrogen (H4)
GTAW ER120S-G 120 ksi Shielding: Ar
FCAW E120T5-K4 120 ksi Self/ Gas Shielded
SAW F12A4-EG, F12P4-EG 120 ksi Flux bake 300°C*2h

5.4 SA543 Type B Class 2 PWHT Requirements & Post Weld Heat Treatment

Temperature Range 620-705°C
Holding Time 1h/25mm thickness (min 30min)
Heating Rate <=150°C/h
Cooling Rate <=150°C/h (to 300°C)
PWHT Notes:
  • PWHT is mandatory for SA543 steel to achieve required mechanical properties
  • Tempering temperature must be carefully controlled to avoid over-tempering
  • Cooling rate should be controlled to prevent residual stresses

6. SA543 Type B Class 2 High Strength Service & Toughness

6.1 SA543 Type B Class 2 Service Properties

Service Capability

  • Very high strength (yield ≥690 MPa)
  • Excellent low-temperature toughness
  • Good resistance to brittle fracture
  • Suitable for demanding pressure vessel applications

Applications

  • Ultra-high-strength pressure vessels
  • Nuclear reactor vessels
  • Large-diameter storage tanks
  • Offshore structures

6.2 SA543 Type B Class 2 Temperature Limitations

SA543 Type B Class 2 is suitable for high strength applications:

  • Recommended maximum service temperature: 400°C
  • Excellent low-temperature toughness
  • For high temperature service, consider Cr-Mo grades (SA387 series)

7. SA543 Type B Class 2 Inspection & NDT Testing Methods

7.1 Non-Destructive Testing

UT ASTM A578/A578M Level C (Most Strict)
MT ASTM A275/A275M Surface Crack Detection
PT ASTM A165 Surface Open Defects
RT ASME V Article 2 Weld Internal Quality

7.2 Specimen Orientation & Location

Transverse (T)

Preferred for tensile & impact

Reflects transverse properties

Longitudinal (L)

Only when width insufficient

Higher strength, lower toughness

Thickness Position

1/4T or 1/2T

Represents worst location

7.3 Retest Procedures

  • Tensile failure: Double retest from same plate; plate acceptable if both pass
  • Impact failure: Additional 3 sets (9 specimens) from same plate; average must meet requirement with individual values >=70% of specified
  • UT failure: Defect removal and re-inspection or rejection

8. SA543 Type B Class 2 Physical Properties & Thermal Conductivity

Density

7.85

g/cm3 (20°C)

Melting Point

~1510

°C

Thermal Conductivity

35-40

W/(m*K) (20-100°C)

Linear Expansion

11.5

*10-6/°C (20-300°C)

Specific Heat

460-500

J/(kg*K) (20°C)

Elastic Modulus

200-210

GPa (20°C)

9. SA543 Type B Class 2 Dimensions & Thickness Tolerance ASTM A20

9.1 Available Dimensions

Thickness 6-200 mm (Standard 6-100mm)
Width 1500-4350 mm
Length 3000-27000 mm
Unit Weight Max 60 MT

9.2 Thickness Tolerances (ASTM A20)

Nominal Thickness Class A (Unrestricted) Class B (Restricted)
6-25mm +1.20mm, -0.30mm +/-0.60mm
>25-50mm +1.50mm, -0.30mm +/-0.80mm
>50-100mm +2.40mm, -0.30mm +/-1.20mm

10. SA543 Type B Class 2 Mill Test Certificate & EN 10204 3.2 Documentation

EN 10204 3.1

Manufacturer Test Certificate

Based on non-specific inspection

EN 10204 3.2

Third Party Inspection Certificate

Witnessed by customer or third party

ASME Data Report

Form CM-1

For ASME stamped equipment

Mill Test Certificate must include:

  • ✓Heat number, plate number, batch traceability
  • ✓Chemical composition (ladle + product analysis)
  • ✓Mechanical properties (tensile, impact)
  • ✓Heat treatment records (temperature-time curves)
  • ✓NDT reports (UT/MT etc.)
  • ✓Dimensional inspection records

11. SA543 Type B Class 2 Equivalent Grades: Ni-Cr-Mo Steel Comparison

Grade Standard Country Yield
MPa		 Tensile
MPa		 Ni Content
%		 Key Differences
SA543 Type B Class 2 ASME USA >=690 795-930 2.25-4.00 ASME BPVC, very high strength Ni-Cr-Mo steel
SA543 Type B Class 3 ASME USA >=485 620-795 2.25-4.00 Lower strength, same composition
SA543 Type B Class 1 ASME USA >=345 485-620 2.25-4.00 Lowest strength, same composition
SA543 Type A ASME USA >=485 620-795 0.50-1.00 Lower Ni content, different composition
High Strength Service Notes:
  • SA543 Type B Class 2: Very high strength, yield ≥690 MPa
  • SA543 Type B Class 3: High strength, yield ≥485 MPa
  • SA543 Type B Class 1: Medium strength, yield ≥345 MPa
  • SA543 Type A: Lower Ni content (0.50-1.00%), different composition
  • Ni-Cr-Mo steel requires controlled heat treatment and welding procedures

Warning: Equivalent grades are approximate. Project-specific Gap Analysis and PQR qualification required. High strength and toughness are critical for demanding pressure vessel design.

12. SA543 Type B Class 2 Design Considerations & Fabrication Guidelines

Design Considerations

  • Very high strength: SA543 Type B Class 2 suitable for demanding pressure vessel applications
  • Low temperature toughness: Excellent resistance to brittle fracture
  • Thickness effect: As plate thickness increases, strength and toughness decrease; allowable design stress must be interpolated per ASME II-D Table 1A

Fabrication Considerations

  • Cold forming: Limited formability due to very high strength; bend radius recommended >=5t (t=plate thickness)
  • Hot forming: Forming temperature 845-915°C, re-quenching and tempering required after forming
  • Machining: Good machinability in quenched and tempered condition
  • Welding: Requires controlled procedures, preheat, and PWHT

Common Failure Mode Prevention

  • Hydrogen-induced cold cracking: Strict low-hydrogen practice, control diffusible hydrogen <=5 mL/100g
  • Reheat cracking: Careful control of PWHT temperature and time
  • Temper embrittlement: Avoid prolonged exposure to 350-550°C range

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