ASME SA542 Type B Class 4a Steel Plate | SA542 Type B Cl.4a QT Cr-Mo Vessel Plate

ASME SA542 Type B Class 4a, also written ASME SA542 TYPE B CL.4A, is quenched-and-tempered 2.25Cr-1Mo alloy plate under ASME SA-542/SA-542M. The specification covers Type A, B, C, D and E, and Class 1, 2, 3, 4 and 4a. Type B is the same 2.25Cr-1Mo idea as Type A, with tighter limits on carbon, phosphorus, sulfur, copper, nickel and vanadium. Class 4a shares the 585–760 MPa tensile band with Class 4, but yield is 415 MPa and elongation is 18%. Temper floor for Class 4a is 675 °C on Type A, B, C, D and E. That is the Class buyers most often mix with SA832 22V and with SA387 Grade 22 Class 2. SHH STEEL is the supplier, exporter and distributor of this Type and Class. Plate is produced to ASME SA-542/SA-542M.

Buyers write ASME SA542 Type B Class 4a, ASME SA542 TYPE B CL.4A, SA542 Type B Class 4a, SA542 Type B Cl.4a, SA542B CL4A, SA-542 Type B Class 4a and SA 542 Type B Cl 4a. ASTM A542 Type B Class 4a is the companion product spec. A purchase order that only says “SA542 Type B” is incomplete. A purchase order that writes Class 4 when the drawing says Class 4a is the wrong yield and the wrong temper floor.

This page is not SA832 22V. SA832 is normalized-and-tempered Cr-Mo-V. It is not SA517 Grade B. It is not SA537 Class 2. It is not ASME SA516 carbon plate. Minimum thickness in the specification is about 5 mm. Maximum thickness is limited by the ability of the heat to meet Class 4a after quench and temper.

Dual marking SA542 / A542 Type B Class 4a is available from SHH STEEL as mill supplier. Certificates can be EN 10204 3.1 or 3.2. Company scope: China steel Mill Agent-SHH STEEL.

This plate sits in the pressure vessel steel plates family and with ASME SA387 as a related Cr-Mo family, not as a substitute. It does not sit with carbon steel plates or ASTM A36.

SA-20 still governs marking, testing location, retests and repair rules.

ASME SA542 Type B Class 4a / ASME SA542 TYPE B CL.4A uses Type B chemistry. Class only changes strength and temper floor.

Heat Analysis and Product Analysis — ASME SA542 Type B (typical Table 1 limits)

Type B is not Type D. Type D adds a vanadium band of about 0.25–0.35% and is 2.25Cr-1Mo-V. Type C and Type E sit on the 3Cr-1Mo-V band, closer in idea to SA387 Grade 21 Class 2 than to Type B. If the ladle is 2.25Cr-1Mo-V, SHH STEEL will not ship it as Type B Class 4a.

Class 4a is the higher-yield partner of Class 4.

Tensile Requirements — ASME SA542 Type B Class 4a

Class 4 is 380 MPa yield, same tensile band, 20% elongation. Class 3 is 515 MPa yield and 655–795 MPa tensile. Class 1 is 585 / 725–860. Class 2 is 690 / 795–930. Do not stamp Class 4 as Class 4a because tensile matches. Do not treat 415 MPa yield as a free swap with SA516 Grade 70 or SA533 Type A Class 1.

Density is 7.85 g/cm³. Notch toughness is commonly added. Write the temperature, energy, location and orientation. Simulated PWHT is common on hydroprocessing work.

SA299 Grade B, SA225 Grade D, SA455 and SA285 Grade C are also vessel plates. None of them is ASME SA542 TYPE B CL.4A.

ASME SA542 Type B Class 4a / ASME SA542 TYPE B CL.4A is selected when the vessel wants quenched-and-tempered 2.25Cr-1Mo at the Class 4a line, with Type B residual control. Typical equipment is high-temperature welded pressure vessels and components written to SA-542 Type B Class 4a. Allowable stress comes from ASME Section II Part D after the Code lists this Type and Class.

SHH STEEL supplies this plate as exporter and stockist. It is not nickel low-temp plate like SA203 Grade D or SA203 Grade E. It is not layered QT carbon like SA724. It is not SA302 Grade C. Stainless inquiries belong on ASME SA240/SA240M or ASTM A240/A240M.

Do not form this plate as if it were as-rolled SA285 Grade A. Quench-and-temper properties are the product. A later PWHT cycle has to be planned and, when required, simulated on coupons.

SA542 Type B Cl.4a is killed, fine-grain 2.25Cr-1Mo at Class 4a strength. Welding is Code welding.

Qualify procedures to ASME Section IX. Use consumables written for 2.25Cr-1Mo QT at 585–760 MPa tensile, not a Class 1 procedure copied down and not an unreviewed SA387 Grade 12 Class 2 procedure. Hydrogen control, preheat, interpass and PWHT follow the qualified procedure and the vessel specification.

The fabricator owns the WPS. SHH STEEL as supplier can share mill heat data for review.

Plates shall be austenitized, quenched in a suitable liquid medium, then tempered. For Class 4a on Type A, B, C, D and E, the minimum tempering temperature is 675 °C (1250 °F). Soak is not less than 1.2 min/mm of thickness and not less than ½ hour. Class 4 uses 650 °C. Class 1, 2 and 3 use 565 °C. Do not temper Class 4a at the Class 4 floor and stamp Class 4a.

If the vessel will see a long PWHT, test coupons shall follow a simulated cycle. This is not the SA832 N+T route and not the SA537 Class 1 heat-treated carbon route. SHH STEEL as mill exporter prints QT, Type B, Class 4a, austenitizing and tempering temperatures on the certificate when the mill record carries them.

Usual delivery from SHH STEEL as supplier and distributor is quenched-and-tempered ASME SA542 Type B Class 4a / ASME SA542 TYPE B CL.4A plate.

The certificate lists ASME SA542 Type B Class 4a and, when dual certified, ASTM A542 Type B Class 4a; heat number; heat analysis including Cr, Mo and Type B residuals; product analysis when ordered; tensile results to the Class 4a table; QT statement with the 675 °C floor; impact and simulated PWHT when ordered. Certificates may be EN 10204 3.1 or EN 10204 3.2.

Usual supply range from SHH STEEL for SA542 Type B Cl.4a QT Cr-Mo vessel plate:

• Thickness: commonly 8 mm – 150 mm, minimum about 5 mm, limited by the ability of the heat to meet Class 4a after QT
• Width: 1500 mm – 4000 mm
• Length: 3000 mm – 12000 mm
• Cut-to-length shells, heads and nest sizes inside those limits

Structural sizes belong on EN 10025-2 or JIS G3106. Weathering plate belongs on EN 10025-5 or Corten A/B. Fine-grain structural belongs on EN 10025-3 or EN 10025-4. QT structural belongs on EN 10025-6.

Dimensional limits follow ASME SA-20. Thickness, width, length, flatness and camber are vessel-plate tolerances. UT to A435 / A577 / A578 is commonly added on reactor plate.

Most export ASME SA542 Type B Class 4a / ASME SA542 TYPE B CL.4A orders add extras. SHH STEEL as supplier does not assume them.

Charpy details. Temperature, energy, location and orientation.

Simulated PWHT. Same-heat coupons follow the vessel cycle.

NDE. UT to A435 / A577 / A578.

Hydrogen-service extras. When the vessel specification names them.

Third-party. EN 10204 3.2.

DIN 17100, ASTM A516, ASME SA515 and ASTM A285 are not SA542 Type B Class 4a.

Ship plate inquiries belong on shipbuilding steel plates or BV Rules. Weathering inquiries belong on weathering steel plates. Stainless inquiries belong on stainless steel products, JIS G4305 or AISI stainless.

Other vessel comparisons: SA203 Grade B, SA302 Grade A, ASTM A516 Grade 70, SA533 Type C Class 2, SA517 Grade P, SA387 Grade 11 Class 2.

SHH STEEL is the supplier, exporter, distributor and stockist of ASME SA-542/SA-542M plate. On ASME SA542 Type B Class 4a / ASME SA542 TYPE B CL.4A that means mill pricing, dual SA542/A542 marking, Type B chemistry, recorded quench and temper at the Class 4a floor of 675 °C, tensile results at 415 MPa yield and 585–760 MPa tensile, 3.1 as standard and 3.2 when specified.

We keep Type and Class on the order. Type B is not Type A and is not Type D. Class 4a is not Class 4. SA542 is not SA387 Grade 22. SA542 is not SA516 Grade 55. SA542 Type B Cl.4a is not SA533 Type C Class 1. If the drawing names Class 4, we will not ship Class 4a and call it close. If the drawing names N+T Cr-Mo-V, we point the inquiry to SA832.

Company scope: China steel Mill Agent-SHH STEEL.

ASME SA542 Type B Class 4a Steel Plate, also searched as ASME SA542 TYPE B CL.4A, is quenched-and-tempered 2.25Cr-1Mo plate under ASME SA-542/SA-542M, with Type B residual control, 415 MPa yield and a 675 °C temper floor. Whether the inquiry says ASME SA542 Type B Class 4a, ASME SA542 TYPE B CL.4A, SA542 Type B Cl.4a or SA542B CL4A, SHH STEEL as supplier, exporter, distributor and stockist supplies plate with Type B chemistry, recorded QT delivery, and EN 10204 3.1 or 3.2 certification.

SHH STEEL is the China mill vendor of ASME SA542 Type B Class 4a / ASME SA542 TYPE B CL.4A QT Cr-Mo Vessel Plate for ASME Section VIII work that actually names this Type and Class.

Contact SHH STEEL for mill rolling, stock inquiry, dual SA542/A542 marking, simulated PWHT testing, 3.2 inspection or a quotation.

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