ASME SA841 Grade A Class 2 Steel Plate | SA841 Gr.A Cl.2 TMCP Vessel Plate

ASME SA841 Grade A Class 2 is the higher-strength Class on Grade A chemistry in ASME SA-841/SA-841M. The plate is made by thermo-mechanical control process, not by a separate normalize cycle and not by quench and temper. The specification exists because fabricators wanted vessel-plate toughness and weldability from controlled rolling and accelerated cooling, without sending every plate through a heat-treat furnace. As Direct Mill Supply by SHH STEEL, the plate is produced to ASME SA-841/SA-841M.

Buyers write the same product many ways: SA841 Grade A Class 2, SA841 Gr.A Cl.2, SA841GRA CL2, SA-841 Grade A Class 2, SA841 A2, SA 841 Gr A Cl 2. ASTM A841 Grade A Class 2 is the companion mill specification. The Code book says Grade and Class together. A purchase order that only says “SA841 Grade A” is incomplete. Class 1 on Grade A is 345 MPa yield. Class 2 is 415 MPa yield. Those two plates do not interchange because someone likes the higher name.

This page is not SA537 Cl.2. SA537 Class 2 is heat-treated carbon-manganese-silicon. The tensile window looks familiar, which is why the two grades get mixed in search boxes. The process is different, the forming temperature limit is different, and the stamp is different. It is not ASME SA516 fine-grain carbon. It is not ASME SA387 chromium-molybdenum. It is not SA533 Type A Class 2 quenched-and-tempered manganese-molybdenum. Grade A in SA-841 may carry small niobium and vanadium for grain control. That does not turn the plate into a Cr-Mo or Mn-Mo-Ni Code line.

Maximum nominal thickness for Grade A is 100 mm. Over 65 mm the Class 2 tensile and yield both step down. Dual marking SA841 / A841 Grade A Class 2 is available when the vessel has to carry both names. Certificates can be EN 10204 3.1 or 3.2. Company scope: China steel Mill Agent-SHH STEEL.

This plate belongs with pressure vessel steel plates. It does not belong with carbon steel plates that have no TMCP Class table, and it does not belong with structural steel plates or ASTM A36/A36M. If a buyer sends a structural cutting list and a vessel drawing on the same email, we separate the two inquiries before rolling.

SA-20 still governs marking, testing location, retests, and repair welding rules unless the purchase order tightens them. TMCP does not cancel SA-20. It only changes how the mill creates the as-rolled properties.

Class 2 does not get a private chemistry table. ASME SA841 Grade A Class 2 uses Grade A chemistry. The Class only changes the tensile line.

Heat Analysis — ASME SA841 Grade A

Product analysis uses the SA-20 / A20 allowances on those heat limits. Manganese is not one number. Below 40 mm the heat band is 0.70–1.35%. Above 40 mm it moves to 1.00–1.60%. That split exists because thicker TMCP plate needs more manganese to hold strength after accelerated cooling. A mill that pours one manganese aim for 12 mm and 80 mm is not following the table.

Grade A nickel stays at 0.25% maximum. Grade B allows 0.60% nickel and 0.30% molybdenum. If a ladle comes in with Grade B residuals, it is not Grade A, even when Class 2 tensile is easy to hit. If chromium and molybdenum sit in a SA387 Gr.11 Cl.2 window, the plate belongs on the Cr-Mo page. If the ladle is carbon only and the process is normalize, look at SA516 Gr.70 or SA515 Gr.70.

Phosphorus and sulfur at 0.030% are the specification ceilings, not a shop target. Export tanks and low-temperature shells often write tighter residuals. Those limits are supplementary. SHH STEEL prints heat analysis, including Nb and V when present, on every certificate and adds product analysis when SA-20 requires it.

Class 2 is the reason this page exists. Grade A only identifies the chemistry.

Tensile Requirements — ASME SA841 Class 2 (Grades A, B, C)

Through 65 mm the Class 2 yield is 415 MPa and tensile is 550–690 MPa. Above 65 mm both numbers drop. A 70 mm plate cannot be sold on the 40 mm line. Class 1 on the same Grade is 345 MPa yield and 485–620 MPa tensile through 65 mm. Do not stamp Class 1 as Class 2 because the coupon came in high.

Density is 7.85 g/cm³. Use that figure for shipping weight and shell mass. Hardness is not a mandatory SA-841 Table 3 line. Typical TMCP Class 2 plate sits around 160–210 HB. If a drawing writes 180 HB max or 200 HB max, put the number on the order. SHH STEEL will then test and print it. Do not read Brinell as a substitute for yield.

Charpy is not automatic on Grade A Class 2 the way it is on some low-temperature Grades later in the same book. Tank specifications, winter erection and exported shells almost always add an impact temperature. Write the temperature, the energy, the location and the orientation. Two tension tests from each plate-as-rolled is the specification habit: one coupon from a corner at each end.

Do not treat 415 MPa yield as permission to substitute ASTM A36 steel plate, ASTM A572 or high strength low alloy plates. Those pages are structural. This page is vessel plate.

SA299 Gr.A, SA225 Gr.C, SA455 and SA285 Gr.C are also vessel plates. None of them is TMCP Grade A Class 2.

The practical question on this page is usually “can I use SA841 A2 instead of SA537 Class 2?” Only if the drawing and the Code allowable line say SA-841 Grade A Class 2. Similar yield is not a substitution rule.

ASME SA841 Grade A Class 2 is used on welded vessels that need the higher TMCP Class and still want Grade A residuals. Designers pick it for tank shells, process drums and other equipment where wall thickness can drop a step versus Class 1, provided the forming shop can live with the TMCP temperature cap.

Allowable stress is not copied from SA537 Cl.2 by habit. It comes from ASME Section II Part D for the SA-841 Grade and Class actually ordered. If Part D or the vessel specification only lists Grade A Class 1, this page is the wrong Class.

Typical service is moderate-temperature welded construction, not creep service and not cryogenic nickel service. SA203 Gr.A and SA203 Gr.D are nickel plates. SA517 Gr.A is QT alloy. Stainless work belongs on ASME SA240/SA240M, ASTM A240/A240M or stainless steel sheets and plates.

The TMCP warning is not fine print. Heat the plate too high in forming or PWHT and the fine structure that created Class 2 yield disappears. Except for Grade G, forming and PWHT stay at or below 650 °C, and only when clause 6.1 and any simulated coupons are satisfied. Do not run a 900 °C normalize on this plate and expect the MTC numbers to survive.

SA841 Gr.A Cl.2 is killed, fine-grain TMCP plate. Welding is still vessel welding.

Qualify procedures to ASME Section IX. Use low-hydrogen consumables. Grade A carbon can sit at 0.20%. That is not high-alloy welding, but it is not a thin SA285 Gr.A fillet either. Calculate carbon equivalent from the actual ladle, including manganese on the thick side of the table.

Preheat depends on thickness, restraint, hydrogen and the WPS. After welding, many shops want PWHT. That is allowed only inside the TMCP temperature window and only when the mill coupons have seen a matching simulation. High heat-input welding on TMCP plate is a separate discussion. If the shop uses heavy SAW passes, write the heat-input limit and the simulated cycle on the order.

Do not copy a SA387 Gr.12 Cl.1 procedure or a SA533 Type B Class 1 QT procedure onto Grade A Class 2 without review. The fabricator owns the WPS. SHH STEEL supplies the plate and the test data. We do not own the shop procedure.

The steel shall be killed and shall meet fine austenitic grain practice under ASME SA-20. Plates shall be produced by TMCP. Slab reheating, reduction schedule, finish temperature and accelerated cooling are the mill tools. There is no mandatory furnace normalize and no mandatory quench and temper in the specified condition.

If the vessel will be warm formed or post-weld heat-treated, the test coupons must follow that cycle. That is the whole point of clause 6.1. A coupon pulled from TMCP plate and tested as-rolled does not prove the shell after a 620 °C hold. Ask for simulated PWHT when the vessel specification already knows the hold.

This is not the normalize route used for SA516 Gr.60. It is not the QT route used for SA537 Cl.1 or SA533 Type C Class 2. SHH STEEL prints TMCP on the certificate so the inspector does not treat the plate as as-rolled carbon.

Usual delivery is TMCP Grade A Class 2 plate, as-rolled by the TMCP route, not furnace-normalized.

The mill test certificate lists ASME SA841 Grade A Class 2 and, when dual certified, ASTM A841 Grade A Class 2; heat number; heat analysis; product analysis when ordered; two-end tensile results to the Class 2 table; TMCP statement; impact results when ordered; simulated PWHT results when ordered; and UT when ordered. Surface is vessel-plate quality. Shot blast and shop primer are available.

Certificates may be EN 10204 3.1 or EN 10204 3.2. Third-party surveyors can witness rolling, cooling and testing when the order says so.

Usual supply range from SHH STEEL for SA841 Gr.A Cl.2 TMCP vessel plate:

• Thickness: 8 mm – 100 mm, which is the Grade A cap in SA-841
• Width: 1500 mm – 4000 mm
• Length: 3000 mm – 12000 mm
• Cut-to-length shells, dish-head blanks and nest sizes inside those limits

A 110 mm inquiry is outside Grade A. Do not “see if the mill can roll it” and still stamp SA841 Grade A. D, E and F stop at 40 mm; that is a different Grade family.

Structural lengths and bridge widths 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 tolerance, width, length, flatness and camber are vessel-plate rules, not structural-bar rules.

Ultrasonic testing to A435, A577 or A578 is common on thicker Class 2 plate and on tank work. Extra-flatness for large heads is a negotiated item. Edge camber after cutting is the fabricator’s problem unless the order asks the mill to cut.

Most export ASME SA841 Grade A Class 2 orders add extras. The specification does not assume them.

Charpy V-notch. Temperature, absorbed energy, specimen location and orientation. Winter tanks and exported shells almost always write this.

Simulated PWHT and warm forming. Same-heat coupons follow the vessel cycle. Tensile and impact are then run on those coupons.

NDE. UT to A435 / A577 / A578. Edge MT or PT after cutting when the shop wants it.

Restricted P, S and CEV. Tighter than Table 1 when weldability is the purchase driver.

Vacuum degassing or restricted residuals. When specified.

Third-party inspection. EN 10204 3.2, with the agency named on the order.

If an item is not written, it is not tested and it is not printed as if it were.

DIN 17100, ASTM A516, ASME SA515 and ASTM A285 are not TMCP Grade A Class 2. EN 10028-5 is the closest European conversation, not an automatic dual stamp.

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

Other vessel comparisons: SA203 Gr.B, SA302 Gr.B, A516 Gr.70, SA533 Type D Class 2, SA562.

SHH STEEL works as a China Mill Direct Exporter for plates to ASME SA-841/SA-841M. On ASME SA841 Grade A Class 2 that means mill pricing, dual SA841/A841 marking, Grade A chemistry, recorded TMCP delivery, Class 2 tensile results at 415 MPa yield through 65 mm, 3.1 as standard and 3.2 when specified.

We keep Grade and Class on the order. Grade A Class 2 is not Grade A Class 1. Grade A is not Grade B. SA841 is not SA516 Gr.55. SA841 is not SA387 Gr.91 Cl.2. SA841 Gr.A Cl.2 is not SA533 Type C Class 1. If the drawing names heat-treated carbon, we point the inquiry to SA537. If it names Class 1, we will not ship Class 2 and call the extra yield a gift. If the shop plans a 900 °C form, we will say TMCP is the wrong process before the slab is booked.

Company scope: China steel Mill Agent-SHH STEEL.

ASME SA841 Grade A Class 2 Steel Plate is TMCP pressure-vessel plate under ASME SA-841/SA-841M, using Grade A chemistry and the Class 2 tensile table. Whether the inquiry says SA841 Grade A Class 2, SA841 Gr.A Cl.2, SA841GRA CL2 or SA-841 Grade A Class 2, SHH STEEL supplies plate with recorded TMCP delivery, Class 2 tensile results, and EN 10204 3.1 or 3.2 certification.

As a China mill Distributor, SHH STEEL provides ASME SA841 Grade A Class 2 / SA841 Gr.A Cl.2 TMCP Vessel Plate for ASME Section VIII work.

Contact SHH STEEL for mill rolling, dual SA841/A841 marking, simulated PWHT testing, 3.2 inspection or a quotation.

ASME SA841 Grade A Class 2 Steel Plate, SA841 Gr.A Cl.2, SA841GRA CL2, SA-841 Grade A Class 2, TMCP vessel plate, Direct Mill Supply by SHH STEEL