ASME SA841 Grade B Class 2 Steel Plate | SA841 Gr.B Cl.2 TMCP Vessel Plate
What is ASME SA841 Grade B Class 2 Steel?
ASME SA841 Grade B Class 2 is steel plate produced by the thermo-mechanical control process under ASME SA-841/SA-841M for welded pressure vessels. The current specification lists Grades A through G. Grade B is used with Class 1 or Class 2. Class 2 is the 415 MPa yield line. As Direct Mill Supply by SHH STEEL, the plate is produced to ASME SA-841/SA-841M.
The same plate is written SA841 Grade B Class 2, SA841 Gr.B Cl.2, SA841GRB CL2, SA-841 Grade B Class 2, SA841 B2 and SA 841 Gr B Cl 2. ASTM A841 Grade B Class 2 is the companion product spec. Do not treat this page as SA537 Cl.2. SA537 Class 2 is heat-treated C-Mn-Si. SA841 Grade B Class 2 is TMCP. Do not treat it as ASME SA516 carbon plate or ASME SA387 Cr-Mo plate.
Maximum nominal thickness for Grade B is 100 mm. Class 1 on the same Grade drops yield to 345 MPa. Dual marking SA841 / A841 Grade B Class 2 is available. Certificates can be EN 10204 3.1 or 3.2. Company scope: China steel Mill Agent-SHH STEEL.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade / Class | ASME SA841 Grade B Class 2 | Confirmed |
| Product Specification | ASME SA-841/SA-841M | Applied |
| Companion Spec | ASTM A841 Grade B Class 2 | Dual cert available |
| General Requirements | ASME SA-20 / ASTM A20 | Applied |
| Process | TMCP | Confirmed |
| Intended use | Welded pressure vessels | As specified |
| Maximum Thickness | 100 mm for Grade B | Per SA-841 |
| Certification | EN 10204 3.1 or 3.2 / third-party | As ordered |
This plate sits in the pressure vessel steel plates family. It is not carbon steel plates without a TMCP route, not structural steel plates, and not ASTM A36/A36M.
Chemical Composition
Chemistry for ASME SA841 Grade B is the Grade table. Class 1 and Class 2 share Grade B chemistry. Grade B allows more nickel and molybdenum than Grade A.
Heat Analysis — ASME SA841 Grade B
| Element | Heat Analysis (%) |
|---|---|
| Carbon (C), max | 0.15 |
| Manganese (Mn), t ≤ 40 mm | 0.70 – 1.35 |
| Manganese (Mn), t > 40 mm | 1.00 – 1.60 |
| Phosphorus (P), max | 0.030 |
| Sulfur (S), max | 0.025 |
| Silicon (Si) | 0.15 – 0.50 |
| Copper (Cu), max | 0.35 |
| Nickel (Ni), max | 0.60 |
| Chromium (Cr), max | 0.25 |
| Molybdenum (Mo), max | 0.30 |
| Niobium (Nb), max | 0.03 |
| Vanadium (V), max | 0.06 |
Product analysis follows SA-20 / A20 tolerances on the Grade B heat limits. If the ladle sits in a Cr-Mo window, the plate belongs under SA387 Gr.11 Cl.2 or SA387 Gr.22 Cl.2, not SA841. If the process is QT Mn-Mo-Ni, look at SA533 Type B Class 2. SHH STEEL reports heat analysis on every certificate.
Mechanical Properties
Class 2 is the strength line. Grade B only tells the chemistry family.
Tensile Requirements — ASME SA841 Class 2 (Grades A, B, C)
| Property | t ≤ 65 mm | t > 65 mm |
|---|---|---|
| Yield strength, min | 415 MPa (60 ksi) | 380 MPa (55 ksi) |
| Tensile strength | 550 – 690 MPa (80 – 100 ksi) | 515 – 655 MPa (75 – 95 ksi) |
| Elongation in 50 mm, min | 22% | 22% |
| Elongation in 200 mm, min | 18% | 18% |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Hardness | Not a Table 3 default | Not a Table 3 default |
Typical mill hardness in the TMCP condition is about 160–210 HB. Print hardness only when the order sets a limit. Class 1 on Grade B is 345 MPa yield and 485–620 MPa tensile to 65 mm. Density 7.85 g/cm³ is used for weight take-off.
Do not treat 415 MPa yield as a reason to substitute ASTM A36 steel plate, ASTM A572 or high strength low alloy plates. Those are structural routes.
Material Comparison
| Grade | Route | Strength idea | Swap? |
|---|---|---|---|
| SA841 Grade B Class 1 | TMCP | 345 MPa yield | Same Grade, lower Class |
| SA841 Gr.B Cl.2 | TMCP | 415 MPa yield to 65 mm | This page |
| SA841 Grade A Class 2 | TMCP | Same Class, Grade A chemistry | No |
| SA537 Cl.2 | Heat-treated C-Mn-Si | Similar numbers, not TMCP | No |
| SA516 Gr.70 | Fine-grain carbon | No TMCP Class table | No |
| SA515 Gr.70 | Si-killed carbon | No TMCP | No |
| SA302 Gr.B | Normalized Mn-Mo | Different alloy | No |
| SA533 Type A Class 2 | QT Mn-Mo | Different family | No |
Nearby vessel pages: SA299 Gr.B, SA225 Gr.D, SA455, SA285 Gr.C.
TMCP Vessel Service
ASME SA841 Grade B Class 2 is selected when the vessel wants TMCP strength near the SA537 Class 2 window without a separate quench-and-temper cycle. Allowable stress comes from ASME Section II Part D after the Code lists the Grade and Class. Section VIII material lists often name SA-841 Grade B Class 2 together with Grade A Class 1.
Typical use is welded tanks, process shells and other equipment written to SA-841 Grade B Class 2. It is not nickel low-temp plate like SA203 Gr.D. It is not QT alloy like SA517 Gr.B. Stainless inquiries belong on ASME SA240/SA240M, ASTM A240/A240M or stainless steel sheets and plates.
Warm forming and PWHT must stay inside the TMCP limit, normally not above 650 °C, with simulated coupons when the vessel cycle is known. Do not form this plate like as-rolled SA285 Gr.A.
Weldability
SA841 Gr.B Cl.2 is killed, fine-grain TMCP plate. Welding is Code welding.
Procedures are qualified to ASME Section IX. Low-hydrogen practice is the usual shop choice. Grade B carbon is capped at 0.15%, but nickel and molybdenum sit higher than Grade A. Calculate carbon equivalent from the actual ladle. Preheat and PWHT follow the qualified WPS and the 650 °C TMCP ceiling unless simulated testing supports the cycle.
Do not copy a SA387 Gr.12 Cl.2 Cr-Mo procedure or a SA533 Type B Class 1 QT procedure onto Grade B Class 2 without review. The fabricator owns the WPS.
Heat Treatment
The steel shall be killed and shall meet fine austenitic grain practice under ASME SA-20. Plates shall be produced by TMCP. There is no separate mandatory normalize or quench-and-temper in the specified condition.
If the vessel will see warm forming or PWHT, test coupons shall follow a simulated cycle. This is not the normalize route used for SA516 Gr.70 and not the QT route used for SA537 Cl.1. SHH STEEL reports TMCP as the delivery process on the MTC.
Delivery Condition
Usual delivery is TMCP Grade B Class 2 plate.
The certificate lists ASME SA841 Grade B Class 2 and, when dual certified, ASTM A841 Grade B Class 2; heat number; heat analysis; product analysis when ordered; tensile results to the Class 2 table; TMCP statement; Charpy results when ordered; and supplementary tests. Certificates may be EN 10204 3.1 or EN 10204 3.2.
Dimensions
Usual supply range from SHH STEEL for SA841 Gr.B Cl.2 TMCP vessel plate:
- Thickness: 8 mm – 100 mm (Grade B maximum in SA-841)
- Width: 1500 mm – 4000 mm
- Length: 3000 mm – 12000 mm
- Cut-to-length shells and nest sizes inside those limits
If the inquiry is 120 mm, Grade B cannot be used under this specification. 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.
Tolerances
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 thicker TMCP plate.
Supplementary Requirements
Most export ASME SA841 Grade B Class 2 orders add extras. SHH STEEL does not assume them.
Charpy details. Temperature, energy, location and orientation.
Simulated PWHT / warm forming. Required when the vessel cycle exceeds as-rolled TMCP assumptions.
NDE. UT to A435 / A577 / A578.
Restricted P, S / CEV. When specified.
Third-party. EN 10204 3.2.
Equivalent Material Grades
| Designation | Standard | Notes |
|---|---|---|
| ASME SA841 Grade B Class 2 / SA841 Gr.B Cl.2 | ASME SA-841/SA-841M | Code name on this page |
| ASTM A841 Grade B Class 2 | ASTM A841/A841M | Companion spec |
| SA841 Grade B Class 1 | SA-841 | Same Grade, lower Class |
| EN 10028-5 P460M / P460ML related | EN | Project comparison only |
| ASME SA537 Class 2 | SA-537 | Heat-treated, not TMCP |
| ASTM A537 Cl.2 | A537 | Same caution |
DIN 17100, ASTM A516, ASME SA515 and ASTM A285 are not SA841 Grade B Class 2.
Applications
| Industry | Typical components |
|---|---|
| Pressure vessels | ASME SA841 Grade B Class 2 shells and SA841 Gr.B Cl.2 heads |
| Storage tanks | SA-841 Gr.B Cl.2 TMCP courses |
| Process equipment | ASME SA841 Grade B Class 2 TMCP vessel plate |
| Dual-certified export | SA841 / A841 Grade B Class 2 plate |
| Fabrication | SA841 Gr.B Cl.2 cut to nest sizes |
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 Gr.E, SA302 Gr.C, A516 Gr.70, SA533 Type C Class 2.
Why Choose SHH STEEL
SHH STEEL works as a China Mill Direct Exporter for plates to ASME SA-841/SA-841M. On ASME SA841 Grade B Class 2 that means mill pricing, dual SA841/A841 marking, Grade B chemistry, recorded TMCP delivery, Class 2 tensile results at 415 MPa yield, 3.1 as standard and 3.2 when specified.
We keep the order on the right Grade and Class. Grade B Class 2 is not Grade B Class 1 and is not Grade A Class 2. SA841 is not SA516 Gr.55. SA841 is not SA387 Gr.91 Cl.2. SA841 Gr.B Cl.2 is not SA533 Type C Class 3. If the drawing names heat-treated carbon, we point the inquiry to SA537. If it names TMCP Class 1, we will not ship Class 2 and call it close.
Company scope: China steel Mill Agent-SHH STEEL.
FAQ
- What names are used for ASME SA841 Grade B Class 2?Buyers write SA841 Grade B Class 2, SA841 Gr.B Cl.2, SA841GRB CL2, SA-841 Grade B Class 2, SA841 B2 and SA 841 Gr B Cl 2. SHH STEEL prints the wording on the purchase order.
- Is ASME SA841 Grade B Class 2 the same as ASTM A841 Grade B Class 2?Chemistry and tensile limits match. ASME SA-841 is the Code version. ASTM A841 is the product spec. As China mill-Direct Supply, SHH STEEL dual-certifies both names when the vessel must be stamped.
- What is the yield strength of SA841 Gr.B Cl.2?415 MPa minimum through 65 mm. Over 65 mm the Class 2 yield drops to 380 MPa. Tensile is 550–690 MPa through 65 mm.
- Is SA841 Grade B Class 2 the same as SA537 Class 2?No. The numbers sit in a similar window. SA537 Class 2 is heat-treated. SA841 Grade B Class 2 is TMCP. Do not stamp one as the other.
- How is Grade B different from Grade A?Grade B carbon is lower (0.15% max). Nickel max is 0.60% and molybdenum max is 0.30%. Class 2 is the same tensile table on Grades A, B and C.
- What is the maximum thickness?100 mm for Grade B. D, E and F stop at 40 mm. That limit is not this page.
- Can the plate be hot formed like normalized carbon plate?Not without a planned cycle. TMCP strength is lost if the plate is heated too high. Forming and PWHT are normally held at or below 650 °C, with simulated coupons when required.
- Can welding be qualified to ASME Section IX?Yes. Use a low-hydrogen WPS written for TMCP vessel plate. The fabricator owns the procedure.
Conclusion
ASME SA841 Grade B Class 2 Steel Plate is TMCP pressure-vessel plate under ASME SA-841/SA-841M. Whether the inquiry says SA841 Grade B Class 2, SA841 Gr.B Cl.2, SA841GRB CL2 or SA-841 Grade B Class 2, SHH STEEL supplies plate with Grade B chemistry, 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 B Class 2 / SA841 Gr.B Cl.2 TMCP Vessel Plate for ASME Section VIII work.
Contact SHH STEEL for mill rolling, dual SA841/A841 marking, 3.2 inspection or a quotation.
ASME SA841 Grade B Class 2 Steel Plate, SA841 Gr.B Cl.2, SA841GRB CL2, SA-841 Grade B Class 2, TMCP vessel plate, Direct Mill Supply by SHH STEEL
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