ASME SA841 Grade B Class 1 Steel Plate | SA841 Gr.B Cl.1 TMCP Vessel Plate
What is ASME SA841 Grade B Class 1 Steel?
ASME SA841 Grade B Class 1 is the lower-strength Class on Grade B chemistry in ASME SA-841/SA-841M. The plate is made by thermo-mechanical control process. Grade B allows more nickel and molybdenum than Grade A. Class 1 is the 345 MPa yield line shared with Grades A and C. 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 1, SA841 Gr.B Cl.1, SA841GRB CL1, SA-841 Grade B Class 1, SA841 B1 and SA 841 Gr B Cl 1. ASTM A841 Grade B Class 1 is the companion product spec. A purchase order that only says “SA841 Grade B” is incomplete. Class 2 on Grade B is 415 MPa yield. Those two plates do not interchange.
This page is not SA537 Cl.1. SA537 Class 1 is heat-treated C-Mn-Si. SA841 Grade B Class 1 is TMCP. It is not ASME SA516 carbon plate and not ASME SA387 Cr-Mo plate. Maximum nominal thickness for Grade B is 100 mm. Dual marking SA841 / A841 Grade B Class 1 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 1 | Confirmed |
| Product Specification | ASME SA-841/SA-841M | Applied |
| Companion Spec | ASTM A841 Grade B Class 1 | Dual cert available |
| General Requirements | ASME SA-20 / ASTM A20 | Applied |
| Process | TMCP | Confirmed |
| Grain practice | Killed, fine austenitic grain | Applied |
| 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 Class table, not structural steel plates, and not ASTM A36/A36M.
Chemical Composition
Class 1 does not get a private chemistry table. ASME SA841 Grade B Class 1 uses Grade B chemistry.
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. Grade A carbon max is 0.20%, nickel max is 0.25% and molybdenum max is 0.08%. Grade B is the leaner-carbon, higher-Ni/Mo Grade. A Grade A ladle cannot be stamped Grade B. If chromium and molybdenum sit in a SA387 Gr.11 Cl.1 or SA387 Gr.22 Cl.1 window, the plate belongs on the Cr-Mo page. If the process is QT Mn-Mo-Ni, look at SA533 Type B Class 1.
SHH STEEL reports heat analysis on every certificate, including nickel and molybdenum, and adds product analysis when SA-20 requires it.
Mechanical Properties
Class 1 is the strength line. Grade B only tells the chemistry family.
Tensile Requirements — ASME SA841 Class 1 (Grades A, B, C)
| Property | t ≤ 65 mm | t > 65 mm |
|---|---|---|
| Yield strength, min | 345 MPa (50 ksi) | 310 MPa (45 ksi) |
| Tensile strength | 485 – 620 MPa (70 – 90 ksi) | 450 – 585 MPa (65 – 85 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 |
Class 2 on Grade B is 415 MPa yield and 550–690 MPa tensile through 65 mm. A Class 1 heat cannot be stamped Class 2 because someone wants the higher name. Typical TMCP Class 1 hardness is about 140–190 HB. Print hardness only when the order sets a limit. Density 7.85 g/cm³ is used for weight take-off.
Charpy is not a hidden default. Write the impact temperature when the vessel specification needs it. Do not treat 345 MPa yield as a reason to substitute ASTM A36 steel plate, ASTM A572 or high strength low alloy plates.
Material Comparison
| Grade | Route | Strength idea | Swap? |
|---|---|---|---|
| SA841 Gr.B Cl.1 | TMCP | 345 MPa yield to 65 mm | This page |
| SA841 Grade B Class 2 | TMCP | 415 MPa yield | Same Grade, higher Class |
| SA841 Grade A Class 1 | TMCP | Same Class, Grade A chemistry | No |
| SA537 Cl.1 | 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 1 | QT Mn-Mo | Different family | No |
Nearby vessel pages: SA299 Gr.A, SA225 Gr.C, SA455, SA285 Gr.C.
TMCP Vessel Service
ASME SA841 Grade B Class 1 is selected when the vessel wants TMCP strength near the SA537 Class 1 window, with Grade B residuals rather than Grade A. Allowable stress comes from ASME Section II Part D for SA-841 Grade B Class 1. Section VIII lists often name Grade A Class 1 and Grade B Class 2. If the drawing says Class 2, this page is the wrong Class.
Typical use is welded tanks, process shells and other equipment written to SA-841 Grade B Class 1. It is not nickel low-temp plate like SA203 Gr.A or 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.1 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%, which helps weldability versus Grade A at 0.20%. Nickel max is 0.60% and molybdenum max is 0.30%. Calculate carbon equivalent from the actual ladle.
Preheat depends on thickness, restraint, hydrogen and the WPS. After welding, many shops want PWHT. That stay inside the 650 °C TMCP ceiling unless simulated testing supports the cycle.
Do not copy a SA387 Gr.12 Cl.1 procedure or a SA533 Type B Class 2 QT procedure onto Grade B Class 1 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.60 and not the QT route used for SA537 Cl.2. SHH STEEL reports TMCP as the delivery process on the MTC.
Delivery Condition
Usual delivery is TMCP Grade B Class 1 plate.
The certificate lists ASME SA841 Grade B Class 1 and, when dual certified, ASTM A841 Grade B Class 1; heat number; heat analysis; product analysis when ordered; tensile results to the Class 1 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.1 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 1 orders add extras. SHH STEEL does not assume them.
Charpy details. Temperature, energy, location and orientation.
Simulated PWHT / warm forming. Same-heat coupons follow the vessel cycle.
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 1 / SA841 Gr.B Cl.1 | ASME SA-841/SA-841M | Code name on this page |
| ASTM A841 Grade B Class 1 | ASTM A841/A841M | Companion spec |
| SA841 Grade B Class 2 | SA-841 | Same Grade, higher Class |
| EN 10028-5 P355M / P355ML related | EN | Project comparison only |
| ASME SA537 Class 1 | SA-537 | Heat-treated, not TMCP |
| ASTM A537 Cl.1 | A537 | Same caution |
DIN 17100, ASTM A516, ASME SA515 and ASTM A285 are not SA841 Grade B Class 1.
Applications
| Industry | Typical components |
|---|---|
| Pressure vessels | ASME SA841 Grade B Class 1 shells and SA841 Gr.B Cl.1 heads |
| Storage tanks | SA-841 Gr.B Cl.1 TMCP courses |
| Process equipment | ASME SA841 Grade B Class 1 TMCP vessel plate |
| Dual-certified export | SA841 / A841 Grade B Class 1 plate |
| Fabrication | SA841 Gr.B Cl.1 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.B, SA302 Gr.A, A516 Gr.70, SA533 Type D Class 1.
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 1 that means mill pricing, dual SA841/A841 marking, Grade B chemistry with nickel to 0.60% and molybdenum to 0.30%, recorded TMCP delivery, Class 1 tensile results at 345 MPa yield, 3.1 as standard and 3.2 when specified.
We keep Grade and Class on the order. Grade B Class 1 is not Grade B Class 2 and is not Grade A Class 1. SA841 is not SA516 Gr.55. SA841 is not SA387 Gr.91 Cl.2. SA841 Gr.B Cl.1 is not SA533 Type C Class 1. If the drawing names heat-treated carbon, we point the inquiry to SA537. If it names Class 2, we will not ship Class 1 and call it close.
Company scope: China steel Mill Agent-SHH STEEL.
FAQ
- What names are used for ASME SA841 Grade B Class 1?Buyers write SA841 Grade B Class 1, SA841 Gr.B Cl.1, SA841GRB CL1, SA-841 Grade B Class 1, SA841 B1 and SA 841 Gr B Cl 1. SHH STEEL prints the wording on the purchase order.
- Is ASME SA841 Grade B Class 1 the same as ASTM A841 Grade B Class 1?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.1?345 MPa minimum through 65 mm. Over 65 mm the Class 1 yield drops to 310 MPa. Tensile is 485–620 MPa through 65 mm.
- How is Grade B different from Grade A?Grade B carbon is 0.15% max versus 0.20% on Grade A. Nickel max is 0.60% and molybdenum max is 0.30%. Class 1 is the same tensile table on Grades A, B and C.
- Is SA841 Grade B Class 1 the same as SA537 Class 1?No. The numbers sit in a similar window. SA537 Class 1 is heat-treated. SA841 Grade B Class 1 is TMCP.
- What is the maximum thickness?100 mm for Grade B. D, E and F stop at 40 mm.
- Can the plate be hot formed like normalized carbon plate?Not without a planned cycle. 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 1 Steel Plate is TMCP pressure-vessel plate under ASME SA-841/SA-841M, using Grade B chemistry and the Class 1 tensile table. Whether the inquiry says SA841 Grade B Class 1, SA841 Gr.B Cl.1, SA841GRB CL1 or SA-841 Grade B Class 1, SHH STEEL supplies plate with recorded TMCP delivery, Class 1 tensile results, and EN 10204 3.1 or 3.2 certification.
As a China mill Distributor, SHH STEEL provides ASME SA841 Grade B Class 1 / SA841 Gr.B Cl.1 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 1 Steel Plate, SA841 Gr.B Cl.1, SA841GRB CL1, SA-841 Grade B Class 1, TMCP vessel plate, Direct Mill Supply by SHH STEEL
Quality Steel Needed? Inquire for Offers
Related Products
