ASTM A302 Grade B pressure-vessel plate: specify the finished product
Gangsteel welcomes ASTM A302 Grade B plate enquiries for welded boilers and other pressure vessels. This is a manganese–molybdenum alloy product specification, not a nickel grade or a general chemistry-only description. A useful buying specification connects the requested plate dimensions and condition with the edition, analysis basis and test evidence needed for acceptance.
Use the identified ASTM edition, then define the order
The current official public ASTM listing checked for this guidance is A302/A302M-17(2022). Specify A302 or A302M, Grade B, and the edition required by the project. The paid full text has not been read for this summary: official public Scope supports the alloy type, tensile range, composition-limited thickness and independent unit systems; detailed chemistry, yield, elongation and treatment guidance below remains labelled public reference.
Scope identifies Grade B as manganese–molybdenum. Grades C and D are the manganese–molybdenum–nickel members, so the family title must not be copied as Grade B’s individual alloy label. Nickel is not specified in the checked Grade B compilations. That means no numerical nickel requirement was established here, not that every actual heat contains zero nickel.
Compare the complete Grade B tensile-test result
| Property | Value | Reference status |
|---|---|---|
| Tensile strength | 80–100 ksi [550–690 MPa] | Official A302/A302M-17(2022) public Scope |
| Yield strength, minimum | 50 ksi [345 MPa] | Public compilation reference, not a read paid table |
| Elongation in 8 in. [200 mm] | 15% | Public reference; applicable specimen adjustments |
| Elongation in 2 in. [50 mm] | 18% | Public reference; not a thickness-band distinction |
Ferrobend’s Grade B family column and the dated SHH/SteelSpecs Grade B compilation agree on the yield and two elongation references. The Grade B yield is 345 MPa, not the lower value associated with Grade A. Confirm the specimen gauge and applicable adjustment when reviewing elongation; changing the gauge changes the comparison basis, not the identity of the plate thickness.
Tensile strength has an upper limit as well as a lower one. A report showing adequate yield alone is therefore not a complete mechanical acceptance record. Check the measured tensile result, yield, elongation, specimen identification and represented plate condition together. These are material test references, not design allowable stresses or a universal operating-temperature rating for equipment.
Keep heat analysis and product analysis in their own columns
The table uses public-reference mass percentages. The September 2026 SHH/SteelSpecs trader compilation supplies the split for manganese, silicon and molybdenum. Ferrobend’s undated family table prints compressed product-style bands for those elements, not heat-analysis requirements; its carbon note applies to both analyses. Neither source is the paid official chemistry table for the identified ASTM edition.
| Element and thickness basis | Heat analysis | Product analysis |
|---|---|---|
| Carbon, ≤1 in. [25 mm], max | 0.20 | 0.20 |
| Carbon, >1–2 in. [>25–50 mm], max | 0.23 | 0.23 |
| Carbon, >2 in. [>50 mm], max | 0.25 | 0.25 |
| Manganese | 1.15–1.50 | 1.07–1.62 |
| Silicon | 0.15–0.40 | 0.13–0.45 |
| Molybdenum | 0.45–0.60 | 0.41–0.64 |
| Phosphorus, max | 0.025 | |
| Sulfur, max | 0.025 | |
| Nickel |
Manganese is a range, not merely a maximum. Evaluate a heat result against the appropriate heat basis rather than the wider product-style band. Silicon and molybdenum need the same discipline. Phosphorus and sulfur have 0.025% heat-reference maxima; the product cells remain blank because separate product limits were not established in the checked sources. Nickel’s numerical cells also remain blank because no Grade B band is specified.
Carbon changes with thickness, so a plate schedule containing more than one thickness may require different carbon-limit comparisons. Identify the ordered nominal thickness and unit system before reading the band. Use actual certified chemistry for fabrication assessment; neither a reference maximum nor a different heat’s report demonstrates the chemistry of the proposed plate.
Separate specification thickness from a commercial rolling range
Official public Scope limits maximum thickness by the ability of the composition to meet the required mechanical properties. It establishes no fixed numerical cap in the public text. A supplier’s rolling or processing range is a capability question, not an alternative specification limit. Request confirmation for the actual thickness, width, length, delivery condition and inspection requirements rather than treating a generic range as available material.
The ASTM unit systems are separately standard and not exact mathematical equivalents. Choose the controlling inch-pound or SI system and apply it independently; do not mix rounded conversions with the other system’s limits. Resolve conflicting dimensions or unit notes before approving an offer or comparing its report with the order.
State the delivery condition and examination scope explicitly
As a labelled compilation restatement only, the dated trader source describes plate 2 in. [50 mm] and under as normally as-rolled, with normalizing or stress relieving when ordered, and plate above that threshold as normalized. Official public Scope does not provide this heat-treatment clause, and the paid clause was not read. Confirm the requirement in the ordered edition; no quench-and-temper default, soaking temperature or tempering schedule is asserted.
The official ASTM abstract says the steel is killed, meets fine-grain requirements and is subject to tension testing. These are family-wide statements, not features limited to a nickel grade. Compilations refer to A20/A20M for common requirements; that named reference should be verified in the ordered edition rather than represented as a citation from public Scope.
| Order line | Define in the enquiry | Acceptance focus |
|---|---|---|
| Product specification | A302 or A302M; Grade B; required ASTM edition | Do the material designation and documents match the order? |
| Plate geometry | Unit system, dimensions, quantity and tolerances | Are the offered sizes and piece identifiers consistent? |
| Condition and tests | Delivery condition, required tests and acceptance criteria | Are results representative and supplementary requirements complete? |
| Certificate form | Report format, traceability and required witnessing | Can results be linked to the ordered heat and plates? |
Impact testing and ultrasonic examination are not promised as default services. Where required, give the method, coverage, specimen conditions and acceptance criteria rather than requesting unspecified “tested plate”. If properties after a fabrication thermal cycle are required, identify the approved simulation and test condition. Welding and forming controls remain matters for qualified procedures based on the actual material, section and service requirements.
Keep ASTM acceptance separate from the ASME route
An ASTM A302 Grade B certificate is not by itself SA-302 acceptance, and an SA-302 Grade B certificate is not automatically ASTM A302 acceptance. Dual certification needs a documented compliance basis for both requirements. The ASME SA302 Grade B page is an ASTM–ASME route comparison only, not a technical source for this ASTM product’s values.
For a different carbon pressure-vessel-plate purpose, see ASTM A285 Grade B plate. The shared letter B does not indicate equivalent chemistry, strength or acceptance. Keep any alternative-material proposal separate from the specified A302 Grade B quotation and obtain the project’s technical approval before substitution.
ASTM A302 Grade B purchasing FAQs
Which edition is identified by the public ASTM listing?
A302/A302M-17(2022) is the current public edition identified for this guidance. The order must state its required edition. Public Scope access does not mean the paid chemistry, yield, elongation or treatment tables were read.
Is Grade B a nickel-bearing steel?
The official Scope identifies it as manganese–molybdenum. Checked Grade B references leave nickel unspecified; do not copy a nickel requirement from C or D, and do not interpret unspecified as proof of zero residual nickel.
Which yield and elongation references belong to Grade B?
The public references are 50 ksi [345 MPa] minimum yield, 15% in 8 in. [200 mm] and 18% in 2 in. [50 mm]. Confirm specimen applicability and the ordered edition before accepting a report.
Can an ASME-only certificate settle an ASTM order?
Not automatically. Review the exact ASTM designation, edition and compliance evidence required by the order. Conversely, an ASTM-only certificate does not establish SA-302 acceptance; dual certification requires its own documented basis.
What needs clarification before a plate is cut into parts?
Resolve dimensions, tolerances, identification transfer, required examinations and the link between test results and each supplied piece. Missing documentation should be clarified before processing rather than reconstructed from generic catalogue values.
Enquire for ASTM A302 Grade B plate
Send the required ASTM edition, unit system, dimensions and quantity, delivery condition, tests and certificate form. Provide project-specific acceptance criteria and identify any proposed alternative separately; availability and the required documentation remain subject to enquiry review.