ASME SA302 Grade A Steel Plate | SA302 Gr.A Mn-Mo Vessel Plate

As a professional China mill-Direct Supply and ASME pressure-vessel plate exporter, SHH STEEL supplies ASME SA302 Grade A Steel Plate produced to ASME SA-302/SA-302M.

On drawings, MTCs and RFQs this grade is written many ways: ASME SA302 Grade A, SA302 Gr.A, SA302 Gr A, SA302GRA, SA302 GR A, SA-302 Grade A, SA-302 Gr.A, ASTM A302 Grade A, A302 Gr.A, A302GRA, Mn-Mo vessel plate, manganese molybdenum boiler plate and A/SA302 Grade A. All of these names refer to the same manganese-molybdenum alloy plate. ASME SA-302/SA-302M is the Boiler and Pressure Vessel Code companion to ASTM A302/A302M.

SA302 Gr.A is the lower-strength Mn-Mo grade in ASME SA-302. Grade B uses a higher manganese band and the next strength table. Grades C and D keep Grade B strength and add nickel. Minimum yield of Grade A is 310 MPa (45 ksi). Tensile strength is 515–655 MPa (75–95 ksi). Molybdenum heat analysis is 0.45–0.60%. Nickel is not specified for Grade A.

The plate is intended for welded boilers and other pressure vessels under ASME Section VIII. It is not a 2.25Ni / 3.5Ni low-temperature grade such as SA203, and it is not a Cr-Mo elevated-temperature grade such as ASME SA387 (SA-387). Compared with carbon vessel steels such as ASME SA516 (SA-516) and ASTM A516, Grade A adds molybdenum for alloy vessel and boiler service at the 310 MPa yield level.

General requirements follow ASME SA-20. Steel is killed and produced to fine-grain practice. Plates 50 mm and under are normally supplied as-rolled unless normalizing or stress relieving is ordered. Plates over 50 mm shall be normalized.

SHH STEEL supplies SA302 Gr.A as true China mill-Direct Supply. Dual marking ASME SA302 Grade A / ASTM A302 Grade A is available for equipment built to ASME Section VIII. Certificates can be EN 10204 3.1 or EN 10204 3.2.

If the project compares other coded vessel plates, SHH STEEL places SA302 Gr.A next to ASME SA537 (SA-537), ASTM A537, ASME SA515 (SA-515) and ASTM A285.

This product belongs to the Pressure Vessel Steel Plates family. It is a Mn-Mo coded vessel plate under ASME SA-302, not a structural Carbon Steel Plates grade.

SA302 Grade A chemistry under ASME SA-302/SA-302M is reported as heat analysis (ladle analysis) and, when specified, product analysis.

Heat Analysis (Ladle Analysis) — Grade A

Product Analysis — Grade A

Grade A uses a lower manganese band than Grade B (heat 0.95–1.30% versus 1.15–1.50%). Molybdenum stays 0.45–0.60% on heat analysis for all four grades. Nickel is not specified for Grade A or Grade B. Tighter residuals or carbon equivalent limits are supplementary requirements.

SHH STEEL reports ladle analysis on every certificate. Product analysis is added when ASME SA-20 product analysis or the vessel specification requires it.

Tensile Requirements — ASME SA302 Grade A per ASME SA-302/SA-302M

These limits apply to SA302 Gr.A at both thin and thick sizes. Density is 7.85 g/cm³. Hardness after the agreed heat treatment is typically around 160–190 HB unless a special window is ordered.

Compared with SA302 Grade B, Grade A has 35 MPa less yield and a lower tensile band, with a slightly higher 50 mm elongation minimum (19% versus 18%). Specimens are prepared under ASME SA-20. If simulated PWHT is specified, coupons are heat-treated to the vessel cycle before testing.

Order SA302 Gr.A / SA302GRA when the ASME SA-302 drawing names Grade A and 310 MPa yield is enough. If 345 MPa yield is required without nickel, use Grade B. If nickel is required at the higher strength table, use Grade C or Grade D. Carbon QT options include ASME SA537 and ASTM A537. HSLA Steel Plates are not a coded substitute for ASME SA-302.

SA302 Grade A is specified for welded boilers and pressure vessels under ASME Section VIII, not for cryogenic 3.5Ni or 9% Ni service. Molybdenum in ASME SA-302/SA-302M supports alloy vessel and boiler service at the 310 MPa yield level. Allowable stress at temperature is taken from the applicable ASME Section II Part D table for SA-302 Grade A, not from a commercial datasheet.

Impact temperature, orientation and energy minimums are agreed on the order. They are not automatic on Grade A. When the vessel specification sets Charpy values, SHH STEEL produces SA302 Gr.A Mn-Mo vessel plate with those sets and lists the results on the 3.1 or 3.2 certificate

SA302 Grade A under ASME SA-302 is a welded boiler and pressure-vessel plate. Mn-Mo steel is welded with low-hydrogen procedures qualified to ASME Section IX.

Consumables are selected to match molybdenum and the required joint strength and toughness. Preheat depends on thickness, hydrogen control and restraint. When ASME Section VIII requires PWHT, the shop cycle is commonly in the 595–650°C range for this alloy family. If properties after that cycle are needed, simulated PWHT of mill coupons should be ordered before shipment.

SHH STEEL recommends a qualified WPS/PQR for each thickness break and can support procedure review through steel welding services. Do not assume an SA516 procedure is automatically valid for SA302 Gr.A.

Heat treatment of SA302 Grade A follows ASME SA-302/SA-302M:

• Plates 50 mm (2 in.) and under are normally supplied in the as-rolled condition. They may be ordered normalized, stress relieved, or both.
• Plates over 50 mm (2 in.) shall be normalized.

Normalizing is heating into the austenite range followed by air cooling. Stress relieving, when ordered, is a separate lower-temperature hold to reduce residual stress. Quench-and-temper practice used for SA533 / SA537 Class 2 must not be applied to Grade A unless the order is changed to a QT specification.

If the specification fixes a normalizing temperature band or holding time per thickness under ASME SA-20, SHH STEEL writes those parameters into the mill instruction and reports them on the certificate.

SHH STEEL delivers ASME SA302 Grade A / SA302 Gr.A as follows:

• ≤ 50 mm: as-rolled as standard, or normalized / stress relieved when ordered

• 50 mm: normalized as required by ASME SA-302

The certificate lists SA302 Gr.A and, when dual certified, A302 Gr.A; heat number; heat analysis; product analysis when ordered; tensile results; heat-treatment condition; agreed Charpy values; and supplementary tests. Plates are industrial vessel plate: heat-treated as required, then pickled or shot-blasted as agreed.

Decorative finishes such as 2B, BA or No.4 are not used. Surface condition is vessel-plate quality for welding, NDE and coating. Heat number and grade marking support ASME Section VIII traceability.

Certificates may be EN 10204 3.1 or EN 10204 3.2. Third-party stamps (BV, LR, DNV, TUV, SGS or the purchaser’s agency) are arranged when written on the order.

Typical supply range from SHH STEEL for SA302 Gr.A Mn-Mo vessel plate:

• Thickness: 6 mm – 150 mm (heavier by mill enquiry)
• Width: up to about 4600 mm
• Length: up to about 12000 mm

Because heat treatment changes at 50 mm in ASME SA-302, the purchase order should state the ordered thickness and the required condition. Cut-to-length shells, heads and nest sizes are available.

Dimensional tolerances follow ASME SA-20 / ASTM A20 for pressure-vessel plates.

Thickness, width, length, flatness and camber are vessel-plate tolerances, not strip tolerances. Restricted thickness or extra-flatness can be accepted when the vessel drawing requires it. Ultrasonic testing to A435 or A578 is added when specified. Cutting to finished sizes is available through steel cutting services.

ASME Section VIII specifications often add tests beyond the base SA-302 Grade A table. SHH STEEL treats the following as supplementary requirements.

Simulated PWHT. Coupons from the same heat and thickness receive the vessel PWHT cycle. Tensile and Charpy tests are run on those coupons.

Nondestructive examination. UT to A435, A577 or A578 with purchaser acceptance levels. Edge MT/PT after cutting if required.

Impact testing. Test temperature, specimen size, orientation and minimum average/single values as written on the RFQ.

Special hardness. HBW or HV window after the agreed heat treatment or after simulated PWHT.

Restricted chemistry. Tighter C, P, S, residuals or carbon equivalent on heat and product analysis per ASME SA-302 / SA-20.

HIC testing. NACE TM0284 with purchaser solution and CLR/CTR/CSR limits. Not automatic on SA302 Gr.A.

NACE / sour-service notes. Review against NACE MR0175 / ISO 15156 or MR0103 only when the datasheet cites the clause.

Z-direction testing. ASTM A770 or purchaser Z15/Z25/Z35 for thick nozzles and restrained joints.

Third-party witnessing. Witness of heat treatment, mechanical tests, UT and documents. Output can be EN 10204 3.2.

Supplementary tests go through steel testing service and appear line by line on the certificate. Items not on the purchase order are not assumed.

For ASME stamping, the purchase order should say ASME SA302 Grade A to ASME SA-302/SA-302M, or dual SA302 / A302 Grade A. Nearby carbon vessel grades include ASME SA516, ASTM A516, ASME SA515 and ASTM A285.

ASME SA302 Grade A / SA302 Gr.A is selected for ASME Section VIII boilers and vessels that need Mn-Mo alloy at 310 MPa yield. Typical applications of ASME SA302 Grade A Steel Plate include:

SHH STEEL supplies SA302 Gr.A with full heat traceability. Related industry pages include petrochemical industry and energy industry. Supporting services include steel cutting services, steel welding services, steel testing service and worldwide shipping service.

SHH STEEL is a China mill-Direct Supply for plates to ASME SA-302/SA-302M. For SA302 Grade A we offer:

• China mill-Direct Supply pricing on SA302 Gr.A / A302 Gr.A
• Dual ASME SA302 / ASTM A302 marking
• Heat analysis and product analysis per ASME SA-20 / SA-302
• EN 10204 3.1 standard; EN 10204 3.2 or nominated third-party inspection on request
• As-rolled or normalized delivery per thickness rule
• Supplementary PWHT simulation, UT, HIC, NACE review and Z-direction testing
• Cutting to shell and head nest sizes
• Technical support to separate Grade A from B/C/D and from SA516 / SA387 / SA537
• Export packing through worldwide shipping service

For company scope and other vessel grades, visit China steel Mill Agent-SHH STEEL.

ASME SA302 Grade A Steel Plate is the manganese-molybdenum, 310 MPa yield vessel grade in ASME SA-302/SA-302M. Whether the inquiry says SA302 Gr.A, SA302GRA, SA-302 Grade A or Mn-Mo vessel plate, SHH STEEL supplies plate with heat and product analysis, thickness-correct heat treatment, optional supplementary tests, and EN 10204 3.1 or 3.2 certification.

As a professional China mill-Direct Supply, SHH STEEL provides ASME SA302 Grade A / SA302 Gr.A Mn-Mo Vessel Plate with full traceability for ASME Section VIII fabrication.

Contact SHH STEEL today for stock, normalizing, dual SA302/A302 marking to ASME SA-302, 3.2 inspection or a quotation.

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