ASTM A299 Grade B Steel Plate | A299 Gr.B Mn-Si Vessel Plate

ASTM A299 Grade B is the high-strength grade in ASTM A299/A299M. The specification covers carbon-manganese-silicon steel plates for welded boilers and other pressure vessels. Two grades are listed: Grade A and Grade B. Grade A takes most of the search traffic. Grade B is the plate a designer writes when the vessel needs the 550–690 MPa tensile window instead of the 515–655 MPa window. As Direct Mill Supply by SHH STEEL, the plate is produced to ASTM A299/A299M.

The same plate is written A299 Gr.B, A299GRB, A299 GR B, A299 Grade B, ASTM A299 Gr.B, ASME SA299 Grade B, SA299 Gr.B, SA299GRB, SA299 GR B and A/SA299 Grade B. They all mean Grade B. ASME SA-299/SA-299M is the Code companion used when the vessel will be stamped to ASME Section VIII.

Do not treat this page as SA516 Gr.70 or A516 Gr.70. Those pages are fine-grain carbon vessel plate with a 485–620 MPa tensile table and a toughness habit shops know by heart. A299 Grade B is silicon-killed carbon with a higher manganese band and a higher tensile table. The two plates can sit on the same bid list. They are not interchangeable on a stamped vessel without a drawing change.

Do not treat it as SA515 Gr.70 or A515 Gr.70. SA515 / A515 is the intermediate-and-higher-temperature silicon-killed carbon family. A299 is manganese-silicon carbon aimed at boilers and vessels that want more Mn-Si strengthening. Do not treat it as SA285 Gr.C or A285 Gr.C. A285 Grade C stops at 380–515 MPa and at 50 mm. A299 Grade B is a different specification and a different strength class.

It is not Mn-Mo plate like SA302 Gr.C or A302 Gr.C. Those grades add molybdenum and, on Grade C and D, nickel. It is not nickel plate like SA203 Gr.B or A203 Gr.B. It is not Cr-Mo like SA387 Gr.11 Cl.2. It is not QT 690 MPa plate like SA517 Gr.F or A517 Gr.F. A mill cannot recertify those heats as A299GRB.

The steel follows ASTM A20 / ASME SA-20. Plates 50 mm and under are commonly supplied as-rolled and may be ordered normalized or stress-relieved, or both. Plates over 50 mm are normally normalized. Maximum thickness is limited only by the ability of the composition to meet the mechanical table. Mills commonly offer about 8–150 mm; heavier sizes are an enquiry.

For Code work the plate is dual-marked ASTM A299 Grade B / ASME SA299 Grade B. Certificates can be EN 10204 3.1 or EN 10204 3.2.

When a project is still choosing carbon vessel plate, a China mill Distributor path through SHH STEEL puts A299GRB next to SA516 Gr.65, SA515 Gr.65 and SA537 Cl.2, so the buyer can see whether they need Mn-Si A299, fine-grain A516, high-temp A515 or heat-treated A537.

This plate is a vessel product. It is not structural ASTM A36 steel plate. A36 is a structural specification with a different yield line and a different marking habit. Do not put A36 on a Section VIII shell and call it A299 Grade B.

Chemistry for ASTM A299 Grade B is reported as heat analysis and product analysis under ASTM A299/A299M Table 1. Carbon is the first number that separates Grade B from Grade A. Manganese bands are shared. Silicon is killed-steel silicon on both grades.

Heat Analysis — ASTM A299 Grade B / A299 Gr.B

Product Analysis — A299GRB / SA299 Grade B

Carbon maxima apply to both heat and product analysis. Grade A allows 0.26% C to 25 mm and 0.28% C over 25 mm. Grade B allows 0.28% C to 25 mm and 0.30% C over 25 mm. A Grade B heat with 0.29% C over 25 mm cannot be stamped Grade A. A Grade A heat cannot be stamped Grade B just because someone wants the Grade B tensile name.

Manganese is the strengthening lever on both grades. Heat Mn is 0.90–1.40% to 25 mm and 0.90–1.50% over 25 mm. Product Mn opens to 0.84–1.52% and 0.84–1.62%. Silicon is 0.15–0.40% heat and 0.13–0.45% product. That C-Mn-Si combination is why the commercial name on this page is Mn-Si vessel plate, not a generic carbon plate name shared with A516 Gr.65.

If the drawing says ASTM A299 Grade B or A299GRB, the ladle must sit in the Grade B table and the tensile test must sit in the Grade B window. SHH STEEL reports heat analysis on every certificate and adds product analysis when A20 / SA-20 or the vessel specification requires it.

Tighter phosphorus, sulfur or residuals are supplementary. Vacuum treatment and other A20 chemistry items are available when written on the order. Do not assume HIC, NACE or ultra-low sulfur because the plate is “boiler quality.”

Tensile of Grade B is one window at all thicknesses. Yield drops 15 MPa once thickness passes 25 mm. That is the same thickness break used on Grade A, with higher numbers.

Tensile Requirements — ASTM A299 Grade B per ASTM A299/A299M

Yield is determined by the 0.2% offset method or the 0.5% extension-under-load method. A 20 mm plate is tested to 325 MPa. A 30 mm plate is tested to 310 MPa. Do not apply the thin-line yield to a 40 mm plate and call the heat compliant.

Grade A in the same specification is 515–655 MPa tensile, with 290 MPa yield to 25 mm and 275 MPa over 25 mm. Elongation minima are the same 16% / 19%. The designer who writes Grade B is buying the extra tensile and the extra yield, not a different elongation rule.

Density is 7.85 g/cm³. Hardness is not a default line in A299. A Brinell window is supplementary. Charpy V-notch is not a hidden default at 0 °C or −20 °C. If the vessel specification wants 27 J at a stated temperature, that request belongs on the mill order. A299 is not A516. Do not assume the A516 impact habit.

Compare nearby pages before anyone treats tensile overlap as identity. SA516 Gr.70 is 485–620 MPa. A515 Gr.65 is a high-temp silicon-killed carbon table. SA285 Gr.B is 345–485 MPa. SA537 Cl.2 is heat-treated carbon at a different strength and heat-treatment route. A299 Grade B is none of those tables.

Order ASTM A299 Grade B when the drawing names Grade B. SHH STEEL does not swap A299GRB for Grade A, for A516 Gr.70, or for SA517 Gr.Q without a written revision.

ASTM A299 Grade B is selected for welded boilers and vessels that want more tensile than Grade A without leaving the C-Mn-Si family. When the vessel is ASME stamped, allowable stress comes from Section II Part D for SA-299 Grade B after dual marking. Impact temperature is an order number.

Typical use is thicker boiler drums, high-pressure steam drums and process vessels specified to A299 / SA299 Grade B. It is not a creep-focused Cr-Mo grade. It is not a cryogenic nickel grade. If the equipment is written to SA203 Gr.E or to A203 Gr.E, this page is the wrong purchase.

A299GRB is silicon-killed carbon with a high manganese band and a higher carbon cap than Grade A. Welding is Code welding, not structural fillet practice from ASTM A36 steel plate.

Procedures for Code work are qualified to ASME Section IX. Low-hydrogen consumables such as E7018 (AWS A5.1) are the usual shop choice. Carbon equivalent should be calculated from the actual ladle, not from a memory of “mild steel.” Grade B can sit at 0.30% C over 25 mm. That is enough to change preheat on a restrained 60 mm joint.

Preheat depends on thickness, restraint, hydrogen and the qualified WPS. After welding, many shops want to PWHT. Simulated PWHT of mill coupons should be on the purchase order when the shop cycle is known. A normalize at the mill does not replace a vessel PWHT number on the drawing.

Do not copy a SA387 Gr.12 Cl.2 Cr-Mo procedure or a SA517 Gr.B QT procedure onto ASTM A299 Grade B. The fabricator owns the qualified WPS.

Plates 50 mm and under are normally supplied as-rolled. They may be ordered normalized, stress-relieved, or both.

Plates over 50 mm are normally normalized.

That split is mill practice tied to A20 / SA-20 and the product specification. As-rolled thick plate is not the default for A299 Grade B above 50 mm. If the drawing says “normalized A299 Gr.B” on a 20 mm plate, that cycle is ordered and recorded. If the drawing is silent on 20 mm plate, as-rolled is the usual supply.

SHH STEEL reports the actual delivery condition on the MTC. Do not read “ASTM A299 Grade B” and assume every thickness left the mill normalized.

Usual delivery is as-rolled to 50 mm and normalized above 50 mm, unless the order says otherwise.

The certificate lists ASTM A299 Grade B and, when dual certified, ASME SA299 Grade B; heat number; heat analysis; product analysis when ordered; tensile results by the 25 mm yield line; heat-treatment condition; Charpy results when ordered; and supplementary tests.

Surface is vessel-plate quality. Shot blasting and shop primer are available.

Certificates may be EN 10204 3.1 or EN 10204 3.2. BV, LR, DNV, TUV, SGS or the buyer’s agency can witness rolling, normalizing and testing when the order says so.

Usual supply range from SHH STEEL for A299 Gr.B Mn-Si vessel plate:

• Thickness: 8 mm – 150 mm (heavier sizes by mill enquiry)
• Width: up to about 4000 mm
• Length: up to about 12000 mm

State thickness clearly on the RFQ. At 25 mm the yield line changes. At 50 mm the usual heat-treatment practice changes. A 20 mm plate and an 80 mm plate are not planned the same way.

Cut-to-length shells and nest sizes are available.

Dimensional limits follow ASTM A20 / ASME SA-20. Thickness, width, length, flatness and camber are vessel-plate tolerances. Extra-flatness is a negotiated item.

Ultrasonic testing to A435, A577 or A578 is added when specified. On thick Grade B boiler plate, UT is a common extra, not a rare one.

Most export ASTM A299 Grade B orders add tests beyond the base tensile table. SHH STEEL does not assume these extras.

Simulated PWHT. Same-heat coupons follow the vessel cycle: heating rate, soak, hold and cooling as stated by the fabricator. Tensile and Charpy are then run on those coupons.

Charpy details. Temperature, energy, specimen orientation and location as agreed. Not a hidden default in A299.

NDE. UT to A435 / A577 / A578; edge MT/PT after cutting.

Hardness survey. Surface HBW when the datasheet sets a window.

Restricted chemistry. Tighter P, S or residuals than 0.025%. Vacuum treatment per A20.

HIC / NACE. Only when TM0284 or MR0175 / ISO 15156 is cited. Grade B is not automatically sour-service plate.

Z-direction. A770 or Z15/Z25/Z35 for nozzles and strained joints.

Third-party. Witness of rolling, normalizing, testing and documents. Output can be EN 10204 3.2.

If an item is not on the purchase order, it is not assumed, not tested and not printed as if it were.

These names are used for project comparison. They are not automatic substitutes.

For stamping, write ASTM A299 Grade B or dual A299 / SA299 Grade B. Nearby pages also include A203 Gr.D and A517 Gr.Q for comparison only.

ASTM A299 Grade B / A299 Gr.B is selected when a boiler or Section VIII vessel needs C-Mn-Si strength above Grade A.

Do not use this grade as a silent stand-in for SA203 Gr.B or SA517 Gr.S. Those drawings name different alloys and different heat treatments.

SHH STEEL works as a China Mill Direct Exporter for plates to ASTM A299/A299M. On ASTM A299 Grade B that means mill pricing, dual A299/SA299 marking, thickness-correct carbon caps at 0.28% / 0.30%, manganese bands at 25 mm, as-rolled or normalized delivery recorded on the MTC, 3.1 as standard and 3.2 when specified.

Heat analysis is on every certificate. Product analysis is added when requested. The 325 / 310 MPa yield lines are applied to the actual ordered thickness, not to a brochure average.

We keep the order on the right specification. Grade B is not Grade A. A299 is not SA516 Gr.55. A299 is not SA285 Gr.A. A299 Gr.B is not SA517 Gr.Q. If the drawing wants fine-grain impact-tested carbon, we point the inquiry to SA516 / A516. If it wants nickel low-temp, we point it to SA203 / A203. If it wants QT 690, we point it to SA517 / A517.

Company scope: China steel Mill Agent-SHH STEEL.

ASTM A299 Grade B Steel Plate is the higher-strength manganese-silicon carbon vessel grade in ASTM A299/A299M. Whether the inquiry says A299 Gr.B, A299GRB, A299 Grade B, SA299 Gr.B or ASME SA299 Grade B, SHH STEEL supplies plate with heat and product analysis, thickness-correct yield at 25 mm, as-rolled or normalized delivery, agreed extras, and EN 10204 3.1 or 3.2 certification.

As a China mill Agent, SHH STEEL provides ASTM A299 Grade B / A299 Gr.B Mn-Si Vessel Plate for boilers and dual-certified Section VIII work.

Contact SHH STEEL for mill rolling, dual A299/SA299 marking, 3.2 inspection or a quotation.

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