ABS Grade A Shipbuilding Steel Plate Supplier

Technical Reviewer: Jack | SHH STEEL Material Solutions Department · Updated: 2026-10-27

Equivalent grades: ABS A ≈ ASTM A131 Grade A ≈ DNV NV A ≈ LR Grade A ≈ BV Grade A ≈ CCS Grade A ≈ NK KA ≈ KR RA ≈ RINA Grade A ≈ GB 712 Grade A (all class-approved, stamped by the issuing society).

ABS Grade A is the base grade of ordinary-strength hull structural steel in the ABS Rules for Materials and Welding, Part 2, Chapter 1, Section 2 (2-1-2). It has a minimum yield point of 235 N/mm², a tensile strength of 400–520 N/mm² and 22 % minimum elongation, and it is the only one of the four ordinary-strength grades (A, B, D, E) for which the Rules ask for no Charpy test on plates up to 50 mm thick. Plates that pass the mill tests under ABS survey are die-stamped or stencilled AB/A and are supplied with a certificate the ABS Surveyor endorses.

Because it carries no low-temperature toughness requirement at ordinary thicknesses, Grade A is used where the hull structure is lightly stressed or remains above freezing in service: inner bottom and internal structure of small and medium vessels, superstructures, deckhouses, non-critical bulkheads, inland barges, pontoons and many shipyard fittings. Where the classification drawing calls for Grade B, D or E in a strake, Grade A cannot be substituted; the reverse substitution (B, D or E supplied for A) is normally accepted because the higher grades meet every Grade A requirement.

SHH STEEL supplies ABS Grade A plate from Chinese mills that hold ABS works approval for the grade, from stock in common sizes or from a mill rolling cycle, with ABS survey arranged at the mill.

Size range. Grade A is rolled on wide plate mills in China from about 5 mm to 100 mm and more, widths 1500–3500 mm and lengths up to about 18 m depending on mill; 6–25 mm plate in 1800–2500 mm width is the bulk of the market. Plates under 6 mm are usually cut from ABS-approved hot-rolled coil, which needs separate approval of the coil process (2-1-2/3.1). Ask for confirmation for plates over 100 mm or wider than 3200 mm.

Product (check) analysis column = heat (ladle) limit adjusted by ASTM A6/A6M-19 Table A “Permitted Variations in Product Analysis”, as required by ABS Rules Part 2, 2-1-2/5.3 (maximum + “over”, minimum − “under”; row chosen by the specified upper limit); arithmetic shown in brackets.

Source: ABS Rules 2-1-2/5.1 and 15.9 Table 1. The heat (ladle) analysis is determined by the mill on each heat and must meet Table 1. Product (check) analysis on the finished plate is not routine; when it is required by the purchaser or Surveyor, ABS 2-1-2/5.3 applies the chemical tolerances of ASTM A6 (or another nationally recognized standard) to the Table 1 limits. Ask for product analysis at enquiry if you need it on the certificate.

Intentionally added elements must also be reported. Grade A is the only ordinary-strength grade with a manganese minimum written as a ratio of carbon (2.5 × C) instead of a fixed value: Grade B needs 0.80 % Mn, D 0.60 % and E 0.70 %. Grade A also has the widest silicon allowance (0.50 %), which is why semi-killed Grade A is still legitimate under the Rules up to 50 mm. In practice, Chinese mills supply aluminium-killed Grade A with typical C around 0.14–0.18 % and Mn 0.5–1.0 %; check the actual figures on the mill certificate, not a typical sheet.

Source: 2-1-2/15.9 Table 2. On the 200 mm gauge alternative B flat specimen, minimum elongation depends on thickness (Table 3):

Tensile tests are taken on two different plates from each heat (one test if the heat is under 50 t), and from both the thickest and thinnest plate when thicknesses in the heat differ by 9.5 mm or more. One frequent certificate error is quoting a 550 N/mm² upper limit: that relaxed limit applies only to Grade A sections, not to plate.

Required average energy at +20 °C where a test applies (2-1-2/15.9 Table 4, full-size specimens, either direction acceptable):

One individual value may fall below the average if it is at least 70 % of it. Sub-size specimens use 5E/6, 2E/3 or E/2. Note 3 of Table 4 removes the test altogether when heavy Grade A is fine-grain treated and normalized. For buyers this means: if you order 60 mm or 80 mm ABS A for foundations or heavy brackets, ask whether the mill will deliver N/TM (no impact) or AR/CR (impact tested); both are legitimate but the certificate must match the route. If your design or a flag-state rule calls for a 0 °C or −20 °C test on Grade A, order Grade B or D instead of adding a special test.

ABS applies a fixed minus tolerance of 0.3 mm on nominal thickness for hull plates regardless of thickness (2-1-1/15.3.2), much tighter than the general ASTM A6 under-tolerance. The mill demonstrates compliance by measuring each plate at defined points; Class C of ISO 7452 may be used instead with ABS agreement. Plus tolerance, flatness, width and length follow ASTM A6 or another recognised standard unless the purchaser specifies otherwise. For plates under 5 mm (cut from coil), tolerances follow a national standard but the minus tolerance still may not exceed 0.3 mm.

Surface defects may be ground out within the limits of 2-1-1/3; grinding areas are excluded from the thickness tolerance. If you plan to shot-blast and prime at the yard, state any surface class (for example ISO 8501-1 rust grade A or B on receipt) in the order.

Quantities are approximate and change daily; all stock plates carry AB/A marking and ABS-endorsed mill certificates. Sizes outside the table (for example 3000 mm width, 60–100 mm thickness, or fixed lengths for a cutting plan) are produced in the next mill rolling cycle, typically 3–6 weeks including ABS survey. Send your size list and we will reply with what is in stock and what must be rolled.

Packing. Plates are bundled by size with steel strapping, marked with heat number, grade and ABS stamp, and shipped in containers (up to about 11.8 m) or break bulk for longer plates.

These are comparisons, not substitutions. A classed hull needs plate made by a mill approved by the society that classes the vessel and certified to that society. Dual or multi-class certification (for example ABS + DNV, or ABS + CCS) can be arranged at the mill when the heat is surveyed by both societies.

All four ordinary-strength grades share the same 235 N/mm² yield and 400–520 N/mm² tensile range; they differ in deoxidation and toughness. Grade B needs Charpy at 0 °C (27 J longitudinal) above 25 mm in most conditions; Grade D is tested at −20 °C and must be fine grain above 25 mm; Grade E is killed fine-grain steel tested at −40 °C, with each plate tested when supplied normalized or TM. The hull steel grade for each strake is set by the classification rules according to structural member category and thickness, so check the approved drawing first. In general, Grade A is used for internal and lightly stressed members, while sheer strakes, bilge strakes, deck stringers and ice-belt plating usually call for B, D, E or higher-strength ABS steel plates.

Compared with land structural steels, Grade A is close in strength to ASTM A36, ASTM A283 Grade C and S275JR class steels but differs in three practical ways: the tighter 0.3 mm minus tolerance, the C + Mn/6 ≤ 0.40 cap, and above all the class survey and stamp. For a barge or pontoon that will be classed, only class-certified plate is accepted; for an unclassed workboat or a dock structure, buyers sometimes choose A36 or S235 for price, and Grade A can also be dual-certified to A131 and ABS for such use.

When ABS A is the right choice: typical uses are non-critical hull plating, internal structure, decks and bulkheads of vessels working in temperate water, barges and pontoons. The Charpy temperature (+20 °C) is fixed by the letter, and the strength by the ordinary-strength level (ReH 235 N/mm²). Pick the strength from the scantling calculation and the letter from the material class and design temperature on the approved drawing. Swapping to a different letter or strength needs class approval of the drawing change, not just a new purchase order.

Typical uses: internal hull structure, double-bottom floors and girders, non-watertight and watertight bulkheads in lightly stressed areas, superstructure and deckhouse plating, hatch covers, inland and coastal barges, pontoons, floating docks, fishing vessels and tugs, rudder and skeg internal plates, and ship repair replacement steel. Offshore and port structures also use Grade A for secondary steel; see offshore platform steel plates for primary structure grades.

Cutting: oxy-fuel, plasma and laser cutting all work without preheat in normal thicknesses. Welding: with C + Mn/6 at or below 0.40 %, Grade A is welded with ordinary-strength consumables approved for the grade (for example ABS Grade 1, 2 or 3 consumables depending on required weld-metal toughness); preheat is generally unnecessary below about 25–30 mm except in cold or humid conditions — follow your approved welding procedure. Forming: plates intended for cold flanging should be ordered as flanging quality (marked F) with S 0.020 % max.

Processing notes for ABS A: cold forming and flanging of ordinary-strength plate are routine. The minimum Mn is set so that this grade can be cold-flanged where noted in 2-1-2. Keep the cut edges of plate thicker than 50 mm free of notches, because thick plate of this grade is controlled more tightly for deoxidation (killed or semi-killed ≤50 mm; killed >50 mm).

Every plate is tested and marked at the mill under ABS survey; the mill certificate lists heat number, ladle chemistry including Ni, Cr, Mo and Cu, tensile results, impact results where required, condition of supply and plate numbers, and is endorsed by the attending Surveyor. On request we add EN 10204 3.2 certificates with third-party witness by TÜV, SGS, BV or another agency, ultrasonic testing (U mark) or through-thickness testing (Z mark), and multi-class certification with any of the nine major class societies (ABS, DNV, LR, BV, CCS, NK, KR, RINA and the former GL, now part of DNV).

On receipt, check: AB/A stamp and heat number on each plate match the certificate; the certificate shows ABS endorsement, not just a mill stamp; thickness at several points is not below nominal minus 0.3 mm; for plates over 50 mm, the condition of supply and impact results agree with the table above.

Charpy acceptance for ABS A by thickness (from 2-1-2; actual results as per standard and mill certificate):

On receipt, check that the test temperature on the certificate is +20 °C and that the energy matches the band for the delivered thickness, not the thinnest band. Also check that the plate number on the stamp matches the certificate line, and that the ABS Surveyor endorsement is present. If UT was ordered (e.g. EN 10160 or ASTM A578 level), check the UT report as well. If the PO asked for 3.2, the inspector’s report must name the witnessed tests and plate numbers.

• Ordering “ABS A” without specifying that ABS certification is required, then receiving GB 712 or A131 plate without class endorsement.
• Accepting a 550 N/mm² upper tensile limit on plate; that limit is for sections only.
• Ordering heavy plate (> 50 mm) without agreeing N/TM or impact testing, then finding no Charpy results on the certificate.
• Substituting Grade A where the drawing requires B or D in a high-stress or low-temperature strake.
• Plates cut from coil without the mill holding approval for coiled plate.
• Ignoring the 0.3 mm minus tolerance when accepting re-rolled or trader stock.

Each of these is avoided by writing the requirement into the purchase order and checking it on the certificate before the plates are cut.

State the grade and rule (ABS Grade A, ABS Rules Part 2), whether multi-class certification is needed, thickness, width, length and quantity per size, condition of supply for plates over 50 mm, any Z or U requirement, surface or primer requirements, certificate type (mill certificate with ABS endorsement, EN 10204 3.2 with third-party witness), packing and destination port. Send the list to SHH STEEL for price, available stock and lead time.

Sample PO line: “Steel plate to ABS Rules Part 2 2-1-2, Grade A, delivery condition [AR/CR/N/TM], 20 × 2500 × 12000 mm, 30 pcs, marked AB/A, certificate endorsed by ABS Surveyor, EN 10204 3.2 [if required], UT [if required], CIF [port].” Each bracketed item changes price, lead time and which mills can supply, so fix them at enquiry stage.

ABS Grade A is the economical base hull steel: 235 N/mm² minimum yield, 400–520 N/mm² tensile, no impact test up to 50 mm and a 0.3 mm minus thickness tolerance. What the Rules leave open has to be fixed in the order: ABS (or multi-class) certification, the supply condition and impact testing for plates over 50 mm, whether product analysis is required, and the certificate type.

SHH STEEL supplies AB/A plate rolled by Chinese mills that hold ABS works approval for the grade, so every plate carries the AB/A stamp and a Surveyor-endorsed certificate traceable to its heat. Common thicknesses are available from stock; other sizes are scheduled into the mill rolling cycle with ABS survey arranged at the mill. On request we add EN 10204 3.2 certificates with third-party witness (TÜV, SGS, BV or another agency) and joint certification with DNV, LR, BV, CCS, NK, KR or RINA.

We accept T/T or L/C payment, with inspection before the balance is paid. Small quantities in several sizes, or Grade A mixed with B, D or higher-strength grades, can be combined in one container. A dedicated coordinator sends production and shipping updates with photos, and our own workshop cuts to size, bevels, drills and machines plates before shipment so they arrive ready for fabrication.

Request a quotation: send SHH STEEL the grade (ABS A), thickness, width, length, quantity per size and destination port, plus any multi-class, Z/U or 3.2 certificate requirement. We reply with price, available stock and lead time.