ASTM A213 A213M Seamless Alloy Steel Tube: B2B Buyer's Guide to T5, T9, T11, T22, T91 and T92 Grades for Boilers, Superheaters and Heat Exchangers

A 25 MW package boiler, a 600 MW supercritical utility boiler, a hydrocracker heat-exchanger bundle, and a sulfur-recovery unit reheater do not shop in the same aisle. They all rely on seamless ferritic and austenitic alloy-steel tubes, but the grade metallurgy, dimensional envelope, and test package can change by an order of magnitude between them. ASTM A213 / A213M is the specification that ties every one of those decisions to a single, internationally recognized standard. If you are sourcing a213 a213m steel tube for a power, refinery, or process-heater package, this buyer's guide walks you through the grades, dimensions, test categories, and the mill-direct route that keeps the procurement cycle auditable and on schedule.

What ASTM A213 / A213M Actually Covers

ASTM A213 / A213M, "Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes," defines the requirements for hot-finished or cold-finished seamless tubes intended for high-temperature service. ASME SA-213 is the ASME Boiler and Pressure Vessel Code reference that carries the same requirements into Section I and Section VIII stamp calculations. Both titles cover the same product form; the choice between them depends on whether the project is code-stamped or built to a non-code commercial specification.

The standard covers two broad metallurgical families:

• Ferritic and martensitic low-alloy steels designated T2, T5, T5b, T5c, T9, T11, T12, T17, T21, T22, T23, T24, T27, T36, T91, T92, T122, T911
• Austenitic stainless steels designated TP304, TP304H, TP304N, TP304LN, TP310, TP310S, TP310H, TP316, TP316H, TP316N, TP316LN, TP317, TP321, TP321H, TP347, TP347H, TP348, TP348H, and the high-performance grades TP201, TP202, XM-15, XM-19, XM-29

Outside diameters typically range from 1/8 inch (3.2 mm) to 5 inches (127 mm), with wall thicknesses from 0.015 inch (0.4 mm) to 0.500 inch (12.7 mm) for the smaller OD sizes. The standard also lists minimum wall thicknesses, which is the reason it is the go-to reference for water-wall, screen, superheater, reheater, and economizer tubing in utility and industrial boilers. Outside that list, you may see project specifications call out A213-type testing on tubes that A213 itself does not list, which is normal practice when an EPC extends the test envelope without changing the basic specification.

How to Read the Grade Family: T2 to T92 (Ferritic) and TP304 to TP347H (Austenitic)

The "T" grades are ferritic / martensitic low-alloy steels with chromium and molybdenum as the principal alloying elements. The "TP" grades are austenitic stainless steels, named after the 300-series. Selecting between them is mostly a temperature-and-corrosion problem, with weldability and cost layered on top.

T91 and T92: the workhorses of modern supercritical and USC units

T91 (9Cr-1Mo-V-Nb-N, UNS K91560) and T92 (9Cr-0.5Mo-1.8W-V-Nb-N, UNS K92460) dominate new-build supercritical and ultra-supercritical (USC) boiler design. T91 was developed in the 1980s and rapidly replaced T22 in many thick-section superheater and reheater applications because it allowed higher steam temperatures at lower wall thickness, which in turn reduced thermal fatigue on the headers. T92, the W-bearing successor, raised the maximum allowable stress by about 20 % at 600-625 °C, which is why the newest 700 °C-class research units in Europe and Asia have gravitated to T92 and the related 9 % Cr martensitic variants.

Both grades are notoriously sensitive to welding. Pre-heat to 200-250 °C, interpass temperature control, post-weld heat treatment (PWHT) at 760 ± 15 °C, and a low-hydrogen consumable set are the four pre-conditions a mill-direct supplier will ask about before issuing an MTC. The reason is that the V-Nb-N carbonitrides that give T91 and T92 their creep strength only form correctly when the base metal and weld heat-affected zone (HAZ) are cooled in a controlled way. Skipping any of those steps leads to Type IV cracking in service, which is the most common failure mode reported in field post-mortems on 9 % Cr components.

TP321H and TP347H: stabilized austenitic for the hottest sections

Above 600 °C, the unstabilized 300-series austenitic stainless steels begin to suffer from sensitization and intergranular corrosion when exposed to the 450-850 °C range during welding or long hold times. Titanium in TP321H and niobium in TP347H tie up the carbon as TiC or NbC, which prevents chromium-carbide precipitation at the grain boundaries and keeps the chromium-depleted zone from forming. The "H" suffix indicates a higher carbon range (0.04-0.10 % C) versus the standard TP321 / TP347 (≤ 0.08 % C), which raises the allowable stress at elevated temperature. For final-stage superheater, primary reheater, and high-temperature heat-exchanger bundles in coal-fired USC and IGCC plants, TP321H and TP347H are the default.

Dimensions, Tolerances, and the Cold-Finished vs Hot-Finished Question

A213 is unusual among ASTM tube specifications because it lets the manufacturer pick between hot-finished and cold-finished production for almost every grade. Hot-finished tubes are made by piercing a billet and rolling the hollow at high temperature; the surface is rough, the OD is loose, and the wall-thickness tolerance is wider. Cold-finished tubes go through an additional drawing or pilgering pass at room temperature, which tightens the OD and wall tolerances, polishes the surface, and improves the mechanical properties through strain hardening. For boiler and heat-exchanger service, cold-finished is the default because the tighter tolerances are required for tube-sheet hole drilling, finning, and bending.

The key dimensional limits the procurement team should check before issuing a PO:

• OD tolerance: ± 0.10 mm for OD ≤ 25 mm, ± 0.13 mm for OD 25-40 mm, ± 0.20 mm for OD > 40-50 mm, and ± 0.25 mm for OD > 50-127 mm under A1016 / A450 (the general delivery condition for A213).
• Wall tolerance: ± 12.5 % of nominal wall, or in the more demanding case of small-bore finned tubes, ± 10 % of nominal wall for wall under 3 mm.
• Length: random single (4-7 m), random double (~7-13 m), or cut-to-length per PO, with a typical length tolerance of +6 / 0 mm on cut pieces.
• Straightness: 1.5 mm per meter of length, maximum 9 mm over 6 m, unless a tighter limit is required for U-bent tubing.
• Ovality: the difference between max and min OD at any cross-section must not exceed the OD tolerance band, but is usually held inside 1.0 % of nominal OD by reputable mills.

For U-bent heat-exchanger service, additional requirements apply: minimum bend radius of 1.5 × OD for austenitic, 2.0 × OD for ferritic, and a post-bend stress relief at 760-790 °C for T91 / T92. The supplier should be told whether the tubes are destined for U-bending at the time of RFQ, because cold-finishing parameters change to accommodate the wall-thinning that happens on the extrados of the bend.

Cross-Standard Mapping: A213 vs EN 10216-2 vs JIS G3462 vs GB/T 5310

A global procurement team will rarely see a single-standard RFQ. Power-plant EPCs in Asia will usually have GB/T 5310 numbers; European EPCs will have EN 10216-2 (P235GH, 16Mo3, 13CrMo4-5, 10CrMo9-10) or EN 10216-5; and Japanese EPCs will have JIS G3462 (STBA 12, 13, 20, 22, 23, 24) and JIS G3463 (SUS 304, 304H, 316, 316H, 321, 321H, 347, 347H). The 9 % Cr family is a special case: A213 T91 maps to GB/T 5310 12Cr9Mo1VNbN and to EN 10216-2 10CrMo9-10 with a tighter chemistry; A213 T92 maps to GB/T 5310 12Cr9MoW2VNbBN and there is no direct EN equivalent yet. The austenitic 300-series crosses cleanly: TP304 = 1.4301 = SUS 304TP = 0Cr18Ni9, TP316 = 1.4401 = SUS 316TP, TP321 = 1.4541 = SUS 321TP, TP347 = 1.4550 = SUS 347TP. The "H" variants are universal: TP321H = 1.4541 + 0.04-0.10 % C = SUS 321HTP, and so on.

When you submit a mill-direct RFQ, send the mill all of the relevant cross-reference numbers up front. Most Chinese mills will quote to the EN 10216-2 P-number and then add "A213 T22 / T91 equivalent" as a note, because EN 10216-2 is what they normally roll. That way you get the European certification package and the American grade name in the same delivery.

Heat Treatment, Mechanical Properties, and How to Read the MTC

A213 specifies a normalized-and-tempered or quenched-and-tempered condition for the ferritic grades, and a solution-annealed condition for the austenitic grades. The tempering temperature has a direct effect on the hardness and, more importantly, on the long-term creep strength. For T91, the standard tempering range is 730-800 °C for at least 30 minutes per inch of wall thickness; for T22 the range is 675-760 °C. The mill test certificate (MTC) per EN 10204 3.1 (or 3.2 for third-party witnessed) will record the actual heat-treatment lot data, the chemical analysis, the room-temperature tensile properties (Rm, Rp0.2, A50), the hardness (HBW or HV10), the impact energy (for thicker walls and for T91/T92 where the buyer has specified it), and the result of the mandatory flattening, flaring, and hydrostatic tests.

What a 3.1 MTC for A213 T91 typically contains

• Heat number and cast number, traced to the steelmaker's heat analysis
• Product analysis: C, Mn, P, S, Si, Cr, Mo, V, Nb, N, Al, Ti, Zr, B (in %, with ASTM A213 Table 1 limits)
• Tensile: Rm 585-760 MPa, Rp0.2 ≥ 415 MPa, elongation in 50 mm ≥ 20 %
• Hardness: ≤ 250 HBW or ≤ 265 HV10
• Flattening test: no crack or defect visible at 2/3 of the original OD spacing
• Flaring test: no crack when flared to a 22 % enlargement of the OD
• Hydrostatic test: typically 2500 psi (17.2 MPa) hold for 5 seconds, or per the order, with no leak
• NDT: eddy-current or ultrasonic test per A1016, 100 % coverage
• Grain size: ASTM No. 1 or finer for T91, per the supplementary requirement S6 when specified

If a procurement document does not request S2 (vacuum degassing), S4 (product analysis), S5 (transverse tension), S6 (grain size), S7 (tensile at elevated temperature), S8 (creep-rupture), or S9 (charpy V-notch), the mill is allowed to omit those. The cost difference between a basic 3.1 and a fully-loaded 3.1 with all supplementary requirements can be 5-10 %, but for any high-temperature service, S7 (tensile at 600 °C) and S8 (creep-rupture) are usually worth the premium because they give the design team actual elevated-temperature allowable-stress data, not the conservative lookup table value.

Mandatory and Supplementary Test Categories

A213 / SA-213 tubes have a layered test regime, and getting the right test category up front saves weeks of post-production negotiation.

Mandatory tests (every lot)

• Chemical analysis (heat + product per S4 when ordered)
• Tensile test at room temperature
• Hardness test (Brinell or Vickers, typically 3 readings per lot)
• Flattening test
• Flaring test (cold-finished only)
• Hydrostatic test or non-destructive electric test (eddy current or ultrasonic, per A1016)
• Visual and dimensional examination

Supplementary requirements (ordered when needed)

• S2: Vacuum degassing of the steel
• S4: Product (check) analysis reported on the MTC
• S5: Transverse tension test
• S6: Grain size determination
• S7: Elevated-temperature tensile test (commonly at 600 °C for T91 / T92)
• S8: Creep-rupture test (commonly 1000-hour rupture strength at 600 °C)
• S9: Charpy V-notch impact test, three specimens, full-size specimens preferred
• S10: Inclusion rating per ASTM E45 (Method A, worst-field)
• S11: Ultrasonic examination per A1016, with reference markers for defect sizing

For the same keyword project, two RFQs can therefore look superficially similar and differ by 20-30 % in landed cost just on test package. The mill-direct supplier can help you trim the test list to what the design actually requires, instead of carrying the full S-series by default.

Six Application Sectors and the Grade They Typically Pull

Boiler, superheater, and heat-exchanger service covers most of the A213 volume sold globally, but the grade and the test package change sharply across the sectors.

1. Utility power — subcritical and supercritical: water-wall T2 or T12; economizer T11 or T22; primary superheater T22 or T91; final-stage superheater and primary reheater TP304H, TP321H, TP347H, or T92; secondary reheater TP316H. Boiler tubing at this scale runs in 100-500 t lots per grade.
2. Industrial power and waste-heat recovery: T5, T9, T11, T22, TP304, TP316 — for package boilers in paper mills, sugar mills, and chemical plants, with heat-recovery steam generator (HRSG) tube banks in TP304 / TP316 for the cold-end and TP321H / TP347H for the hot-end.
3. Refinery and petrochemical — fired heaters: T5, T9, T11, T22, TP304, TP321, TP347 for ethylene cracking furnaces, catalytic reformer heaters, and sulfur-recovery unit waste-heat boilers. Radiant tubes tend to be HK40 or HP40 (centrifugally cast), but convection sections and shield tubes are often A213.
4. Hydrocrackers and hydrotreaters: TP321, TP321H, TP347, TP347H for reactor feed / effluent heat-exchanger bundles, where high-pressure hydrogen and H2S partial pressure push the material choice toward stabilized austenitic.
5. Heat exchangers in chemical, fertilizer, and LNG service: TP304 / TP304L / TP316 / TP316L for low-temperature and cryogenic sections; TP321 / TP347 for medium-temperature sections; and heat exchanger tube bundles in U-bent or straight-tube configuration.
6. Aerospace and high-temperature test rigs: smaller lots of T91, T92, TP347H, and proprietary nickel-base superalloys (not A213 but rolled in adjacent specifications).

The application is the strongest signal of which A213 grade to specify first. Once the application is fixed, the cross-standard equivalent, the test package, and the heat-treatment condition follow.

Mill-Direct vs Stockist: Where the Real Savings Are

The structural difference between a mill-direct order and a stockist order is bigger than the price line on the quote sheet. A mill-direct order ships from the production line of the manufacturer that made the steel and pierced the tube; the heat number, the cast number, and the entire MTC chain are continuous back to the steelmaker. A stockist order is one or two trading companies downstream; the MTC is usually a copy of the original mill MTC with the stockist's stamp, and the buyer has to do extra work to verify the lot. For a standard 5 t order of T22, the price difference between mill-direct and stockist is typically 8-15 %. For T91 and T92, which are tighter to schedule, the gap can be 15-25 %. For small lots under 2 t, the gap can be even larger because the stockist has to break a production-lot minimum.

Beyond price, the four operational reasons to go mill-direct:

• Direct MTC chain. No photocopy of a photocopy in the QA file. Useful when the third-party inspector wants to trace the lot back to the steelmaker.
• Heat-treatment lot control. The mill can hold a single heat for one delivery, instead of mixing two or three heats in a stockist's warehouse to make a delivery weight.
• Custom chemistry and special test package. Vacuum degassing, S7 elevated-temperature tensile, and S8 creep-rupture are straightforward to add at the mill; at a stockist, you may have to settle for what is in stock.
• Mill bundling with pipe fittings and pipe flanges. Many mill-direct suppliers also produce the matching BW fittings, SW fittings, threaded fittings, and matching flanges in carbon & carbon alloy steel and stainless, so the project can be shipped in one container with one set of QA documents. That removes a layer of interface risk and a layer of MTC reconciliation.

Five Procurement Pitfalls Specific to A213 / A213M

RFQ Checklist: Ten Lines to Get a Clean Quote

A well-formed RFQ saves a week of clarification emails. The ten lines below cover the field-tested minimum that gets a mill-direct quote back inside two business days.

1. ASTM / ASME specification and grade: e.g., ASTM A213 / SA-213 T22, or A213 TP321H
2. OD × wall × length, with length tolerance: e.g., 50.8 mm × 5.0 mm × 6000 mm cut, +6 / 0 mm
3. Quantity: total pieces or total weight, with a ± 10 % call-out allowed
4. Test category: EN 10204 3.1 or 3.2, plus supplementary requirements S2, S4, S5, S6, S7, S8, S9 as needed
5. Heat-treatment condition: normalized-and-tempered, or quenched-and-tempered, with specific tempering temperature band for T91 / T92
6. End finish: plain ends, beveled ends (30° ± 5° with 1.6 ± 0.8 mm land), or swaged ends
7. Surface condition: as-pickled, as-cold-drawn, polished (specify Ra), or bright-annealed
8. Packaging: wooden box, steel-belted bundle, plastic end-caps, VCI paper, desiccant
9. Cross-reference equivalents: EN 10216-2 P-number, JIS G3462 / G3463 symbol, GB/T 5310 number
10. Delivery terms: FOB, CFR, or DDP, with port of discharge and target delivery week

Five Buyer FAQs on A213 / A213M Steel Tube

Q1. Is ASTM A213 the same as ASME SA-213? Technically yes. A213 is the ASTM designation; SA-213 is the ASME Boiler and Pressure Vessel Code reference. They share the same requirements, but the ASME version is mandatory for code-stamped boilers, heaters, and pressure vessels. Always check whether the project specification calls out A213, SA-213, or "A213 equivalent."

Q2. Can A213 tubes be used for U-bent heat-exchanger service? Yes, but with conditions. Cold-finished A213 tubes are the standard feedstock for U-bending. Specify the post-bend stress relief separately (760-790 °C for T91 / T92; 950-1000 °C for the austenitic grades), and ask for the bend-radius and ovality limits on the drawing.

Q3. What is the typical delivery lead time for A213 T91 from a mill-direct Chinese supplier? For a 50-100 t order, the typical production lead time is 45-60 days after PO, plus 25-30 days for ocean freight to most major ports. For TP321H and TP347H, lead time can stretch to 60-75 days because the steel is made in smaller heats and the demand from USC and IGCC projects is high.

Q4. Does A213 cover duplex stainless steels? Not directly. Duplex grades (S31803, S32205, S32750) are covered by ASTM A789 / A790, not A213. If the heat-exchanger service requires duplex, the procurement team will order to A789 (seamless) or A790 (welded) and reference A213 only for the test and inspection regime.

Q5. Can an A213 tube be hot-dip galvanized? It is not common. The hot-dip galvanizing bath (≈ 450 °C) sits inside the tempering range of T22 and T91, which can change the hardness and the creep properties. For corrosion protection in atmospheric service, paint or a zinc-rich primer is preferred. For buried service, the common practice is to use a polyethylene or polypropylene wrap, or to upgrade to a higher-alloy austenitic or duplex grade.

Sourcing from EZ Steel Industrial

EZ Steel Industrial manufactures and supplies a213 a213m steel tube in the full grade range from T2 through T92, plus the matching TP304H, TP321H, TP347H, and other 300-series austenitic grades, from a three-location network covering Cangzhou (alloy steel and pipe fittings), Yangzhou (large-scale carbon and alloy steel pipe), and Lishui (stainless steel and copper-nickel corrosion-resistant materials). The company holds ISO 9001 quality management certification, API 5L and API 5CT product certifications, and PED compliance, with hydrostatic, ultrasonic, and PMI capability in-house, plus EN 10204 3.1 and 3.2 mill test certificates on every heat. The website catalogue covers a213 a213m steel tube alongside boiler tubing, heat exchanger tube, and the matching pipe fittings, flanges, gaskets, fasteners, and valves, so a single mill-direct RFQ can pull the full piping package in one shipment with one QA file.

For a quotation on T22, T91, T92, TP321H, TP347H, or any other A213 grade with a custom test package, contact the export team with the specification, OD × wall × length table, supplementary requirements, target delivery window, and the cross-reference equivalents from EN 10216-2, JIS G3462 / G3463, or GB/T 5310. The mill-direct reply typically returns inside two business days with a quote, a preliminary MTC sample, and a production slot.