What are the stainless steel grades covered under JIS G3463 steel tube specification?

If you are evaluating tube material for a new build, a replacement order, or a multi-standard project package, understanding exactly which grades are listed under JIS G 3463 is the first step before comparing them against the equivalent JIS G3463 steel tube products and the parallel ASTM/EN grades that show up in the same procurement document.

This guide walks through the stainless steel grades that JIS G 3463 covers, explains the heat-treatment and delivery conditions, and shows how each grade maps to the products EZ Steel Industrial supplies under its stainless steel tube program.

Scope of JIS G 3463

JIS G 3463 covers seamless and welded austenitic stainless steel tubes (and a defined set of duplex tubes) primarily used for:

• Boiler tubes and superheater tubes
• Heat exchanger tubes
• Condenser tubes and catalyser tubes
• Chemical and petroleum industry heat-transfer service

The standard generally applies to tubes with an outside diameter of 15.9 mm to 139.8 mm and wall thicknesses selected from the JIS thickness series. Tubes used for fired heaters, sanitary tubing, and structural applications are explicitly out of scope and are covered by separate JIS standards.

Austenitic Stainless Steel Grades Covered

The largest family in JIS G 3463 is the austenitic stainless series, designated with the symbol “TB” (Tube, Boiler/Heat Exchanger) or “STB” in older revisions. The 2023 edition lists the following designations:

In addition to the standard austenitic designations, the 2023 revision also lists SUS890LTB, SUS821L1TB, and other lean-duplex/economic grades that have been adopted in the Japanese boiler market for condensers and economizer tubing. EZ Steel Industrial can supply tubes in any of these JIS G 3463 designations as part of our stainless steel tube inventory, with mill test certificates issued per EN 10204 3.1.

Heat-Treatment and Delivery Condition

JIS G 3463 specifies that austenitic tubes shall be supplied in the solution-annealed condition unless otherwise agreed. The minimum solution-treatment temperatures defined in the standard are:

• SUS304 / SUS304H / SUS304L: 1010 °C and above, with rapid cooling
• SUS309 / SUS310 series: 1030 °C and above, with rapid cooling
• SUS316 / SUS316H / SUS316L: 1010 °C and above, with rapid cooling
• SUS321 / SUS347: 920 °C and above, with rapid cooling to preserve stabilization
• Duplex SUS329 grades: 950–1100 °C, water-quenched to maintain the dual-phase balance

Surface finish typically follows the customer’s drawing; pickling, passivation, and bright-annealed options are all available on request to match downstream welding or bending operations.

Mechanical and Testing Requirements

For each grade the standard defines minimum tensile strength, proof stress (0.2 % offset), and elongation values, together with hardness limits. The typical envelope for the most common grades is:

Testing required by the standard includes hydrostatic or eddy-current inspection, flattening and flaring tests, and dimensional verification. At EZ Steel Industrial, every JIS G 3463 heat we deliver is also subjected to additional PMI, ultrasonic, and intergranular-corrosion testing on customer request — particularly important for boiler tubing used in superheater banks where tube failure has immediate safety implications.

JIS G 3463 vs ASTM A213 / A249 and EN 10216-5

For international projects, JIS G 3463 grades are often cross-referenced with ASTM and EN designations. The following mapping covers the most common equivalents and is the basis for the heat exchanger tube and boiler tube program we run for EPC customers:

These cross-references are critical when a project uses both Japanese-built islands and Western European specifications, because the chemistry and mechanical-property envelopes are very similar but not always identical. EZ Steel’s engineering team can advise on dual-certification lots where the same heat is delivered against both JIS and ASTM requirements.

Selecting the Right Grade for Your Service

For most boiler, superheater, and heat-exchanger service conditions, a quick selection logic works as follows:

• SUS304TB / 304LTB — general water, steam, and air service; the default choice for economizer and air-preheater tubing
• SUS316TB / 316LTB — preferred when chloride content in the process fluid is moderate (e.g., coastal cooling, brackish water)
• SUS316TiTB, SUS321TB, SUS347TB — for welded constructions operating in the sensitization range (450–850 °C)
• SUS310TB — for high-temperature radiant sections, reformer outlets, and furnace tubes
• Duplex SUS329J-series — when chloride stress-corrosion cracking is the dominant failure mode and higher strength is required

If the design envelope includes frequent thermal cycling, localized corrosion, or weld-repair scenarios, the stabilized 321/347 grades or the duplex 329 series usually outperform the standard 304/316 options.

Manufacturing and Supply Notes from EZ Steel Industrial

EZ Steel Industrial Co., Ltd. has supplied JIS G 3463 stainless tubes to boiler makers, petrochemical EPCs, and shipyards since 1994. Our three-plant network covers Cangzhou (alloy and fittings), Yangzhou (carbon and alloy pipe production), and Lishui (stainless and copper-nickel). For JIS G 3463 orders we typically:

• Source billet from approved mills and re-test the heat chemistry at our own PMI station
• Cold-pilot or cold-draw to the required OD and wall within the 15.9–139.8 mm envelope
• Solution-anneal in continuous or batch furnaces, with chart records retained for each lot
• Perform hydrostatic, eddy-current, and ultrasonic inspection, plus flattening / flaring on the first piece of every batch
• Issue EN 10204 3.1 mill test certificates and, on request, 3.2 certificates witnessed by independent third parties

The same production line is used for our heat exchanger tube range, U-bend tubes, and finned tubes, which means project packages combining JIS G 3463 tubes, ASTM A213 tubes, finned elements, and matching pipe fittings / flanges can be shipped from a single source.

Common Pitfalls When Sourcing JIS G 3463 Tubes

A few points are worth double-checking before placing an order:

1. Confirm whether the spec calls for seamless or welded + solution-annealed — JIS G 3463 covers both, but the pressure rating differs.
2. Verify the solution-treatment temperature on the MTC, especially for 321/347 lots, where under-treatment will leave stabilization incomplete.
3. For replacement tubes on existing Japanese-built units, check whether the original call-out used the legacy STB340 / STB410 / STB510 symbols from older editions and request the modern equivalent.
4. If the project also references EN or ASTM, ask for dual certification up front to avoid re-testing on site.

Closing Notes

JIS G 3463 remains one of the cleanest and most internationally compatible specifications for stainless boiler and heat-exchanger tubing. The 2023 revision aligns the grade list more closely with ASTM A213/A249 and EN 10216-5, which simplifies procurement for global EPCs. Whether you need a single replacement coil of SUS304TB or a full project package of SUS316LTB plus finned sections, EZ Steel Industrial can support both — backed by EN 10204 3.1/3.2 certification, project documentation, and just-in-time delivery from our Cangzhou, Yangzhou, and Lishui facilities.

For technical datasheets, current stock lists, or a quotation on a specific JIS G 3463 grade, contact our export team at export@ezsteelpipe.com or visit the JIS G3463 product page for full specifications.