JIS G3461 STB510 High Pressure Boiler Tube
JIS G3461 is the Japanese Industrial Standard titled "Carbon Steel Boiler and Heat Exchanger Tubes." It covers three strength grades of seamless and electric-resistance-welded carbon steel tube intended for service in boilers, superheaters, heat exchangers, condensers, and similar heat-transfer equipment - particularly in chemical and petroleum plants and in power generation. The three grades are STB340 (tensile ≥340 MPa), STB410 (tensile ≥410 MPa), and STB510 (tensile ≥510 MPa). STB510 is the strongest of the three and is used where higher working pressures or temperatures call for it.
Tubes under JIS G3461 are produced either by a seamless process (hot-finished or cold-finished) or by electric resistance welding (ERW). All STB510 tubes, regardless of manufacturing route, are required to be supplied in the normalized condition. Killed steel is used as the raw material to ensure consistent mechanical properties and to avoid porosity-related defects in service.
GNEE is a manufacturer, supplier and exporter of JIS G3461 STB510 Heat Resistant Carbon Steel Pipe and Tubes made of high quality raw materials. GNEE products are designed as per major international standards and sold in many countries around the world.
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STB510 Chemical Composition
STB510 is a plain carbon steel - not an alloy. The standard places upper or range limits on the five common elements (C, Si, Mn, P, S) and intentionally does not require chromium, molybdenum, or nickel additions. This is what distinguishes STB510 from the alloy grades STBA12, STBA22, and others in JIS G3462.
| Element | C | Si | Mn | P | S |
|---|---|---|---|---|---|
| STB510 | 0.25 max | 0.35 max* | 1.00 – 1.50 | 0.035 max | 0.035 max |
* Si may be specified in the range 0.10 – 0.35% by the purchaser. No intentional addition of Cr, Ni, Mo, or Cu is required by JIS G3461 for STB510 - these are typically reported as residual or trace levels only.
For product analysis (verification on the finished tube), JIS G0321 tolerances apply. Tubes are routinely subjected to ladle and product chemical analysis to confirm compliance with the heat-analysis limits shown above.
STB510 Mechanical Properties
The tensile requirements of JIS G3461 STB510 are tested per JIS Z 2241 using No.11 or No.12 test pieces, parallel to the tube axis. The minimum elongation depends on both the outside diameter and the wall thickness of the tube.
| Property | Symbol | Value | Test condition |
|---|---|---|---|
| Tensile strength (min) | Rm | 510 MPa (N/mm²) | Longitudinal, per JIS Z 2241 |
| Yield point or 0.2% proof stress (min) | ReH or Rp0.2 | 295 MPa (N/mm²) | Upper yield point preferred; 0.2% proof stress used where not pronounced |
| Elongation (min) - OD < 10 mm | A | 17% | No.11 test piece |
| Elongation (min) - 10 ≤ OD < 20 mm | A | 20% | No.11 test piece |
| Elongation (min) - OD ≥ 20 mm, WT > 7 to < 8 mm | A | 25% | No.11 or No.12 test piece, longitudinal |
| Rockwell hardness (max, mean of 3) | HRBW | 92 | - |
For heat-exchanger tubes, the purchaser may optionally specify an upper tensile-strength limit, calculated as the minimum value shown above plus 120 MPa. This upper limit is useful where the tube will be flanged, expanded, or otherwise cold-worked into tube sheets and excess strength could make these operations difficult.
Elongation by wall thickness (OD ≥ 20 mm, No.12 test piece)
| Wall thickness (mm) | Min elongation (%) |
|---|---|
| 1 < t ≤ 2 | 16 |
| 2 < t ≤ 3 | 18 |
| 3 < t ≤ 4 | 19 |
| 4 < t ≤ 5 | 20 |
| 5 < t ≤ 6 | 22 |
| 6 < t ≤ 7 | 24 |
| 7 < t < 8 | 25 |
Heat Treatment and Manufacturing
JIS G3461 specifies the heat-treatment condition by manufacturing route. For STB510, the standard requirement is normalizing for all routes - hot-finished seamless, cold-finished seamless, and electric-resistance-welded. A cold-finished ERW tube that was normalized before cold finishing may be supplied annealed. Other grades in the same standard may be supplied in the as-manufactured condition with optional low-temperature annealing or normalizing.
Manufacturing and finishing symbols
| Symbol | Meaning |
|---|---|
| S | Seamless (pipe manufacturing method) |
| E | Electric resistance welded (pipe manufacturing method) |
| H | Hot-finished |
| C | Cold-finished |
| G | As electric resistance welded (finishing method) |
Example marking: STB510-S-H denotes a hot-finished seamless STB510 tube; STB510-E-G denotes an as-electric-resistance-welded STB510 tube. ERW tubes per JIS G3461 have the internal and external weld flash controlled to a smooth contour, with the internal weld height limited to 0.25 mm or less.
Dimension Range
Per JIS G3461, STB510 is generally produced in outside diameter range 15.9 to 139.8 mm, with wall-thickness tolerances depending on the manufacturing method (hot-finished seamless, cold-finished seamless, or ERW). Common trade availability extends OD to approximately 177.8 mm. Standard lengths are 3 to 12 metres or as specified by the purchaser.
| Parameter | Range |
|---|---|
| Outside diameter | 15.9 – 139.8 mm (standard); up to ~177.8 mm common |
| Wall thickness | Per JIS G3461 tolerance tables (varies by OD and route) |
| Length | 3 – 12 m, or per order |
| End finish | Plain end, beveled end, or threaded per order |
Optional Testing
In addition to the mandatory tensile, hardness, flattening, and dimensional checks, JIS G3461 allows the following optional tests to be specified by the purchaser: flattening test, flaring test, reverse flattening test (for ERW tubes), and hydrostatic test. NDT such as eddy-current or ultrasonic examination may be agreed upon for critical service.
Applications of STB510
STB510 is used for heat-transfer equipment and high-pressure boiler service where higher strength than STB340 or STB410 is required. Typical applications include:
Boiler tubes - water tubes, smoke tubes, and generating tubes
Superheater tubes
Air preheater tubes
Heat-exchanger tubes - shell-and-tube, condenser, and cooler service
Catalyst tubes in chemical and petrochemical processing
High-pressure process piping in refineries and chemical plants
Power-plant auxiliary tubing in fossil-fuel and combined-cycle stations
For elevated-temperature alloy steel boiler tubes (chromium-molybdenum grades such as STBA12, STBA22, STBA23, STBA24, STBA25), JIS G3462 is the applicable standard - not JIS G3461. STB510 should not be substituted for alloy grades in high-temperature service beyond its carbon-steel capability.
JIS G3461 STB510 Low Carbon Seamless Steel tube packaging and shipping
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Why choose GNEE
GNEE supplies JIS G3461 STB510 tubes in both seamless and ERW forms, in the normalized condition, with full traceability and third-party inspection (ISO, PED, BV available on request). Manufacturing covers the standard OD range 15.9 – 139.8 mm, with extended trade availability up to ~177.8 mm and lengths to 12 m or per order. Mill Test Certificates reference JIS G3461 and include heat analysis, product analysis, tensile, hardness, and dimensional results.
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FAQ
1. What is JIS G3461 STB510?
JIS G3461 STB510 is a Japanese Industrial Standard grade of seamless and electric-resistance-welded (ERW) carbon steel tube used for boilers and heat exchangers. The grade designation indicates a minimum tensile strength of 510 MPa. It is the highest-strength grade in the JIS G3461 family, which also includes STB340 and STB410.
2. What is the difference between STB510, STB410, and STB340?
All three are JIS G3461 carbon steel boiler and heat exchanger tubes with progressively higher strength. STB340 has tensile ≥340 MPa and yield ≥175 MPa; STB410 has tensile ≥410 MPa and yield ≥255 MPa; STB510 has tensile ≥510 MPa and yield ≥295 MPa. STB510 is selected where higher working pressures or temperatures are required.
3. What is the chemical composition of JIS G3461 STB510?
STB510 is a plain carbon steel. Per JIS G3461: Carbon 0.25% max, Silicon 0.35% max (may be specified in 0.10–0.35% range by purchaser), Manganese 1.00–1.50%, Phosphorus 0.035% max, Sulfur 0.035% max. No intentional chromium, nickel, molybdenum, or copper additions are required.
4. What are the mechanical properties of STB510?
Minimum tensile strength 510 MPa and minimum yield strength 295 MPa. Minimum elongation ranges from 17% (OD < 10 mm) to 25% (OD ≥ 20 mm, wall thickness > 7 mm), per JIS Z 2241. Maximum Rockwell hardness is 92 HRBW. An upper tensile-strength limit equal to the minimum value plus 120 MPa may be specified by the purchaser for heat-exchanger service.
5. What heat treatment does STB510 require?
Normalizing is required for STB510 across all manufacturing routes - hot-finished seamless, cold-finished seamless, and ERW. A cold-finished ERW tube that was normalized prior to cold finishing may be supplied in the annealed condition after final cold working.
6. What is the size range for STB510 tubes?
JIS G3461 STB510 is generally produced in outside diameter 15.9 to 139.8 mm with wall-thickness tolerances per the standard's tables for the relevant manufacturing method. Common trade availability extends OD to approximately 177.8 mm. Lengths are typically 3 to 12 m.
7. What is STB510 used for?
STB510 is used for boiler tubes, superheater tubes, air preheater tubes, heat-exchanger tubes, condenser tubes, and catalyst tubes in chemical, petrochemical, and power-plant service. For elevated-temperature alloy boiler tubes (chromium-molybdenum), JIS G3462 (STBA grades) is the correct standard.
8. Is STB510 seamless or welded? Can it be supplied either way?
STB510 can be supplied as seamless (hot-finished S-H or cold-finished S-C) or as electric-resistance-welded (ERW, E-G) tube, all under the same JIS G3461 grade designation. The choice depends on size, pressure rating, and application; ERW is typically more economical in smaller diameters, while seamless is preferred for higher-pressure and critical service.
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