JIS G3463 Carbon steel and Molybdenum Alloy Steel Pipes for Boiler and Heat Exchanger Applications

1. Scope  

JIS G 3463 applies to seamless and welded carbon steel (STB) and molybdenum alloy steel (STBA) pipes used in boilers, heat exchangers, and pressure vessels.  

2. Ordering Information  

When ordering pipes under this standard, the following must be specified:  

- Standard number (JIS G 3463)  

- Steel grade (e.g., STB340, STBA12, etc.)  

- Dimensions (outer diameter and wall thickness)  

- Length (fixed or random)  

- Test requirements (e.g., hydrostatic or nondestructive testing)  

- Additional requirements (if any, such as special tolerances or heat treatment)  

3. Steel Grades and Chemical Composition  

The standard covers several grades, categorized into:  

(A) Carbon Steel Pipes  

| Grade | C (max) | Si | Mn | P (max) | S (max) |  

|-------|---------|----|----|---------|---------|  

| STB340 | ≤0.25 | ≤0.35 | ≤0.60 | ≤0.035 | ≤0.035 |  

| STB410 | ≤0.30 | ≤0.35 | ≤0.60 | ≤0.035 | ≤0.035 |  

| STB510 | ≤0.30 | ≤0.35 | 0.30–0.90 | ≤0.035 | ≤0.035 |  

(B) Molybdenum & Alloy Steel Pipes  

| Grade | C (max) | Si | Mn | Mo | P (max) | S (max) |  

|-------|---------|----|----|-----|---------|---------|  

| STBA12 | ≤0.15 | 0.25–0.50 | 0.30–0.60 | 0.45–0.65 | ≤0.030 | ≤0.030 |  

| STBA20 | ≤0.15 | 0.25–0.50 | 0.30–0.60 | 0.45–0.65 | ≤0.030 | ≤0.030 |  

| STBA22 | ≤0.15 | ≤0.50 | 0.30–0.60 | 0.80–1.10 | ≤0.030 | ≤0.030 |  

| STBA23 | ≤0.15 | ≤0.50 | 0.30–0.60 | 1.15–1.50 | ≤0.030 | ≤0.030 |  

| STBA24 | ≤0.10 | ≤0.10 | 0.30–0.60 | 0.90–1.10 | ≤0.020 | ≤0.010 |  

4. Mechanical Properties  

| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |  

|-------|----------------------|----------------------|----------------|  

| STB340 | ≥340 | ≥175 | ≥30 |  

| STB410 | ≥410 | ≥205 | ≥25 |  

| STB510 | ≥510 | ≥275 | ≥21 |  

| STBA12 | ≥360 | ≥175 | ≥30 |  

| STBA20 | ≥360 | ≥175 | ≥30 |  

| STBA22 | ≥410 | ≥205 | ≥25 |  

| STBA23 | ≥440 | ≥225 | ≥22 |  

| STBA24 | ≥415 | ≥205 | ≥20 |  

5. Manufacturing & Heat Treatment  

- Pipes are manufactured by seamless or welding processes.  

- Heat treatment (annealing, normalizing, or tempering) is required for certain grades.  

- Welded pipes must undergo nondestructive testing (NDT) unless otherwise agreed.  

6. Inspection & Testing Requirements  

- Hydrostatic testing (or nondestructive testing as an alternative).  

- Tensile test (one test per batch).  

- Flattening test / Flaring test (for welded pipes).  

- Hardness test (if specified).  

- Chemical analysis (per heat).  

- Visual and dimensional inspection.  

7. Marking & Certification  

- Each pipe must be marked with:  

  - Manufacturer’s name or trademark  

  - Standard number (JIS G 3463)  

  - Steel grade  

  - Size (OD × thickness)  

  - Heat number  

- Inspection certificate must be provided upon request.  

8. Tolerance Requirements  

- Outer diameter: ±1% or ±0.5 mm (whichever is greater).  

- Wall thickness: Varies by manufacturing method (typically -10% to +12.5%).  

- Length: For fixed lengths, ±100 mm is common.  

Conclusion  

JIS G 3463 ensures the quality of boiler and heat exchanger tubes by specifying material composition, mechanical properties, testing, and inspection criteria. The latest version may include updates on allowable tolerances, testing methods, or additional grades, so always refer to the most recent edition for compliance.  

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