GOST 8732 Seamless Hot-deformed Steel Pipes

 1. Scope  

- Applies to seamless hot-deformed steel pipes with diameters ≥ 20 mm and wall thicknesses ≥ 2.5 mm.  

- Used in pressure systems, structural applications, and high-temperature services (unless otherwise specified).  

 2. Ordering Information  

Buyers must specify:  

- Pipe dimensions (outer diameter, wall thickness, length).  

- Steel grade (e.g., carbon steels per GOST 380, alloy steels per GOST 4543).  

- Manufacturing accuracy (normal or increased precision).  

- End condition (plain, beveled, or threaded).  

- Additional requirements (e.g., heat treatment, hydrostatic testing, non-destructive testing).  

 3. Material & Manufacturing Requirements  

- Steel grades:  

  - Carbon steels: 10, 20, 35, 45 (GOST 1050).  

  - Alloy steels: 15XM, 12X1MF (GOST 4543).  

- Heat treatment: Normalization, annealing, or tempering (if required for mechanical properties).  

- Surface quality: Must be free from cracks, laps, and scale (minor defects allowed if within thickness tolerances).  

 4. Dimensional Tolerances  

- Outer diameter: ±1.0–1.5% (varies by pipe size).  

- Wall thickness: ±10–15% (depends on manufacturing precision).  

- Length:  

  - Random length: 4–12.5 m.  

  - Fixed length: ±100 mm tolerance.  

 5. Test Requirements  

- Mandatory tests:  

  - Hydrostatic pressure test (for all pipes; pressure calculated per GOST 3845).  

  - Tensile test (for mechanical properties).  

  - Flattening test (for ductility; samples must withstand compression without cracks).  

  - Bend test (for pipes with wall thickness ≤ 10 mm).  

- Optional tests (if specified in order):  

  - Impact testing (for low-temperature applications).  

  - Ultrasonic testing (UT) or eddy current testing (ET) for defect detection.  

  - Chemical analysis (per heat or batch).  

 6. Marking & Certification  

- Each pipe must be marked with:  

  - Manufacturer’s trademark.  

  - Steel grade.  

  - Heat number.  

  - Standard designation (GOST 8732-20XX).  

- Certification: Manufacturer provides a conformance certificate including:  

  - Test results.  

  - Heat treatment data (if applicable).  

  - Compliance with GOST 8732.  

 7. Packaging & Storage  

- Pipes are bundled or crated to prevent damage.  

- Anti-corrosion protection (oiling or coating) for long-term storage.  

Here are the steel grades defined by GOST 380 (carbon steels) and GOST 4543 (alloy steels), which are commonly referenced in Russian standards like GOST 8731 and GOST 8732 for pipes and strips.

Steel Grades defined by GOST 380 & GOST 4543

 1. GOST 380-2005: Carbon Steel Grades  

Common Grades (Ordinary Quality, Marked as "Ст")  

- Group 1 (Supplied with Mechanical Properties Only)  

  - Ст0 (Low strength, non-critical uses)  

  - Ст1кп, Ст1пс, Ст1сп  

  - Ст2кп, Ст2пс, Ст2сп  

  - ... up to Ст6сп  

- Group 2 (Supplied with Mechanical + Chemical Properties)  

  - Ст3кп (Low carbon, boiling)  

  - Ст3пс, Ст3сп (Semi-calm/calm, general construction)  

  - Ст4кп, Ст4пс, Ст4сп  

  - Ст5пс, Ст5сп (Higher strength)  

- Group 3 (Guaranteed Weldability + Chemical Composition)  

  - Ст3Гпс, Ст3Гсп (With manganese for better weldability)  

Key Notes:  

- кп (кипящая, "boiling" – rimmed steel, high oxygen).  

- пс (полуспокойная, "semi-calm").  

- сп (спокойная, "calm" – fully deoxidized, best for welding).  

 2. GOST 4543-2019: Alloy Structural Steel Grades  

Common Grades (Chemical Composition + Heat Treatment)  

 Chromium (Х) & Chromium-Molybdenum (ХМ) Steels  

- 15Х (0.12–0.18% C, 0.70–1.00% Cr) – Gears, shafts.  

- 20Х (0.17–0.23% C, 0.70–1.00% Cr) – High-strength parts.  

- 40Х (0.36–0.44% C, 0.80–1.10% Cr) – High-stress components.  

- 12Х1МФ (0.08–0.15% C, 1.0% Cr, 0.25–0.35% Mo, V) – Heat-resistant for boilers.  

 Chromium-Nickel (ХН) Steels  

- 12ХН3А (0.09–0.15% C, 0.60–0.90% Cr, 2.75–3.15% Ni) – High-toughness parts.  

 Manganese (Г) Steels  

- 14Г2 (0.11–0.18% C, 1.20–1.60% Mn) – Structural uses.  

Key Notes:  

- Suffix "А" (e.g., 12ХН3А) denotes high-purity steel (reduced S/P).  

- Heat treatment (annealing, quenching) is often required for alloy steels.  

 Comparison Table  

| Standard | Steel Type       | Example Grades          | Key Applications          |  

| GOST 380 | Carbon (ordinary)  | Ст3сп, Ст5сп              | Construction, pipes, welding. |  

| GOST 4543 | Alloy structural  | 20Х, 40Х, 12Х1МФ         | Machinery, boilers, high-stress parts. |  

 Relevance to Pipe Standards (GOST 8731/8732)  

- GOST 8731 (Welded Pipes): Typically uses GOST 380 grades (e.g., Ст3сп).  

- GOST 8732 (Seamless Pipes): Uses both GOST 380 (carbon) and GOST 4543 (alloy, e.g., 15XM for high-temperature service).  

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