Se lavori sulla media pressione cinese, progetti a media temperatura, come caldaie industriali, recipienti per lo stoccaggio di sostanze chimiche, o serbatoi a pressione comunali: hai bisogno di un acciaio che soddisfi i GB/T della Cina 713 standard for reliability and cost-effectiveness.GB 20G pressure vessel steel è la soluzione giusta: come acciaio al carbonio-manganese adatto per il servizio a pressione, la sua forza equilibrata, saldabilità, and affordability make it ideal for China’s industrial infrastructure. Questa guida ne analizza le proprietà, applicazioni del mondo reale, processo di produzione, and material comparisons to help you solve mid-range pressure equipment challenges.
1. Material Properties of GB 20G Pressure Vessel Steel
GB 20G’s performance comes from its optimized carbon-manganese composition and strict quality control—engineered to handle medium temperatures (fino a 450 °C) and pressures (fino a 8,000 psi) while remaining easy to fabricate. Let’s explore its key properties in detail.
1.1 Composizione chimica
GB 20G adheres to China’s GB/T 713 standard, with elements controlled to avoid brittleness and ensure compatibility with domestic manufacturing processes. Below is its typical composition (for plates ≤ 60 mm di spessore):
| Elemento | Simbolo | Gamma di contenuti (%) | Key Role |
|---|---|---|---|
| Carbonio (C) | C | 0.17 – 0.24 | Enhances strength; kept moderate to preservesaldabilità (critical for on-site vessel fabrication) |
| Manganese (Mn) | Mn | 0.35 – 0.65 | Aumentaresistenza alla trazione without sacrificingduttilità at medium temperatures |
| Silicio (E) | E | 0.17 – 0.37 | Aiuta la disossidazione durante la produzione dell'acciaio; supports stability at 300–450 °C |
| Fosforo (P) | P | ≤ 0.035 | Minimized to prevent brittle fracture in cold or cyclic pressure conditions (per esempio., Northern China winters) |
| Zolfo (S) | S | ≤ 0.035 | Controlled to avoid weld defects (per esempio., porosità) in humid Chinese industrial environments |
| Cromo (Cr) | Cr | ≤ 0.20 | Trace element; no significant impact on standard performance |
| Nichel (In) | In | ≤ 0.20 | Trace element; enhances low-temperatureimpact toughness (for Northeast China’s -20 °C winters) |
| Vanadium (V) | V | ≤ 0.05 | Trace element; refines grain structure for uniform strength across thick plates |
| Molibdeno (Mo) | Mo | ≤ 0.10 | Trace element; slightly improves high-temperature creep resistance (for small boilers) |
| Rame (Cu) | Cu | ≤ 0.30 | Trace element; adds mild atmospheric corrosion resistance for outdoor tanks in Southern China |
1.2 Proprietà fisiche
These traits make GB 20G suitable for China’s diverse industrial environments:
- Densità: 7.85 g/cm³ (consistent with carbon steels)—simplifies weight calculations for large vessels (per esempio., 15-meter diameter storage tanks)
- Punto di fusione: 1,420 – 1,460 °C (2,588 – 2,660 °F)—compatible with domestic welding processes (ME, TIG, submerged arc welding)
- Conducibilità termica: 45.0 Con/(m·K) A 20 °C—ensures even heat distribution in boilers, reducing thermal stress in cyclic use
- Coefficiente di dilatazione termica: 11.7 × 10⁻⁶/°C (20 – 100 °C)—minimizes expansion/contraction damage in China’s seasonal temperature shifts (per esempio., -20 °C to 35 °C)
- Proprietà magnetiche: Ferromagnetic—enables non-destructive testing (NDT) like magnetic particle inspection to detect hidden weld defects.
1.3 Proprietà meccaniche
GB 20G’s mechanical performance meets GB/T 713 requirements for medium-pressure service. Below are typical values:
| Proprietà | Metodo di misurazione | Valore tipico | GB Standard Minimum Requirement |
|---|---|---|---|
| Durezza (Rockwell) | HRB | 70 – 85 HRB | N / A (controlled to avoid brittleness) |
| Durezza (Vickers) | alta tensione | 140 – 170 alta tensione | N / A |
| Resistenza alla trazione | MPa | 410 – 550 MPa | 410 MPa |
| Forza di snervamento | MPa | 225 – 345 MPa | 225 MPa |
| Allungamento | % (In 50 mm) | 24 – 30% | 24% |
| Resistenza all'impatto | J (A 0 °C) | ≥ 35 J | ≥ 27 J (for general service) |
| Fatigue Limit | MPa (rotating beam) | 170 – 210 MPa | N / A (tested per project pressure cycles) |
1.4 Altre proprietà
GB 20G’s traits solve key challenges for Chinese industrial projects:
- Weldability: Excellent—even novice welders can join it without preheating (saves time on rural construction sites with limited equipment)
- Formabilità: Good—can be bent into curved boiler shells or tank walls (common in Chinese small-to-medium factories) senza perdere le forze
- Resistenza alla corrosione: Moderate—resists water and mild chemicals; for harsh conditions (per esempio., coastal Guangdong), add epoxy coatings or zinc plating
- Duttilità: High—absorbs sudden pressure spikes (per esempio., in chemical reactors) without fracturing, a key safety feature for Chinese industrial sites
- Toughness: Reliable—maintains strength at 0 °C, suitable for cold regions like Heilongjiang and Inner Mongolia.
2. Applications of GB 20G Pressure Vessel Steel
GB 20G’s versatility and GB compliance make it a staple in China’s industrial sector. Here are its key uses:
- Pressure Vessels: Medium-pressure chemical reactors and gas cylinders (≤ 8,000 psi)—compliant with China’s GB 150 pressure vessel standard.
- Boilers: Industrial boilers for factories and district heating systems—tolerates temperatures up to 450 °C, perfect for China’s northern winter heating needs.
- Storage Tanks: Large oil, acqua, and chemical storage tanks—its formabilità allows for seamless curved walls, and its low cost fits budget-conscious projects.
- Petrochemical Plants: Low-to-medium pressure process equipment like heat exchangers and small distillation columns—resists mild chemical corrosion and cyclic temperatures.
- Attrezzature industriali: Hydraulic reservoirs and compressor housings—used in China’s manufacturing hubs (per esempio., Guangdong, Jiangsu) for reliable pressure containment.
- Construction and Infrastructure: Municipal water pressure tanks and wastewater treatment reactors—affordable for public projects in small-to-medium cities.
3. Manufacturing Techniques for GB 20G Pressure Vessel Steel
Producing GB 20G requires strict compliance with GB/T 713 to ensure compatibility with Chinese industrial needs. Here’s the step-by-step process:
- Produzione dell'acciaio:
- GB 20G is made using an Forno ad arco elettrico (EAF) (aligns with China’s “dual carbon” obiettivi, recycling scrap steel) O Fornace ad ossigeno basico (BOF). Workers control carbon (0.17–0.24%) and manganese (0.35–0.65%) to meet GB standards.
- Rotolamento:
- The steel is Laminato a caldo (1,100 – 1,200 °C) into plates of varying thicknesses (6 mm a 100+ mm). Hot rolling refines the grain structure, enhancing tenacità for medium-temperature service.
- Trattamento termico (Optional Normalization):
- For thick plates (> 30 mm) or cold-climate projects: Plates are heated to 880 – 920 °C, held for 30–60 minutes, then air-cooled. This process uniformizes the microstructure and boosts impact toughness.
- Lavorazione & Finitura:
- Plates are cut with plasma or laser tools to fit vessel sizes. Workers drill holes for nozzles and manholes, then grind edges smooth for tight welds (no leaks allowed, per GB 150).
- Trattamento superficiale:
- Rivestimento: To protect against Chinese environmental conditions:
- Epoxy Liners: For chemical tanks—resists acids and alkalis for 15+ anni, compliant with China’s environmental regulations.
- Zincatura: For coastal projects (per esempio., Zhejiang, Fujian)—stops saltwater corrosion from the East China Sea.
- CRA Cladding: For sour gas equipment—adds a thin stainless steel layer (per esempio., 304l) to prevent sulfide stress cracking.
- Pittura: For boilers and outdoor tanks—uses cold-flexible, weather-resistant paint that remains durable at -20 °C (for Northern China).
- Rivestimento: To protect against Chinese environmental conditions:
- Controllo qualità:
- Chemical Analysis: Use spectrometry (per GB/T 223) to verify element levels.
- Mechanical Testing: Trazione, impatto (A 0 °C), and hardness tests on every heat of steel (GB/T 228.1, GB/T 229).
- NDT: Ultrasonic testing (100% of plate area) finds internal defects; radiographic testing checks all welds (per GB/T 11345).
- Hydrostatic Testing: Finished vessels are filled with water and pressed to 1.5× their design pressure for 30–60 minutes—no leaks mean they pass GB 150 standard.
4. Casi di studio: GB 20G in Action
Real Chinese projects demonstrate GB 20G’s reliability in medium-pressure applications.
Caso di studio 1: Industrial Boiler (Heilongjiang, Cina)
A textile factory in Harbin needed a boiler to generate steam for production and heat for winter (ambient temperature -20 °C). They chose GB 20G plates (12 mm di spessore, normalized) for itssaldabilità and cold toughness. The boiler operates at 400 °C and 4,000 psi daily. Dopo 7 anni, it has no cracks or corrosion—even in Harbin’s harsh winters. The factory saved 25% on material costs vs. using alloy steel.
Caso di studio 2: Chemical Storage Tank (Jiangsu, Cina)
A chemical company in Suzhou needed a 10-meter diameter tank to store 300,000 liters of dilute sulfuric acid. They used GB 20G plates (10 mm di spessore) with an epoxy liner for corrosion protection. The tank was fabricated on-site in 2 weeks and has operated for 5 years with zero leaks. This project saved the company ¥500,000 vs. using stainless steel.
5. GB 20G vs. Other Materials
How does GB 20G compare to other pressure vessel steels, including international and Chinese grades?
| Materiale | Similarities to GB 20G | Differenze chiave | Ideale per |
|---|---|---|---|
| Grado SA516 60 | Carbon steel for pressure vessels | ASME standard (NOI.); higher yield strength (414 MPa); pricier | Global projects needing ASME compliance |
| EN P235GH | EN carbon steel | Similar strength; EN standard; better for European projects | EU-aligned medium-pressure projects |
| GB 15CrMoR | Chinese alloy steel | Higher chromium/molybdenum; better high-temp resistance; 50% pricier | Chinese high-temperature boilers (＞450 °C) |
| 304 Acciaio inossidabile | Resistente alla corrosione | Excellent rust resistance; 3× more expensive; forza inferiore | Chinese coastal high-corrosion projects |
| Plastica (HDPE) | Low-pressure use | Corrosion-proof; Debole; cheap | Small residential water tanks (≤ 100 psi) |
Yigu Technology’s Perspective on GB 20G
Alla tecnologia Yigu, GB 20G is our top recommendation for Chinese medium-pressure, medium-temperature projects. It meets GB/T 713 and GB 150 standard, making it fully compatible with domestic industrial needs—from Northern China’s cold boilers to Southern China’s chemical tanks. We supply custom-thickness plates (6–100 mm) with epoxy, zinco, or CRA treatments, tailored to regions (per esempio., Heilongjiang projects get normalized plates for cold toughness). For clients transitioning from low-grade steels, GB 20G offers the right balance of performance and cost, avoiding the premium of alloy or stainless steels.
FAQ About GB 20G Pressure Vessel Steel
- Can GB 20G be used for sour gas pressure vessels in China?
Yes—with extra protection. Add a CRA cladding (per esempio., 316L acciaio inossidabile) or thick epoxy liner to resist sulfide stress cracking. Ensure the steel’s sulfur content is ≤ 0.025% (meets China’s GB/T 713 sour service requirements). - What’s the maximum temperature GB 20G can handle?
GB 20G safely operates at temperatures up to 450 °C for long-term service. For temperatures above 450 °C (per esempio., large power plant boilers), choose GB 15CrMoR (acciaio legato) which offers better creep resistance. - Is GB 20G compatible with Chinese welding standards?
Yes—fully compatible with China’s GB/T 985 (welding procedures) and GB/T 5117 (carbon steel electrodes). Most domestic fabricators are familiar with welding GB 20G, reducing on-site construction time and costs.