Xylan Coated Metal Hex Nut

QS Fastener: Xylan Coated Metal Hex Nut

Name: Xylan Coated Metal Hex Nut
Size: 7/8 Inch
Type: Heavy Type
Material: ASTM A194 2H
Surface Finish: Xylan Coated Red PTFE
Standard: API 20E

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Xylan Coated Metal Hex Nut is manufactured from ASTM A194 Grade 2H alloy steel, featuring a heavy-duty 7/8-inch structure that complies with API 20E standards. It is specifically designed for petroleum, chemical, and marine engineering applications. Its core advantage lies in the innovative red Xylan coating (PTFE-based), which combines exceptional corrosion resistance (over 2,000 hours in salt spray testing) with self-lubricating properties, effectively addressing bolt galling issues in high-pressure flanges and humid environments. The product maintains stable performance in extreme temperatures ranging from -50°C to 260°C. When paired with ASTM A193 B7 bolts, it significantly extends equipment maintenance intervals and reduces total lifecycle costs by 30%.

1. Forging Process (Hot Forging)
The ASTM A194 2H hex nut (base material of Xylan Coated Metal Hex Nut) undergoes hot forging to ensure continuous and complete metal grain flow, enhancing mechanical properties and fatigue life.

1.1 Forging Temperature Control
- Forging temperature range: 950~1200°C (e.g., 42CrMo4 at 1000~1100°C), suitable for metal hex nuts requiring subsequent Xylan coating.
- Heating method: Induction or gas furnace heating to minimize excessive scale formation, which could affect the coating adhesion of Xylan Coated Metal Hex Nut.
- Soaking time: 15~20 minutes per 25mm thickness to ensure uniform austenitization.

1.2 Forging Process Details
1) Pre-forging:
- Closed-die forging minimizes flash, improving material yield (critical for the high-cost base material of Xylan Coated Metal Hex Nut).
- Forging pressure: 800~1200 tons to ensure complete mold filling.

2) Finish forging:
- Final forging temperature ≥850°C to prevent coarse grain structure, which could compromise the ultimate strength of Xylan Coated Metal Hex Nut.

1.3 Metal Grain Flow Optimization
- Hot forging enhances the fatigue strength of Xylan Coated Metal Hex Nut by 20%~30% compared to machined alternatives.

2. Heat Treatment (Quenching & Tempering + Dehydrogenation)
The base material of Xylan Coated Metal Hex Nut undergoes quenching, tempering, and dehydrogenation to meet ASTM A194 2H standards.

2.1 Quenching and Tempering
1) Quenching process:
- Temperature: 850~880°C, holding time 1.2~1.5 min/mm to ensure uniform core hardness of Xylan Coated Metal Hex Nut.
- Quenching medium: Fast quench oil (VG 68) or PAG solution (reduces distortion risk).

2) Tempering process:
- Temperature: 550~650°C, holding time 2~4 hours to achieve tempered sorbite structure in Xylan Coated Metal Hex Nut.
- Performance requirements: Tensile strength ≥850 MPa, elongation ≥14%.

2.2 Dehydrogenation
- Xylan Coated Metal Hex Nut requires baking at 200~230°C for 8~24 hours after plating/pickling to prevent hydrogen embrittlement.
- Compliance with ASTM F1940 testing (200-hour constant load without fracture).

3. Quality Control Measures
- Metallographic inspection: Ensures uniform tempered sorbite microstructure in Xylan Coated Metal Hex Nut.
- Hydrogen content control: Thermal conductivity method verifies hydrogen content <1 ppm, ensuring base material integrity prior to coating.

Through these processes, Xylan Coated Metal Hex Nut delivers long-term reliability in high-temperature, high-pressure, and corrosive environments, making it ideal for demanding applications in petroleum and chemical industries.

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