Graphite packing, also known as graphite filament packing or flexible graphite packing, is a high-performance sealing material engineered for demanding industrial applications. It is manufactured from pure, exfoliated graphite ribbons that are compressed and reinforced to create a robust, pliable seal. Unlike traditional braided packings, graphite packing offers exceptional thermal conductivity, chemical inertness, and self-lubricating properties, making it the superior choice for sealing pumps, valves, agitators, and flanges in extreme environments involving high temperatures, aggressive media, and rapid thermal cycling. Kaxite Seals specializes in manufacturing premium-grade graphite packing solutions that deliver unmatched reliability and longevity.
Choosing the right sealing material is critical for operational safety and efficiency. Kaxite Seals' graphite packing stands out due to its unique combination of properties:
Kaxite Seals offers a comprehensive range of graphite packing styles to meet specific application requirements. Below are the detailed specifications for our standard and reinforced series.
| Parameter | Specification / Value |
|---|---|
| Material Composition | 99.5% Pure Exfoliated Graphite, Reinforced with Corrosion-Resistant Inserter |
| Temperature Range | -400°F to +3000°F (-240°C to +1650°C) Non-Oxidizing; Up to 850°F (454°C) Oxidizing |
| pH Range | 0 - 14 (Except strong oxidizing acids like nitric, chromic, etc.) |
| Density | 90 - 110 lbs/ft³ (1.44 - 1.76 g/cm³) |
| Thermal Conductivity | High, ≥ 100 W/m·K (in-plane, typical) |
| Compressibility | 40 - 60% |
| Recovery | 15 - 30% |
| Available Sizes (Square Cross-Section) | 1/8", 3/16", 1/4", 5/16", 3/8", 1/2", 5/8", 3/4" |
| Standard Spool Length | 25 ft (7.62 m) or 50 ft (15.24 m) |
| Primary Applications | Valve stems, Static flanges, Heat exchangers, Expansion joints, Autoclaves |
| Parameter | Specification / Value |
|---|---|
| Material Composition | Pure Graphite Foil laminated with Inconel 601/825 wire mesh (or SS316 for lower temp) |
| Temperature Range | -400°F to +2100°F (-240°C to +1150°C) Inert; Up to 1200°F (650°C) Oxidizing |
| pH Range | 0 - 14 (Except strong oxidizing agents) |
| Density | 110 - 130 lbs/ft³ (1.76 - 2.08 g/cm³) |
| Tensile Strength | Significantly higher than pure graphite packing |
| Extrusion Resistance | Excellent, due to metal reinforcement |
| Available Sizes (Square Cross-Section) | 1/4", 5/16", 3/8", 1/2", 5/8", 3/4" |
| Standard Spool Length | 10 ft (3.05 m) or 25 ft (7.62 m) |
| Primary Applications | High-speed pump shafts, Agitators, Mixers, Severe service valves, High-pressure applications |
Selecting the appropriate graphite packing from Kaxite Seals depends on your specific operating conditions. Use this guide as a reference:
Proper installation is key to achieving optimal performance and service life from your Kaxite graphite packing.
Q: Can graphite packing be used in pumps handling strong oxidizing acids like nitric or sulfuric acid?
A: Caution is advised. While pure graphite has broad chemical resistance, it can be attacked by strong oxidizing agents in high concentrations at elevated temperatures. For such services, it is crucial to consult the chemical compatibility charts provided by Kaxite Seals. In many cases, a specially treated or reinforced grade may be recommended, or an alternative material should be considered.
Q: How does graphite packing compare to traditional PTFE or aramid fiber packings?
A: Graphite packing outperforms PTFE and aramid in high-temperature applications (above 500°F/260°C). It has far better thermal conductivity, which prevents heat build-up. It is also more chemically inert than aramids and has superior creep resistance compared to PTFE. However, for lower-temperature, high-abrasion applications, aramid might be more suitable.
Q: Is lubrication required for graphite packing during operation?
A: Generally, no. One of the major advantages of graphite packing is its self-lubricating property derived from the graphite layers. In most applications, a slight leakage of the process fluid provides sufficient cooling and lubrication. For dry-running or abrasive services, a compatible external lubricant or flush might be recommended by Kaxite engineers.
Q: What is the typical expected service life of Kaxite graphite packing?
A: Service life varies greatly depending on the application: shaft speed, temperature, pressure, media, and installation quality. Under standard conditions in a hot water pump, it's not uncommon for Kaxite graphite packing to last 1-3 years or more before requiring adjustment or replacement, significantly longer than many organic packings.
Q: How do I determine the correct size and number of rings for my stuffing box?
A: The packing cross-section should be sized so that the inside diameter of the cut ring fits snugly on the shaft with a slight drag. A common rule is: Packing Cross-Section = (Stuffing Box ID - Shaft OD) / 2. The number of rings is calculated by dividing the stuffing box depth by the packing cross-section width. Our technical team at Kaxite Seals can provide precise calculations based on your equipment drawings.
Q: My graphite packing is leaking excessively right after installation. What could be wrong?
A: Initial leakage is normal and required for lubrication and cooling. However, excessive leakage usually indicates under-tightening of the gland. Follow the run-in procedure: gradually tighten in small increments while the equipment is running. If leakage persists, check for incorrect ring sizing, damaged rings, improper cutting (jagged ends), or a damaged shaft/sleeve surface.
Q: Does Kaxite offer graphite packing in pre-formed die-molded rings?
A: Yes. While spooled packing is common, Kaxite Seals also provides precision die-molded rings for specific valve models and applications. These rings ensure perfect dimensional accuracy, eliminate installation errors from cutting, and are ideal for maintenance kits. Contact us with your valve or equipment model number for availability.
