In demanding industrial environments where extreme temperatures, aggressive chemicals, and high pressures are the norm, finding a reliable sealing solution is paramount. This is where Graphite Packing comes into play. Unlike traditional fibrous packings, graphite packing is engineered from high-purity, flexible graphite foil. This unique material structure provides a superior seal with exceptional thermal conductivity, chemical inertness, and self-lubricating properties. It is the go-to choice for sealing pumps, valves, agitators, and flanges in industries ranging from chemical processing and power generation to pharmaceuticals and oil & gas. Kaxite has been at the forefront of advancing graphite packing technology, developing formulations that meet the most stringent international standards for performance and safety.
Kaxite's graphite packing stands out in the market due to its meticulously controlled manufacturing process and premium raw materials. Our products are designed not just to seal but to enhance operational efficiency and equipment lifespan.
To ensure you select the correct graphite packing for your application, Kaxite provides a comprehensive range of products with specific technical parameters. Below is a detailed breakdown of our standard high-purity flexible graphite packing.
| Parameter | Specification / Value | Test Standard |
|---|---|---|
| Base Material | High-Purity Exfoliated Graphite (Carbon Content >99%) | ASTM D5617 |
| Maximum Service Temperature (Air) | 870°C (1600°F) | ASTM D5373 |
| Maximum Service Temperature (Inert) | 3000°C (5432°F) | - |
| Minimum Service Temperature | -240°C (-400°F) | - |
| pH Range | 0 - 14 | - |
| Density (Shore) | 1.1 - 1.7 g/cm³ | ASTM D6138 |
| Tensile Strength | ≥ 5.0 MPa | ASTM D828 |
| Compression Recovery | ≥ 40% | ASTM F36 |
| Thermal Conductivity | 10 - 150 W/m·K (in-plane) | ASTM E1461 |
| Chemical Compatibility | Excellent resistance to most acids, alkalis, organics, and molten metals. Not recommended for strong oxidizing agents (e.g., concentrated nitric acid, fluorine) at high temperatures. | - |
Kaxite graphite packing is available in a variety of cross-sectional sizes and spool lengths to fit standard and custom gland dimensions.
| Cross-Sectional Shape | Standard Sizes (Width x Thickness) | Standard Spool Length | Common Gland Size (Shaft/Stem Diameter) |
|---|---|---|---|
| Square Plaited / Braided | 3mm x 3mm (1/8" x 1/8"), 5mm x 5mm (3/16" x 3/16"), 6mm x 6mm (1/4" x 1/4"), 10mm x 10mm (3/8" x 3/8"), 13mm x 13mm (1/2" x 1/2") | 3.6 meters (12 feet) or 30-meter (100 ft) coils | 10mm - 150mm (3/8" - 6") |
| Reinforced (e.g., with Inconel wire) | 6mm x 6mm (1/4" x 1/4"), 10mm x 10mm (3/8" x 3/8"), 13mm x 13mm (1/2" x 1/2") | 3.6 meters (12 feet) | 25mm - 300mm (1" - 12") for high-pressure/extreme service |
| Die-Formed Rings (Sets) | Custom sizes based on ID, OD, and cross-section. Standard cross-sections: 3mm, 5mm, 6mm, 10mm. | Pre-cut ring sets (3, 4, 5, or 6 rings per set) | Ideal for specific valve stems, pump shafts, and expansion joints. |
Q: What are the main differences between graphite packing and traditional asbestos or PTFE-based packings?
A: Graphite packing offers several key advantages. It has a much higher temperature tolerance than PTFE and is non-toxic and more chemically versatile than historical asbestos packings. Graphite is self-lubricating, reducing shaft wear and maintenance torque, and its excellent thermal conductivity helps dissipate frictional heat. It also exhibits minimal creep relaxation, maintaining a seal longer without adjustment.
Q: For which types of equipment and media is graphite packing most recommended?
A: Graphite packing from Kaxite is highly recommended for sealing centrifugal and reciprocating pumps, agitator shafts, valves (gate, globe, control), expansion joints, and flanges. It is ideal for media such as hot oils, steam, aggressive chemicals (acids, alkalis), solvents, hot gases, and even certain molten metals. Always consult our chemical compatibility chart for specific media.
Q: Can graphite packing be used on both rotating and static equipment?
A: Absolutely. Flexible graphite packing is versatile. For dynamic applications like rotating pump shafts, a braided or reinforced style is often used for added structural integrity. For static applications like flange seals or manway covers, pure flexible graphite tape or die-formed rings are perfectly suitable and highly effective.
Q: What is the proper procedure for installing graphite packing rings?
A: Correct installation is critical. First, clean the stuffing box and shaft thoroughly. For spiral-wound rings, wrap the graphite tape around a mandrel of the correct size, cut rings on a 45-degree angle, and stagger the joints 90 degrees between rings. For braided or die-formed rings, place each ring individually. Use a split bushing to seat each ring firmly and evenly. Tighten the gland follower hand-tight only initially, then run the equipment and make final adjustments after a brief heat cycle to allow the packing to settle.
Q: How tight should the gland follower be on graphite packing?
A: A common mistake is over-tightening. Graphite packing should be initially tightened only until slight resistance is felt—hand-tight is often sufficient. After the equipment runs and heats up, the packing will expand slightly. Then, and only if a slight leak is observed, tighten the gland nuts in small increments (typically 1/6th of a turn) until a minimal, controlled weep is achieved. This allows for lubrication and cooling. Over-tightening causes excessive heat, wear, and shaft damage.
Q: Does graphite packing require a break-in period?
A: Yes, a proper break-in period is essential for optimal performance and longevity. After initial installation and hand-tightening, run the equipment under normal conditions for 15-30 minutes. Allow the packing to warm up and conform to the shaft and stuffing box. Then, stop the equipment and make a slight adjustment to the gland follower if necessary. Continue this cycle of short runs and minor adjustments until a stable, minimal-leak condition is achieved.
Q: Is Kaxite graphite packing suitable for high-speed pump applications?
A: For high-speed rotary applications, we recommend our reinforced graphite packing grades. These incorporate a corrosion-resistant metal wire (like Inconel or stainless steel) or filament within the graphite structure. This reinforcement adds strength, reduces radial wear, and prevents extrusion under high shaft speeds and pressures, making it an excellent choice for demanding pump services.
Q: What are the limitations of graphite packing? Are there any chemicals or conditions to avoid?
A: While highly resistant, graphite is a form of carbon and can be oxidized. It should not be used in the presence of strong oxidizing agents like concentrated nitric acid, sulfuric acid above 98%, or elemental fluorine, especially at elevated temperatures. It is also not recommended for use in highly abrasive slurries without special consideration, as particulate matter can become embedded and accelerate shaft wear. In such cases, a composite packing or alternative may be suggested.
Q: How can I identify when my graphite packing needs to be replaced?
A: Key indicators include a persistent increase in leak rate that cannot be controlled by standard gland adjustment, a significant increase in operating temperature at the stuffing box, visible degradation or extrusion of the packing material, or a scheduled maintenance shutdown. Proactive replacement based on run-hours or manufacturer recommendation is often more cost-effective than waiting for failure.
