Graphite PTFE Packing is a high-performance sealing material engineered for demanding industrial applications. It combines the exceptional self-lubricating properties and chemical resistance of expanded PTFE (Polytetrafluoroethylene) with the superior thermal conductivity and stability of high-purity graphite. This composite structure creates a robust, versatile seal ideal for rotating and reciprocating equipment handling aggressive media, high temperatures, and challenging pressures. Unlike traditional braided packings, this material offers reduced friction, minimal shaft wear, and extended service life, leading to lower maintenance costs and improved operational efficiency. It represents a significant advancement in sealing technology for industries where reliability is non-negotiable.
Our Graphite PTFE Packing is manufactured to precise standards. Below are the detailed technical specifications.
| Parameter | Specification / Value | Test Standard |
|---|---|---|
| Base Material | Expanded PTFE (ePTFE) impregnated with high-purity flake graphite | - |
| Color | Black | Visual |
| Specific Gravity | 1.5 - 1.7 g/cm³ | ASTM D792 |
| Tensile Strength | > 15 MPa | ASTM D638 |
| Compression Set | < 15% (after 22 hrs at 25°C) | ASTM D395 |
| pH Range | 0 - 14 | - |
| Parameter | Range / Limit | Notes |
|---|---|---|
| Temperature Range | -200°C to +280°C (-328°F to +536°F) | Continuous service. Short-term peaks to 300°C possible. |
| Maximum Pressure | Up to 25 MPa (3600 psi) | Dependent on shaft speed, size, and media. |
| Maximum Shaft Speed | Up to 25 m/s (82 ft/s) | For rotating applications. Lower for reciprocating. |
| Chemical Compatibility | Excellent resistance to most chemicals except molten alkali metals and fluorine at high T. | Consult compatibility charts for specific media. |
| Cross-Section (Square) | Spool Length | Packaging |
|---|---|---|
| 3mm x 3mm (1/8") | 50 meters, 100 meters | Plastic spool, boxed |
| 5mm x 5mm (3/16") | 50 meters, 100 meters | Plastic spool, boxed |
| 6mm x 6mm (1/4") | 30 meters, 50 meters | Plastic spool, boxed |
| 8mm x 8mm (5/16") | 30 meters, 50 meters | Plastic spool, boxed |
| 10mm x 10mm (3/8") | 20 meters, 30 meters | Plastic spool, boxed |
| 13mm x 13mm (1/2") | 10 meters, 20 meters | Plastic spool, boxed |
| Custom sizes | On request | Contact engineering |
Graphite PTFE Packing is the seal of choice across numerous critical industries due to its robustness and versatility.
Q: What are the main advantages of Graphite PTFE Packing over traditional asbestos or aramid fiber packings?
A: This packing offers superior chemical resistance across a broader pH range, operates at higher temperatures, and is inherently self-lubricating. It generates significantly less friction, leading to energy savings and dramatically reduced shaft wear. It is also cleaner and non-hazardous, unlike asbestos-based products.
Q: Can this packing be used for both rotating and reciprocating shafts?
A: Yes, it is engineered for both dynamic sealing applications. However, installation practices and recommended number of rings may differ. For reciprocating service (e.g., plunger pumps), ensuring proper ring cutting and staggering is even more critical to prevent fluid passage along the joints.
Q: How does the graphite component improve the performance?
A: The graphite acts as a solid lubricant, reducing friction and adhesive wear. Crucially, it greatly enhances the thermal conductivity of the packing, allowing heat generated at the shaft interface to be dissipated radially through the packing and into the stuffing box housing, preventing destructive heat buildup.
Q: Is this packing suitable for potable water or food contact applications?
A: Yes, specific grades are manufactured using FDA-listed raw materials and are suitable for incidental food contact. It is non-toxic, tasteless, and odorless. Always specify your requirement for food-grade or USP Class VI certification when ordering for such applications.
Q: How do I determine the correct cross-sectional size and number of rings for my pump?
A: The cross-section is determined by the clearance between the shaft and the stuffing box bore. Standard rule: Packing Size = (Stuffing Box Bore - Shaft Diameter) / 2. The number of rings is typically 5-7 for rotating shafts and 4-6 for reciprocating, but always refer to the original equipment manufacturer's (OEM) specification or consult with our engineering team.
Q: What kind of leakage should I expect after installation?
A: A slight weeping or a film of fluid is normal and necessary for lubrication and cooling in most applications. Drip rates of 1-60 drops per minute are often acceptable, depending on the fluid and service. A steady stream indicates the gland may be too loose, while no leakage and a hot gland often signal dangerous over-tightening.
Q: What chemicals or conditions is Graphite PTFE Packing NOT compatible with?
A: While highly resistant, it is not recommended for use with molten alkali metals (e.g., sodium, potassium) and certain fluorine compounds at very high temperatures and pressures. Always request a chemical compatibility report for your specific media, temperature, and concentration.
Q: How long can I expect this packing to last in service?
A: Service life varies widely based on operating conditions: shaft speed, media, temperature, pressure, alignment, and installation skill. Under normal conditions in a standard chemical pump, lifespans of 12-24 months or more are common, significantly outperforming many conventional packings.
