Braided Packing: High-Performance Compression Seals
Braided packing consists of fibers (PTFE, graphite, carbon, aramid, or synthetic blends) precisely interwoven into square or interlock configurations, then impregnated with lubricants, graphite, or PTFE dispersions for superior sealing in dynamic rotary and reciprocating applications. These packings excel in stuffing boxes, pumps, valves, and mixers within oilfield wireline equipment, BOP actuators, and surface pumps, handling pressures up to 500 psi and shaft speeds to 4,000 fpm.
The multi-filament construction provides self-lubrication, thermal conductivity, and chemical resistance (pH 0-14), with low-friction operation that reduces shaft wear by 40-60% compared to traditional rope packing. Common treatments include break-in lubricants for initial seating and rust inhibitors for extended service life.
Standard Braided Packing Types and Specifications
| Style/Type | Material Composition | Max Pressure (psi) | Temp Range (°C) | Shaft Speed (fpm) | Primary Applications |
|---|---|---|---|---|---|
| PTFE Pure | 100% PTFE filament | 300 | 260 | 4,300 | Chemical pumps, valves |
| GFO® Style | Graphite-filled PTFE | 500 | 260 | 1,900 | Steam, acids, high-speed |
| Carbon Yarn | Carbon fiber + PTFE/graphite | 400 | 280 | 2,500 | Paper mills, solvents |
| Aramid | Aramid fiber + lubricant | 500 | 260 | 1,500 | Slurries, abrasives |
| Graphite Flex | Expanded graphite + Inconel wire | 600 | 450 | 1,200 | High-temp valves, fire-safe |
Size and Packing Density Specifications
| Cross-Section (inches) | Packing Density (ft/lb) | Typical Bore ID (inches) | Recommended Gland Height (inches) |
|---|---|---|---|
| 1/8 | 80 | 0.5-1.0 | 0.38-0.50 |
| 3/16 | 25-48 | 1.0-2.0 | 0.56-0.75 |
| 1/4 | 16.6 | 2.0-3.0 | 0.75-1.00 |
| 3/8 | 8.5-12 | 3.0-4.0 | 1.13-1.50 |
| 1/2 | 5.7-6.4 | 4.0-6.0 | 1.50-2.00 |
Performance Characteristics by Material
| Material | pH Range | Friction Coefficient | Chemical Resistance | Thermal Conductivity |
|---|---|---|---|---|
| PTFE | 0-14 | 0.05-0.10 | Excellent | Low |
| Graphite | 0-14 | 0.10-0.20 | Excellent | High |
| Carbon | 2-12 | 0.15-0.25 | Good | Medium |
| Aramid | 3-11 | 0.20-0.30 | Fair | Medium |
Braided packings conform automatically to stuffing box irregularities through axial compression (20-30% gland load), creating a labyrinth seal path that prevents leakage while accommodating thermal expansion and shaft misalignment up to 0.5°.