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Stripped threads, corroded fittings, and damaged bolt ends are a frustrating reality for DIYers, mechanics, and fabricators alike. Whether you're storing hardware, shipping components, or masking threads before powder coating, these PVC vinyl rubber thread protector caps give you a reliable, flexible solution in 37 precise inner diameters.
Made from high-hardness PVC rubber, each cap features a closed dome end, smooth shiny surface, and uniform wall thickness — available in inner diameters from Φ1.5mm to Φ24mm (typically 1.5–24 mm / 0.06–0.94 in). Yellow is one of seven available colors, making it ideal for color-coding, safety marking, or high-visibility identification in busy workshops.
Use these caps to protect external threads on bolts, threaded rods, hydraulic fittings, and pipe ends during storage, transit, or surface finishing. They're equally at home in automotive garages, industrial facilities, and home workshops — anywhere clean, protected threads matter.
Cap exposed bolt threads and hydraulic fittings during repairs or storage to prevent corrosion, cross-threading, and contamination from oil and grime.
Protect threaded rod ends and pipe fittings during shipping and storage. Use yellow caps to mark components requiring inspection or calibration.
Mask external threads before spray painting or powder coating (low-temp cure). Caps remove cleanly without leaving residue on threads.
Color-code your hardware storage by thread size using different cap colors — yellow for one size range, red for another — for instant visual identification.
| Material | PVC Rubber (vinyl compound) |
|---|---|
| Color | Yellow (also available: Black, Red, White, Clear, Blue, Green) |
| Inner Diameter Range | Φ1.5mm – Φ24mm (37 sizes) |
| Available Sizes | Φ1.5, 1.8, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24mm |
| Cap Type | Closed-end dome cap (external thread protector) |
| Surface Finish | Smooth, shiny |
| Chemical Resistance | Oil, water, hydraulic fluid, mild acids; not recommended for continuous immersion in acetone or brake fluid |
| Temperature Range | Suitable for masking up to typically 80°C / 176°F (powder coat low-temp cure) |
| Packing Qty | Select variant: 1 pc, 5 pcs, 10 pcs, or 50 pcs |
Prolonged exposure to direct sunlight may cause gradual fading over several months to a year. For indoor or shaded use, the yellow stays bright. If long-term UV resistance is critical, black caps are the most stable option. Yellow is ideal for color-coding and safety marking in workshop environments.
Yes, but we recommend a quick deburring if the edges are very sharp. The rubber is tough, but burrs can cut into the cap during installation. Once properly fitted, the cap will protect both your hands and surrounding surfaces from the sharp metal.
Yes — the PVC rubber compound resists petroleum-based oils, gasoline, diesel, and hydraulic fluids, as well as water and mild acids. For continuous immersion in aggressive solvents such as brake fluid or acetone, we recommend testing a sample first.
Absolutely. These caps are commonly used to mask threads during spray painting and powder coating (low-temp cure only, up to typically 80°C / 176°F). For high-temperature baking above 100°C, silicone caps are recommended instead.
These caps are designed for external thread protection — they fit over the outside of a bolt or threaded rod. The closed dome end fully seals the thread tip. Standard bolt covers often refer to hex cap covers; ours are round, flexible, and optimized for small diameters and tight spaces.
This listing is for individual colors and sizes. For custom assortments — such as a mix of yellow, red, and blue in the same size — please contact customer service. We can create mixed color or mixed size packs for your specific needs.
Measure the outer diameter of the thread or rod you want to protect. Select a cap with an inner diameter that matches or is very slightly smaller than your measurement — the rubber will stretch to grip the thread securely. For example, a Φ6mm bolt typically fits a Φ6.0mm cap.
