A frequent source of leaks and assembly failure for hobbyists, DIYers, and industrial users is the fundamental mismatch between the type of thread sealant used and the thread standard it’s applied to. Specifically, using a sealant intended for tapered threads on straight threads, or vice versa, often results in a poor seal or complete joint failure.
The confusion stems from not understanding how different thread types actually seal.
Understanding Thread Standards and Sealing Methods
The most common thread standards you’ll encounter are NPT/NPTF (National Pipe Thread/Fuel) and parallel (straight) threads like BSPP (British Standard Parallel Pipe) or metric threads.
| Thread Type | Sealing Method | Sealant Requirement | Risk of Mismatch |
| Tapered (e.g., NPT/NPTF) | Metal Interference: Threads wedge together; sealant fills voids. | Requires a sealant (tape or liquid) to fill the helix gaps left by machining. | Using a sealant designed only for straight threads won’t provide enough bulk to fill the wedge gaps. |
| Straight (e.g., BSPP, Metric) | Gasket/O-ring: Sealing is accomplished by a separate component (gasket or O-ring) seating on a face. | Requires a thread locker/hydraulics sealant to prevent spiral leakage and keep the threads from loosening. | Using a thick sealant intended for NPT on a straight thread with a gasket can interfere with the gasket’s compression and cause leaks. |
The key takeaway is that tapered threads rely on the sealant for the leak-proof function, while straight threads relyon a gasket or O-ring, and the sealant simply locks the threads and prevents ‘spiral leakage.’
Incure ProGrip™ 209 Hydraulic/Pneumatic Thread Sealant
For most high-performance, clean sealing needs—especially within hydraulic and pneumatic systems where thread confusion is common—a specialized, medium-viscosity, chemical-resistant liquid sealant provides the best versatility.
This product is engineered to work across a broad range of metal threads, but it excels in providing the secure seal needed for both:
- Tapered Threads (NPT): Its consistent viscosity is optimized to completely fill the gaps in the thread helix, providing the reliable, high-pressure seal that NPT/NPTF joints require.
- Straight Threads (BSPP/Metric): When used on straight threads in addition to a mechanical seal (like an O-ring), ProGrip™ 209 cures to prevent “spiral leakage” (slow leakage along the thread path) and locks the joint against vibration loosening. Crucially, as a liquid, it applies thinly enough not to over-bulk and interfere with the seating of the primary gasket seal.
Why ProGrip™ 209 is the Smart Choice for Thread Compatibility:
- Contamination Elimination: It’s a liquid, meaning it eliminates sealant tape shredding and the risk of contamination, regardless of whether you’re working on tapered or straight threads. This is vital in sensitive hydraulic circuits.
- Medium Viscosity: The sealant has the ideal body to fill the deep voids in tapered threads while still being thin enough not to cause hydraulic lock or interfere with the necessary gasket seating on straight threads.
- Fluid Compatibility: It offers excellent chemical resistance, making it compatible with a wide array of hydraulic fluids, oils, and gases used in both types of systems, overcoming another potential ‘sealant conflict.’
To ensure successful sealing, always identify your thread type first (e.g., NPT vs. BSPP) and clean your threadsthoroughly. By choosing Incure ProGrip™ 209, you select a robust, versatile sealant that minimizes the risk of failure caused by thread type mismatch, giving you a clean, leak-proof, and locked connection.