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Polyethylene Female Threaded Compression Fitting (Female Threaded Compression Fitting)
A Female Threaded Compression Fitting is one of the most common compression fittings in cold-water distribution networks, irrigation systems, and light process lines. It is used to connect the end of a polyethylene pipe to a male-threaded device (such as a nipple, riser, ball valve, gate valve, filter, pressure reducer, etc.). On one side, the fitting locks onto the polyethylene pipe with a bushing and split ring; on the other side, its female thread connects to the male-threaded part.
Components and Materials Used
Material quality directly affects service life, sealing, and installation safety. A common combination of parts in a polyethylene female threaded compression fitting is as follows:
| Part | Recommended Material | Technical Feature | Application Note |
|---|---|---|---|
| Body and cap nut | Polypropylene copolymer (PP‑C) with UV stabilizer | Strength, chemical and sunlight resistance | Choose an impact‑resistant grade for outdoor use |
| Split/locking ring | Polyoxymethylene (POM) | Mechanical lock on the pipe, dimensional stability | Seat fully to the end of travel to prevent slippage |
| Bushing/spacer | Polyethylene | Coaxiality and uniform stress distribution | Prevents scratching of the pipe surface |
| Sealing O‑ring | Nitrile rubber (NBR) | Sealing under pressure, oil resistance | Do not use unsuitable greases; use a compatible lubricant |
| Internal thread | Usually G (BSPP) or R (BSPT) per size | Connection to male‑threaded part | Matching the thread type on both sides is critical |
Note: The presence of a UV stabilizer in the body and cap nut significantly increases durability for outdoor and sunny installations.
Operating Temperature and Pressure Range
Nominal pressure (PN): For sizes under 63 mm typically PN16 (up to 16 bar); for larger sizes, PN10 to PN16 is common depending on manufacturer design.
Recommended temperature range: For continuous cold‑water service typically 0 to 40 °C. Sub‑zero use is allowed only with proper insulation, avoidance of impact and mechanical stresses, and in non‑freezing circuits. Above 40 °C, apply allowable pressure derating.
| Polyethylene pipe OD (mm) | Common female thread (inch) | Recommended working pressure (bar) | Typical application |
|---|---|---|---|
| 20 | 1/2 – 3/4 | 16 | Drip irrigation, light take‑offs |
| 25 | 3/4 – 1 | 16 | Risers, connections to small gate valves |
| 32 | 1 – 1¼ | 16 | Area distribution lines |
| 40 | 1¼ – 1½ | 16 | Garden and light‑industrial manifolds |
| 50 | 1½ – 2 | 16 | Local trunk lines |
| 63 | 2 | 16 | Filtration unit inlet/outlet |
| 75 | 2½ | 10–16 | Semi‑industrial routes |
| 90 | 3 | 10–16 | Primary lines for large complexes |
| 110 | 4 | 10–16 | Tank inlets and pump stations |
The figures above are general guidelines and may vary with brand design or project conditions. Always refer to the product’s technical label.
Advantages and Limitations
Advantages
- Fast installation without specialized welding tools; suitable for field repairs
- Can be opened and reassembled multiple times; easy maintenance
- Reliable sealing with NBR O‑ring
- Good resistance to moisture, many fertilizers, and common irrigation chemicals
- Compatible with sunlight in UV‑stabilized versions
- Cost‑effective price‑to‑performance for cold‑water networks
Limitations
- Suitable for cold water and non‑corrosive fluids; use specialized fittings for hot or corrosive fluids
- Impact sensitivity increases below freezing; avoid stress, hammering, and freezing
- Thread type (BSPP/BSPT) and sealing class must be precisely controlled
Common Applications
- Connecting the end of a polyethylene pipe to valves, filters, pressure reducers, and meters
- Take‑offs in sprinkler and drip irrigation systems
- Raw water, agricultural, and landscaping distribution lines
- Temporary site installations and relocatable projects
Size and Thread Selection Guide
- Determine the pipe outside diameter from marking or caliper (e.g., 32 mm).
- Know the network pressure class (PN10/PN16) and align it with the recommended pressure table.
- Identify the counterpart thread type (parallel G or tapered R) and its inch size.
- For outdoor installations, prefer the UV‑stabilized version.
- For specific fluids (fertilizer, weak acid), check chemical compatibility with material specifications.
Step‑by‑Step Installation Instructions
- Cut the polyethylene pipe cleanly with a sharp cutter; keep the cut square.
- Lightly bevel the pipe mouth to protect the O‑ring.
- Disassemble the cap nut; place parts on the pipe in order: cap nut → split ring → bushing.
- Ensure the O‑ring groove is clean and, if needed, apply a light NBR‑compatible lubricant.
- Insert the pipe fully to the seating stop inside the body; no gap should remain.
- Tighten the cap nut by hand to the stop, then a maximum of a quarter to half a turn with a suitable wrench. Do not overtighten.
- Thread the female end onto the male‑threaded part; if needed, use compatible thread tape or sealant.
- Perform gradual pressure testing and leak inspection at working pressure.
Maintenance and Safety Notes
- Before winter, drain water or insulate lines exposed to freezing
- Avoid mechanical impact on fittings in cold weather
- Periodically inspect O‑rings and replace if worn or cut
- Do not use solvents and oils incompatible with NBR
Common Errors and Solutions
- Leakage at thread: thread types on the two sides do not match or sealing is insufficient → verify G/R type and use suitable sealant.
- Pipe slippage: pipe not fully inserted or split ring not seated correctly → disassemble and reinstall in the correct order.
- Cap nut cracking: excessive torque or impact in cold weather → observe recommended torque and provide thermal protection.
Purchasing and Quality Control Tips
- Clear marking including size, nominal pressure, and production date
- Uniform color and absence of deep scratches on body and threads
- Intact packaging film to prevent dust contamination
- For outdoor projects, choose the UV‑stabilized version
“Tamambaha” supplies female threaded compression fittings in sizes 20–110 mm with common inch threads. With technical advice, swift preparation, and shipping across the region, it streamlines selection through delivery. While Tamambaha is not the only source for this product and you may purchase from other stores, our support team can offer practical guidance—tailored to your project—on choosing size, thread type, and pressure class.
