Thermoplastic Stub Ends
Stub Ends with Short or Long Neck for Backing-Flange Installations
DN 25 – DN 200
Size Range
Socket Weld / Backing Flange
Connection
PP / PPH / PVDF
Material
PN 6 / 10 / 16
Pressure
Stub Ends for Flanged-Joint Pipeline Connections
UNP’s Thermoplastic Stub Ends are short pipe sections with an integral raised face flange-end, used in combination with separate metal backing flanges to create flanged joints in thermoplastic pipelines. The stub end is welded to the pipe; the backing flange slides over it and bolts to the matching flange on the other side.
This two-piece flange arrangement keeps all wetted parts (the stub end and its raised face) in the same thermoplastic material as the pipe — eliminating corrosion of the flange. The backing flange (steel, SS, or aluminium) is never in contact with the media.
Available with short neck (compact, for tight installations) or long neck (for stress relief and easier welding) configurations.
Why Choose This Fitting
- ✓Two-piece flange — non-wetted backing flange
- ✓Short neck or long neck options
- ✓PN 10 / PN 16 raised face
- ✓Socket weld pipe-side connection
- ✓PP / PPH / PVDF materials
Dimensions, Materials, Testing
Stub End Dimensions
All dimensions in millimeters unless noted.
| Pipe Size | OD (mm) | Short Neck Length (mm) | Long Neck Length (mm) | Flange Face Thk (mm) |
|---|---|---|---|---|
| 25 | 25 | 55 | 105 | 12 |
| 32 | 32 | 60 | 110 | 14 |
| 40 | 40 | 65 | 115 | 15 |
| 50 | 50 | 70 | 125 | 16 |
| 63 | 63 | 80 | 135 | 18 |
| 75 | 75 | 85 | 140 | 19 |
| 90 | 90 | 95 | 150 | 21 |
| 110 | 110 | 105 | 165 | 22 |
| 125 | 125 | 115 | 175 | 25 |
| 160 | 160 | 130 | 190 | 28 |
| 200 | 200 | 150 | 215 | 32 |
Materials of Construction
| Material | Description |
|---|---|
| PP (Polypropylene) | General-purpose, low-cost option for mildly corrosive media at moderate temperatures. |
| PPH (Polypropylene Homopolymer) | Higher mechanical strength than PP — better for pressure service. |
| PVDF (Polyvinylidene Fluoride) | Superior abrasion resistance and high mechanical strength. |
| ISO.PP (Isotactic Polypropylene) | Improved temperature and chemical resistance vs standard PP. |
Connection Types Available
| Connection | Description |
|---|---|
| Socket Weld | Heat-fused socket joints for permanent, leak-tight assemblies. |
| Butt Weld | End-to-end heated fusion for in-line pipe sections. |
| Threaded | Removable threaded fittings for serviceable connections. |
| Flanged | Bolted flange joints for easy disassembly and inspection. |
Testing & Quality
| Test | Standard / Result |
|---|---|
| Hydrostatic Test | BS EN 12266-1 / DIN 8077 / DIN 8078 |
| Visual / Dimensional Inspection | 100% Sampled |
| Pressure Rating | PN 6 / PN 10 / PN 16 (depending on size & material) |
| Temperature Range | 0°C to 80°C (PP) / 0°C to 95°C (PPH) / -40°C to 140°C (PVDF) |
| Certifications | ISO 9001:2015 |
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Order Your Thermoplastic Stub Ends
Tell us your pipe size, neck length preference, and material — we’ll supply stub ends with matching backing flanges.