How to weld PPR pipes yourself
Step-by-step guide to welding polypropylene pipes. Temperature, heating time, common mistakes, and correct dimensions.
PPR pipe types by PN (pressure)
PN (Pressure Nominal) is the nominal operating pressure at 20°C. The higher the PN, the thicker the wall and the higher the temperature it can handle.
| Class | Max. pressure at 20°C | Max. pressure at 70°C | Application | Color |
|---|---|---|---|---|
| PN10 | 10 бар | 2.5 бар | Cold water, irrigation systems | White/green |
| PN16 | 16 бар | 4 бар | Cold water with higher pressure | White |
| PN20 | 20 бар | 6 бар | Hot water up to 70°C | White |
| PN25 stabi | 25 бар | 10 бар | Heating, hot water 80°C+ | With fiberglass or foil |
For irrigation: PN10 is sufficient (operating pressure 3–4 bar). PN16 for systems with a pump station and pressure of 5+ bar. PN20/25 are unnecessary for irrigation.
Step-by-step welding
Preparing the welding iron
Insert the nozzles for the diameter you plan to weld. Tighten the screws with a wrench. Turn on the welding iron at 260°C. Preheat for 10–15 min until the temperature stabilizes (indicator light goes off = ready). Do not touch the Teflon coating with metal — paper only.
Important: Temperature below 250°C — weak joint; above 280°C — polypropylene burns and loses strength. 260°C ± 5°C is the standard.
Cutting the pipe and chamfering
Cut with a pipe cutter (scissors for 20–25 mm only; roller for all sizes). The edge must be PERPENDICULAR! For stabi pipe with fiberglass, it is critical to chamfer at 45° for 2–3 mm with a deburring tool; otherwise, the fiberglass layer will interfere with the joint.
Marking the insertion depth
Use a marker to draw a line on the pipe at a distance of "insertion depth + 2 mm":
- 20 мм труба → 16 мм позначка
- 25 мм → 18 мм
- 32 мм → 20 мм
- 40 мм → 22 мм
- 50 мм → 24 мм
- 63 мм → 26 мм
Heating the pipe and fitting simultaneously
Insert the pipe into one nozzle (outer part), the fitting into the other (inner). SIMULTANEOUSLY. Heating time by diameter:
| Діаметр | Heating time | Joining time | Holding time |
|---|---|---|---|
| 20 мм | 5 сек | 4 сек | 3 хв |
| 25 мм | 7 сек | 4 сек | 3 хв |
| 32 мм | 8 сек | 6 сек | 4 хв |
| 40 мм | 12 сек | 6 сек | 4 хв |
| 50 мм | 18 сек | 8 сек | 5 хв |
| 63 мм | 24 сек | 10 сек | 6 хв |
Joining (without rotation)
Remove the pipe and fitting from the nozzles SIMULTANEOUSLY (in sync). Smoothly, WITHOUT ROTATION, insert the pipe into the fitting up to the mark. Hold motionless for 4–8 sec. Do not move for 3–6 min (holding time).
Prohibited: rotating, pushing, or tilting the joint during cooling. Any movement deforms the microstructure — the joint cracks within 2–6 months.
Inspection and pressure test
A proper joint: a uniform bead around the entire pipe perimeter, with no misalignment or gaps. 30 min after the last weld, fill the system with water. Pressure test at 1.5× operating pressure for 30 min BEFORE closing walls.
Common mistakes
- Overheating the pipe: 10 sec instead of 5 for 20 mm → polypropylene flows and narrows the inner diameter. Result: pressure drop and clogging
- Underheating: the pipe has not softened → the layers do not fuse → the joint cracks within 1–3 months
- Rotating during joining: even 5° deforms the microstructure → risk of leaks
- Not chamfering stabi pipe: the fiberglass layer on the outer edge does not fuse with the fitting → instant leak
- Wet surface: moisture on the pipe or fitting → steam inside the weld → bubble → seal failure
- Closing walls BEFORE pressure testing: finding a leak after closing = destroying tile and screed. TEST IS MANDATORY before closing
For professional installers and greenhouses
- For pipes 75 mm+ — socket fusion or electrofusion (EF) welding. Standard thermal nozzles are not suitable for large diameters
- Standards: DSTU EN ISO 15874 (PPR pipes), DIN 8077/8078 (German standard). Products marked with these standards guarantee quality
- Thermal expansion of PPR: 1.5 mm per 1 m per 10°C. For hot lines 20 m long — allow 30 mm (expansion loops or L-compensators)
- Professional brands: Wavin Ekoplastik, Aquatherm, Bänninger, Pilsa, Kalde — with ISO certificates for tenders
- Pressure test per DIN 1988-600: 1.5× operating pressure for 2 hours with no drop exceeding 0.2 bar
Need pipes and fittings?
Our catalog offers PPR pipes PN10–PN25 in all diameters and a full range of fittings.