HDPE Pipe Welding & Joining
HDPE pipe welding is the process of fusing one piece HDPE conduit to another piece of conduit or to a fitting. Joins can be made using several different processes, including: butt fusion, socket fusion, saddle fusion, electrofusion and non-weld joins (couplings).
HDPE Welding Basics
When joining any HDPE pipes to each other or to fittings it is important to remember:
- Adequate training on both the tools and equipment used in pipe welding for HDPE.
- Heater plates should be clean and in correct working order. They should be heated to the proper temperature based on the type of weld being done.
- Butt/Fusion Welds – 400° F - 450° F
- Socket Fusion: 490° F – 510° F
- Saddle/Sidewall Fusion: 490° F - 510° F
- Pipe surfaces and fitting surfaces must be properly prepared and clean and dry.
- Pipes should be free from unacceptable cuts, gouges, or defects.
- Correct equipment should be used, and equipment must be in good working order.
- When needed, use a temporary shelter to eliminate problems from wind and inclement weather.
- Make an “S” curve between coils when using coiled pipe, and allow several hours for pulled-in pipes to recover from tensile stress.
Butt Welding
Butt or Fusion Welding uses a heating plate on the squared ends of the HDPE pipes to be joined. After the specified time, the heating plate is removed; pieces are put together and cooled under pressure. Butt welding can be used to join 2 pipes or a pipe to a fitting.
Max Heater Plate Removal Times
| Pipe Wall Thickness | Time |
|---|---|
| 0.20”– 0.36” | 8 Seconds |
| >0.3”– 0.55” | 10 Seconds |
| >0.55” – 1.18” | 15 Seconds |
| >1.18”– 2.5” | 20 Seconds |
| >2.5”– 4.5” | 25 Seconds |
Melt Bead Size
| Pipe Wall Thickness | Melt Bead Size |
|---|---|
| ≤ 0.15” | 1/32” – 1/16” |
| 0.15”– 0.30” | 1/16” |
| 0.30”– 0.75” | 1/8” – 3/16” |
| 0.75”– 1.15” | 3/16” – 1/4” |
| >1.15”– 1.60” | 1/4” – 5/16” |
| 1.60”– 2.20” | 5/16” – 7/16” |
| 2.20”– 3.00” & greater | 7/16” – 9/16” |
Socket Fusion
Socket Fusion uses custom shaped heating plates instead of a standard flat plate. More surface area of pipe is covered with this, which make the time to heat and fuse the pipe shorter. Usually refers to joining pipe to fitting instead of pipe to pipe. Need less pressure, less machinery, but is usually for pipes under 4’’.
Socket Fusion Heating/Cooling Times - Fused to MDPE
| Pipe Size | Heating Time | Cooling Time |
|---|---|---|
| 1/2” CTS | 7-8 sec | 30 sec |
| 3/4” CTS | 5-6 sec | 30 sec |
| 1” CTS | 9-10 sec | 30 sec |
| ½” IPS | 5-6 sec | 30 sec |
| ¾” IPS | 8-10 sec | 30 sec |
| 1” IPS | 10-12 sec | 30 sec |
| 1-1/4” IPS | 12-14 sec | 45 sec |
| 1-1/2” IPS | 12-14 sec | 45 sec |
| 2” IPS | 16-20 sec | 45 sec |
| 3” IPS | 20-25 sec | 60 sec |
| 4” IPS | 25-30 sec | 60 sec |
Socket Fusion Heating/Cooling Times - Fused to HDPE
| Pipe Size | Heating Time | Cooling Time |
|---|---|---|
| 1/2” CTS | 8-10 sec | 30 sec |
| 3/4” CTS | 10-12 sec | 30 sec |
| 1” CTS | 12-14 sec | 30 sec |
| ½” IPS | 8-10 sec | 30 sec |
| ¾” IPS | 12-14 sec | 30 sec |
| 1” IPS | 14-16 sec | 30 sec |
| 1-1/4” IPS | 18-20 sec | 60 sec |
| 1-1/2” IPS | 18-20 sec | 60 sec |
| 2” IPS | 20-26 sec | 60 sec |
| 3” IPS | 25-30 sec | 75 sec |
| 4” IPS | 30-35 sec | 75 sec |
Saddle Fusion
Sidewall or Saddle Fusion is similar to Socket Fusion, but is used to join a perpendicular fitting to the surface of a pipe. The fitting an pipe are then allowed to under pressure.
Heating and Cooling Times
| Pipe Size/th> | Max Heat Time | Min Cooling Time |
|---|---|---|
| 1-1/4” IPS | 1/16” melt pattern at fitting base. Not to exceed 15 seconds when hot tapping. | 5 min + 30 min |
| 2” IPS | 1/16” melt pattern at fitting base. Not to exceed 15 seconds when hot tapping. | 10 min + 30 min/td> |
| 3” IPS & Greater | 1/16” melt pattern at fitting base. | 10 min + 30 min |
Electrofusion
Electrofusion – joins pipes and fittings using special fittings that have a resistive wire built in, and that wire fuses the join. Voltage is applied with an electrofusion processor, wich heats the wire, heating and melting the inside of the fitting and outside of the pipe wall.
Non-Weld Joins
Non-Welded Joins are preferred in some cases. Coupling systems allow joins to be made without special tools, often by one person, and can be used in compact settings like manholes. We carry several different brands of HDPE Couplers.
- Shur Lock couplings have been air pressure tested to more than 125 psi and water seal capabilities withstand pressures up to 20 feet. They are used to join HDPE to PVC pipe, using a coupler and 2 external band clamps
- Clear-Lock couplings are easily installed with no special tools.
- Redi-Lock couplings install with a nut driver.