- Chemical Resistance
- Safety Data Sheets (SDS)
- Material Properties
- PRO Systems
- PE Pressure Pipe
- PE Pipe Selection
- MAOP for PE Pipes
- Temperature Influences
- Selection of Wall Thickness for Special Applications
- Hydraulic Design for PE Pipes
- Surge and Fatigue
- Slurry Flow
- Pneumatic Flow
- Expansion and Contraction
- External Pressure Resistance
- Allowable Bending Radius
- Thrust Block Support
- Conductivity, Vibration and Heat Sources
- Polyethylene Jointing
- Handling and Storage
- Trench Preparation for Buried Pipes
- Relining and Sliplining
- Pipeline Detection
- Above Ground Installation
- Accommodation of Thermal Movement by Deflection Legs
- Service Connections for PE Pipes
- Concrete Encasement
- Fire Rating
- Testing and Commissioning
- PVC Pressure Pipe
- PVC Pressure Pipe Standards
- Pressure Considerations
- PVC Temperature Considerations
- Mine Subsidence
- Water Hammer
- Thrust Support
- Air and Scour Valves
- Soil and Traffic Loads
- Bending Loads
- PVC Pipe Jointing
- Jointing Components with Ductile Iron Flanged Joints
- Service Connections for PVC Pipe
- PVC Pipe Handling and Storage
- Below Ground Installation
- Above Ground Installation for PVC Pipe
- Testing and Commissioning for PVC Pressure Pipe
- Detecting Buried Pipes
- FLUFF – Friction Loss in Uniform Fluid Flow
- Technical Notes
Vinidex PE pipes are produced in a range of sizes between 16 mm to 1000 mm diameter, and these pipes can be joined by a variety of methods.
Methods include mechanical joints and a range of thermal fusion procedures. The nature of the PE materials precludes the use of adhesive based systems.
Thermal fusion proceeds by melting the PE material at the joint surfaces, bringing the molten surfaces together under closely controlled pressures, and holding the surfaces together until the joint has cooled.
In all thermal fusion processes, the field pipe jointing should only be performed by trained fusion operators using properly maintained and calibrated fusion machines.
The fusion compatibility of PE materials must be established before welding, and if doubts exist then the advice of Vinidex engineers should be sought.
Butt fusion is generally applied to PE pipes within the size range 90 mm to 1000 mm for joints on pipes, fittings, and end treatments. Butt fusion provides a homogeneous joint with the same properties as the pipe and fittings materials, and ability to resist longitudinal loads.
Butt fusion machines need to be sufficiently robust to align and pressurise the pipe ends within close tolerances, and to provide heating and pressurisation of the jointing surfaces within required parameter tolerances.
All butt fusion should be performed under cover, and the ends of the PE pipes blocked off to assist with temperature control and prevent contamination of the joints.
The butt fusion process consists of the following steps which are shown in principle in the Figure
The combinations of times, temperatures, and pressures to be adopted depends on the PE material grade, the diameter and wall thickness of the pipes, and the brand and model of fusion machine being used. Vinidex engineers can provide guidance in these parameters.
The final weld beads should be fully rolled over, free from pitting and voids, correctly sized, and free from discolouration.
When correctly performed, the minimum long term strength of the butt fusion joint should be 90% of the strength of the parent PE pipe.
|Zone 1||Initial Bead Pressure P1
|Zone 2||Heat Soak Pressure P2
|Zone 3||Change over Time T3||Seconds (max)|
|Zone 4||Weld Pressure Build-up
Welding Pressure P3
Welding/Cooling Time T5
For more information about butt welding parameters, refer to PIPA Injdustry Guideline POP003-Butt Fusion jointing of PE pipes and fittings recommended parameters
In field applications full QA records of times, temperatures and pressures achieved for all joints should be recorded, and the locations of welds identified on as-constructed site plans.
The most reliable methods of weld evaluation are the destructive type. Destructive test methods require tensile testing of welds and pipe in order to establish the strength of the weld as a percentage of pipe strength.
Flexural testing may also be required in order to evaluate the effect of any joint misalignment.
Hydrostatic pressure testing will not determine the strength of butt welds, due to the stress across the plane of the butt weld being only 50% of the hoop stress in the pipe section.
Weld beads are normally left in place on the pipe section, unless required to be removed from the outside diameter to allow slip lining, or from the inside diameter to prevent potential material blockage in sewer rising mains.
Vinidex PE electrofusion system consists of moulded couplings, tapping saddles, and fittings with electric elements contained in the fitting.
When a controlled electrical current is passed through the resistance wire, there is a temperature increase, the resulting heat being transferred to the jointing surfaces until melting occurs. The joint surfaces are held under pressure until cooled.
Vinidex electrofusion fittings require an Electrofusion welder capable of barcode scanning and an output range of 8-48v. The fittings’ barcode contains the fusion parameters required to successfully complete the fusion process. Power supply should be 240 Volt 50Hz, single phase supply. Where a generator is used, please seek technical advice regarding minimum size requirements as this varies according to the power required by the fitting.
Vinidex electrofusion fittings use a single connection pin of 4.0 mm diameter.
Electrofusion control boxes must not be used in explosive atmospheres. In deep trenches, tunnels, or mine workings, the power source may require approval by the local electricity utility.
All electrofusion joints must be carried out under cover to prevent contamination by dust, moisture and dirt, and be clamped to prevent movement in the joint until the cooling period has been completed.
- Cut the pipes square, and mark the pipes at a length equal to the socket depth.
- Scrape the marked section of the pipe spigot to remove all oxidised PE layers to a depth of approximately 0.3mm. Use a hand scraper, or a rotating peel scraper to remove the PE layers. Do not use sand paper. Leave the electrofusion fittings in the sealed plastic bag until needed for assembly. Do not scrape the inside of the fitting, clean with an approved cleaner to remove all dust, dirt, and moisture.
- Insert the pipe into the coupling up to the witness marks. Ensure pipes are rounded, and when using coiled PE pipes, re rounding clamps may be needed to remove ovality. Clamp the joint assembly.
- Connect the electrical circuit, and follow the instructions for the particular power control box. Do not change the standard fusion conditions for the particular size and type of fitting.
- Leave the joint in the clamp assembly until the full cooling time has been completed.
For more detailed guidelines on Electrofusion jointing see PIPA Industry Guideline POP001-Electrofusion jointing of PE pipes and fittings for pressure applications
Socket fusion of Vinidex PE systems is available in the diameter range 20mm to 110mm.
Socket fusion consists of jointing couplings, and fittings with a close tolerance moulded socket section into which the pipe or fitting spigot is inserted.
The fusion process is achieved by heating the spigot, and socket jointing surfaces above the crystalline melt point temperature of PE by insertion into a heated element tool. The heated joint sections are then assembled, and held until cooling to ambient temperature takes place.
The heater elements are PTFE coated, and at all times must be kept clean and free from contamination. The heater tools need to be set and calibrated to maintain a surface temperature range of 260°C +/- 5°C. All jointing must be performed under cover to prevent contamination of the joints by dust, dirt, or moisture.
1. Cut the pipes square, clean the spigot section with a clean cloth and a non depositing alcohol to the full depth of the socket. Mark the length of the socket. Clean the inside of the socket section.
2. Scrape the outside of the pipe spigot to remove the oxidised layer from the pipe. Do not scrape the inside of the sockets.
3. Confirm the temperature of the heating elements, and ensure that the heating surfaces are clean.
4. Push the spigot, and socket sections on to the heating elements to the full length of engagement, and allow to heat for the appropriate period. See the Table below.
5. Pull the spigot and socket sections from the heating elements, and push together evenly to the full length of engagement without distortion of the joints. Clamp the joints and hold until fully cooled. The weld flow bead should then appear evenly around the full circumference of the socket end. The completed joints must be allowed to cool fully to ambient temperature before performing pressure tests.
|Pipe Diameter DN||Tool heating time||Assembly time||Cooling time|
Vinidex PE pipes are provided with flange connections by using PE stub ends jointed to the ends of the pipes by either electrofusion or butt welding.
These are used in conjunction with metal backing plates, and rubber sealing gaskets in order to provide a demountable joint. Sealing gaskets are made from natural rubber or polychloroprene depending on the fluid being carried.
Where hot fluids or chemical reagents are carried, the suitability of the sealing gasket material must be determined, and the advice of Vinidex engineers obtained. The sealing gaskets must be clean and free from creases when fitted to the flange assembly.
Flanges are available across the full size range of Vinidex PE pipes (up to 1000mm diameter), and to the same pressure PN rating as the pipes.
Metal backing plates are available in hot dip galvanised form, and thickness to AS 2129, and AS 4087 as required. The thickness of the metal backing plate must be assessed for the operating pressures in each particular pipeline using the requirements of AS 2129 and AS 4087.
The fixing bolts must be tightened evenly around the flange. Bolts must not be over tightened, and a torque wrench should be used to prevent buckling of the metal backing plate.
The cutting of threads is not recommended.
Where threaded fittings are used then:
- Only PTFE tape should be used as a sealant. Hemp, paste, and petroleum compounds must not be used.
- The joint should be made firm by hand, or by strap wrench to prevent over straining of the joint. Serrated jaw wrenches must not be used.
- Where possible, the pipeline system should be designed so as to ensure that PE/metal thread joints are such that the male thread is PE, and the female thread form is metal.