An Introduction to Electrofusion jointing with Caldervale Technology Ltd Products

The Caldervale range of Electrofusion products consists of the Calder and Proxima brands of electrofusion processors plus a basic entry model called Electron and a selection of specialised models for example Evolution for fusing 80 volt electrofusion couplers, Nomad a battery powered processor and Aquafuse for fusing non pressure drainage systems.

In addition to, and complimenting the electrofusion processor range you will find a complete range of Maxifuse brand installation tools, including pipe restraining clamps for large & small diameter connections, pipe scrapers & re-rounding clamps for correct pre joint preparation and polyethylene pipe temporary closure by squeeze off tools. All the foregoing products are manufactured and/or designed by Caldervale Technology Limited in the United Kingdom

Maxifuse tools are designed to simplify the construction of, addition to, repair and tie-in of polyethylene pipework systems when using the Electrofusion method of jointing.

The electrofusion method simplifies the joining of dissimilar polyethylene pipes because the same installation procedure is followed for all qualified S.D.R. rating and material.

The majority of Caldervale electrofusion processors utilise the barcode fusion mode, when used in this mode, the fusion data, which can be different for individual couplers and fittings, is contained within a 24 character barcode which is usually attached to the fitting or on an accompanying card.

The barcode reader wand or scanner reads this information into the processor which then automatically sets the fusion time and other parameters prior to the fusion process being initiated. The fusion information can then be recorded internally inside the processor unit for inspection at some later time.

A second 26 character traceability barcode can also be found with the 24 character fusion barcode, this contains technical data about the fitting itself and can also be read by the scanner and recorded in the processor memory.

All processors utilising the barcode fusion mode will also fuse using the manual mode when used with fittings that can be manually fused. The manual fusion mode is selectable from the processor menu, this mode can also be used when the scanner is not available.

For fittings that can be fused using barcode and manual fusion processes the fusion time is usually attached to, or accompanying the fitting, where this is not the case, the fitting supplier should be contacted to provide the fusion time.

Safety and Field Precautions

National and local legislation and gas & water company field installation safety standards and precautions should be followed at all times when using Caldervale products.

• When used in gas installation work, treat electrical equipment as a potential source of ignition and follow proper practices for working in an explosive atmosphere.           

• The electrofusion processor, its power supplies and all supply line connections must be located out of trench wherever possible.

• Caldervale electrofusion processors and Maxifuse tools and accessories are designed for use with most conventional brands of fittings. However, where there is doubt, the user must determine the suitability of the fittings for use with Caldervale and Maxifuse tools or refer back to the manufacturer or their local agent prior to use.

• During the assembly of pipe networks or connections care should be taken to avoid the build up of gas or water pressure within the system, in a gas installation, any build of gas must be safely vented following gas company procedures, Pressure build up of any kind in the area of a fusion joint may adversely affect fusion quality.

• Electrofusion fittings should be kept in their original packaging until time of installation. Fittings should not be stored without their packaging. Dust, dirt, oil, or water will contaminate an unprotected fitting.

• Where it is possible, electrofusion processors should be stored and used out of direct sunlight and where there is a free flow of air, this will aid in keeping the processor cool and extend the operating time. Excessive exposure to heat (including use near a generator exhaust,) will increase internal heat build up resulting in the processors internal safety devices shutting down the unit. 

The following notes are intended as a guide for using the appropriate Caldervale and Maxifuse tools and indicating their limits of capability when used in the assembly of pipes, fittings and couplers.

Pipe preparation & restraint

It is essential that the sections of pipe being joined together are both adequately prepared and supported before being joined together with an electrofusion coupler, failure to do this can produce a joint which can fail immediately it is put under pressure, either by the application of a pre commissioning pressure test or by the later application of pressure from the medium being carried by the pipe system.

Successfully passing a pressure test or the initial application of pressure does not mean the a wrongly prepared joint is okay, in fact a joint which appears to be good can be severely de limited meaning that leakage at the joint, or even complete failure may occur at a time in the future, sometimes months or years after the initial installation.

To produce the successful electrofusion joint it is necessary to follow this simple procedure.

• Cut the pipe ends as square as is possible with pipe cutters for small sizes up to
• 63mm or 2 inches, a guillotine cutter for mid size pipes up to 315mm or 12 inches or large diameter cutter for sizes above these.

• Mark the pipe with a marker pen a minimum distance of 50% of the coupler length plus 25-50mm or 1-2 inches

• Apply the appropriate size pre preparation re rounding tool to bring the pipe to as near round as possible.

• Release the pre preparation re rounding tool and move along the pipe to a point beyond the mark made by the marker pen, re tighten the pre preparation re rounding clamp

• Again with the marker pen mark the area between the pipe end and the distance mark with a hatch pattern.

• It is essential that all of the surfaces of the 2 pipe ends be removed to a depth of 0.25mm in the fusion zones, this is sufficient depth to remove surface oxidisation while retaining a seal in the cold zones, allowing pressure to build up when the coupler is heating.

• Due to the increasing sizes of available couplers from 20mm to 800mm and above it is not possible to propose a single tool that will scrape all sizes, when designing Maxifuse tools we try to make a single tool cover as many sizes as possible but this is not always achievable on smaller sizes.

• Use the appropriate Maxifuse pipe preparation tool, set correctly to remove the pipe outer surface including the hatch markings, any marks remaining after the first pass will indicate incomplete surface removal and indicate that a second pass of the scraping tool is required.

• Should hatch areas marks clearly remain untouched after a second pass and the Maxifuse preparation tool has been set correctly using the manufacturers guidelines, consider cutting and discarding this short length of pipe as it may have an irregular wall thickness.

• Assuming that the pipe preparation has been successful and while the pre preparation re rounding tool is still in position, the coupler can be introduced on to the prepared pipe end after which the pre preparation re rounding clamp can be removed. The bag that the coupler is packed in should be used as a cover around the pipe and coupler as an aid to joint cleanliness.

• The other pipe end should be prepared in similar manner using the pre preparation re rounding clamp and preparation tool. When the second pipe is correctly prepared it should be introduced into the free side of the coupler after removing the bag, The bag should be retained for collecting the swarf from the scraping process prior to recycling.

• For ease of movement of the pipes, especially those of larger sizes, consideration should be given to using a number of appropriately sized Maxifuse pipe rollers positioned on either side of the joint, not only will these aid movement of the pipes, they will also keep the joint clear of the ground.

• A restraining clamp should now be applied to the joint, clamping both pipes together thereby preventing unnecessary movement of the pipes. Pipe movement relative to each other and the coupler throughout the fusion and cooling cycle is a cause of incomplete fusion and of joint failure, it is essential therefore to correctly apply and use the appropriate type of Maxifuse restraining clamp on every joint.

The fusion cycle

The fusion cycle is the application of electrical energy to a resistive wire coil wound inside the electrofusion coupler in close proximity to the pipes, the heating effect caused by the current flowing through the wire causes it to heat up and melt the surrounding plastic to a point where the plastics in the coupler and pipe wall join together to form a single material.

On completion of the heating cycle time, the processor switches off the power, this terminates the heating and allows the mixed plastic material to solidify as it cools, the resulting join has been found under test to be stronger than the associated pipe work, again closely following a few simple steps will produce a good reliable joint.

• Prior to starting the fusion process it is essential to ensure that the fusion processor has a suitable power supply capable of providing the required energy. If supply power is derived from a commercial or industrial supply, any inline fuses or circuit breakers should be checked to ensure that they adequately rated. Where power is taken from a portable generator, the generator should be rated sufficiently and note should be taken of possible power de rating due to altitude, in addition adequate fuel should be available to maintain the generator for the full duration of the heating and cooling cycle.

• Always start the generator with the fusion processor disconnected and allow to run for 2 minutes to stabilise the output volts, connect the processor and switch on, follow closely the information shown on the display, selecting the fusion mode when asked too.

• Prior to starting the fusion process it is important to chose the fusion mode, manual, barcode or embedded resistor fusamatic are all possible with Calder and Proxima models, The mode is selected from the processor menu.

• Manual fusion mode requires the operator to simply input the appropriate time shown on the coupler or fitting, the actual method of time input is dependant upon the actual model of processor, the time input process is shown in the instruction books supplied and is extremely easy. The usual output voltage from the processor to the coupler is 40 volts however some couplers require a higher voltage and this can be selected again by following instructions. The default voltage is 40 volts.

• Embedded resistor/Fusamatic mode requires a special output chord with a voltage sensing point, not all processors have this particular mode, the Fusamatic output chord is detachable from the processor enclosure by a special plug and lead.
• When in Fusamatic mode the fusion time is calculated by the processor and the coupler supply voltage is fixed at 40 volts.

• Barcode mode requires the operative to scan or swipe the barcode label as instructed by the processor menu, the processor then calculates the fusion time and voltage from information encoded in the barcode characters and sets itself accordingly, the data is also entered into the processor menu where it can be downloaded at a later date.

• On completion of the fusion heating cycle the electrofusion processor will shut down the output volts, however it is important that the pipe and coupler are left undisturbed until the completion of the cooling time, even if this means leaving the processor connector plugs connected to the coupler power sockets

• Only properly trained and qualified personnel should make fusion joints.