15 June 2023
There are various sources online depicting the history of polyethylene discovery and production. One of the earliest discoveries seems to be by German chemist Hans von Pechmann back in 1898, by accident whilst researching diazomethane. A similar accidental discovery occurred in the UK in 1933 by Eric Fawcett and Reginald Gibson at the Imperial Chemical Industries (ICI) works in Northwich, England.
It was not until 1935 that another ICI chemist, Michael Perrin, developed this accident into a reproducible high-pressure synthesis for polyethylene that became the basis for industrial low-density polyethylene (LDPE) production beginning in 1939. Because polyethylene was found to have very low-loss properties at very high frequency radio waves, commercial distribution in Britain was suspended on the outbreak of World War II, secrecy imposed, and the new process was used to produce insulation for UHF and SHF coaxial cables of radar sets. During World War II, further research was done on the ICI process and in 1944, DuPont at Sabine River, Texas, and Union Carbide Corporation at South Charleston, West Virginia, began large-scale commercial production under license from ICI.
In November 1953 Prof. Dr. Karl Ziegler, a German chemist, and his research staff first succeeded in polymerizing ethylene in the presence of organo-metallic catalyst blends under “mild” pressure and temperature conditions – the low-pressure process for the manufacture of high density polyethylene had been discovered. It was for this discovery that Karl Ziegler, together with the Italian chemist Giulio Natta, was awarded the Nobel Prize for Chemistry in 1963.
Over in the USA, The first installation of PE gas distribution pipe took place in Caney, Kansas, in 1959, with pipe manufactured by Phillips Petroleum. By the mid-1960s, utilities began to make the transition from steel and cast iron to PE pipe. DuPont and Phillips Petroleum were two of the early main developers of PE pipe.
By the end of the 1950s both the Phillips- and Ziegler-type catalysts were being used for high-density polyethylene (HDPE) production.
In the UK during the early 1960’s, the Gas Council Engineering Research Station was built, in Tyne & Wear. The Gas Council later became British Gas, who continued to use the facility until circa 1995.
The first UK gas polyethylene pipe installation was completed in the UK in 1969, with a socket and saddle installation used on smaller diameter pipes, and butt fusion being used on larger diameter pipes.
Around 1975 electrofusion was first proposed for use in the UK, despite being used in some European countries since around 1955 the limiting factor in the UK is suspected as cost. British Gas developed the Gascoil electrofusion coupler in an attempt to create a standardized fitting for mass-production in the UK. British Gas also developed its own electrofusion welding unit around the same time, in a wooden case. This was never really commercialized or sold.
Shortly after, the DuPont electrofusion welding unit became one of the first to be sold commercially throughout the UK. In addition to this, electrofusion fittings from the European market were also approved for use in the UK, opening up greater availability and increased market competition.
In to the 1990’s and 2000’s it was widely recognized that polyethylene pipes had significant benefits over more traditional materials, when used in gas and water distribution networks, as well as other sectors and had become business as usual in most networks. The benefits include: life expectancy, corrosion resistance, flexibility, ease of installation, lower risk of leakage (if installed correctly).
As the application of polyethylene pipe systems and electrofusion has increased over the last 30 years, the technology and understanding has followed accordingly. The market for electrofusion couplers is now vast and almost every manufacturer has subtle differences in design, installation and dimensions.
As an industry, we now fully understand the criticality of the process of installation for both butt fusion and electrofusion on polyethylene pipe systems.
Throughout the development and growth of the butt fusion and electrofusion market, Hy-Ram have been closely involved, innovating relevant tooling to ensure the operator has access to relevant equipment to complete a quality installation.
For electrofusion, we need to consider the following to achieve a successful weld:
- Contamination – The surface of the polyethylene pipe should be clean and free of any substance that could affect the weld i.e. water, dirt, grease. Some asset owners promote the use of electrofusion welding wipes on the pipe for this aspect of the process. Electrofusion couplers should also be kept in their sealed bags until ready to use. It is also recommended that the local atmosphere is controlled, often with the use of a welding shelter or tent.
- Surface Preparation – The surface of the polyethylene pipe should be scraped or peeled in a uniformed and complete manner to remove the oxidized layer which occurs during and after the manufacturing process. It is widely understood that the removal of this oxidized layer improves the molecular diffusion across the welding interface, and therefore provides a more homogeneous weld.
- Clamping, Alignment & Re-Rounding – All electrofusion welds should be completed with adequate and suitable tools to re-round (if necessary), align and sometimes offer load, in the case of top tee or branch saddle fittings.
Do you know how the above affects UK electrofusion installations?
Please see the below failure analysis:
- 29% Scraping related (Scraping either not done or inadequately done)
- 29% Contamination related (Mud, water, oil, weld wipes etc.)
- 31% Misalignment (Exclusion or incorrect application of the pipe clamp)
- 11% – Other causes like multiple weld attempts made on the same fitting and material defect
Data gathered over a 10 year period, from UK electrofusion installations.
How can Hy-Ram help?
Hy-Ram are a UK manufacturer of electrofusion tooling for all applications from 16mm-710mm+.
Through decades of development, testing and worldwide distribution, we have a vast portfolio of products to support our clients in ensuring quality assurance for electrofusion installations.
Please see details of these below:
1. Contamination
To remove contamination from polyethylene pipes Hy-Ram offer welding wipes (Isopropyl) in varying concentrations to suit.
https://www.hy-ram.co.uk/product/alcohol-wipes/
It should be checked with the asset owner for approval, prior to use, as not all networks support the use and prefer other methods.
Welding shelters are often advisable or in some cases mandatory on some networks or projects. These offer protection from adverse weather conditions, temperature fluctuations and impact of dust, dirt and other forms of contamination risk on the overall quality of the electrofusion weld.
https://www.hy-ram.co.uk/product/welding-shelter/
2. Surface Preparation
To correctly prepare the polyethylene pipe surface in a uniformed and complete manner, Hy-Ram manufacture and distribute mechanical scrapers or peelers as they are known in some markets.
https://www.hy-ram.co.uk/product_category/pipe-scrapers/
These are mandated for use on some networks and in fact are as such in the UK Water sector, as per WIS 4-32-08, 2016.
“Mechanical pipe end scrapers (e.g. rotary scrapers) shall be used when preparing pipe ends for electrofusion socket jointing”.
“The tool shall remove a layer 0.2 mm to 0.4 mm thick from the outer surface of the pipe”.
For the UK gas sector, GIS/PL2-5:2018 states:
“The pipe surface shall be removed to a depth of between 0.05 mm and 0.1 mm for pipe diameters less than 63 mm and between 0.05 mm and 0.2 mm for pipe diameters equal to or greater than 63 mm”.
There are similar specifications across other regions worldwide, as the industry has recognized the value in the correct tool.
Typically markets have focused on the preparation of the ends of the pipes, with the use of mechanical scrapers, such as our PrepMaster Mono https://www.hy-ram.co.uk/product/prepmaster-mono/ and PrepMaster Multi https://www.hy-ram.co.uk/product/prepmaster-multi/.
Recently we challenged ourselves to offer a similar mechanical scraping solution for the middle of the pipes, to allow for optimum preparation of the pipe surface prior to welding top tee and branch saddle fittings. After completing a significant development program, we are now supplying and supporting improved installations in many areas of the sector, including networks that have witnessed failures in these types of electrofusion welds and see value in a uniformed and repeatable process of surface preparation.
The PatchMaster range of products are offered as single purpose, dedicated units or multi units that support several pipe size applications in one unit.
To see more about these products, please visit https://www.hy-ram.co.uk/product/patchmaster-mono/ or https://www.hy-ram.co.uk/product/patchmaster-multi/.
3. Clamping, Alignment & Re-Rounding
To correctly support the welding process with correct fitment, clamping and alignment, Hy-Ram manufacture and distribute a large range of options covering differing styles and applications.
https://www.hy-ram.co.uk/electrofusion/
These are mandated for use on some networks and in fact are as such in the UK Water sector, as per
WIS 4-32-08, 2016.
“Pipe re-rounding clamps shall be used to correct ‘out of round’ pipe ends (whether in stick or coil form) to enable insertion into the round electrofusion sockets. Additionally, alignment clamps shall be used to hold the pipe ends in the fitting and shall ensure the pipes are held in a fixed position without movement throughout the fusion and cooling periods. Pipe re-rounding and pipe alignment clamps shall be of robust construction”.
For the UK gas sector, GIS/PL2-5:2018 states:
“Restraining clamps are required for jointing fittings to in-line pipes and pipes at 45° and 90° to each other”.
“Re-rounding clamps shall be suitable for use with pipes conforming to GIS/PL2-2 and GIS/PL2-8, to assist in the assembly of electrofusion fittings conforming to GIS/PL2-4”.
Once again, many regions in the world have matured over decades of polyethylene pipe installation, and therefore mandate the use of re-rounding, alignment and positioning clamps, including top loading clamps for electrofusion top tees.
Hy-Ram can offer a broad range of equipment in this area of the market, as we recognize that there are varying challenges within the field, hence sometimes different solutions can be required to suit.
Typically our range caters for pipes from 16mm up to 710mm, but if you have requirements outside of this, please do not hesitate in making contact with us.
Below we can see some different solutions:
Manual Re-Rounding Clamps (16 – 400mm)
Hydraulic Re-Rounding Clamps (400 – 710mm)
Manual Alignment Clamps (16 – 315mm)
Manual Positioning Clamps (63 – 500mm)
Hydraulic Re-Rounding Alignment Clamps (400 – 710mm)
Electrofusion Tapping Saddle Clamping (63-500mm)
The development and advancement of the global polyethylene pipe market has been in many ways a major success story, with an incredible amount of ingenuity, hard work and innovation from so many organizations and individuals.
Hy-Ram are extremely proud to have been part of the journey, by working together with asset owners, contractors and industry regulators to develop a suite of tools to support the efforts and desire for compliant and technically correct installations.
If you have any comments, memories or enquiries based on any of the above, please do not hesitate in contacting us via our website https://www.hy-ram.co.uk/, email enquiries@hyram.com or phone +441623 422982.
