McElroy explains why HDPE is a common-sense solution to efficiency, improved safety, and quality.
The world’s infrastructure is changing. In piping systems both above- and underground, system design, installation, and maintenance have become top priorities, alongside considerations for sustainability, cost effectiveness, and quality assurance.
Because of the ever-increasing need for oversight and improved safety, welded high-density polyethylene (HDPE) pipe has emerged as one of the fastest-growing pipe materials available worldwide.
Thermoplastic pipe welding – also known as butt fusion welding and poly pipe welding – is the process by which two plastic pipe ends are faced, heated, and forced together under pressure to form a welded joint that is stronger than the material surrounding it.
Poly pipe welding is a reliable, trusted, and standardised method for joining plastic pipe together. Many standards exist to ensure the welding is performed properly and consistently. In Australia, ISO high force standards outline the acceptable practices for heat welding for polyethylene pipe and fittings, including heat and cool times and pressures required for different sizes of HDPE pipe. Since its arrival on the market in the 1960s, welded HDPE has become one of the most trusted materials for installation.
Much like iron, steel, and PVC pipe, HDPE can be used in a variety of applications, from municipal water and wastewater to natural gas to conduit for wire and cables.
HDPE, however, takes things a step further, bringing a myriad of benefits when welded with quality equipment and following a recognised standard. Those benefits include:
Corrosion free: Unlike traditional piping materials like iron or steel, HDPE does not rust or tuberculate, and when properly installed is expected to last more than a century without issue.
Leak free: Welded HDPE has an allowable water leakage rate of zero, as the bond formed during the pipe welding process is stronger than the surrounding pipe material.
Trenchless installation: HDPE can be installed using trenchless methods that keep disruption in the area to a minimum and reduce machinery, manpower, and time required for the work.
Longevity: When welded with quality equipment, a trained operator, and an accepted welding standard, the lifespan of HDPE piping systems can exceed 100 years.
Cost and time efficiency: Because poly pipe welding can be done using a single operator and a single machine (that in some cases can even be driven to the pipe welding site without extra heavy machinery), the amount of heavy equipment required for the project is often lower than what’s expected for metal pipe. HDPE is lightweight and versatile, and can be bent to fit into spaces that might call for joints or specialised fittings in traditional piping materials.
Quality assurance: HDPE and other plastic pipe – such as polypropylene, which is widely used in indoor applications like HVAC – can be joined in a way that provides a digital “thumbprint” for each joint welded and installed. Data-logging tools can record pertinent welding parameters like the pressure and standard used, heating/cooling times, GPS location of the weld, and more.
Trenchless opportunities
With thermoplastic pipe, installation methods go beyond traditional trench-digging. Eliminating the need for a trench not only reduces the amount of manpower needed for installation – it also minimises the disruptions around the site, such as streets or waterways.
Some trenchless installation methods include horizontal directional drilling (HDD), pipe bursting, slip-lining, submerged/floating pipe.
Utilising HDD, the City of Gold Coast was recently able to complete a large-scale water recycling network, constructing two of the longest marine pipeline crossings of their kind in all of Australia. To compensate for the area’s population boom – by 2050 the area is expected to double to 1.2 million people – the existing infrastructure, installed in the 1980s, had neared capacity. During the first phase of the project, a 1200mm diameter welded HDPE pipeline was pulled under the Nerang River bottom between Winchester Street and Waterways Drive. The pipeline is designed to handle increased volume of wastewater that, after treatment and reclamation, goes on to irrigate golf courses, parks, and more.
Replacing guesswork with guarantees
Quality assurance can take many forms, especially on a poly pipe welding jobsite. Whether replacing old or failing infrastructure or installing new service, it’s critical to ensure the pipe is installed correctly.
For poly pipe welding, quality assurance considerations include:
Training and certification: Certified welding technicians undergo classes to ensure they are well-versed in the welding process. McElroy University offers several certification classes that cover a wide range of poly pipe welding processes, from small-diameter and manual welding to large-scale pipe welding. These classes are available worldwide and are taught by McElroy Certified Instructors, ensuring that students are ready for the job ahead.
Accepted standard: To ensure consistency and quality of each joint, an accepted standard should be used when welding HDPE or other plastic pipe. These guidelines establish things like proper melt depth, the pressure needed for the size and type of pipe being joined, heat and cool times, and more.
Quality poly pipe fusion machine: A high-quality fusion machine is one of the most important tools on any fusion jobsite. A quality machine will be ready for the job ahead and, in many cases, may reduce the need for extra heavy machinery or manpower. Many McElroy machines are designed around a single operator, allowing one person to control the fusion from start to finish.
Data-logging tools: During and after the poly pipe fusion process, data-logging tools can record and store the fusion parameters. Data-logging devices provide the tools to improve decision-making and overall jobsite performance in the field. McElroy’s DataLogger® 7 takes that a step further with an additional suite of quality assurance innovations, including GPS information for each individual joint, the operator who performed the weld, and exception reporting that lets inspectors, contractors, and engineers find potential issues in the fusion site before it goes into service.
The poly pipe welding industry is a fast-growing one, and it’s constantly shifting to meet the changing needs of modern infrastructure. McElroy is committed to remaining at the forefront of fusion technology and providing tested, trusted machinery that will improve the world’s infrastructure one weld at a time.
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