The truth about mechanical pipe joining

The truth about mechanical pipe joining

By Marcel Ley, regional sales manager of Victaulic South Africa

There are several myths surrounding the mechanical joining of HDPE piping. 

The mechanical joining of HDPE piping is the best way to ensure job-site safety, while at the same time saving time and money.

As innovations gain traction, so do the replacement of older technologies. One such product is HDPE that has infiltrated several industries, such as mining and construction, by presenting an alternative to the aging concrete- or steel-piping solutions of the past. The composition of the material displays impeccable resistance to chemicals, as well as excellent corrosion resistance and low weight properties that have seen it become the preferred choice of modern-era engineers.

Most of these myths are simply fictitious but persist across various industries.

However, as with all pipe applications, sections require joining and the orthodox welding, threading, fusing and soldering methods pose not only time delays, but add to the safety risks and increased financial implications as specialised workmanship is required for the installation.

For years, butt fusion and electrofusion have been considered the top joining methods for HDPE piping. People commonly overestimate the performance advantages of fusion and until now it has been widely accepted as the easiest, most efficient method for joining HDPE pipe.

As mechanical joints are widely embraced in metallic piping applications, many highlight concerns surrounding the performance and reliability factors of mechanical joints in relation to HDPE piping. And while most of these myths are simply fictitious, they persist across various industries, leading practitioners to believe that mechanical joining is not a suitable method to consider.

The first myth is that HDPE piping with mechanical joints does not perform optimally when buried.

Truth: [bold] In fact, certain mechanical joints have been specifically designed with buried applications in mind. Products have been fabricated out of durable ductile iron housings and fluoropolymer-coated hardware, ensuring that couplings are protected against an array of conditions.

The second myth surrounds the concern that fusing provides stronger joints, and while fusion has traditionally been seen as the choice method of joining, recent data and studies may prove otherwise.

Truth: Fused joints are susceptible to several variables such as the skill of the technician, surface contamination, and hot or cold conditions – all impact the overall integrity of the joint. Further, there are currently no visual or non-destructive manners in which to inspect the quality of the joint.

Thirdly, many consider that grooving pipe ends creates a point of weakness.

Truth: However some company solutions have been designed specifically to allow the coupling keys to engage the groove profile. Therefore, providing a fully restrained joint up to the working pressure of the pipe. Moreover, the joint is designed so that the groove is filled with the keys on the coupling’s metal housing.

Essentially, the reduced pipe wall thickness at the groove is reinforced by a restrained ring of iron – a much stronger material than HDPE to begin with. This design adds to the strength of the joint, rather than detracting from it.

Another myth is that the method of fusing remains a faster alternative to joining.

Truth: The reality is that fusing HDPE is a slow process even in ideal conditions. Variables ranging from weather conditions, the skill of installers, and the quality of their machinery impact the success of the joint.

Quality couplings ensure an installation time of 10 times faster compared to fusing, and with only simple hand tools, workers will be able to install the joint without expensive fusing equipment, expertise, power sources, and certified fusion installers. The installation of the joint is not determined by weather conditions and offers the ideal solution to joints in tighter spaces, as no complex equipment is required for the installation.

Finally [bold], many believe that mechanical coupling solutions are expensive alternatives.

Truth: [bold] As mechanical couplings are faster and easier to install, and require little maintenance, projects can save on labour and skilled installation costs which will ultimately negate the cost of the couplings.


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