Taking the rough with the smooth for water jetting success

Mr David Kennedy
23/12/2020 - 12:49

It is an irony that the use of abrasives has been one of the notable causes of the growth of the water jetting industry.

The development of technology to allow a high pressure water jet to be combined with an abrasive, and to focus its energy for cutting applications, has been one of the key innovations of the last 30 years, says Jeremy Twigg, who has worked in the water jetting industry over the last five decades.

“Combining ultra high pressure water jetting with  small volumes of fine abrasive, delivered directly into the water jet at the nozzle, creates a hugely powerful cutting tool that retains key sustainability advantages,” he explains.

Abrasive water jet cutting, as it is called, represents one of the technology leaps that has driven the development of water jetting over the last 40 years.

Water jetting advantages

“It was a gamechanger,” says Jeremy Twigg. “Abrasive water jet cutting provides an intrinsically safe method for cutting pipes and structures that contain volatile liquids and gasses. As such, it has become a vital tool for the oil and gas exploration and petrochemical industries.”

The same process of change has occurred with industrial cleaning and surface preparation.

For decades, abrasive blast cleaning, using compressed air, was the dominant process. There has always been a problem: the process creates a large amount of landfill waste. While dust is an environmental and health hazard.

Over recent years, though, water jetting has come to the fore, as asset owners and contractors have seen and experienced its advantages, in terms of safety, sustainability and operational effectiveness.

WJA 40th anniversary 

Jeremy Twigg shared his views to help mark the 40th anniversary of the founding of the Water Jetting Association’s (WJA), the UK’s member organisation for the water jetting industry.

The commercial director of RGL, based in Romsey, near Southampton, in Hampshire, with offices in London and Manchester, began as an apprentice engineer at pump manufacturer Harben Systems, in Salisbury, Wiltshire.

That business has since been incorporated into Flowplant Group, another WJA-member.

In 1984 he moved to a newly set up family business, Rentajet, then founded his own trailer-mounted jetting unit manufacturing company, Manfield Industrial, and worked in the pioneering world of drain jetting in the Middle East before moving back to the UK to go into business with his brother, establishing RGL as a water jetting contracting specialist.

AWJCC - Steel - Proven Gas Works - 10495 - Gas Holder - Robot - Rig - Cutting Glasgow 2020
Abrasive water jetting cutting being used on a gas holder in Glasgow, Scotland

Surface preparation standard

Since then, RGL has delivered on-site high pressure and ultra high pressure water jetting services to many customers in the UK, and a growing number internationally, notably in the Middle East and Africa.

RGL has been an early adopter of many industry innovations, and has played its part in supporting their development, for example through the use of vacuum systems to contain and recover wastewater and aerosol spray.

Another key catalyst that has shaped the growth of water jetting, says Jeremy Twigg, was the introduction of BSEN ISO 8501-4:2006 – the international standard for surface preparation.

ISO 8501-4 has established clear, measurable specifications for the outcomes of a range of processes for steel structures, including hydroblasting, coating and corrosion removal, and the taking back of surfaces to bare metal.

For the first time, water jetting contractors could demonstrate their surface preparation methodologies achieved a set international standard, while delivering other significant benefits over abrasive blasting. In turn, this led to manufacturers developing coatings that can be applied to hydroblasted surfaces, further embedding it as a key industrial process.

Improving equipment reliability

As a member of the UK Institute of Corrosion, RGL had the opportunity to liaise with the team that created ISO 8501-4. This led it to being invited to support the institute’s corrosion engineering division in the production of technical guidance document for the use of water jetting for surface preparation.

Even before that, though, the development of ultra high pressure water jetting equipment in the 1990s, with the subsequent improvement of the reliability was also key.

EU regulations that reduced the reaction force of handheld equipment to 250 newtons resulted in water jetting pressures being increased, while water volumes decreased.

This paved the way for the introduction of abrasive water jet cutting. It also required the significant investment in new jetting equipment, says Jeremy Twigg.

“The main challenge, as water pressures increased was the need to improve the reliability of the  equipment,” he explains. “In the early days of UHPWJ, we had to send a fitter out with the jetting teams. He would be kept busy replacing and rebuilding nozzles as they failed.

“As engineering standards improved and new materials were introduced, such tungsten, ceramics and industrial sapphires in pump plungers and nozzles, machines could be run for 1,000s of hours before they failed, instead of 100s. This has allowed engineers and specifiers to include water jetting as a viable option for many new applications.”

Concrete Hydrodemolition - Robotic
Jeremy Twigg - WJA technical committee member and RGL commercial director

Hydrodemolition a “no brainer” 

For tasks such as surface preparation and hydrodemolition, especially in temperate regions where water is plentiful, water jetting is now a “no brainer” says Jeremy Twigg, who for 15 years has been a member of the WJA’s technical committee.

“Hydrodemolition allows civil engineers to remove concrete without vibration or damaging the steel reinforcement,” he says.

“Other methods are slower, compromise the integrity of the structure or are more dangerous for the operative. The last 40 years has been a continuous process of education of civil engineers. Once they see water jetting in action, they see a Pandora’s box of opportunities, and all largely positive.

“A significant caveat is where water jetting is being considered in a country where clean water is scarce, or where water jetting skills or technologies have yet to be well developed.

“Even in the UK, water availability and price can hamper the uptake of water jetting on some projects. If a hydrant or city supply is available, the cost of is quite low (about £1.50-2.00 per cubic metre) but if we have to tanker it in using a truck this rises considerably.”

Another key development has been the growth of semi-automated, or robotic, water jetting. This is the process of carrying out water jetting using remotely controlled machines rather than hand-held lances.

Concrete Hydrodemolition - UHP Precision - Hand Held Safety Lance - Rebar
Precision hydrodemolition of concrete by an operator using a handheld lance is still an important water jetting capability

Rise of robotic systems

Remote control technology is vital for abrasive water jetting. There is no protective material tough enough to withstand a jet of water pressured to 40,000+ pounds per square inch, spiked with garnet abrasive.

Robotic technology is becoming increasingly viable across other water jetting applications as well. “Every year, RGL tries to push back the boundaries, and do more water jetting using remote-controlled technology,” says Jeremy Twigg.

“We’re currently at about 50-50 – half robotic and half hand-held. In the next five years, I can see us shifting to a position where robotic systems taking the larger share of the water jetting we do. Though there will always be a place for hand-held jetting because of the nature of the task and the environment it is sometimes required.”

Jeremy Twigg is certain that the WJA has a big role to play in the development of water jetting in the UK and, potentially, internationally.

He explains: “The WJA is one of the best-established water jetting associations in the world. Its codes of practice and training courses are respected and used internationally, especially in the Middle East’s oil, gas and petrochemical industries.

“As such, I think the WJA has a role to play in leading the development of global standards and I will be encouraging my colleagues in the association to accept opportunities to take up this role.

“Our number one priority is to maintain the safety of our operatives and everyone else associated with a water jetting project. Keeping that front and centre underpins other quality and technical standards that drives water jetting forward as an engineering solution.”