The history of Aarsleff Pipe Technologies goes back to the beginning of the 1970s, when the management at Per Aarsleff A/S saw potential in installing new sewer pipes. However, the oil crisis meant that focus shifted to the energy sector for some years.

After the oil crisis, the ideas of working with sewer pipes re-appeared. However, it soon turned out that the best opportunity was renewal of outworn pipe systems. By coincidence, an employee had heard about an English method that made it possible to seal pipes from the inside by inserting a ‘sleeve’ in a defective pipe. It sounded so exciting that it was decided to contact the English company in Northampton.

There was great potential in applying and improving the English product. At the same time, the English company was very interested in a partnership, and a licence was issued to Per Aarsleff. The licence has since been terminated and today, the company has its own product.

Today, Aarsleff Pipe Technologies is an international company with subsidiaries, offices and partners all over the world. The company’s specialty is No-Dig renewal of pipe systems. Per Aarsleff has more than 30 years of experience, and is one of the leading companies in the world within the field.

Today, the company produces the liners in its liner factory, in dimensions up to DN 2,000 mm, and has its own impregnation factory. In most places, the company is responsible for carrying out the work for customers.

Growing the company

More than 60 years later, the original staff of 14 has grown to 3,200 employees. The annual revenue, which was 5,300 the first year, has 60 years later increased to €570 million. Approximately 35 per cent of the company's revenue comes from work performed abroad.

Per Aarsleff is a general infrastructure contractor. As well as the No-Dig industry, construction activities include roads, bridges, tunnels, airports, sewer systems with reservoirs, energy supply, communications network and wind turbine foundations.

“The company focuses on industrialisation and optimisation of production and in this way, we aim at cost optimising all phases,” Divisional Manager Hans Christensen said.

Today, Pipe Technologies generates revenue of €115 million, and the division has almost 600 employees.

Pipe Technologies has a market leading position in the area around the Baltic Sea and a number of subsidiaries in the rest of Europe.

Also, work is carried out in a number of companies and departments in Taiwan, Sri Lanka and India.

History of the product line

To a wide extent, Per Aarsleff’s technology has been developed at the company’s laboratory, and it is based on the experiences the company has from renewal projects in Denmark and internationally.

“In the beginning, we purchased the finished liners in England and impregnated them in a primitive way. The impregnation process took place in a building which was long enough to allow the impregnation to take place undercover, and thus avoid the curing process being initiated by sunlight,” Mr Christensen said.

To optimise impregnation and thus quality, the company built an impregnation factory so that this part of the work could be carried out under controlled conditions. Since then, the factory also has a sewing machine allowing liners with a diameter of up to 2 m to be made.

The development of installation and curing methods

Originally, the liners were water-inverted and cured by hot water reticulation. This method is still used when working with large dimensions – small dimensions are inverted by means of compressed air and steam curing. For very small dimensions curing is now done by LED light.

To continue improving the company’s competitiveness, the factory also has the facility to sew and impregnate glass fibre liners that are UV-light cured.

Per Aarsleff has carried out impressive sliplining projects with GRP. The pipes can either be produced in one of the two factories or purchased from external producers – depending on the profitability of each individual project. The company is capable of producing GRP pipes in all profiles, in dimensions up to DN 3,000 mm.

“Aarsleff Pipe Technologies’ methods for No-Dig renewal of main pipes are the most effective methods on the market,” said Mr Christensen.

“Our methods and units are highly advanced and flexible, and in most cases we are able to avoid excavation completely. We are able to renew even very long pipe stretches in one run without having to dig up things like gardens and roads.

“Our methods make it possible to carry out renewal projects quickly and with minimum disturbance to citizens, business owners and traffic,” said Mr Christensen.

There are some clear financial advantages connected with the No-Dig methods compared to traditional methods.

Irrespective of the extent of a renewal project involving main pipes, the company starts the work with a thorough planning stage – including CCTV inspections. Information is also collected from the relevant authorities and from the many partners that are often involved in a large project. The company always prepares a renewal plan that indicates what is going to take place in the short run, but at the same time, take the long view so that the customer knows the short and long-term economic consequences.

“We are the only supplier that is a total system vendor, and we are capable of renewing main pipes as well as laterals. Laterals are renewed from the main pipe in lengths up to 18 m, including a tight transition between main pipe and lateral. The process is a total solution where we are responsible for the entire production line from production of the felt liner to installation of the complete system,” Mr Christensen said.

The company is a member of the Danish Control Scheme for Pipeline Rehabilitation. This means that the Aarsleff CIPP lining complies with the requirements for declaration, control of both short-term and long-term properties, and current tests of installations.

In addition to being a contractor, the company sells unimpregnated liners and equipment to a number of countries worldwide.

The company said that it considers No-Dig work as an industrial product where profitability is subject to experience and logistic repetition.

Today, Aarsleff Pipe Technologies is capable of renewing highly complicated pipe systems without excavation – whether the pipes are installed beneath roads, companies or residential properties. Pipe repair capability includes:

• Laterals with hat profiles
• Installation of siphons under rivers, up to DN 2,000 mm and lengths up to 300 m
• CIPP lining of main pipes in dimension area DN 100–200 mm
• Renewals of downpipes, chimneys and vent ducts in buildings
• CCTV – before, during, and after projects
• Inspection, renewal and cancellation of manholes.

Product developments

In recent years, Copenhagen Energy, Water and Drainage (KE) has worked on getting a more flexible working procedure in connection with renewal of laterals.

The project was based on inspection and renewal of all laterals situated on the roads to Copenhagen. The project has a financial framework of approximately DKK 25 million per year (approximately $US 4.7 million). The project was put out to tender in a CCTV inspection contract and a No-Dig contract that was awarded to Per Aarsleff A/S, Pipe Technologies.

The result of the co-operation has been the development of new methods and quality improvements. Long-term co-operation has resulted in flexible case handling as both the client and the company have a permanent staff working with the job.

No-Dig has turned into an industrial product where it is possible to benefit from the effect of repetition in the entire logistics during the execution of the work.