Trenchless Technology Cover Story

Long Life Objective for Link-Pipe Sewer Repairs

August 1998

Lembit Maimets and Nataliya Hearn founders of Link-Pipe Inc

Spot Repair Pioneer Fixes Goal on Durable Structural Rehab

by Paul J. Miller

Company founder Lembit Maimets and Nataliya Hearn pose with Link-Pipe repair products.

Company founder Lembit Maimets and Nataliya Hearn pose with Link-Pipe repair products.

Spot repair methods sometimes seem to be an afterthought of the current sewer rehabilitation industry. Not so with Link-Pipe Inc.'s repair system.

First patented in 1978, the company has offered dependable spot repair technology for 20 years. Link-Pipe's products continue to stand as the only mechanical spot repair system in the industry, according to Lembit Maimets, founder and president of the Richmond Hill, Ontario-based firm in a northern suburb of Toronto. The product's history makes it a pioneer in the pipeline rehabilitation industry.

The Link-Pipe product grew out of Lembit's experience of 20 years in a city services career. Lem noted the small portion of pipes which are actually damaged when pipe rehabilitation is undertaken. "I noticed that a very small part of the pipes was actually damaged," said Lem. "Usually the damage in non-reinforced pipe doesn't exceed six percent of the total linear footage. Relining seemed to be lining a lot of good pipe." Lem found various studies in different locales corroborated this data.

Repairing the specific damages seemed "so sensible" instead of relining the entire pipeline. Lem combined his background as a structural engineer to develop a locking repair sleeve product to repair and seal the damaged pipe segments.


Long Service Life

Guiding the product development is Lem's concern for sound engineering principles applied to the problems of infrastructure rehabilitation. Long service life in repair materials has been the prime objective in the development of all Link-Pipe products. "It has always been our mission to create a repair to last as long as the host pipe," said Lem. Recent inspections in Toronto and New York have found repair sleeves to be in excellent condition, leading Link-Pipe to extend its 10-year warranty on the installations.

Dr. Nataliya Hearn, who heads testing and technology development for LinkPipe, commented, Durability of the infrastructure is very important. We have infrastructure installations of 50-60-70 years old, in some cases, and it is deteriorating very rapidly. That is why the focus on the economics of infrastructure has shifted much more to rehabilitation than to new installations."

Lem underscored the service life of rehabilitation methods: "If we use materials that have a low service life, can you imagine the damage that has occurred over the last 60 to 100 years in the pipes? If we now repair them with materials that only last 10 to 15 years, suddenly we will get allthe 60-year damage coming up in a very short period of time." Lem cautioned, "We are courting disaster unless we design repair methods that last a long time." 


Mechanical Spot Repair

Link-Pipe mechanical repair products utilize a compressed stainless steel sleeve or a hinged PVC product sleeve which, when locked in place, provides the full structural support needed to restore the pipe load capacity. The repair sleeves, which run from I to 3 ft in length, can be overlapped as needed to repair damaged pipe sections. A grout-coated foam covering provides a secondary "filler and sealer" material to fill the annular space.

The spot repair sleeves are easily transported and readily installed by trained municipal crews or TV-inspection contractors, becoming a "just in time" repair package. Many cites keep the repair sleeves on their trucks for immediate repairs. The company also has developed networks of contractors and distributors across the country to install the repair products.

Twenty years of spot repair product developments are the backdrop for Nataliya Hearn and Sini Stojicic's review of product testing reports.

Twenty years of spot repair product developments are the backdrop for Nataliya Hearn and Sini Stojicic's review of product testing reports.


Lembit Maimets started Link-Pipe in 1978 with the development and patenting of his first product which later was called Snap-Lock. In 1989, Lem entered a joint venture with the Iseki/Toa Co. of Japan. Eventually, the patent for Snap-Lock was sold to Iseki/Toa and Lem retained the rights in North America. Since then, further new product developments at Link Pipe have resulted in a grout sealed repair sleeve and new applications for pressure pipe and potable water lines.

Key management personnel include Olev Maimets, son of the founder, who is director of marketing for Ontario. Sinisha Stojicic ("Sini") is director of corporate development and concentrates on marketing and product innovation. Despite the title, Sini said, "In the real world, I and everyone else on the staff must jump into the manholes whenever necessary to assist with projects." Nataliya Hearn directs the testing and technology development for the company. She is also an assistant professor in the University of Toronto Department of Civil Engineering.


A new chapter

Lem came to Canada in 1947 from the Baltic country of Estonia, landing with one U.S. nickel to his name. After working in the "bush" of northern Ontario for a few years, Lem returned to Toronto and was married in 1951. He began studies at the University of Toronto while working full time for a local municipality.

After earning a degree in civil engineering in 1956, Lem was employed as a senior structural engineer for the City of Toronto, a career which culminated with the construction of the new City Hall. In 1965, he was appointed as the director of building and assistant department head for the Borough of Scarborough. Lem joined a private consulting group In 1971 as manager of structural engineering and building services.

It was during a design project on a water intake line from Lake Ontario for a local refinery that Lem began developing his idea for the repair sleeves. Since the concept looked promising, Lem resigned from the project and started developing the repair sleeve. He received his first patent in 1978 and organized the Link-Pipe company a year later.

Today, Lem holds 16 patents for a variety of products with multiple applications of the technology. "We have different technologies and pipeline rehabilitation is just one area of our interests," said Sini. "We have products that we haven't commercially introduced." The product applications range from medicine to outer space aeronautics.

One product application with a science fiction flair is a conceptual patent for the design of structures to be launched into outer space. The product uses principles of coiled steel, like the compressed repair sleeve, which can be designed into structures for antennas or even space stations. Lem commented on the new product ideas: "We have not promoted them. We 're waiting for an opening whereby a small application may become practical. I have lived long enough not to dream too much! The younger people here dream on. So I'll pass this on to them."


Grouting sleeves are prepared in the field for launch into the manhole for sewer rehab.

Grouting sleeves are prepared in the field for launch into the manhole for sewer rehab.

New Applications

A new product application area for Link-Pipe repair sleeves is the rehabilitation of gas lines. The modified sleeves are being developed for internal repair of cast-iron gas distribution lines. The Gas Sealer Sleeve was tested successfully in pilot projects with Long Island Lighting Co. in late 1997. (A story detailing these projects appeared in the June '98 Gas Supplement of Trenchless Technology.)
Entry into the gas rehabilitation market requires a level of testing and product verification far exceeding that of the sewer industry. "We have carried out testing here according to the gas industry standards," said Lem. "Now we need third party testing."

Link-Pipe has entered a testing program with Cornell University of Ithaca, N.Y., to validate the performance claims of the sleeves. Nataliya said, "Once the testing goes through this summer, the technology is basically approved for use in the gas industry." Sini explained that the product then may be commercialized and introduced to the open market.


Loss of potable water through leaking joints and cracks in waterlines is prevalent in both developing and developed countries, Lem observed. Rehabilitation of waterlines is another application for the repair sleeves. Link-Pipe offers one particular sleeve for potable water usage in which the sealant has been FDA-approved and can withstand high internal water pressure. Lem commented that in the development of the pressure repair sleeves, the testing objective is to ensure that all materials and sleeve performance are in compliance with potable water specifications.

Objective testing for their products is a prime goal. Lem expressed the opinion that this is needed for the overall industry, not only for gas repair applications. He believes that thorough testing programs could lead to the development of standards for the rehabilitation industry. While he values the contribution of NASTT and the No-Dig Conferences to the overall promotion of the industry, Lem believes these agencies "are not exactly equipped to lead in establishing standards."

Lem observed, "The industry has created a tremendous surge of new ideas, which is good. But when we get to the standards, they should be set by academicians, not by industry.

"When we talk about advancement, industry development is great. When we talk about protecting public interests and standards, that's where academics should come in. Then we have proper standards," said Lem. "This is my basic philosophy. I don't want to send anything out that isn't academically backed."


International Commerce

Lem reported that Link-Pipe's business has been growing. Modest growth of 10 percent marked 1997, but current year reports are tracking at about 30 percent growth in sales volume, according to Sini. Lem indicated that the firm is shipping more than 4,000 units per year, and has nearly 20,000 repair sleeves installed. "So we're in the right trend,' said Lem. "We want to make sufficient inroads abroad, as well, to get a broader base and more stability, not so dependent on regional sales."

Link-Pipe has an office in Hong Kong to pursue installations in East Asia. International sales representation is active in Singapore, Taipei and Beijing, Lem said. Representatives in Europe provide sales contacts for Link-Pipe in Spain, Belgium, Germany and Sweden. Currently, Link-Pipe has joint ventures in South Korea and Egypt, where a project was just completed near Aswan.

"All this out of these modest little quarters here in Toronto," said Lem with a chuckle. "These machines (pointing to the computers, faxes, modems) keep us in contact through the Internet."

The small ring worn by these Canadian engineers is a symbol of their professional oath to uphold the public interest. From left, Nataliya Hearn, Olev Maimets, Sini Stojicic and Lem Maimets.

The small ring worn by these Canadian engineers is a symbol of their professional oath to uphold the public interest. From left, Nataliya Hearn, Olev Maimets, Sini Stojicic and Lem Maimets.


International commerce is second nature to the cosmopolitan staff of Link-Pipe. Every employee has multicultural ties to ethnic, social and language groups beyond English. Lem boasts of one staff member who speaks the languages of over half of the world's population - English, Mandarin, Hindi and Cantonese.

Lem has surrounded himself with trained engineers. A common emblem shared by most of them is a small metal ring worn on their small fingers, Nataliya explained the origins of the ring, which is a custom primarily of Canadian engineering schools. It relates to a bridge built in the beginning of the century that collapsed prior to opening. Originally, the rings were fashioned from metal taken from the demolished bridge. Sini said, "It's to remind us in our everyday work of our responsibility to society and to our profession."

"We take an oath upon graduation to uphold these ideals and to protect the public interest," said Olev. "We get the ring after we've completed the oath."

The Link-Pipe engineers take their oaths seriously. Their concern for the longevity and durability of their repair sleeves is rooted in a deep sense of responsibility to society and to the profession for the care of the infrastructure.

After all, as Lem says, "Spot repairs are so sensible."

Paul Miller is the editor of Trenchless Technology.