Adachi Construction and Industry developed the “SPR Method,” the first of its kind in the world to renew aging sewage pipes without digging or disrupting running sewage inside the pipes. This is a method whereby strips of newly developed plastic (polyvinyl chloride) are attached in a spiral form to the inner wall of sewage and other pipes. This method offers excellent anti-corrosion, anti-wear, anti-chemical, and anti-dragging characteristics, and improves pipe strength as well. This method is attracting much attention from an environmental standpoint, since it minimizes the effect of construction on traffic, generates no heavy equipment noise or exhaust, and produces no industrial waste such as excavated soil or aged pipes to be discarded. In 1998, the “Free Cross-section SPR Method (Self-Running Pipe Formation Method)” was developed for adaptation to various cross-sectional profiles such as rectangular or horseshoe-shaped culverts.
Adachi Construction and Industry http://www.adachik.co.jp/
Established in 1966, Adachi Construction and Industry specializes in civil engineering works (water and sewer systems) while addressing a variety of other challenges. By specializing in a specific business, the company maintains a high level of technological expertise and human resources. Currently, its main specialties are the repair, maintenance, and formulation of earthquake/disaster measures for aging culverts. Serving in the capacity of vice president of the Japan SPR Association established in 1989, the company participates in activities for the dissemination of this method and improvement of relevant technologies.
By rolling a strip of plastic material in a spiral form, a pipe is made right inside a sewage culvert.
Though plastic strips are hard, they are flexible enough to be deformed, which made free cross-section pipe-making possible.
Sewage pipes are a vital lifeline, but remain out of sight. No one notices the renewal construction of culverts going on just a few feet below the road on which one walks daily. There is a method employed whereby construction can be undertaken without digging up the ground or disrupting the flow of sewage. Mr. Akimoto is the one who took the initiative in developing the “SPR Method,” the first of its kind in the world, and says that he was “appointed to pursue dreams.” He adds, “The company obtained certain information about the social needs for such a construction method. We thought no one would be willing to do it except us, then we made the first entry and became the winner of the market.” The idea sprang up in the early 1980s in connection with a renewal project for the water distribution piping system at Haneda Airport. Since we could not interfere with the landing or take-off schedules of flights, we could not dig up the runways or taxiways. After all, this project adopted a successful method from Europe, but the R&D of pipe renewal methods suitable for the situation regarding Japanese sewage became an issue for the Tokyo Metropolitan Sewage Bureau and other related bureaus. “The initial stage was far from a project, and more like a hobby, or source of amusement (laughing). We came up with a lot of fanciful, unrealistic ideas, with which we thought we could obtain patents (again laughing). What led to the current method was the idea of using tin plate and rolling it spirally to produce a pipe. It couldn’t be used for sewage because tin plate gets rusted, and stainless steel was cost-prohibitive.” When a strip-shaped material is rolled in a spiral manner and attached to the inner wall of a culvert, the problem is what type of material to use. It was when Mr. Akimoto received a message to the effect that Sekisui Chemical imported a technology from Australia for producing pipe by rolling a plastic strip material in a spiral form. Sekisui Chemical was also contemplating the commercial application of this technology on its own. “We decided to give plastic a try and attempted to produce a simple pipe using a machine, but found that the pipe getting increasingly thicker as it was rolled (laughing). Based on the idea that tape can be wound up tightly when pulled as it is rolled, we continued our trial production while adjusting the tension using hydraulics.” After the trail period, Mr. Akimoto proposed the idea of joint development to the Tokyo Metropolitan Sewage Bureau, and Sekisui Chemical submitted a similar proposal to the Sewage Bureau. The participants, Adachi and Sekisui, were then ready.
A newly established agency, the “Tokyo Metropolitan Sewage Service,” verified the technology of both manufacturers. An agreement was finally reached by which Adachi was designated to promote mechanical development, while Sekisui was to provide plastic strip materials, thus launching a workshop in 1986. “We often had arguments. Rigid polyvinyl chloride is hard and if you apply too much power with a machine, it breaks with a snap. The development staff from Sekisui Chemical insisted that our machines are designed for rolling steel not plastic materials, and so on (laughing).”
Breaking was not the only problem. A plastic strip can easily sag due to its own weight or may not retain shape since it tends to roll up. Therefore, Mr. Akimoto made more and more requests regarding material, such as providing steel in plastic strips. Moreover, the rolling machines were gradually improved and modified, given the more difficult projects handled than at the start of trial production in 1986. The technology of both manufacturers was improved through such projects and matured onsite, and both are still continuing efforts for improvement. At present, they have an advanced SPR method that has been upgraded to handle “free cross-sections” of almost any culvert shape up to 5,000 mm in diameter, but chasing their dream has yet to end.
“An ideal should be high enough to be an ideal (laughing). We progress step by step. Currently, our method is self-running and semi-automated, but the ultimate goal is for complete automation all the way to the final process, without anyone diving into a manhole. Also, the production and installation of in-water, submerged pipe should be possible even during the full-capacity flow of running sewage.”
At times, though they began by using a dig-free method, they ended up in a situation where they had no choice but to dig, though such funny stories are things of the past now.
“When we come up with new ideas, we go ahead and make prototype machines of all kinds regardless of the cost involved (laughing). If you need to develop something new, sometimes you need to ignore experience and rules. Logic comes to us later. So, first of all, materialize it into a shape, and for engineers, budgeting comes next (laughing).”
(Other prizewinners)
From Adachi Construction and Industry: Koji Uchida, Kenji Muraki, Hamao Yamashiro
From Sekisui Chemical Co., Ltd.: Akira Imagawa, Yasushi Kitayama, Hiroshi Sugahara, Akihiko Takaya, Mitsuhiko Watanabe
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