A majority of the sewer and drainage pipes laid in the ground are unsound by now, and the pipe rehabilitation market is growing rapidly worldwide. For the control system of its newest pipe liner curing system, a leading full-service provider relies on the Simatic S7-1200 in combination with Basic Panels and TIA Portal.
I.S.T. Innovative Sewer Technologies GmbH, founded 16 years ago and headquartered in Bochum, Germany, is today a market leader in pipe and sewer rehabilitation. The company, with 60 employees, has its own research and development department as well as subsidiaries in Copenhagen, Madrid, Zurich, Bahrain, and the United States. Its success is based not only on the company’s uniquely diverse and high-quality product portfolio but also on competent and comprehensive customer support. The innovations developed to meet specific customer needs very often set new standards.
The common methods for trench-free rehabilitation include what is known as pipe lining, in which a tube made of fiber composite materials, mostly based on unsaturated polyester resins, is inserted into the defective pipe and cured using various techniques. I.S.T.’s Power Light system, which takes advantage of the larger nominal diameters of UV-sensitive photoinitiators to rapidly cure pipe liners, was the final puzzle piece allowing the company to become a full-service provider. For this development, I.S.T. recruited Thomas Reutemann, who can look back on 25 years of experience as a pioneer in UV irradiation.
The pipe liner curing system is used when a partial rehabilitation of the sewer or pipe section is no longer cost-effective due to extensive damage. “Compared with curing using hot water or steam, the UV system has the advantage of achieving the result much faster,” explains Reutemann, “and for quality assurance it is associated with better logging and monitoring, in terms of both temperature and speed, but also visually with video cameras.” The Power Light systems designed for trucks consist of UV light sources with different output levels for pipe sizes up to DN 1500, together with front- and rear-facing cameras, UV curing drums with up to 320 m of cable length, and a control cabinet with a control panel.
Because these systems are sold and used worldwide, for the control system Reutemann has always relied on the well-known global player Siemens, which made him feel well looked after and supported. Though he previously used Simatic ET 200 modules as control units, at I.S.T. he now relies on a much less expensive Simatic S7-1200 with CPU 1214C and a total of 12 analog and digital input/output modules in the curing drum as well as on a higher level in the control cabinet. Additionally, a Simatic HMI Basic Panel KTP1000 is used for operation, and the drive technology in the drum – a Sinamics G120 built-in device – and the contactors, all supplied by Siemens.
Profinet communication and remote maintenance
This provides Reutemann with several additional advantages: “Not only can I easily access all the relevant curing data through our OPC server as well as on the panel and copy this in real time to my industrial PC, but I also have easy options for remote maintenance thanks to the integrated Profinet interface of the Simatic S7-1200. This means the customer does not need a service technician on-site, which leads to considerable cost savings. The interplay between the control system and the touch panel was implemented really well, as with the drives too, by using TIA Portal as the uniform engineering platform with common data storage.”
Of the technology functions integrated into the Simatic S7-1200, Reutemann uses the proportional-integral-derivative (PID) controller to maintain the procedurally prescribed speed of the light chain in the pipe during curing. “Once the lamps are lit, the customer enters the appropriate set-point value on the panel and only needs to press Start – the PID controller of the control system then ensures via the drive that the motor always turns the cable drum at the same speed.” An SM 1231 TC (thermocouple) signal module processes the exothermic temperature of the resin infrared sensors during curing and transfers the value to the Basic Panel, where it is then copied to the log.
Objective: Comprehensive logging
Being able to flexibly expand the Simatic S7-1200 with a wide range of modules now results in further benefits for I.S.T. in an important project that is even more likely to set new standards. Because a UV system is normally sold along with two robots – one for the necessary preliminary work in the pipe and one that mills and machines new openings for house connections after the curing – Reutemann’s next goal is comprehensive logging that integrates all the data, from inspection data to UV data to the robot data, in a single sewer rehabilitation software program on a shared data medium. Here he has again proved to be an innovator and pioneer who appreciates the advantages of state-of-the-art technology: “The Simatic S7-1200 allows us to connect the CAN (controller area network) bus used by the robots through an auxiliary module and to transfer their data to the control system and to our PC through the OPC server.”