HOT|COOL NO. 1/2019 - "District Heating Finance and Economy"

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SURVEILLANCE SYSTEM TO CHOOSE To establish a well-functioning, active surveillance system is crucial for receiving information in due time and localize any damage where moisture enters the PUR insulation. This enables you to repair the damage before it spreads, and ensures that the damage does not influence the expected service life of the pre-insulated pipe system. So, the surveillance system is a very important tool for asset management. The surveillance system must ensure that the following faults are reported quickly: • Weld faults • Installation faults, casing joint installation • Product faults • Excavation/backfilling damages

The casing joint system you choose is important to ensure that you get the system service life you expect and not unforeseen expenses for repairing damages. So it is important to choose a casing joint system with the same service life as the rest of the pipe system. The casing joints must also be easy to install to minimize the risk of faults and it must also be possible via inspection of the installed casing joints to ensure they have been installed correctly. Typically, you can choose between the following casing joint systems • Shrinkable PE casing joints, which are mastic sealed • Shrinkable cross-linked PEX casing joints, which are mastic sealed • Weld casing joints, which are fusion-welded with the outer casing of the pipe Weld casing joints are considered by the market to be the ultimate, but also the most expensive casing joint solution. Weld casing joints require more installation equipment, but also enable the energy company to require independence of persons as regards weld data input by scanning data by means of a QR code on the casing joint as well as requirements to documentation of the welding process.

• Fatigue damage of steel • Corrosion of service pipe

The most widely used surveillance system is the so-called Nordic system with 2 uninsulated 1.5 mm2 copper wires in the pre-insulated components. The fundamental function of the surveillance system is to give a signal, if moisture enters the insulation.

See below example where a GPS localization of the installed casing joint is possible:

Surveillance systems can be designed after very different principles: • Passive system. Measurements of the system are made manually by a measuring technician at preset intervals e.g. once or twice a year. No active surveillance of the system between these measurements. Fault detection is carried out by the measuring technician. • Active system that is based on the resistance measurement principle with information as to whether there is moisture in the insulation or not. It is possible to carry out further analyses of resistance values and galvanic resistance to assess whether the insulation is wet or dry, and whether moisture, if any, comes from inside the service pipe or outside. Any fault finding is carried out by a measuring technician.

No matter which type of casing joint is chosen, it is pivotal for the quality of the installation and the expected service life of the system that the casing joints fitters are trained and certified to install the casing joints in question. Therefore, the project owner should always require that fitters have completed a certifying course at the supplier’s and make requirements to the contents of the course.

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