A pre-insulated district heating pipe is three layers: a steel flow pipe, polyurethane foam insulation, and a polyethylene jacket around it. A factory-made pipe is tight and tested. A joint made at the work site is automatically neither of those.
It is precisely at the joint that two pipe ends are connected, the jacket is opened and resealed, and the foam insulation is topped up on site. For this reason the joint is the weakest point of the entire line, and that is why it has its own standard.
Why a joint leaks
A leak almost always begins with moisture. If water remains between the jacket and the pipe or gets in there later, the insulation gets wet, its thermal insulation capacity weakens, and the steel pipe starts to corrode out of sight.
A wetted joint does not repair itself. The eventual result is a dug-up street and an interrupted heat supply. The cost is not the price of the joint component but the excavation, the repair, and the disruption of the outage.
The starting point of the standard is a design service life of at least 30 years.EN 489:2009
What EN 489 requires
EN 489 is the European standard for joints in pre-insulated district heating pipes. It does not describe a single product but sets the requirements that a tight joint must meet.
Key type tests include the soil stress test, in which the joint is repeatedly loaded to simulate ground movement, and the water tightness test, which verifies that the joint keeps water out from the outside. The starting point of the standard is a design service life of at least 30 years.
An independent test institute, such as the German Fernwärme-Forschungsinstitut (FFI), carries out the type tests and issues a test certificate. The joint systems supplied by Kampek are tested to the EN 489:2009 standard.
Two approved systems
Kampek supplies two EN 489:2009 type-tested systems for the same problem. Covalence DualSeal RJS-E is a wraparound shrink sleeve with a cross-linked PE-X backing and a dual adhesive: an anchoring hot-melt adhesive at the edges and a viscoelastic sealant in the centre.
BG Industry manufactures prefabricated shrink couplings whose material is jacket-grade HDPE PE 100 with butyl mastic as the seal. The choice between the two depends on pipe size and installation method. Both meet the same EN 489 standard. Which one suits which case is covered separately in its own article.
Installation conditions matter a great deal
A type-tested product seals only if it is installed correctly. The surface must be dry and clean, and with a shrink sleeve the correct shrink temperature must be reached across the entire joint area.
The back of the Covalence sleeve has a Permanent Change Indicator pattern that disappears once the correct heat has been reached. This lets the success of the installation be verified afterwards. Detailed installation instructions always come from the manufacturer; Kampek provides installation advice by phone.
