District heating – pipes, pre-insulated systems and valves
In short: district-heating lines today are typically built from pre-insulated pipe systems to EN 253. The system consists of:
- a steel service pipe;
- polyurethane foam insulation;
- a polyethylene casing.
The service pipe is elevated-temperature or line-pipe grade steel. The system also includes pre-insulated fittings, branches, shut-off valves and joint-insulation kits. For conventional, non-pre-insulated sections we supply P235GH pipe, EN 10253-2 fittings and EN 1092-1 flanges.
This guide is for heat utilities, contractors and buyers building new lines or renewing existing networks.
What makes district heating special?
- Continuous thermal load. The line carries hot water all year round, at higher temperatures in the heating season.
- Thermal expansion. Expansion of long buried sections must be handled in the design: with expansion joints, changes of direction or pre-stressing.
- Soil and moisture. The casing protects against external corrosion. Built-in alarm wires detect moisture in the insulation.
- Long service life. District-heating lines are built for decades, so quality and documentation decide the purchase.
Pre-insulated or conventional?
| Section | Typical solution | Standard |
|---|---|---|
| Buried trunk and distribution lines | Pre-insulated pipe with steel service pipe | EN 253 |
| Pre-insulated fittings, branches | Factory pre-insulated elbows, tees, reducers | EN 448 |
| Substation and chamber sections | Steel pipe with conventional insulation | EN 10216-2 / EN 10217-2 |
| Flanged joints, valves | Weld-neck flanges, gate valves, ball valves | EN 1092-1 |
The designer sets the exact system and the service-pipe grade from temperature, pressure and the utility's specifications.
The complete package
- Pre-insulated pipes to EN 253, in the design DN and insulation series.
- Pre-insulated fittings, branches and reducers, plus joint-insulation kits.
- Steel pipe for substations and chambers: P235GH, EN 10216-2 / EN 10217-2.
- Fittings: EN 10253-2 elbows, tees, reducers.
- Flanges, gaskets, bolting: EN 1092-1 weld-neck and blind flanges, graphite or fibre gaskets, elevated-temperature studs.
- Valves: gate valves, ball valves, drain and vent valves.
- Expansion joints and supports where the design requires them.
Buyer checklist
- System: pre-insulated (EN 253) or conventional.
- Service pipe: grade, OD × wall, standard.
- Insulation series and casing diameter (for pre-insulated systems).
- Fittings and branches list, by type and size.
- Flanges and valves: PN, type, material.
- Certificates: EN 10204 3.1 for pressure parts.
- Delivery: scheduled to the construction phases.
Common mistakes
- Different insulation series for pipe and fittings.
- Missing joint-insulation kits. Without insulating the site joints the system cannot be closed.
- The steel section in the substation does not match the specified elevated-temperature grade.
- Delivering everything at once while construction proceeds in phases, which causes site storage problems.
Frequently asked questions
What steel is the service pipe made of?
Elevated-temperature or line-pipe grade steel according to EN 253. The exact grade comes from the design and the utility's specification.
Do you also supply conventional steel pipe for substations?
Yes. P235GH pipe, fittings, flanges, gaskets and valves, in one quote with the pre-insulated system.
Which sizes of pre-insulated pipe can I order?
We offer pre-insulated pipe across the full size range used in Hungarian district heating networks: from the smallest house connections (e.g. DN 20, DN 25) up to the largest-diameter trunk lines. In your RFQ, state the DN, service-pipe wall thickness, insulation series and bar length; we confirm the available size and insulation series in our quote.
Can you deliver in phases?
Yes, as partial deliveries or in time slots, matched to the construction schedule.
Request a quote
Send your design or material list. We quote the complete district-heating line, from the pre-insulated system to the substation valves, in one offer.
Related: Line pipes · Boiler & high-temperature pipes · Butt-weld fittings · Flanges · Expansion joints · Steam guide
Send us your material list – one quote for the complete package (pipe, fittings, flanges, gaskets, bolting), sourced direct from manufacturers, no minimum order.
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