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Heating Without Loss
ZPU JOŃCA Sp. z o.o.
A diffusion barrier along the entire length of the pipeline
Winner of many awards and honors


ZPU Międzyrzecz system preinsulated pipes are assigned for:

  • building underground and over ground pipelines,
  • transmission of medium at a maximum temperature of 149°C depending on thermal insulation system used, with the possibility of exceeding this temperature by up to 150°C over 100 hours at one single time at operating pressure of up to 2,5 MPa.

Production and delivery programme covers pipes pipe fittings and preinsulated fittings with a line pipe diameter from DN 20 to DN 1200.

 ZPU Międzyrzecz system preinsulated products have the following approvals granted by COBRTI Instal in Warsaw:

  • National technical evaluation IBT-CAT-2018/0445 wyadnie 1 "Pre-insulated pipes, fittings, valves and compensators and teams connector system ZPU Międzyrzecz to the underground and above-ground heating networks" issued by the Building Research Institute in Warsaw with the expiration date and 3 May 2023.
  • National technical assessment ITB-KOT-2018/0446 issue 1 "Pre-insulated pipes, fittings, fittings and compensators, and ZPU Międzyrzecz DUO connectors for underground heating networks" issued by the Building Research Institute in Warsaw, valid until June 29, 2023.

Designing, development works, production, delivery, installing and maintenance of ZPU Międzyrzecz preinsulated pipes and fittings for underground heat distribution networks, covered by systems of quality and environment management meeting standard requirements PN - EN ISO 9001: 2009 and  PN-EN ISO 14001:2005.

A confirmation of requirement fulfilment, included in the above mentioned standards, is QUALITY AND ENVRONMENT MANAGEMENT SYSTEMS CERTIFICATE NO. JS-96/9/2021 with an expiration date on 19 September 2024 granted by the Polish Centre of Research and Certification (Polskie Centrum Badan i Certyfikacji) in Warsaw.

ZPU Międzyrzecz preinsulated pipes and fittings constitute a joint construction consisting of a steel line pipe located centrally inside a casing pipe of rigid polyethylene (high density PEHD) and thermal insulation made of polyurethane foam (PUR) filling the space between pipes. Ends of preinsulated pipes and fittings are not insulated at the length of 150 mm + 20 mm with diameters of up to DN 200, and at the length of 200 mm + 30 mm with diameters of DN 250 or more.

ZPU Miedzyrzecz system provides possibility of connection with already existing networks constructed in a traditional way.

Materials used in ZPU Międzyrzecz system preinsulated pipes

Line pipes

These are, depending on needs:

  • attested seamless steel pipe made according to PN-EN 10216-2, steel grade 235 GH,
  • certified steel pipe with welded seams according to PN-EN 10217-2 or PN-EN 10217-5, steel grade P 235 GH,
  • attested galvanized steel pipe according to DIN - 2444 in the case of pipes for the transmission of drinking water.

To increase the adhesion of the polyurethane foam to the steel conduit pipe, the external surface of the steel pipe is cleaned by shot peening. ZPU Międzyrzecz pre-insulated pipes and fittings have the ends of a steel pipe prepared for welding by bevelling.

Thermal insulation

It is made of rigid polyurethane foam, according to requirements of PN/EN-253 and AT/96-01-0049-04 standards.

Daltofoam TE 34217 / Suprasec 5005

Polyurethane foam produced with the use of cyclopentane as foaming agent. Thermal conductivity ratio ?50 = 0,029 W/mK. Maximum temperature of heating medium: 145°C at continuous work.

Elastopor H 2130 / Suprasec 5005

Polyurethane foam produced with the use of cyclopentane as foaming agent. Thermal conductivity ratio ?50 = 0,027 W/mK. Maximum temperature of heating medium: 149°C at continuous work.

Daltofoam TE 44204 / Suprasec 5005

Polyurethane foam produced with the use of CO2 as foaming agent. Thermal conductivity ratio ?50 = 0,0302 W/mK. Maximum temperature of heating medium: 142°C at continuous work.

Casing coat

Depending on needs:

  • pipes of rigid polyethylene HDPE, according to standard PN/EN-253, inner surface of polyethylene pipe is crowned,
  • pipes coiled spirally - type SPIRO, made of galvanized sheets according to PN-81/H-92125, or of aluminium sheets produced according to PN-87/H-92833.
  • other pipes in case of special usage - e.g. in mining, gas engineering, etc.

Joint assemblies

ZPU Miedzyrzecz offers execution of joint assembly consisting in sliding thermal shrinkable polyethylene PEHD muff over the joint, and execution of thermal insulation by means of filling the space of the joint with PUR foam elements, and sealing contacts with thermal shrinkable bands or tapes. Using polyethylene PEHD muffs can be an alternative the above mentioned solution. Depending on requirements, also muffs coiled and electrically welded or thermal shrinkable electrically welded muffs are used. All types of joint assemblies offered ensure 100% pipeline leak tightness.

Pipeline leak detection system

ZPU Międzyrzecz preinsulated pipes and fittings can be equipped with pipeline leak detection system installation. This system, built into pipes and preinsulated elements, signals network emergency states and enables to locate damages. The system is composed of signalling circuits and devices serving to signal and locate pipeline leak.

Our company installs leak detection systems of their own production into ZPU Międzyrzecz system elements, or other systems on request (e.g. Brandes, Levr, EMS). 
ZPU Międzyrzecz offers two types of pipeline leak detection systems:

  • impulse system (reflect metrical),
  • resistance system.

Impulse system working principles

Alarm system consists of two bare copper conduits of a 1.5 mm2 section, located inside polyurethane foam, parallel to line pipe, shifted mutually at an angle of 120° (situated in a position reflecting "10 to two" on a dial-plate of a clock). In order to make it easier to connect them in a signalling circuit during assembling, one of the conduits is covered with tin, which gives it a grey-silver surface colour, and the second is of pure copper colour.

Damage detection consists in using reflect metrical method with the help of impulse technique. Damage locator type L 301 is the device used to supervise heating pipelines. It can signal the fact of damage occurrence and, at the same time, automatically locate the place of its occurrence. The locator consists of programmable source of impulses sent to measuring circuit. Measuring circuit consists of a "line" created from a steel pipe and a measuring conduit. Sent impulse returns to the locator after a period of time resulting from propagation time (for preinsulated pipes the time is 60-150 m/?s depending on heat distribution network configuration). Detection of damage place takes place by means of measuring time of the impulse return, and the type of damage by means of impulse polarization. The locator can supervise four independent segments of a network that are up to 1000 m long each.

Pipeline operation can also be supervised by other devices - detectors, which can signal a breakdown occurrence on supervised segments without the possibility of locating the place of its occurrence. In this situation additional devices need to be used in order to locate the place of damage occurrence. We have a vast range of one-, two- and four-circuit detectors in our offer, which can supervise segments that are up to 1000 m, 2000 m or even 7000 m long.

Resistance system working principles

The system is based on using resistance changes between signalling-resistance conduit and a steel line pipe, caused by moisture or water getting through a leak in the line or casing pipe into thermal insulation. Resistance change is signalled by a signalling device, while the place of moisture leak is detected by means of a locator - device used to measure distance. Measuring circuit consists of a pair of conduits (1mm2 section): bare signalling conduit (resistance wire of 0.58 ?/m resistance) and a mixed conduit in insulation of 0.02 ?/m resistance, sealed in insulation foam, running along the axle of line pipe elements.