FAQ
1. Please give me your opinion on the use of your pre-insulated pipes for chilled water transfer.
Subject: application of pre-insulated steel double pipes for outdoor chilled water installation.
We kindly ask for your opinion whether the preinsulated steel double pipes manufactured by your company can be used
for the transmission of chilled water.
Technical and operational parameters of the transmitted medium:
– minimum temperature – 3°C
– maximum operating pressure – up to 4 bar
– type of medium – 30% water solution of propylene glycol
2. In connection with the implementation of the construction of a low-parameter heat network of preinsulated steel pipes with the use of heat shrinkable couplings and the discovery of a high level of groundwater, we ask for an opinion on the possibility of using preinsulated steel pipes with heat shrinkable couplings below the level of occurrence of groundwater.
Subject: use of TS type cross-linked heat shrinkable joints in the zone below the level of occurrence of groundwater.
In response to your question, Zakład Produkcyjno Usługowy Międzyrzecz POLSKIE RURY PREIZOLOWANE
Sp. z o.o., 4 Zakaszewskiego St., Międzyrzecz, as a manufacturer of preinsulated products of the ZPU Międzyrzecz Sp. z o.o. system, confirms the possibility of using TS-type heat shrinkable joints on district heating networks laid in the ground below the level of ground water occurrence. However, in order to achieve greater tightness of the joint and as a protection against workmanship errors, we recommend additionally using heat shrinkable bands as a second seal.
In addition, we would like to inform you that the TS connectors offered by us with double sealing (with the use of a cap
and additional shrinking bands with glue), are manufactured in compliance with PN-EN 489 standard and ensure 100% watertightness, provided that they are properly assembled in accordance with the “Manual for making and sealing a TS-type connector assembly ”of the ZPU Międzyrzecz Sp. z o.o. system, by personnel having the appropriate skills and experience, and above all a certificate of completion of training, issued by Zakład Produkcyjno Usługowy Międzyrzecz POLSKIE RURY PREIZOLOWANE Sp. z o.o. with its registered office at 4 Zakaszewskiego St. in Międzyrzecz (Poland).
3. How and if at all it is possible to combine M-Pex® pipes with traditional pre-insulated steel pipes. I am in the process of preparing a request for proposal for the supply of pipes and I am analyzing various options for implementation. In the description of M-Pex® pipes, it says that they are intended for the distribution of water from the source of generation to the consumer. In our case, it is the connection to the existing network made traditionally.
Responding to the question on combining M-Pex® pipes with steel pre-insulated pipes, we would like to inform you as follows:
Photo No. 1 and 2 Transition fitting HELA H, PN 6 and PN 10 for ø25÷ø32 mm
Photo No. 3 and 4 HELA H, PN 6 and PN10 transition coupling for ø40÷ø110 mm
Photo Nos. 5 and 6 Straight fitting with female thread HELA M
3.1 It is possible to connect M-Pex® pipes with pre-insulated steel pipes.
3.2 These connections are made in two ways:
– carrier pipes are mechanically connected with couplings of type ,,H“ (Photo Nos. 1÷4) and ,,M” (Photo Nos. 5 and 6),
– it is possible to weld pipes with the use of coupling type ,,P” (Photo No. 7 and 8) with a welding end /applies only to M-Pex® 6 bar pipes/.
3.3 Pipeline connections are insulated at the construction site using NT-type or TS-type heat shrinkable couplings
with the appropriate size for the pipes to be joined.
4. Please confirm the possibility of using M-Pex® pre-insulated pipes without protective pipes and strain relief plates for pipes buried at a depth of 1.2m under the parking slab for cars and trucks and partially under the roadway.
Zakład Produkcyjno Usługowy Międzyrzecz POLSKIE RURY PREIZOLOWANE Sp. z o.o., 4 Zakaszewskiego St., as the manufacturer of M-Pex® preinsulated pipes of the ZPU Międzyrzecz Sp. z o.o. system, confirms the possibility of using the above-mentioned pipes laid in the ground at a depth of 1.2m under the parking slab, intended for cars and trucks, and partially under the roadway, without the need for protective pipes and pressure relieving plates.
5. Please provide the conditions for the installation of pre-insulated compensator type KP-168-125.
Zakład Produkcyjno Usługowy POLSKIE RURY PREIZOLOWANE Sp. z o.o. ul. Zakaszewskiego 4, informs that during the installation of the bellows compensator type KP-168-125, it is necessary to maintain alignment in the vertical and horizontal planes, deviation of the compensator’s axis from the axis of the pipeline may not be greater than 0.5° over a section of min. 12m on both sides of the compensator. Also, fittings (tees, shut-off valves) that could cause lateral forces cannot be installed on these sections. In the 12m section before and after the compensator, the backfill must be compacted to ID=1 according to PN-B-06050, which will act as a directional support. The distance between the compensators must result from the calculations, which must take into account the embedment, the length of the pipeline the temperature of the heating medium and the friction forces occurring on the side of the casing pipe. The calculated elongation of the pre-insulated pipeline must not exceed its compensation capacity.
6. Please tell me, when installing pre-insulated pipes with impulse leak detection alarm system, is the direction of pipe alignment important or does it not matter?
We would like to inform you that pre-insulated elements that are equipped with impulse alarm installation should be laid in the trench so that the manufacturer’s label is always on one side of the connector – lay with the label towards the power source. This is to ensure the correct connection of the alarm installation wires. The alarm installation wires should be at the top of the pre-insulated pipe, in the “10 a.m.” and “2 p.m.” alignment. (the tin whitened wire should be on the right side looking in accordance with the direction of the flow of the medium from the heat source, and the copper wire on the left side). Then the unipolar wires are opposite each other.
7. Can pre-insulated products with steel carrier pipe be gas welded? Is this posted somewhere as written in your guidelines for the installation of pre-insulated pipe heat networks?
According to the information contained in our “Manual of execution and acceptance” of the system of ZPU Miedzyrzecz Sp. z o.o. (page 7) all connections of steel line pipes are to be made by arc welding. Gas welding is allowed only for steel line pipes with a wall thickness of up to 2.9mm. In addition, according to the “Instruction for Welding of Conduit Pipes of District Heating Networks from Preinsulated Pipes and Elements” contained in the “Technical Conditions for Execution and Acceptance of District Heating Networks from Preinsulated Pipes and Elements”-Essue 4, issued by COBRTI INSTAL for larger wall thicknesses for gas welding, the approval of the owner of the network must be obtained.
8 On a straight section of DN80/160 pre-insulated pipeline with a length of about 100 m, measured from the 90° elbow to the 90° elbow, can a parallel tee with a branch diameter of DN50/125 located at a distance of about 12 mb from the compensation elbow be designed?
According to the “Design Guidelines” of the system of ZPU Miedzyrzecz sp. z o.o., parallel tees should be designed at a distance of no more than 2/3 of the length Lmax from the actual fixed or virtual point (as shown in the figure below). In this case, Lmax for DN80/160 is 55m, for an average pipeline laying at a depth of 1.0m measured from the ground surface to the axis of the pipeline, hence the TR-80/50 tee should be located no more than 2/3×55m = 36.6m from the virtual fixed point. The distance of the tee branch from the 90° elbow is:
(100m:2) -36.6m = 13.4m. The length of the compensation arm of the parallel branch [L’] is calculated, as for compensation in the “L”-shaped system, according to the “Guidelines for the Design of the System of ZPU Miedzyrzecz Ltd.”
In addition, we would like to inform you that you should not design the preinsulated parallel branch of the thermal network as an extension of the main section using a parallel tee, and you should not install preinsulated shut-off, venting, drainage fittings and preinsulated branches in the calculated compensation zones.
The figure below shows an incorrectly designed section of the thermal network.
9. We ask for an answer, what to do in the situation when, after the welding work on the heat pipeline and leakage tests, rainfall caused flooding and silting by sand of the mounting holes? How can the shrinking of the heat shrink coupler be “strengthened”?
In response to your question, Zakład Produkcyjno Usługowy Międzyrzecz POLSKIE RURY PREIZOLOWANE
Sp. z o.o., 4 Zakaszewskiego St., I would like to inform you that the installation of NT-type heat shrinkable joints should be carried out in accordance with the “Instructions for the Construction and Encapsulation of the Joint Assembly” of the ZPU Międzyrzecz Sp. z o.o. system in favourable weather conditions. If during the installation of the preinsulated network, after the welding work and leakage tests, due to heavy rainfall the installation trenches, where the preinsulated pipelines were fitted with heat shrinkable sleeves and heat shrinkable bands, were flooded and silted by sand, we propose to additionally use 10 cm wide bituminous tape for joint encapsulation, according to the instruction prepared for you and attached to this letter.
Particular attention should be paid to thoroughly clean the outer and inner surfaces of the shrink sleeve immediately before installing it
and inner surface. For this purpose, it is necessary to:
– thoroughly remove sand from the inner part of the cap,
– remove the film protecting the adhesive, located inside the cap,
– carefully clean the inner and outer surface from dirt and dust with acetone, and then dry.
After cleaning the cap, especially on its inner surface, there should not be any contaminants that can weaken the adhesion of the cap in the shrinking zone. The strength and tightness of the shrink joint depends on the accuracy of cleaning the cap.
All other activities related to the installation of NT-type connectors should be carried out strictly according to the following instructions.
INSTALLATION MANUAL
additional sealing – bituminous tape 10 cm wide – for heat shrinkable joints type NT System ZPU Międzyrzecz Sp. z o.o.
I. Introduction
This instruction manual describes the procedure for applying additional sealing to NT-type heat-shrinkable joints of the ZPU Międzyrzecz Sp. z o.o. System by using a 10 cm wide bitumen tape between the HDPE protective pipe of the connected pre-insulated products and the heat-shrinkable sleeve.
This instruction should only be applied when, during the installation of the heating network, adverse weather conditions or unintended actions at the construction site have resulted in contamination or damage to the bitumen adhesive layer lining the inner surfaces of the heat-shrinkable sleeve ends.
II. General Conditions for Thermal Insulation and Hermetization of NT Joints
Thermal insulation and hermetization can only be performed after:
A successfully conducted pressure leak test of the pipeline,
Inspection and acceptance of welded joints in accordance with PN-EN 970:1999 (“Visual examination of welded joints”), PN-EN 1435:2001 (“Radiographic examination of welded joints”), PN-EN 1714 (“Non-destructive testing of welded joints. Ultrasonic testing”), PN-EN 25817:1997 (“Arc-welded steel joints. Guidelines for defining quality levels based on welding defects”), and PN-EN 26520:1997 (“Classification of welding defects in welded joints with explanations”),
In the case of an installed pipeline leak detection system, after connecting the signal wires and conducting technical tests in accordance with the instructions “Leak Detection of Pipelines – Signal Wire Connections,” “Pipeline Leak Detection – Signal Wire Connections,” or “Installation Manual for the BRANDES System for Pipework with a Plastic Sheath.”
The heat-shrinkable sleeve must be stored in white foil at a temperature below 25°C in a shaded area until immediately before shrinkage. Failure to meet these conditions may result in sleeve deformation.
Thermal insulation and hermetization should preferably be performed under favorable weather conditions—in dry, sunny weather with an ambient temperature above +5°C. If hermetization must be performed in high humidity (rainfall), these operations should be carried out under a portable shelter, such as a tarpaulin tent.
Thermal insulation and hermetization should be carried out by a trained worker with a certificate authorizing the performance of the aforementioned activities, issued by ZPU Międzyrzecz Sp. z o.o.
The surface temperature of the carrier and protective pipe during thermal insulation should be 30°C to 35°C.
The polyurethane foam at the ends of the pre-insulated pipes must be dry. A portion of the foam at the joint faces of the pre-insulated elements should be removed to a depth of up to 15 mm.
The carrier pipe in the joint assembly must be cleaned of contaminants, dust, etc.
The surface of the protective pipe should be cleaned and dried up to 30 cm from the pipe end.
The excavation at the location of thermal insulation and hermetization of the joint assembly should be widened and deepened by approximately 20 cm.
The joint cover—either an HDPE polyethylene sleeve or a heat-shrinkable HDPE polyethylene sleeve, as well as heat-shrinkable bands—should be placed on the pre-insulated pipe before welding the steel carrier pipe.
III. Preparatory and Auxiliary Activities
Begin thermal insulation by removing, using a knife or scraper, part of the PUR foam insulation from the joint faces of the connected pre-insulated elements to a depth of up to 15 mm. Special attention should be paid to the condition of the polyurethane foam at the welded joint faces. If it is moist, it should be removed.
Clean the carrier pipe of contaminants, dust, etc. If the weld joint was covered with a lubricant during inspection, degrease the area using, for example, carbon tetrachloride.
Clean and dry the surface of the protective pipes of the connected pre-insulated elements over a length of about 30 cm from the edge of the protective pipe and over a length of about 1 m on one of the pre-insulated elements onto which the heat-shrinkable sleeve will be slid. To do this, remove a polyethylene layer of 0.1 to 0.25 mm thickness from the protective pipe surface. Abrasive work should be performed manually or using an electric belt sander with sandpaper of 50 to 70 grit or by hand. The prepared protective pipe surface should be cleaned of contaminants with acetone and dried using a cleaning cloth.
Carefully clean the inner and outer surfaces of the heat-shrinkable sleeve of contaminants, dust, and sand, then dry it. This includes:
Removing sand from the inside of the sleeve,
Removing the protective foil covering the adhesive inside the sleeve,
Thoroughly cleaning the inner and outer surfaces of contaminants and dust using acetone and drying them.
Heat the surface of the protective pipe at the joint with the sleeve and band using a propane-butane gas burner. One minute after heating is stopped, the surface temperature of the protective pipe should be at least 60°C.
IV. Sequence of Activities – Thermal Insulation Execution
Slide the cleaned heat-shrinkable sleeve symmetrically onto the welded joint so that the overlap on both ends of the protective pipe is equal. Using a marker or white correction pen, mark the outer edges of the sleeve: sleeve length—600 mm, total uninsulated steel pipe ends length—300 mm for diameters up to DN 200 mm, so the overlap of the heat-shrinkable sleeve on the protective pipe of the welded pre-insulated elements should be: (600 – 300)/2 = 150 mm. This 150 mm measurement should be taken from the edge of the protective pipes and marked with a white marker (correction pen) around the circumference of the protective pipe along the sleeve edge.
Measure approximately 20 mm from the marked outlines of the sleeve edges for positioning the outer edge of the bitumen tape.
Prepare two sections of bitumen tape for installation on both ends of the protective pipe of the connected pre-insulated elements. Measure and cut the tape length to allow an overlap of approximately 40 mm after wrapping it around the HDPE protective pipe.
Install the bitumen tape at both ends of the connected pre-insulated elements by wrapping it tightly around the protective pipe.
Remove the protective foil from the bitumen tape.
After placing the bitumen tape, visually inspect its correct positioning before sliding the sleeve into its final position.
Slide the heat-shrinkable sleeve into its final position.
Shrink the ends of the heat-shrinkable sleeve according to the “Joint Assembly and Hermetization Instructions” of the ZPU Międzyrzecz Sp. z o.o. System.
Shrink the heat-shrinkable bands on both ends of the sleeve according to the same instructions.
Perform a leak-tightness check according to the “Joint Assembly and Hermetization Instructions” and complete the thermal insulation.
For any questions related to NT-type heat-shrinkable joint installation using additional bitumen tape, contact:
Zakład Produkcyjno Usługowy Międzyrzecz POLSKIE RURY PREIZOLOWANE Sp. z o.o.,
ul. Zakaszewskiego 4,
66-300 Międzyrzecz
tel. +48 95 741 25 26, 741 27 01, 741 27 02, 742 00 9;
fax +48 95 742 18 36, 742 01 36
www.zpum.pl
zpu@zpum.pl