Pre-Insulated (Thermal Insulated) Galvanized Steel Pipes - Geothermal Pipe - Technical Specifications

Main Service Pipe

You can find the manufacturing standard and galvanising standards of galvanised pipes in the table below.

Technical Specifications



TS EN 10255+A1


TS 11348 EN 10240


TS EN 1461


DIN 244




Rigid Polyurethane (PUR) Insulation

Rigid polyurethane foam is an insulation material with extremely low thermal transmission coefficient, consisting of mixing of polyol and isocyanate in certain ratios and pressure injection of these materials. PUR, which is injected between the carrier pipe and the casing pipe (HDPE), provides heat insulation as well as enabling two pipes operating as one pipe by bonding them together, and filling in the space between the pipes longitudinally. In the manufacturing of pre-insulated pipes, the PUR in accordance with the standard TS EN 253 has to meet the following minimum requirements:

Technical Specifications


Polyol and Isocyanate

Minimum cellular mass density

55 kg/m3 ISO 845

Max. Thermal Conductivity Coefficient

0,029 W/mK ISO 8497

Average cell structure

< 0,5 mm

Closed cell content

> %88 ISO 4590

Min. Radial Compressive Strength

0,30 MPa ISO 844

Water absorption at high temperature

< 10% when tested according to TS EN 253 5.3.5

Axial cutting strength

23 °C ± 2 °C ≥ 0,12 N/mm²

140 °C ± 2 °C ≥ 0,08 N/mm²

Temperature range

-50 °C / +148 °C

Impact strength

No damage must exist - when tested in accordance with EN 253 5.4.5
ISO 3127

Linear Water Tightness

Must be Watertight When tested in accordance with EN 253 5.4.6



Service life of insulation according to continuous service temperature

3 years at 140 ˚C

30 years at 120 ˚C

50 years at 115 ˚C

HDPE Casing Pipe

Extruded polyethylene casing pipe is used on the outermost part, which protects the insulation material from external factors and chemicals. The HDPE casing pipe manufactured in accordance with the standards TS EN 253 and TS EN 12201-2 must contain antioxidants, UV stabilisers and carbon black.

Technical Specifications


EN 253, EN 12201-2


EN 253 bölüm tablo 5


PE 80 – PE 100 ISO 9080


> 944 kg/m3 ISO 1133

Thermal Conductivity Coefficient

0,43 W/mK

Thermal Stability (OIT)

> 20 min (210 °C) ISO 11357-6

Temperature Range

40 °C / + 80 °C

Cracking resistance under stress

> 300 hrs(4 MPa, 80 °C) ISO 16770

Post-thermal treatment changes

<%3 (no damage must exist) ISO 2505

Melt Flow Index (MFI 190°C/5kg)

0,2 < MFR ≤ 1,0 g/10dk ISO 1133

Carbon black content

> by mass % 2,5 ± 0,5 ISO 6964

Carbon black propagation degree

<3 ISO 18553

Breaking elongation

>% 350 ISO 6259-1

Hydrostatic Strength

10,8 bar

80°C 165 sa ISO 1167-1-2

Inner surface treatment

Corona process on extruded line (on-line)

UV Protection


Galvanised Steel Pipes
DN INCH Outer Diameter dₐ (mm) Wall Thickness t (mm) Outer DiameterD (mm) Wall Thicknesss (mm) Inner Diameter (mm) Thickness (mm) L (mt)
Ø 15/75 15 1/2" 21,3 2,60 75 3,0 69,0 23,85 6 2,12
Ø 20/90 20 3/4" 26,9 2,60 90 3,0 84,0 28,55 6 2,74
Ø 25/90 25 1" 33,7 3,20 90 3,0 84,0 25,15 6 3,56
Ø 32/110 32 1 1/4" 42,4 3,20 110 3,0 104,0 30,8 6 4,61
Ø 40/110 40 1 1/2" 48,3 3,20 110 3,0 104,0 27,85 6 5,05
Ø 50/125 50 2" 60,3 3,60 125 3,0 119,0 29,35 6 6,78
Ø 65/140 65 2 1/2" 76,1 3,60 140 3,0 134,0 28,95 6 8,42
Ø 80/160 80 3" 88,9 4,00 160 3,0 154,0 32,55 6 10,76
Ø 100/200 100 4" 114,3 4,50 200 3,2 193,6 39,65 6 15,60
Ø 125/225 125 5" 139,7 5,00 225 3,4 218,2 39,25 6 20,64
Ø 150/250 150 6" 168,3 5,00 250 3,6 242,8 37,25 6 24,74
  • Non-insulated pipe ends will have a length of 150 - 250 mm ±10 mm.
  • Upon request, manufacturing can be made in lengths, diameters and insulation thicknesses different from the values in the table.
  • Our company reserves the right to make changes on this and all other data in the brochures, written documentation and on our website. You may contact our company for getting up-to-date information.

Pre-Insulated Galvanized Steel Pipes

Pre-insulated galvanized steel pipes are one of the most preferred pipe types by industrial organizations and commercial pipe system manufacturers in terms of efficiency, strength and safety. These pipe systems offer versatile and practical solutions to meet the needs. Pre-insulated galvanized steel pipes are specially designed with the combination of the excellent strength of steel and modern insulation materials. In our article, we will talk about the production of galvanized pipes and geothermal galvanized pipes and the features, advantages and usage areas of these systems.

What is Galvanized Steel Pipe?

Galvanized steel pipes are pipes produced by coating the steel pipe with zinc using the hot dipping technique in galvanizing pools. The process we call galvanizing is coating the surface of the steel pipe with molten zinc. The galvanized steel pipe obtained after this process becomes advantageous in terms of structural integrity as well as corrosion resistance. The lifespan of steel pipes increases and allows use in many adverse environmental conditions.

What is Pre-Insulated Galvanized Steel Pipe?

Pre-insulated galvanized pipes are pipes obtained by coating galvanized steel pipes using modern insulation materials. In this way, galvanized steel pipes have superior thermal insulation properties and minimize heat transfer. The pre-insulation material polyurethane foam (PUR) surrounding the galvanized steel pipe prevents energy loss and prevents heat exchange. The outer layer of these geothermal galvanized steel pipes is covered with extruded polyethylene sheath pipe for protection.
HDPE casing pipe complies with TS EN 253 and TS EN 12201-2 standards and contains antioxidants, UV stabilizers and carbon black.
Pre-insulated galvanized pipes produced by Yalçın Boru to these standards are among the most preferred in the industry due to their resistance to external factors, impacts, moisture and all physical conditions.

Advantages of Pre-Insulated Galvanized Steel Pipes

The advantages offered by pre-insulated galvanized steel pipes can be listed as follows:
  • It offers a very high performance in terms of thermal insulation. Fluid transported at a consistent temperature contributes to energy efficiency. It preserves heat in district heating and cooling systems.
  • Zinc coating is one of the most effective materials against corrosion. Zinc used in the coating of pre-insulated galvanized steel pipes creates a protective film on the pipe surface. In this way, it provides the advantage of protection against moisture and other corrosive elements.
  • It is extremely resistant to rust.
  • It can be used in both outdoor and underground applications.
  • Another advantage of geothermal galvanized steel pipes is their long life.
  • These pipes are very economical. Since it can be used for a long time, maintenance and replacement costs are low.
  • Its usage area is very wide.
  • Since the pre-insulation and sheath pipe are integrated into the galvanized steel pipe, it is easy to install and the installation time is short.

Usage Areas of Pre-Insulated Galvanized Steel Pipes

These geothermal pipes have a wide range of uses due to the many advantages they offer. Usage areas of pre-insulated galvanized steel pipes are as follows:
  • water distribution networks
  • Wastewater and sewage systems
  • Natural gas distribution systems
  • oil pipelines
  • construction projects
  • Heating and cooling systems
  • maritime activities
  • farming areas

What is the Lifespan of Pre-Insulated Galvanized Steel Pipes?

The lifespan of galvanized steel pipes is up to 50 years. When pre-insulation is applied to these pipes, their lifespan may vary depending on the service temperature. Insulation life is as follows according to continuous service temperature: 3 years at 140 ˚C, 30 years at 120 ˚C and 50 years at 115 ˚C.

What are the Prices of Pre-Insulated Galvanized Steel Pipes?

Pre-insulated galvanized steel pipe prices vary depending on various factors such as diameter, thickness and weight of the steel pipe, HDPE sheath pipe and insulation material. You can contact us to get information about current prices and our other products according to the sizes you need.

Pre-insulated galvanized steel pipes have a delicate production process that requires professionalism. Steel pipes need to be galvanized correctly. Afterwards, it should be covered with high quality insulation material and the casing pipe should be mounted on it. Therefore, if you want to use these pipes safely for many years, you should choose a reliable brand. We recommend that you choose geothermal galvanized steel pipes produced by Yalçın Boru, the industry leader with years of experience.

You can also examine our pre-insulated steel pipe, pre-insulated plastic pipe, pre-insulated rockwool reinforced seamless steel pipe and other pipe types to choose the geothermal pipe suitable for your projects.

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