Pre-insulated piping system for temperatures above 145°C is designed as so called sliding system. The carrier pipe expands within insulation without jacket moving in the ground. Expansion is absorbed by bends end expansion joints. The system can be installed above or under the ground.
The design of the sliding system is technically demanding, please consult with us any technical queries.
This system is used for distribution:
- any media with temperature above 145°C up to 300°C
Welded steel pipes P235GH EN 10217-2 , EN 10217-5 (DIN 1626), or seamless steel pipes P235GH according toEN 10216-2 (DIN 1629).
|Dimension standard:||EN 10217-1 (DIN 2448)|
|Material:||P235GH (St 37.0)|
|Certificate:||EN 10204 – 3.1 B|
|Lengths:||6 000 mm, or 12 000 mm|
|Elasticity||206 000 N/mm2|
|Characteristic stress||225 N/mm2|
|Strength tensile||350 N/mm2|
|Thermal conductivity||46 - 54,5 W/mK|
|Thermal extensibility||0,12 . 10-4K-1|
The mineral wool is used in a form of compressed, or grained shaped blocks:
|Product NOBASIL PVT|
|Compression strength||50 kPa|
|Thermal conductivity||< 0,040 W/(m K)|
|Permanent thermal conductivity||230°C|
|Technical delivery conditions:||PN 117 - 72 - 87|
|Product RBP 18|
|Density||170 kg/ m3 ± 10%|
|Thermal conductivity||< 0,044 W/(m K)|
|Permanent thermal resistivity||750°C|
|Technical delivery conditions:||DIN 181 65|
|Centringable lamellar segments LSP|
|Density||>50 kg/m3 for supplementary insulations|
Polyuretane foam – PUR
Properties according to standard EN 253, calculated continues operating temperatures 140°C for 30 years. Maximum short operating temperature: 150°C.
|Specific weight of grain (EN 253, čl. 126.96.36.199)||> 60 kg/m3|
|Total specific weight (EN 253, čl. 188.8.131.52)||> 80 kg/m3|
|Thermal conductivity||< 0,027 W/(mK)|
|Water absorption||≤ 10%|
|Compression radial strength at 10% compression||min 0,3 MPa|
|Sheering axial strength before and after ageing||at 23 ± 2°C min. 0,12 MPa|
|at 140 ± 2°C min. 0,08 MPa|
Jacket HDPE pipe
For underground application HDPE jackets with corona-treated surface are used. This ensures an optimum adhesion between outer casing and insulation.
|Density||960 kg/m3 (+20°C)|
|Thermal tensibility coefficient||180.10/°C|
|Melt flow rate (MFR 190/5)||0,35 ÷ 0,65g/10 min|
|Thermal conductivity||0,43 W/mK|
|Strength tensile||≥ 17 MPa|
Jacket pipe SPIRO
For aboveground systems jacket pipes made of spiral coiled galvanized steel (aluminium) belt (according to PA 12 0314, or DIN 24 145) are used.
Sliding system designing
All the basic designing principles of bonded system (up to 145°C) are applied for sliding system. The sliding piping system is delivered as one functional unit, please consult with us all construction parameters, mainly expansion issues.
This data can be found in COMPONETS section, where it is stated the loss per 1 m of piping / 1°C, assuming underground application, soil temperature 8°C and soil lambda 1,5 W/m/°K.
Thermal dilatation compensation
For calculation of thermal extension of service pipe , the same principals are used as for bonded system. Please take into consideration possible sudden temperature changes of steam and mechanical stresses in the system.Compensation components as permanently working axial compensators or dilatation elbows are used in the pipeline to absorb expansion. Dilatation elbow are special components, in which carrier pipe is separated from insulation layers and can freely move inside the component.
When calculating axial forces, it is necessary to take into consideration the friction force between carrier pipe and sliding layer - value is set to 10kPa by internal standard PIPECO N03-97. The value of friction stress is applied to perpendicular projection of service pipe in dilatation section. Another force element in dilatation section between two anchors is created by resistance of axial compensator (if used) and this value is stated by compensator manufacturer as force per 1mm of compensator compression. Calculation of expansion section is based on above mentioned parameters and the stress in service pipe must not exceed allowed value 150 MPa.
The installation is done without pre-heating. No compensation pads are used in elbows. Because the carrier tube is permanently moved axially into the compensator, it is necessary to ensure that the influence of axial forces prevent carrier tube buckling and ultimately jamming compensator. Therefore, in the prescribed distances in front of axial compensator, bitumen cardboard is wrapped around casing HDPE pipe to protects the casing from damage during micro-movements.