PE80 natural gas pipes are used in the parts of natural gas lines with 4 bar pressure. Natural gas lines consist of 20 bar steel pipe, 4 bar intermediate line and 0.4 bar indoor lines. Polyethylene pipes in composite structure have begun to be used for trial purposes in parts of 20 bar. Its use will become widespread with the establishment of standards. Work continues on composite pipes that will not be affected by fire inside the building.
Polyethylenes are divided into 3 according to their density as Low Density, Medium Density and High Density. While pipe strength and rigidity increase from low to high, flexibility and impact resistance increase. Natural gas pipes are preferred because they are flexible and have better impact resistance than high density.
Natural gas pipes are in PE80 class. The environmental stress value that can be reached at medium density is 8.0MPa for now. As this value increases, the wall thickness will decrease and the amount of fluid passing through will increase. Since these pipes are of SDR11 class, when they are used for water, PN is used at 12.5 bar pressure, while the safety coefficient is 2.5 instead of 1.25, they can be used at 4 bar pressure in the natural gas line. Since the polymer chain is affected by hydrocarbon structures, the safety coefficient was chosen as high.
Since the pipes can be produced as coils, they provide great convenience in laying. Since the amount of welding is reduced, short lines can be laid and they save fitting and labor.
In order to reduce the possibility of natural gas leakage from sources to zero, only electrofusion welding, which is the safest welding method, is used. Current is passed through the copper wire placed in the fittings. The current passing wire heats up. It melts plastic with the energy it releases. The volume of the melted plastic increases and it melts by contacting with the pipe. Molecular welding occurs with the pressure force created by compression in the intermediate area. With its flexible structure, it is not damaged in earthquakes and eliminates the risk of explosion.
PE80 Natural gas pipes are produced in the group of machines called extruder lines. Pipe production range is Ø25-500 mm. Electrofusion fittings are produced by molding in injection machines. Placing copper in electrofusion fittings makes the fitting complex. It is very important that the wire does not touch each other for welding.
Fittings are passed over the pipe after the oxide layer on the outer surface of the pipes is removed. Welding machine cables are attached to the metal pin on the fittings. After being scanned with a barcode, welding is done according to the welding parameters in the machine's memory. The swelling of the polyethylene from the spaces near the pin indicates that the weld is healthy. It is the safest and most expensive welding method with no work to be done on workers and the width of the welding area.
- It is not affected by earthquakes with its elastic structure.
- It maintains its elastic properties when the temperatures drop to -40 ° C.
- It can be used in the construction site as coils.
- It shows high resistance to chemicals.
- Corrosion does not occur due to the fluid inside and the soil structure outside.
- Its density is 0.940 gr / cm3, so it is 8 times lighter than steel.
- It can be combined outside the channel and then left to the channel. It reduces the amount of excavation.
-It does not require precise digging of the ground gradually.
-THINGS TO PAY ATTENTION
-Care should be taken to ensure that the pipe surface is free from oil and dirt in welded joining applications. These structures, which form an intermediate film layer, prevent the production of healthy welding.
-The oxidized layer on the pipe surface should be removed with trimming equipment.
-Before the pipe is inserted into the fitting, the distance it will enter should be marked on the pipe with a pencil. Otherwise, it cannot be understood how much has entered or not. This may cause the amount of source region to remain at a risky level.
-Since they are not produced in carbon black, pipes should not be stored in environments exposed to sunlight. Stock areas must be covered.
The service life of the product is 50 years.
FREQUENTLY ASKED QUESTIONS
1 - In which pressure lines can PE80 natural gas pipes be used?
The 20 bar main lines of the natural gas lines are used as steel. PE80 natural gas pipes are used in the secondary lines of 4 bars. In the building, steel pipes in mbar level are used again. The reason for not using plastic pipes here is to prevent damage to the pipes in fires.
2 - Why is it yellow in color?
Standards require natural gas pipes to be yellow or yellow striped. Yellow color ensures separation of natural gas lines from drinking water lines.
3 - Can the leftovers from these pipes be used in drinking water?
Can be used. Compressive strength of 4 bars in natural gas corresponds to 10 bars in water. Because the natural gas safety coefficient is taken as 4.
4 - What are the joining methods?
Natural gas pipes are combined only with electrofusion fittings. This method has been chosen for safety since the welding area is very wide.