“Tvertrubplast” Ltd produces delivery pipes of low pressure polyethylene for domestic water pipelining and transmission of liquid and gaseous matters to which polyethylene is chemical-resistant.

Pressure pipes can be produced from PE-63 low pressure polyethylene, PE 80 average density polyethylene or PE-100 low pressure polyethylene. Low pressure polyethylene pipes are manufactured on tube extrusion lines.

Usually trench method is used for pipelining of polyethylene pipes but there are also some innovation techniques, for example, guided underground drilling or pulling of a new plastic tube inside an old metal one. Due to these two methods there is no need to open the ground and dismantle old lines or do other actions resulting in big costs.

 Basic Advantages of Low Pressure Polyethylene pipes in Comparison with Other Types of pipes:

• Durability;
• Polyethylene pipes do not require constant tending;
• High corrosion and chemical resistance. Deposit on internal side is impossible.
• Low heat conduction;
• Tube destruction as a result of water freezing is highly unlikely;
• Light weight;
• Polyethylene pipes are laid straight into the ground without any special protection or insulation;
• Destruction aroused by hydroblows is highly unlikely;
• Reliability of welded joints during the whole period of working life;
• Ecological compatibility;
• Purity of water due to absence of rust;
• Less efforts at construction process;
• High technological effectiveness as manufactured polyethylene pipes are much longer than metal ones;

Welding

Here are basic types of polyethylene tube joining:

• butt-seam welding;
• coupling electric welding;
• mechanical joining by means of connections;

Now butt-seam welding is the most popular method of polyethylene tube joining. The welding ends are grasped with special retainers placed on general guides. Then a special saw began facing. End surfaces of the joining pipes are warmed with an electrical heater and pressed together by hydraulics. Foreign welding sets are controlled by digital equipment and, thus, the quality of welding joints is much higher.

Coupling electric welding of polyethylene pipes is carried out by special electric welding machines with embedded heaters. This type of welding is effective for reconstruction of present pipelines in case the area is limited and also for plunge cutting by means of saddle branch connectors and embedded heaters.

Mechanical joining is carried out with the help of special compression fittings for pipes of little diameter or by flange sleeves for collars of more than 63 mm diameter pipes.

Main characteristics of LPP pipes are following: mean outer diameter (mm), side nominal thickness (mm), standard dimension ratio (SDR) of nominal outer diameter to nominal thickness of a tube side and maximal working water pressure in the pipeline (MPa) at a temperature of 20 degrees (C) (MWP=2MD/C(SDR+1), MD – minimal durability).