Reinforced concrete pressureless pipes are used for the construction of gravity drainage systems: sewage, gutter, drainage. They are considered the most economical and reliable material. Let us further consider the features of pressureless pipes .
The nuances of choice
The inner surface of pressureless pipes should have a slight roughness. The lower its value, the less likely it is to form a plaque and clog.
When choosing non-pressure pipes, special attention must be paid to abrasion resistance. In addition, it is important to consider the parameters of thermal conductivity, the ability to restore shape, rigidity, maintainability.
Classification
It should be said that reinforced concrete pipes are generally produced in different types. The criterion for classification is the purpose of the products. On this basis, pipes are distinguished :
- Non-pressure (sewer , for example). They are used for the construction of highways for transporting fluids by gravity. The flow cross section should be 5% smaller than the pipe size.
- Pressure concrete. They are used for the device of highways, through which the fluid is transported under significant pressure.
- Bell-shaped concrete. These products have an extension at one end and a narrowing at the other.
- Pressureless bell-shaped. Pipes of this type are corrosion resistant and durable. As practice shows, the quality of the inner surface is maintained throughout the entire operational period. Liquid flows through these pipes by gravity.
Concrete is considered a universal material. That is why it is used when creating plumbing systems and other communications. However, unlike other construction works, additional materials and components are used in this case.
Design Features
Pressureless pipes can be seam and bell-shaped. The shape of the latter is cylindrical, and the surface of the sleeve part is stepped. In such pipes, a sealant, a sole, and also a special butt joint may be provided .
Folded pipes differ from raster pipes in the way of connecting individual elements. Different sealants are used to seal products.
Reinforced concrete pipes are a more advanced version of concrete elements. They are characterized by greater strength, resistance to deformation, compression, stretching, and other destructive processes. The operational period may be several decades. The design of these pipes is characterized by the presence of reinforcement made of durable steel rods. To increase the strength in the manufacture of the product are coated with special compounds.
Terms of Use
Concrete and reinforced concrete pipes are available in very different diameters. Despite their sufficiently large mass, it is easy to transport them. Products can be used in road construction, when laying utilities in residential buildings.
In the manufacture of heavy concrete is used. Non-aggressive liquids move in pipes at a temperature not exceeding 40 degrees and a pressure of up to 20 atm. When using pressureless pipes, the conditions are less severe. However, the parameters may vary depending on environmental conditions. As a rule, pressureless pipes are buried no more than 6 m.
Connection Features
Smooth pipes are connected using couplings. These products are made from concrete brand M-300.
Pipes and couplings are reinforced with longitudinal spirals and rods. The diameter of the latter is not less than 6 mm, and the gap between them is not more than 200 mm. Reinforced concrete pipes, the wall thickness of which is less than 70 mm, are reinforced with single spirals, and if more than 70 mm - double.
Strength test
Pipes, as mentioned above, are coated with a special protective layer. Its thickness should be at least 10 mm. Water absorption of products - not more than 8% by weight of concrete, dried to constant weight.
When testing pipes for water resistance, the pressure is set:
- 0.5 atm. - for products with normal strength.
- 1 atm - for pipes of increased strength.
To determine the mechanical strength, whole pipes are selected or their elements are cut at least 1 m long. They are placed in presses on wooden blocks. Bars are also installed along the upper cylinders. To evenly distribute the pressure, rubber bands or a layer of gypsum are laid under them.
The pressure is transmitted through the upper bars in the calculation of 500 kg / min. for every meter of pipe. The increase in load is carried out intermittently for 2 minutes.
Transportation and storage
Transportation and maintenance of pipes are carried out in accordance with the requirements of State Standards 6482-2011 and 13015.
According to GOSTs, pressureless pipes are stored and transported in the working position (horizontally). Products must be laid on inventory pads or other supports made of wood (other material).
Rolling of pressureless pipes is carried out on the liners, making sure that the sleeve ends or sockets they do not rest on the floor or linings.
Transportation and storage of products in an upright position is allowed if their length is up to 2.5-2.5 m. At the same time, their rigid stability must be ensured.
Pipes are stored in warehouses with finished products in containers or stacks. Products must be sorted by brand. The number of rows in the stack depends on the diameter of the pipe passage. This number should not exceed the parameters indicated in the table:
Diameter (mm) | Number of rows |
300-400 | 5 |
500-600 | 4 |
800-1200 | 3 |
1400-2400 | 2 |
3000 | 1 |
Pipes in rows must be laid so that the sockets of adjacent rows are directed in different directions.
Under the bottom row on a dense flat base lay two linings. They must be parallel. Each lining is placed at a distance of 0.2 product lengths from the ends. The pads should be designed to prevent the pipes from rolling out the bottom row and their sockets in contact with the floor.
When loading, unloading, transporting measures must be taken to prevent damage to products.
In railway rolling stock or vehicles used to transport pipes, it is necessary to provide saddle-shaped linings. Such elements prevent the displacement and contact of the products with each other, as well as contact with the bottom of the vehicle.