Dimensions and types
External water supply systems are rarely supplied with steel pipes, as they have very low corrosion resistance. Often, they are used in places where there is a large working pressure with dynamic overloads and hydraulic shocks, in seismically active regions and in places with possible ground movement. Several types of pipes are used in water supply networks:
- Welded gas-water pipes( diameter from 6 to 150 millimeters);
- Seamless oil, gas and water( wall thickness from 4 to 9 millimeters);
- With thin walls and spiral seam. Despite the thin walls, they are very durable.
Steel pipes laid in the ground are connected by electric welding, and those that are mounted in tunnels and wells are connected to the flanges. Flanges are cooked to the ends of pipes before the installation of the pipeline by electric arc welding. Individual pipes are combined in sections, and those, in turn, are in loops. The length of the section depends on the weight and method of turning the pipes. Individual sections are connected either on the edge of the trench, or in the trench itself.
Preparation for welding operations must be very thorough. All welding places must be well cleaned from rust, scales and dirt to metallic luster. If this is not done properly, contamination occurs at the junction points, and the fastening becomes very unreliable.
Note! Stripping should occur no earlier than four hours before the start of work.
Technical characteristics according to GOST
Each product has its own GOST, and steel pipes are no exception, their GOST 3262-75.This group includes galvanized and zinc-coated steel welded pipes, which are used for gas, water, heating systems. They are manufactured with rolled and threaded cylindrical threads of steel in accordance with GOST 1050-88 and GOST 380-88 without the norms of chemical compositions and mechanical properties. The water pipes are steel, the GOST of which indicates their technical characteristics, are easily amenable to electric welding.
Pipes for water supply of steel are manufactured according to nominal passage and wall thickness:
- Conditional pass of pipes: 150, 125, 100, 90, 80. 65, 50, 40, 32, 25, 20, 15, 10, 8, 6 millimeters;
- Thickness of the walls of light pipes: 4;3.5;3.2;3;2.8;2.5;2.35;2;1.8 millimeters;
- Average thickness: 4.5;4;3.5;3.2;3;2.8;2.2;2 millimeters;
- For the reinforced: 5.5;5;4.5;4;3.2;2.8;2.5 millimeters;
Note! The size of the pipes is sometimes indicated in inches: 1 inch = 25.4 millimeters.
Steel pipes are manufactured in two types: galvanized and non-zinc. It is necessary to take into account that the first have a mass of 3% more than the second, this affects the layer of zinc, which is applied at a thickness of at least 30 microns.
Determining the diameter in the field
When changing pipes, it is often necessary to measure its diameter. To do this, you need a special tool, but you can do without a ruler and knowledge of the calculation formula. The diameters of water pipes of steel are determined in many ways. Let's consider some of them.
- The roulette wheel turns around the outside diameter. The resulting length is divided by the number Pi( 3.14) - this will be the outer diameter;
- To determine the inner diameter, the method for calculating the wall thickness at the cut is used. It is made by a ruler or a caliper. From the outer diameter, the thickness of the wall, multiplied in two, is subtracted, and as a result, an inner diameter is obtained.
These two methods are often enough to calculate all the required diameters. However, there are many other methods to do this, but they are more complex, and they are used by professionals. For non-professionals the above methods will give all the necessary data for the rapid determination of the diameter without special tools.
Tip! Despite the ability to determine the diameter of the tool, it is better to always carry a special measuring tool, which will give more accurate data.
