Casing - what is it? This name is unfamiliar to a wide range of people. Of course, in order to delve into this issue as much as possible, it is necessary to have special knowledge, which is given at least in a vocational school. However, such a detailed specificity is not necessary for an ordinary person, therefore we restrict ourselves to general concepts.
The article will deal with the following questions:
- Casing - what is it?
- Where does it apply?
- What is it for?
- What types are there?
Casing: important points
- The casing pipes used for the well largely determine the possible life of this hydraulic structure.
- When choosing a material, it must be borne in mind that any defects or malfunctions that have arisen will be impossible to eliminate.
- Wrong choice of casing elements can lead to the fact that even an aquifer will become worthless in a few years.
Casing Assignment
In order to understand the casing - what it is and which of them are used to equip the well, it is necessary to clearly understand the purpose of this structural element.
It is on this basis that the material with the most suitable operational characteristics is selected.
Consider the tasks that such a pipe should perform:
- The main task of casing is to ensure the integrity of the walls of the well throughout the entire operational period. Casing pipes must have good strength to withstand any movement of the soil. With the right material, the well life should be more than 50 years on soils of any complexity.
- The second main task that you should pay attention to before choosing equipment (especially for soils with a high number of aquifers unsuitable for drinking purposes) is to ensure the integrity of the structure. Threaded casing pipes should prevent penetration of the top and water from other horizons into the well. The entire water intake is carried out only from a specific aquifer, suitable for its physical and chemical characteristics.
Therefore, when choosing pipes, it is necessary to pay attention to the way they are joined. Preference should be given to threaded connections.
Types of pipes used for casing wells
Casing - what it is, any specialist can tell in detail. In simple words, then this is a common reinforcing material. However, it is necessary to choose it correctly, since the work of the whole system will depend on quality. In practice, different types of pipes are used to perform casing of water wells of various depths. The main ones include metal, plastic and asbestos-cement.
The entire range of these products is manufactured according to GOST 632-80.
Metal pipes
Steel casing for the arrangement of wells can be used for structures on sand and limestone (artesian wells). This type is characterized by good strength and resistance to any mechanical stress. Steel casing diameters range from 114 to 508 mm. With a wall thickness of five to six millimeters, this equipment will last at least 50 years. In addition, it is worth accepting the fact that in case of siltation of a well, it is possible to use a drilling tool to restore its working capacity, and this is not available for other types of pipes.
But black steel also has a number of significant drawbacks. First of all, its tendency to corrosion is striking, which leads to the appearance of rust in water (although this problem is solved by modern filters). The second and perhaps most important thing is the high cost of thick-walled pipes. That is why the main scope of steel casing is the arrangement of deep wells with a significant operational resource. For drilling shallow wells on sand, it is advisable to use cheaper materials.
Asbestos-cement pipes
Another traditional material used for casing wells is asbestos cement. The main advantage of such pipes is low cost, resistance to corrosion and chemical attack of aggressive environments, in other respects they lose to steel products. The main disadvantage is the increased fragility, which leads to the need to increase the wall thickness, and this entails the need for drilling a well with a larger diameter. In addition, this material cannot be used in the construction of filter columns.
The main field of application of such casing is artesian wells (for limestone) , their depth is not more than one hundred meters.
Plastic pipes
Recently, plastic casing for threaded wells, whose manufacturers guarantee a significant operational resource, has become increasingly popular. Of course, it is still difficult to judge the longevity, but the fact that such products differ in low cost, are not subject to corrosion, are chemically neutral, it can be said with a great deal of confidence.
Basically, PVC materials (PVC-U), polypropylene or low-pressure polyethylene are used for casing . The design of such pipes has a small specific gravity, they are quite simply mounted due to the presence of threaded connections.
The disadvantages include poor resistance to mechanical damage, re-drilling such a well is quite problematic, and most often simply impossible.
The main field of application of such pipes is sand wells, the depth is not more than 50-60 meters, in addition, they are ideal for the installation of filter columns.
It is not recommended to independently decide on the choice of material for casing wells, this should be done by a specialist who is able to evaluate all the features of the soil at the drilling site. Remember that, despite a significant range of materials for this purpose, any error at the design stage will lead to a decrease in the well’s life.