Casing - what is it? Types and purpose of pipes

Casing - what is it? This name is unfamiliar to a wide range of people. Of course, in order to get as far as possible into this issue, it is necessary to have special knowledge, which is given at least in a vocational school. However, a simple person does not need such a detailed specificity, so we confine ourselves to general concepts.

In this article we will discuss the following questions:

1. Casing - what is it?
2. Where is it applied?
3. What is it for?
4. What kinds are there?

Casing: notes

• The used casing pipes for the well in many respects determine the possible service life of this hydraulic structure.
• When choosing a material, it is necessary to take into account that any defects or faults that occur can not be eliminated.
• Incorrect choice of casing elements can lead to the fact that even a water-bearing well will become unusable in a few years.

Purpose of casing pipes

In order to understand, the casing - what it is and which ones are used to build the well, it is necessary to clearly understand the purpose of this structural element.

It is from this that the material with the most suitable performance characteristics is selected.

Consider the tasks that such a pipe should perform:

• The main task of casing is to ensure integritywalls of the well throughout the operational period. Casing pipes should have good strength to withstand any shifts in the soil. With properly selected material, the life of the well should be more than 50 years on soils of any complexity.
• The second main task to be addressedattention, before selecting equipment (especially for soils with a high number of aquifers, unsuitable for drinking purposes), is to ensure the integrity of the structure. Casing pipes with thread must prevent penetration of the upper layer and water from other horizons into the well. All water intake is carried out only from a certain aquifer, suitable for its physical and chemical characteristics.

Therefore, when choosing pipes, it is necessary to pay attention to the way they are docked. Preference should be given to threaded connections.

Types of pipes used for casing a well

Casing - what it is, can in detailtell any specialist. If in simple words, then this is the usual reinforcing material. However, it is necessary to choose it correctly, since the quality of the system will depend on the quality. In practice, different types of pipes are used to perform casing of water wells of different depths. The main ones are metal, plastic and asbestos-cement ones.

The entire range of this product is manufactured in accordance with GOST 632-80.

Metal pipes

Steel casing for well completion canUse for sand and limestone (artesian wells). This type has good strength and resistance to any mechanical stress. Diameters of casing from steel vary 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 the well, it is possible to use a drilling tool to restore its performance, and this is not available for other types of pipes.

But black steel has a number of significantshortcomings. First of all, its tendency to corrosion, which leads to the appearance of rust in water (although such a problem is solved by modern filters) is evident. The second and, perhaps most important, is the high cost of thick-walled pipes. That is why the main area of ​​application 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 forwell casing, - asbestos cement. The main advantage of such pipes is low cost, resistance to corrosion and chemical attack of corrosive media, they lose to steel products in other indices. 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 having a larger diameter. In addition, this material can not be used in the construction of filter columns.

The main scope of such a casing is artesian wells (on limestone), their depth is not more than one hundred meters.

Plastic pipes

Recently, more and more popularplastic casing for wells with thread, manufacturers of which guarantee a significant operating life. Of course, it is still difficult to judge durability, but the fact that such products differ in insignificant value, are not subject to corrosion, are chemically neutral, can be said with a high degree of certainty.

Basically, to perform a casing, applymaterials from PVC (NPVH), polypropylene or polyethylene of low pressure. The design of such pipes has a low specific weight, they are easily installed thanks to the presence of threaded connections.

The shortcomings include a weak resistance to mechanical damage, re-drill such a well is problematic enough, but most often it is simply impossible.

The main area of ​​application of such pipes is wells for sand, the depth is not more than 50-60 meters, in addition, they are ideally suited for the installation of filter columns.

Independently decide on the choicematerial for casing wells is not recommended, it should be done by a specialist who can assess 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 operating life of the well.