The property of an object to perform certain functions assigned to it, while maintaining operational characteristics within certain limits corresponding to specified modes and conditions of use, is reliability. Reliability indicators can be very different, but the quality of a particular product depends on them in many respects.
Components
There are three main components of this definition:
- performance of established functions;
- time required for this;
- certain operating conditions.
If we talk about the performance of the specified functions, then it is worth noting two concepts that relate to the theoretical and practical understanding of what constitutes reliability. Reliability indicators from this point of view are as follows: serviceability and operability of the specified product.
Operability and serviceability
Efficiency is a certain state of an object, in which it remains able to perform these functions with parameters determined by technical documentation. At the same time, it is worth noting that it is incorrect to identify operability and serviceability, since the second is a condition in which it fully meets the established requirements in the technical documentation.
Time is another important element that implies reliability. Reliability indicators in this case include this concept by no means accidentally, since the physical essence of reliability is that any product must, without fail, preserve its technical parameters for a certain time.
Other components
In addition, the definition of reliability also includes operating conditions. For technical systems that operate under different conditions, different times before the appearance of the first cases of failure may be characteristic.
One must correctly understand the broad meaning of the term “reliability”. Reliability indicators include a wide range of quality without any specific definition of their quantitative assessment and certain properties. However, in the process of establishing the reliability of a particular object or the general technical system, there is a need to disclose those concepts and properties that are included in the complex indicator. For example, for specialized equipment of various power plants, such concepts include the following:
- durability;
- maintainability;
- reliability.
And they themselves also depend on a number of other parameters.
Secondary indicators
If we talk about what the main reliability parameters depend on, three main factors can be distinguished. It:
- Quality. Quality indicators (reliability) include a set of properties, which determine the degree of suitability of a technical device for its intended use.
Quality directly depends on how this or that product is used. For example, if a specialized steam turbine unit, which was originally designed to carry basic loads, will be used in a special maneuverable mode, then such operation will ultimately begin to negatively affect its condition and, accordingly, its quality, as well as poor results when the calculation of reliability indicators.
- Vitality. It represents the ability of a particular technical device to prevent any serious violations, as well as to exclude the development of all kinds of accidents and physical equipment malfunctions.
- Security. A certain property of technical devices, which provides for the lack of the possibility of any situations that are dangerous to people and their environment. Thus, in the process of calculating the reliability indicators, these features are also taken into account.
During the consideration of reliability issues of various complex systems, the concept of stability as a result of the failure of individual elements is also considered. In some cases, the concept of “safety” can also be used.
What is it?
Safety is the property of any equipment to remain in good condition during storage. Like other indicators of system reliability, it provides for the ability of the product to maintain its basic technical characteristics within specified limits. If we assume that storage is an integral part of operation, then safety is reliability in storage conditions.
We can say that this parameter is quite complex, and it will be quite difficult to evaluate any specific characteristic, since any safety indicators of products can serve as safety criteria.
The main feature of this concept is that constant failures prevail due to a decrease in the installed characteristics of components, which occurs due to their aging. Safety is a rather important technical concept, and in combination with reliability it allows you to determine the reliability of a particular equipment in different conditions. This is all the more important for the reason that a large number of equipment has some specific storage periods that are equal to or even exceed the established working period. The determination of the reliability indicators of technical systems includes a very large number of other factors that differ in nature.
Example
As an example, we can consider the reliability of a steam turbine power unit, which includes:
- quality of materials used in the manufacturing process;
- perfection of the developed design;
- manufacturing technology used;
- applicable technology of transportation and installation of equipment;
- quality of fuel used;
- operating and maintenance conditions for devices.
And this is only a short list of what includes a characteristic of reliability indicators. The creation and application of new, continuously increasing complexity of installations requires the need to constantly ensure their more and more high degree of reliability. That is why a specialized “theory of reliability” was developed, which has recently become quite widespread.
Theory
Today, a mathematical apparatus of the theory of reliability is provided, which is often used in practice to solve a huge number of the most diverse problems that appear in the production and operation of various equipment. Thus, the basic concepts that determine the reliability (longevity) indicators of equipment include:
The wording of these concepts is fully consistent with the basic philosophical concept of the whole and the element. Various technical objects that are considered in this theory of reliability are presented in the form of all kinds of systems, which are a set of functionally interconnected and interacting elements. This system is designed to perform a given program integrity. As elements, individual parts of the system are considered that can independently carry out certain tasks.
The choice of the system, as well as the various parts forming it, is very arbitrary. If an expanded statement of the problem is used, then any system ultimately becomes part of a larger system, and any elements are divided into parts, which in turn turn into its elements. Thus, the division of various equipment into elements and systems directly depends on the hierarchical level at which the tasks are solved.
GOST, the concept of a system and an element is combined in one term - "object".
What is he like?
The object is called a specific device of the system or its individual element, which is adopted in order to study some of its specific properties outside of all sorts of connections with other parts.
In the process of operation of the entire system as a whole, as well as of its individual element, such cases may appear in which a complete or partial loss of their functional properties occurs. In the theory of reliability, such a loss of working capacity is usually called a failure, and it is one of the basic concepts.
Failure and its features
A refusal is any event that involves a violation or a complete cessation of the operability of the object in question. Moreover, it happens:
- sudden or gradual;
- dependent or independent;
- partial or final.
If the failure of a particular element does not provide for the failure of the remaining parts, it is customary to call it independent, while the failure of the device due to breakdown of other elements is called dependent.
Sudden failures, based on the name, occur absolutely unexpectedly without any noticeable signs of their appearance, while gradual failures involve wear or aging of the material, too long exposure to excessive loads, which leads to a gradual decrease in performance while fully or partially maintaining the operability of the equipment used .
Final or complete failures are a form of equipment failure in which the system loses its functionality or the parameters overcome acceptable limits until the cause of the failure is eliminated. Partial ones only lead to the activation of an alarm, as well as to the need to reduce operating parameters to a certain level.
Among other things, it is worth noting the fact that a special place is given to failures or their aggregates, which are the reason for the transition of the object to the ultimate state, upon reaching which its subsequent use for its intended purpose is inappropriate or unacceptable.
How is the reliability of the equipment during production?
In order to ensure high reliability and durability of various products, it is necessary to correctly observe the manufacturing and installation technologies of any system. The analysis of statistical information indicates that in the overwhelming majority of cases emergency stops of specialized equipment are the cause of the corresponding technological defects, therefore modern manufacturers try to use a number of specialized measures that allow minimizing the risk of malfunctions in various systems even at the stage of manufacturing and installation.
Regardless of what basic reliability indicators the manufacturer is trying to provide, they should work in the following areas:
- Increased factory readiness through the release of reliable equipment. For example, pipelines, turbines, boilers and specialized water treatment equipment can be supplied in enlarged units, while the overwhelming majority of assembly and welding operations are transferred from the original installation site to the factory floor, since in such conditions it is much easier to achieve an extremely high quality of work.
- Widespread use of the most modern technologies for ensuring quality control at each individual stage of production, from the input control of various semi-finished products and raw materials to the control of finishing procedures, full-scale or bench tests. The feasibility of conducting input control has been repeatedly confirmed by the statistics of defects that were discovered during the specialized control of various products.
- The use of advanced technological production devices with program control, which allow the most detailed processing of components and manufacture of the product with maximum accuracy.
- Mechanization and automation of complex procedures, increased use of advanced technologies.
Practice has already repeatedly proved that the use of modern equipment in the production process, as well as full compliance with the established operating modes, can significantly determine the reliability of the final product. In this case, you need to correctly understand the features of the production of this or that equipment or any products, as well as the main risk factors, in order to use all the necessary measures to eliminate or minimize them. Thanks to this, the assessment of reliability indicators will always be high, regardless of what kind of work is being done.