Evaluation of product quality

The quality of products in accordance with GOST 15467-79 should be understood as a set of its properties, due to which it is able to satisfy, in accordance with its purpose, certain needs.

The term "products" according to GOST R ISO 9000-08 (clause 3.4.2) is considered here as a result of a process that is a set of different activities of interrelated and interacting ones and transforming inputs into outputs (clause 3.4.1 of the same GOST). Thus, the definition of product quality should be carried out in the evaluation areas:

• Its compliance with the requirements (expectations or needs that are established and are mandatory or only assumed - the definition follows from clause 3.1.2 of GOST 9000-08);
• Ability to satisfy needs, that is, to determine the set or level of required characteristics and its usefulness.

Section 4 of GOST 15467-79 states that the evaluation of product quality should be carried out by applying the following methods:

• Differential, based on individual quality indicators, each of which characterizes one property of the product (for example, water hardness characterizes the content of Ca and Mg salts, capable of forming deposits or scale in the equipment);
• Complex - complex quality indicators are used (for example, for surface water, the 1st, 2nd, 3rd, 4th or 5th grade of quality can inform that the water is conditionally clean, slightly contaminated, contaminated, dirty or Extremely dirty);
• Mixed - the assessment is conducted using single and complex indicators (for water in surface sources, single indicators, such as rigidity, and complex ones, such as the quality class) are regulated;
• Statistical - mathematical statistics are applied (the order of use in the control of product quality is regulated by a series of GOSTs P 50779).

Compliance testing is performed for each quality indicator before shipment to the consumer. This procedure is called acceptance for external or operational control for the internal consumer.

The scope of control, including such methods of assessing the quality of products, as differential, complex or mixed, for which tests are conducted, is prescribed in technical specifications or contracts (contracts). If the specification does not reflect the true quality requirement, then it can not be guaranteed. For example, for vessels operating under high pressure, regulatory documents should regulate not only the material from which the device is made, its design and dimensions, but also such operations as manufacturing, installation, adjustment, technical diagnosis, operation and repair. That is, all the requirements, the mandatory observance of which guarantees the reliability and safety of the vessel operating under pressure.

The ability (in accordance with its purpose) to satisfy certain needs can be considered on the example of mandatory requirements for the quality of chemically purified water intended for steam generation. Such water in the technological documentation is called chimochischennoy (desalted) or nutrient (fed to feed boilers, which produces steam).

The evaluation of product quality is carried out according to certain indicators: requirements are set depending on the parameters of steam (low, high or medium pressure). For example, for boilers with a working pressure of 9 kgf / cm², 18 kgf / cm² and 50 kgf / cm², the hardness of the feed water should not be higher than 70 μmol / kg, 15 μmol / kg and 5 μmol / kg, respectively. Compounds of copper, in terms of Cu, for the first two cases are not regulated, and for boilers with a working pressure of 50 kgf / cm², their content in feed water should not exceed 20 μg / kg.

The evaluation of product quality is carried out by competent laboratories, the general requirements to which are established by GOST R ISO / IEC 17025-09. The standard sets 15 quality management requirements in a test or calibration laboratory and 10 technical requirements. Only with their implementation the laboratory can be certified within the framework of the QMS operating in the organization or an accredited independent body. The last option of confirming competence, of course, is more weighty.

The management system refers to the structure of the organization used to manage processes or activities that convert inputs of resources to a product or service that meets the organization's objectives. For example, the satisfaction of quality requirements of the customer, compliance with safety rules or the achievement of environmental objectives.

The quality evaluation of products in many foreign firms is based on the statistical management of the process, based on the Six Sigma method. For statistically controlled processes, the probability of an unexpected failure is limited to six standard deviations from the normal distribution, that is, less than 4/1000000000. Introduction of this method allows to guarantee high and stable quality of products.