Welded manufacturing is an indispensable production process in today's industry and always remains important and critical. This importance of welding processes in various production stages requires complete and complete completion of all steps, from the contract stage to the delivery of the product. In recent years when quality has gained so much importance, the level of competence of welding personnel and inspection personnel in the welded enterprises should be accurately and effectively determined.

Welded production is a production process that is widely used today in various sectors due to its widespread use and cost-effectiveness. However, despite these widespread and frequent usage, welding applications bring many problems. In many places, these processes are defined as special processes. Because a large number of variables can be set at the same time and correctly, a quality weld seam can be made. The reason why so many problems occur in welding processes is that many different variables can be applied many times and with the same quality repeatable. In order to solve these variables and being reproducible in welding processes, a serious quality control and quality assurance system should be established and qualified personnel should work in the enterprise.

The works to ensure the quality of welding, as it is believed, begin not only during the welding process, but also during the procurement process of this process. Because, if the necessity of a resource that is not used by the manufacturer or exceeds its capacity is revealed, there will be problems that cannot be prevented in the production stage. Therefore, it is necessary to make a decision at the contract stage by considering all production processes.

In short, the following three steps are important to ensure the quality of the welding: welding method approvals, certification of welders and welding instructions.

The first step is to verify the welding method to be selected according to the relevant materials and variables. To this end, the International Standards Organization (ISO) has identified five different methods:

• TS EN ISO 15610 Specification and specification of welding procedures for metallic materials - Characterization based on tested welding consumables
• TS EN ISO 15611 ... Qualification based on previous welding experience
• TS EN ISO 15612 ... Qualification through adaptation of a standard welding procedure
• TS EN ISO 15613 ... Qualification based on welding test
• TS EN ISO 15614 ... Welding procedure test

The second stage is to ensure that a number of welding personnel are documented in accordance with the relevant production and project requirements.

The final stage is the preparation of welding instructions for welding personnel and welding personnel.

However, these stages are not only known, but also in order to ensure quality assurance in welded production, they must be used in a healthy and continuous manner. In many cases to date, problems have arisen due to the misuse or non-use of the welding method or personnel identified before welding.

The first published standard in order to create a systematic in welded manufacturing work, published by the European Standardization Committee in 1994 EN 729 is a set of standards. Based on these standards, which were used until recently, the ISO 3834 standards series was published by the International Standards Organization (ISO). These standards are:

• TS EN ISO 3834-1 Quality requirements for the melting of metallic materials - Part 1: Criteria for selecting the appropriate level of quality requirements
• TS EN ISO 3834-2 ... Comprehensive quality requirements
• TS EN ISO 3834-3 ... Standard quality requirements
• TS EN ISO 3834-4 ... Basic quality requirements
• Documents required to confirm the conformity of TS EN ISO 3834-5 ... ISO 3834-2, 3 and 4 standards with the quality requirements

EN 15085 standards are a series of standards which includes production, revision and maintenance criteria of railway vehicles and parts by European Committee for Standardization.