In the selection of materials used in the production of pressure vessels, the material's resistance to fluid, weldability, mechanical and thermal loads and market conditions are taken into consideration. In the selection of the most suitable materials in production, the following factors, which have an impact on weldability, are taken into account: the chemical structure of the material, the effect of stresses, the thermal changes during the welding process and the thickness of the material. For example, during the welding process, continuous changes occur in the steel materials with the effect of high temperature. For this reason, welding processes can be carried out in steels with high welding ability without special precautions and these changes cause problems in welded structure. If the steel material has limited weldability, even a normal welding process can lead to changes in the welded product which cause serious problems. For example, cracks may occur during or after the welding process or reductions in strength values may occur. Therefore, special precautions should be taken before welding works on such materials.
In the meantime, it is necessary to confirm whether the welding consumable to be used during the joining of the specified material, the welding method to be applied and the welding parameters to be applied before the production works start, shall be verified by welding method verification studies. Another important point in welded manufacturing should be checked whether welders or welding operators who have welded manufacturing have sufficient training, experience and capability and whether there are welder documents. These conditions are very important for achieving the predicted welding quality. In the meantime, the thickness and dimensions of the materials to be joined should also be suitable.
In general, pressure vessels use a single-sided or double-sided but fully penetrated welding method depending on the thickness of the material. The main welding methods are submerged arc welding, electric arc welding and submerged arc welding. In general, the welding method to be applied depends on the possibilities of manufacturing. However, each method has its advantages and disadvantages.
What is ISO 3834 Welded Manufacturing Management System?
The most important point in welding works is that there are hardly detected errors in the completed welding. The majority of these errors are directly related to the quality of the weld and can only be detected by destructive inspection methods. A small number of welding defects are detected by non-destructive testing methods. Therefore, the essential quality is to ensure the design and production stages. Achieving this depends on controlling all processes with an effective quality control system.
The first studies in this direction are the EN 729 standard series. Published by the European Committee for Standardization (CEN) in 1994, these standards define the quality criteria for arc welding of metallic materials. The standards that make up the array are:
- EN 729-1 Quality requirements for welding - Fusion welding of metallic materials - Part 1: Selection and application guidelines
- EN 729-2 ... Section 2: Comprehensive quality requirements
- EN 729-3 ... Section 3: Standard quality requirements
- EN 729-4 ... Section 4: Basic quality requirements
Enterprises have used this set of standards until recently. However, the International Standards Organization (ISO) has published a series of ISO 3834 standards on the same subject. Both sets of standards are similar in content. The ISO 3834 standard provides guidance for welding operations in metallic manufacturing plants.
When both standards involved in the implementation caused some confusion, the European Standardization Committee and the International Standards Organization convened in 2005 and agreed to publish the ISO 3834 Welded Manufacturing Management System standard. In this way, the EN 729 series of standards is no longer applied and only the ISO 3834 standard is introduced in the welded manufacturing sector. In our country, Turkish Standards Institute has published the following standards based on ISO standards:
- 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 ... Section 2: Comprehensive quality requirements
- TS EN ISO 3834-3 ... Section 3: Standard quality requirements
- TS EN ISO 3834-4 ... Section 4: Basic quality requirements
- TS EN ISO 3834-5 ... Section 5: Documents required to verify the conformity of ISO 3834-2, ISO 3834-3 or ISO 3834-4 standards with quality requirements
Today, the European Union directives also refer to the ISO 3834 standard. For example, European Union pressure vessels directive 97 / 23 / EC46 and EN 13814 Gaming and entertainment area structures and machines - Safety standard.
ISO 3834 Welding Management System What Does Business Gain?
ISO 9001 Quality Management System is a general quality certification and does not fully meet the production processes of a specific activity or working with different materials. For this reason, welded manufacturing enterprises should be evaluated and certified separately by an independent, impartial and competent certification body according to TS EN ISO 3834 standard. However, thanks to this document, businesses gain a commercial value and the production processes are carried out to provide certain products of the desired quality, providing more confidence for customers. As ISO 3834 standard becomes increasingly widespread, it allows enterprises to document their competencies. ISO 3834 certification is the following gains:
- The welding requirements of the ISO 9001 standard are fully met
- Reduces the need for repetition, repair and repair
- Activities are completed within the planned time
- Increases reputation and recognition in the domestic and foreign markets
- Welding work is coordinated more efficiently
- Increased employee satisfaction and proactive workforce in the enterprise
- Easier bidding for different jobs
- New technologies are used efficiently and costs are reduced
- Welded manufacturing quality increases in the enterprise
- Increases the reliability of the enterprise with customers
