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2.10. The position of non-destructive testing in industrial production
In the standards harmonised with Directive (PED 97/23/EC) directive for tube boilers
(power plant boilers), mantled boilers (boilers for district heating), pressure vessels and
industrial piping the requirements relating to the inspection and destructive and non-
destructive are contained in the same part of corresponding standard.
It is similar for gas supplying systems, but they also include requirements for welding.
In the standard inducing common rules for non-destructive testing of welding joints is
specified:
′′The organisation which performs the testing has to be organised independently of
production and its activities have to be controlled by quality assurance system.
If an external testing organisation is requested for inspection, it has to be accredited
according to EN ISO/IEC 17025′′.
Standard EN ISO/IEC 17025 includes common requirements for competitiveness of
laboratories for testing and calibration. European Accreditation issued the document EA-
4/15:2003 ′′Accreditation of bodies which perform non-destructive testing ′′.
3. INSPECTION FOR MAINTENING OF EQUIPMENT IN FUNCIONAL STATE
Available thermal power plant equipment in our regionis close to or beyond the
prescribed operating life. For that it is required to be regularly inspected regarding the
state of materials and components in order to save their functionality. Generally, in
Bosnia and Herzegovina the power plants should beinspected every second year, and
retrofitted every fourth year. The inspection programs for power plants maintenance are
defined by national electrical companies.
As an example for maintenance program ASME Code, Sec. XI, can serve, as generally
available standards, which includes the inspection programmes for nuclear power plant
components supervised by the Authorised Inspection Agency, but also the programmes of
German Thermal Power Plants Association can serve for this purpose.
To achieve relevant data about material and component state all available NDT
methods are used. As an example for the retrofit of turbine in block 7 of Thermal Power
Plant "Kakanj" was included visual examination, ultrasonic testing, testing by magnetic
particles and by dye penetrants, and also metallographic analysis of material micro-
structure by replication, ultrasonic thickness measurement and hardness measurements in
selected regions of the component. This will be illustrated by examples in next text.
3.1.Components state inspection
Enormous number of reports about extended equipment inspection are generally
stored not systematically and oftenthey are not available, making difficult, or even
impossible, to follow the changes of equipment during lifetime.
Gathered experience have shown that sometimes the original testing base data are
missing, like quality of component material, not to mention parameters and findings of
previously performed testing. This is specially the case when the tests are performed by
external institutions, including component manufacturer.
Today achieved level of computers and informatics allows developing software in
which following data might be stored, like:
• original initial data about component,
• maintemance programmes,
• location, type, applied procedures parameters and findings of testing,