IFMASS10

192

• 400 – lack of fusion and incomplete penetration,

• 500 – imperfections in shape and dimensions,

• 600 – other imperfections.

1.2. Assessment of imperfection effect

The assessment of imperfections significance for product function capacity, when

fracture mechanics analysis is missing, is performed at:

–

nominal level (product is accepted or rejected without analysis),

–

ordinal level (products are classified based on drawings, photographs, radiograms,

replications and similar documents taken from corresponding catalogues),

–

metrics(metrification) level (measuring dimensions, location of discontinuity, occur-

rence frequency and other actions).

At the nominal level are mainly assessed planar discontinuities: cracks, lack of fusion,

incomplete penetration, notjoined inserts.Ordinal level is applied mainly for castings, and

metrification level for welded joints and forgings.

1.3. Defects

Under the term ''defect'' unacceptable imperfections and discontinuities in material and

product are comprised. In general, the defects can be repaired by grinding and/or welding,

but defective object will be frequently rejected. In special cases defect can be accepted

under the condition of regular inspection or monitoring in service.

2. LAST CHANGES IN NON-DESTRUCTIVE INSPECTION PERFORMANCE

In past fifteen years a significant changes took place in non-destructive testing prac-

tice. The changes are the resultof impressive development of electronics, informatics and

material’s design, but more important is the fact that non-destructive tests present a

powerful tool for quality assurance of products, thus for security and reliability of

equipment in service,and for the maintenance. This is followed by intensive standar-

dization of the equipment and materials, on one side, and by training, qualification and

certification of personnel in non-destructive testing, on the other side.

The Directive 97/23/EC – PED(“Pressure equipment”) has obliged in a proper way the

owners, users and manufacturers of equipment to apply and obey corresponding standards

and codes, and the authorised accredited national bodies and independent accredited and

nostrified inspections and certification bodies to verify their application.

2.1. Equipment and devices for non-destructive testing

Regarding the function the standard equipment for NDT does not passed significant

changes, but a row of improvements have been involved.

X – Ray devices are operating with ceramic tubes. Control unit is now digitalised and

can memorise several programs, including default program for x-ray tube warming-up. It

controls tube temperature, and switch off the device, if necessary.

Gamma defectoscopes are in general protected from depleted uranium. New isotope

Se-75 is available for testing steel in thicknesses 10 to 40 mm. It is to notice that Ir-192 is

not used anymore to test steel bellow 20 mm in thickness.

Illuminators and densitometers belong to the x-ray devices requiring regular inspe-

ction. The films are classified based on sensitivity and granularity. Manual processing of

films is not anymore in use, dominantly automatic device are used for processing.