206 / 352
202
Figure 15: Bolt M 76X6 No 11 of inner casing
of medium pressure turbine
Figure 16: Indication on thread of bolt M 76X6
No 11, obtained by magnetic particles testing
4.3. Turbine unit 5 in Thermal Power Plant ′′Kakanj′′
In turbine unit 5 (110 MW) in the scope of general inspection according to specified
programme, 576 nuts and 315 bolts had been examined in July 1998, by:
• visual inspection of bolts and nuts,
• magnetic particles testingof bolts and contact surfaces of nuts,
•hardness measurement of bolt head and corresponding nuts.
The cracks were detected on the contact surface of 8 nuts M 80x6 and 3 nuts M 64x4.
Cracks were detected on the bolt No 11 M 72x6 thread of medium pressure casing.
CONCLUSION
During last fifteen years an impressive improvement in non-destructive testing device
has been achieved, following the more and more strict requirements from the industry
regarding the quality, structural integrity and life extension. The improvement are
presented for frequently used methods, and examples of own experience are presented
and discussed.
REFERENCES
1.
SECTOR Cert, 53840 Troisdorf, Kirchstrasse 12: Manual for NDT personnel training, (1996-
2006)
2.
CEN, Rue de Stassart 36, B-1050 Brussels: European standards regulating non-destructive
testing (1993-2007)
3.
ASME Code, Sec. V i Sec. XI, Edition(1993-2004)
4.
AEA, Beč, Non-destructive testing Manuel for industrial management and quality control
personnel, (1999).
5.
ASTM: Manual for non-destructive testing, Second edition, Volume 10: Review of non-
destructive testing, (1996)