Radiographic inspection techniques

Ultrasonic and radiographic inspection techniques are used for long-term evaluations because of their lower sensitivity. The advantages of these techniques are that they are nonintrusive and do not normally require special mounting equipment or access to the process. The common intrusive techniques of corrosion test specimens, electrical resistance, and linear polarization probes require exposure to the process. 

Radiographic inspection is considered as a legal alternative for pressure testing of petrochemical installations. It has the major advantage that it does not require shutdown of the installation. Other NDT techniques such as ultra-sound or eddy-current may be used alternatively or complementary. 

Examinations will include liquid penetrant or magnetic particle techniques when surface examination is specified, ultrasonic or radiographic techniques when volumetric examination is specified, and visual inspection techniques will be used to determine surface condition of components and for evidence of leakage. Specific techniques, procedures and equipment, including any special techniques or equipment will be in accordance with the requirements of IWA-22 00 of ASME Section XI and will be defined in the in-service inspection program. 

Penetrant techniques can be used to highlight surface flaws such as open porosity and surface-breaking cracks for optical or radiographic inspection. The usefulness... 

The efficiency of gas turbines is limited by the maximum allowable turbine inlet temperature (TIT). The TIT may be increased by cooling of the blades and vanes of the high pressure turbine. Cooling channels can be casted into the components or may be drilled afterwards. Non-conventional processes like EDM, ECD or Laser are used for drilling. Radiographic examination of the drilled components is part of the inspection procedure. Traditional X-Ray film technique has been used. The consumable costs, the waste disposal and the limited capacity of the two film units lead to the decision to investigate the alternative of Real-Time X-Ray. 

Pneumothorax may occur as a complication of the subclavian puncture technique, and when this technique is used, the radiograph obtained after device placement should be inspected specifically for this comphcation (Fig. 18.34). A potentially more important complication is hemothorax, with or without an associated pneumothorax. 

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