Inspection radiography

Janet Minter visited Garrett Ceramic Component Division, to perform microfocus radiography inspection. 

The last ASTM Standard E94 which classified Industrial Radiography films was published in 1984. Since that time inspection contracts in the U. S. and worldwide have continued to specify Type 1 and Type 2 films which no longer existed. Film manufacturers continued to classify their film using the same nomenclature. 

Practical experience has shown that, depending on the field of application, a considerable reduction in inspection costs can be had when opting for radioscopy rather than radiography. By comparison with film technique, the inspection time of turbine blades for aircraft jet propulsion engines is reduced by 45% to 60%. When adding film costs, approximately DM 450.000,- can be saved per year /3/. As far as... 

However, in various industrial sectors the application of the radioscopic inspection technique is aggravated by a lack of the respective standards, contrary to radiography. This leads to complicated approval bureaucracy by the respective supervisory or certificatiomn authorities. 

Real Time Radiography (RTR) is an advanced method of radiography in which the image is formed while the job is exposed to ionising radiation. RTR is often applied to objects on assembly lines for rapid inspection. Accept-or-reject decisions may be made immediately without the delay or expense of film development. The main advantages of RTR are thus, reduction in inspection cost and processing time. 

As the safety and quality of industrial components, equipments and constructions is correlated with the inspection sensitivity and this is influenced in radiography by the film system class, a continuous supervision of the film systems on the market seems to be urgently necessary. To support the confidence of the film users in the film properties specified by the film manufacturers such a system for quality assurance for industrial x-ray films is proposed by some manufacturers and BAM. This system will be open to all manufacturers, distributers and users of x-ray films. It will deal with all film systems inclusive those which are not specified by a manufacturer as for instance mixed systems. The system for quality assurance will be based... 

Projection radiography is widely used for pipe inspection and corrosion monitoring. Film digitisation allows a direct access to the local density variations by computer software. Following to a calibration step an interactive estimation of local wall thickness change based on the obtained density variation is possible. The theoretical model is discussed, the limitations of the application range are shown and examples of the practical use are given. The accuracy of this method is compared to results from wall thickness measurements with ultrasonic devices. 

Projection radiography has long been used for pipe inspection and corrosion monitoring. In this traditional tangential wall thickness estimation the distance of border lines of the projected wall shadows of a pipe onto the film is a direct measure for the wall thickness. This method is not considered here, newer developments can be found in / /. 

It is to be taken into account that there is a difference between ultrasonic and radiography defect imaging, so the ultrasonic image recognition knowledge required for the person interpreting the inspection results. The ISONIC postprocessing mode allows to ease sueh interpretation because it s maximally approached to inspection standards. 

With reference to obtained results the high-teeh manual ultrasonic inspection performed by ISONIC system becames competitable with radiography, providing highest sensitivity, low inspection cost, obvious and objective documentation. 

Studying modem approaches for such schemes, one can see that knowledge of operational conditions and potential degradation mechanisms play a prominent role. Surprisingly, the role of NDT is often limited to tlie use of conventional methods such as ultrasonic wall thickness measurements, ultrasonic inspection, radiography, and last but not least visual inspection. 

In co-operation with LM Glasfiber, a complete section of a rotor blade was produced with a number of well defined defects in order to perform an initial sensitivity test by means of ultrasound, vibrations techniques and real-time radiography. Based on the results of this initial test it was found that automated ultrasonic inspection was the best suited teclmique. In co-... 

A Practical Approach to Inspection of Concrete Structures using High Energy Radiography and other Advanced NDE-Methods. 

Nondestmctive evaluation, also termed nondestmctive testing or nondestmctive inspection, is extensively used in weld testing (14). Nondestmctive tests do no impair the serviceabiUty of the material or component under stress. The most widely used tests for evaluation of welds are Hquid penetrant, magnetic particle, ultrasonics, and radiography. Acoustic-emission tests are increasingly used. Nondestmctive tests detect and characterize, in terms of size, shape, and location, the various types of weld discontinuities that can occur. 

Corrosion-fatigue cracks can be detected by nondestructive testing techniques such as magnetic particle inspection, radiography, ultrasonics, and dye penetrant. Corrosion-fatigue cracks may occur in numerous tubes simultaneously. Nondestructive testing of tubes at locations similar to those in which cracks are observed can be useftil. 

Identification. Incomplete fusion generally results in discontinuities along the side walls of a joint. When these discontinuities emerge at surfaces, they can be observed visually if accessible (Figs. 15.10 and 15.11). Defects of this type may also be detected by ultrasonics, radiography, magnetic particle inspection, and eddy-current testing. 

Elimination. Since laminations result from steel-making and steelforming processes, little can be done to eliminate defects once they have survived quality inspections at the mill. If laminations are suspected, ultrasonics or radiography may disclose them. They may also be observed visually at cut ends of plate, pipe, or tubes if the cut intersects the lamination. 

All pressure vessels should be tested, inspected, and marked in accordance with code requirements. FurUier inspection of field fabrication vessels may include Uie radiography of all seams and oUier pertinent tests. 

The second degree of freedom is to design-out crevices where possible, although it must be remembered that crevice corrosion can go on underneath deposits. Crevice corrosion at a butt weld with incomplete root penetration is a common case (Fig. 9.7a). Where internal inspection is not possible and crevice corrosion is recognised as likely, A"-radiography of each weld can be specified. 

Silk, M. G., Can Non-Destructive Inspection Be Reliable y4/om, 377, 4-7, March (1988) Allinson, M., Flash Radiography , (E2/2 Unit Committee), UK Corrosion 87, (1987) Saunderson, D. H., The MFE Floor Scanner-A Case History , Colloq. The Economics of Non-Destructive Evaluation , Inst, of Elect. Engrs., January (1988)... 

The soundness of welds is checked by visual inspection and by non-destructive testing (radiography). 

Description Conventional wet fluorescent AC yoke magnetic particle inspection used for detection of cracks at a surface. Blending the welds and sanding smooth increases sensitivity. Polish and etch as in a creep evaluation looking for microscopic damage. Replicas can be taken for laboratory analysis. Conventional radiography used to inspect welds for cracks. Internal visual inspection of pressure vessels for surface blistering. Monitors the sound that cracks emit when they are stressed. 

This specification does not include requirements for 100% radiographic inspection. If this higher joint factor is to be used, the material shall be purchased to the special requirements of Table IP-10.5 for longitudinal butt welds with 100% radiography in accordance with Table IP-2.2.9. 

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