1. PT Inspection Penetration Test
One of the methods for detecting discontinuities or surface defects in metals is PT inspection or penetrant. PT inspection is one of the most common methods of non-destructive testing that can be performed with little skill and cost compared to other non-destructive tests. Surface cracks and pores that are not visible to the naked eye by penetrant testing. (PT) are detected. This method has many applications in identifying weld pores. It should be noted that austenitic steels such as stainless steel 316 and non-ferrous metals that can not be tested by magnetic particle (MT) method are evaluated by the penetrant method.
The penetration test can be performed in two ways, using visible and fluorescent paint. By first cleaning and drying the surface of the desired part, the surface must be free of any foreign objects such as chips to penetrate the liquid. Penetrates well into the cracks.
Then we cover the desired surface with penetrant liquid, which can be done by spraying the penetrator or immersing the part inside the penetrator. Due to its penetrating capillary nature, it penetrates into the cracks and to ensure its penetration, we wait for a while and then remove the excess penetrating material from the surface.
Spray the developer, which is a white powder, on the surface. The appearance causes the penetrating liquid to be pulled out of the cracks and as a result the paint bounces off the surface.
Then, by eye inspection under white light (if visible color is used) or ultraviolet light (if fluorescent color is used), the colored signs are observed and the location of defects and cracks is determined.
In fact, to perform this test, we need 3 penetrating, exfoliating and cleaning sprays. One of the famous brands supplying these sprays (sprays) is MAGNAFLUX company.
General Uses:
Detection and detection of surface defects in porous materials
Applications:
Detection of cracks and holes in welding
Detection of surface defects in casting
Detection of cracks due to fatigue in stressed bodies
Limitations: The body must have an almost non-porous and smooth surface.
Estimated time for evaluation: Less than one hour
Note: According to ASME Sec VIII standard, certification of PT inspectors should be based on ASNT SNT-TC-1A. Also, the method of performing the PT test or its main reference is in ASME Sec V. In fact, reviewing and approving the PT guidelines for equipment manufactured to the ASME standard is based on ASME Sec V.
2. Radiographic images of weld defects Radiographic images of some weld defects
One of the common methods for identifying weld defects is radiographic examination (radiography) of the weld, which is called RT for short.
Certification of non-destructive testing personnel in accordance with US ASNT standards and certification in accordance with SNT-TC-1A is performed at three levels (Levels 1, 2 and 3). Other standards such as the European standard (EN 473) may also be used as a reference for certification and certification in some projects. It needs more attention and attention.