Liquid Penetrant Testing (PT)

Liquid Penetrant Testing (PT)

Pic1 : Using Penetrant Test

The basic principle of liquid penetrant testing is that when a very low viscosity (highly fluid) liquid (the penetrant) is applied to the surface of a part, it will penetrate into fissures and voids open to the surface. Once the excess penetrant is removed, the penetrant trapped in those voids will flow back out, creating an indication. Penetrant testing can be performed on magnetic and non-magnetic materials, but does not work well on porous materials. Penetrants may be "visible", meaning they can be seen in ambient light, or fluorescent, requiring the use of a "black" light. The visible dye penetrant process is shown in Pic 1. When performing a PT inspection, it is imperative that the surface being tested is clean and free of any foreign materials or liquids that might block the penetrant from entering voids or fissures open to the surface of the part. After applying the penetrant, it is permitted to sit on the surface for a specified period of time (the "penetrant dwell time"), then the part is carefully cleaned to remove excess penetrant from the surface. When removing the penetrant, the operator must be careful not to remove any penetrant that has flowed into voids. A light coating of developer is then be applied to the surface and given time ("developer dwell time") to allow the penetrant from any voids or fissures to seep up into the developer, creating a visible indication. Following the prescribed developer dwell time, the part is inspected visually, with the aid of a black light for fluorescent penetrants. Most developers are fine-grained, white talcum-like powders that provide a color contrast to the penetrant being used.

Steps to use of penetrant

1.Clean the surface of the material

Pic 2 : Use Cleaner/ Removal

Cleaned the surface of test beforehand to dirt , paint , oil , or plump did not result in an indication that are not very relevant or false .A method of cleansing can use a cleaning fluid ( cleaner / remover ) , for cleansing redusi an alkali , or steam degreasing .The ultimate goal of this step is a surface that is cleanly in which each defect visible and formed to the surface , dry , and free from contamination.

2. Spray penetrant into the area to be inspection:

Pic 3 : Use Penetrant Liquid

Test penetrant were then applied to the surface of the material material tested. Penetrant should be given ' Dwelling Time ' to percolate into each possibilities defect that is usually 5 to 30 minutes. Dwelling Time especially depends on penetrant used, material tested and size deficiency sought. As expected, small hitch takes more time old in penetrasinya. Because the incompatible they need to be careful to not to apply a solvent based penetrant to the surface that will be examined with penetrant that has been washed.

3. Clean up the Penetrant

Pic 4 : Clean up the Penetrant

After used Penetrant Liquid, please to Clean up the Penetrant on workpiece, the clean up can use Cloat Former, the cleaner/remover can to spray at cloat former, and than clean up the work piece with cloat former.

4. Use Developer Liquid

Pic 5 : Use Developer Liquid

After penetrant have been in clean in the surface of a workpiece use cleaner , and next use developers on a workpiece , wait 5-1 minutes . If there is an indication defect welds , so defect welds will appear in a workpiece

Developers interesting penetrant from defect come out to the surface to form a visible indication , is commonly known as blood - out .Any area blood - out can indicating the location of the , orientation and a kind of the possibility of a flaw on a surface. Interpret the results and characterization flaws in an indication that discoveries could be require various training and / or experience size an indication is not actual size from defect.

5. Inspection

Pic 6 : Inspection

Inspector will use visible light in intensity adequate ( 100 feet -- wax or 1100 lux typical ) to dye penetrant look.Ultraviolet ( uv-a ) of radiation intensity adequate ( 1,000 mikro-watt per centimeters public square, along with low level light ambient ( less than 2 foot-candle ) for examination penetrant fluorescent.Inspection the surface test to do after 10 to 30 minutes development, based on the type of products.

6. Post Cleaning

Pic 7 : Post Cleaning

If already convinced with the indications defect welds that appears , then immediately do cleaning on a workpiece .To maintain a workpiece the lifetime .

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