Plant Service

Liquid Penetrant Testing

    Liquid penetrant testing is a nondestructive material examination procedure used to check for deficiencies such as cracks by spreading a thin liquid dye onto the material's surface, followed by the application of a developer. It is a common method used to check for deficiencies in welds, pipes, bars and other materials. Liquid penetrant testing is also known by several other names, such as liquid penetrant examination, dye penetrant testing, dye penetration test, and dye penetrant inspection.

    Liquid penetrant testing (PT) is a one of non-destructive test, which can detect surface-breaking defects-such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks. It can change invisible defects to visible defect by using liquid dye. Mechanism of this test is based on capillary action. Low-tension liquid penetrant is applied into clean and dry surface-breaking defects to spread. After appropriate time has gone, remove excess penetrant and draw out it by developer. Then it is appeared the defects visibly. Liquid penetrant testing (PT) can be applied to non-metal materials which are not porous it, however, it is impossible to detect inner defects. It shall be selected proper method depending on test piece –immersing of liquid dye, removing excess it, drawing out it by developer.