Liquid Penetrant Testing Level 2 (PT-2) Practice Exam

Which type of penetrant is typically used for porous materials?

1. Solvent removable penetrants

2. Water washable penetrants

3. Post emulsifiable penetrants

4. Solvent suspended penetrants

The correct answer is: Post emulsifiable penetrants

The appropriate choice for penetrant testing on porous materials is post emulsifiable penetrants. This type of penetrant is beneficial for applications involving porous substrates because it is designed to penetrate deep into the pores of a material while allowing for effective removal of excess penetrant. Post emulsifiable penetrants initially behave as oil-based penetrants, being absorbed into the porosities of the material. After a specific dwell time, a developer or emulsifier is applied which causes the penetrant to change properties, allowing it to be washed away from the surface while remaining trapped in the defects or pores. This ensures that the penetrant remains in place, thus maximizing the likelihood of detecting any discontinuities present in the material. Other types of penetrants, such as solvent removable, water washable, and solvent suspended penetrants, may not effectively penetrate and remain within the defects of porous materials due to their formulation and the way they interact with surface contaminants. Therefore, post emulsifiable penetrants are specifically favored in applications where material porosity could influence the detection of flaws.