Ensaios por Líquido Penetrante: Garantindo Qualidade e Integridade

The complexity and requirements defined in the design of certain parts have led manufacturers and buyers to develop methods to ensure the sanity of materials.

The test by Liquid Penetrant is part of the so-called Non-Destructive Testing which are currently great allies in detecting discontinuities and are an integral part of a Quality Management System.

The purpose of the test is to ensure the reliability of parts or equipment by obtaining a visual image related to a discontinuity on the surface, discovering its nature without damaging the part and separating the materials approved or not, according to a pre-established criterion.

Application in a wide range of metallic and non-metallic materials, as long as they are not porous. The test basically consists of, after previously cleaning the part's surface, applying a low viscosity liquid that penetrates into the discontinuities, where it is retained even with the removal of the excess. Then, a developer is applied, which is usually a talc suspension to suck the retained liquid from the discontinuities and create a contrast for visualization. Once the discontinuities are detected, the evaluation is done with pre-determined standards

1. Advantages of the method

• Easy application;
• Independent of the shape and size of the part;
• Good detection sensitivity.

Disadvantages of the method

• Only detects discontinuities open to the surface;
• Previous cleaning of the surface is necessary;
• Does not evaluate the depth of the indications.

3. Depending on the pigment used, the Liquid Penetrant can be classified as:

• Visible or Colored;
• Fluorescent.

Every evaluation should be carried out by a professional duly trained and qualified for the method used