Liquid Penetrant Testing


Liquid Penetrant Testing (LPT) is a widely used non-destructive testing method for detecting surface-breaking defects in non-porous materials such as metals, plastics, and ceramics. Also known as dye penetrant inspection, it can detect surface cracks, porosity, laps, and other discontinuities that can compromise the integrity of a material or component. If you’re looking to ensure the safety and reliability of your components, LPT is an effective solution.

How It Works:

During LPT, a liquid penetrant is applied to the surface of the material being inspected. The penetrant is drawn into any surface-breaking defects by capillary action. After a sufficient amount of time has passed for the penetrant to seep into the defects, the excess penetrant is removed from the surface, and a developer is applied. The developer draws the penetrant out of the defect and spreads it out, making it visible to the inspector. The inspector then examines the surface for any visible indications of defects.


LPT is a cost-effective and efficient method for detecting surface discontinuities in materials. It is quick and easy to perform, making it a valuable tool for inspecting large volumes of components. LPT is also portable and adaptable, making it ideal for use in the field or in remote locations.


LPT is commonly used in the aerospace, automotive, construction, and manufacturing industries. It is often used to inspect components such as welds, castings, forgings, and machined parts for surface cracks, porosity, laps, and other defects that could compromise the component’s performance.


LPT is not effective in detecting subsurface defects, and it is only suitable for use on non-porous materials. Additionally, LPT may not detect defects that are smaller than the penetration depth of the penetrant, and it may not be suitable for use on complex shapes or components with irregular surfaces.

Our Expertise

Sai NDT is ISO 9001:2015 certified and has extensive experience in a variety of industries, including refineries, petrochemical companies, oil and gas companies, offshore rigs, manufacturing companies, and other process industries. Our team of technicians is certified as per ASNT SNT TC 1A and PCN standards, ensuring that we provide top-quality liquid penetrant testing services. We undertake all types of assignments, including on-call jobs, annual rate contracts, and planned or emergency plant turnarounds. We’re committed to delivering exceptional service that exceeds our clients’ expectations. Please contact us for your LPT needs.