Penetrant examination is an effective and relatively low-cost method for locating surface-breaking defects on clean, fairly smooth, nonporous surfaces. Penetrant testing is widely used to detect surface-breaking flaws in both ferrous and nonferrous materials. A liquid penetrant examination is a testing method that supplement visual inspection, revealing defects that would be invisible or difficult to detect by the naked eye. It can be used both on-site or in a laboratory application with either color contrast or fluorescent techniques. In the laboratory, it is particularly suitable for the inspection of batch quantities of machined parts.

Penetrant examination reveals surface-breaking flaws in the form of bleed out of a visible or fluorescent dye. The technique is based on the ability of a liquid penetrant to be drawn into a clean surface breaking flaw by capillary action. After a period of time, known as dwell, excess surface penetrant is removed and a developer is applied. The developer draws the penetrant from the flaw to reveal its presence and produce a surface indication which under proper lighting conditions can be evaluated by a qualified inspector against applicable standards or per client’s specification.

At LBNiW, we utilize penetrant inspection on metallic and non-metallic specimens identifying various surface defects. Typical on-site applications include welds, castings, forgings, and structures. Our penetrant testing techniques detect the following defects:

• Welds: cracks, porosity, undercuts, overlap, lack of fusion or lack of penetration
• Forgings: illuminating cracks, laps or external bursts
• Rolled products: cracks, seams or laminations
• Castings: cold shuts, hot tears, porosity, blow holes or shrinkage
• In-service components: fatigue cracks

At LBNiW, we provide highly skilled and experienced penetrant testing specialists qualified and certified to level 2 according to ISO 9712 (EN473). Our PT services are available in-house and on-site for either new build or in-service applications. Our inspectors have spent many years performing PT testing of equipment across various industries; they know where to look and what to look for beyond the obvious. They can identify potential problems so they can be addressed before they become critical. They operate with integrity and according to the standards defined by respected industry bodies. The industry best practices are incorporated into our latest working procedures, which are set out in our comprehensive quality management system.

• Highly sensitive method, capable of finding very fine flaws
• Relatively easy to use
• Fast inspection results, the surface discontinuity is detected in a single application regardless of its direction
• Used on a wide range of material types (any nonporous material can be inspected)
• Large areas or large volumes of parts/material can be inspected rapidly and at low cost
• Test objects with complex geometries can be inspected easily
• Indications are produced directly on the surface of the part providing a visual image of the anomaly
• Portable technique especially with the use of aerosol spray consumables

• Can only detect defects open to the surface
• Surface preparation before testing including cleaning, de-greasing, and drying, can be time consuming
• Dirty testing method, may require time-consuming cleaning after examination
• The method cannot be applied to painted objects
• Unsuitable for very rough surfaces
• Interpretation of results is sometimes difficult as spurious indications are possible from surface blemishes
• It may pose a risk to fumes exposure, particularly in confined spaces
• Precautions must be taken with respect to handling penetrant chemicals