The majority of water, waste water and gas pipes are buried underground and out of site (and in some cases out of mind). When these pipelines are constructed they generally have a protective coating added in-situ on the outside of the pipe wall.
A 100% effective protection is not always possible, and as cracks or other defects in the coating may result in serious pitting corrosion, it is essential that the coating is applied and inspected by experienced personnel. Coatings may be organic types like elastomers (natural and synthetic rubber), thermoplastics (electrostatic spraying of polyamide powder) and thermosetting plastics (epoxy) or inorganic types like zinc and cadmium. Most of the paint systems used apply coatings of organic materials. Other common coatings for buried pipes are bituminous paints that may contain layers of asbestos felt. When inspecting the condition of the metallic pipe walls, BEM™ has the big advantage that if coating layers are largely undamaged and in good visible condition, they don’t need to be disturbed or removed. This is a huge advantage in time and cost versus other methods that do require a smooth, bare metallic surface for scanning. BEM™ can scan directly through these layers, even up to 1” (25mm) thick, making it a truly non-destructive testing method.
A visual inspection of coatings is conducted as a prior to external pipe BEM™ Condition Assessment on above or below ground pipes and other ferrous based infrastructure. If the coating appears to be in relatively good condition, it can often be worthwhile conducting a quick and easy Coating Porosity Detector (CPD) test. The CPD is used for detection of coating porosity (pin-holes, or holidays) in dielectric (insulation type) coatings on conductive substrates. Coating assessment with the CPD is recommended as an ancillary service to investigate the condition of a coating.