Touch Point Corrosion (TPC)
Definition - What does Touch Point Corrosion (TPC) mean?
Touch point corrosion is a non-uniform type of corrosion that occurs in piping systems. It is common in areas where the pipes are in contact with other metal and non-metallic materials that offer support; this form of corrosion is observable at the base of a pipe. In the oil industry, baseline inspection and non-destructive test analysis are common practices aimed at preventing leakages and impurities whenever the refined oil is in transit. Identifying these points helps in preventing sagging of the pipes under different optimum pressures.
Touch point corrosion is also known as pipe support corrosion.
Corrosionpedia explains Touch Point Corrosion (TPC)
This form of corrosion is dominant in petrochemical facilities and refineries. The inaccessible areas present between the pipe rests and the the support materials tend to collect substances that easily contribute to the formation of a corrosion cell. These spots are undesirable, hence the need for testing and inspection which follows preparations such as disassembling and scaffolding of the pipes. Non-destructive tests are therefore used to evaluate these types of problems.
To maintain the stability of the pipeline, it is important to ensure that clamps, pads, supports, beam locations and hangers do not form localized areas of corrosion. It is likely that this form of corrosion originates from a combination of galvanic, pitting and crevice corrosion. Since it is a non-uniform corrosion, it may cause a spread along the baseline of the pipe system and eventually cause damage and unexpected leaks. Generally, proper insulation is required in these points that touch the pipes to prevent moisture and chemicals from creating acidic and alkaline conditions that accelerate the corrosion of metal.