Coatings are an important element of a pipeline's external corrosion protection system. Line pipe is coated in accordance with recognized standards in plants under well-controlled conditions. These plant-applied coatings have an excellent reputation for reliable, long-term performance. In contrast, pipeline coatings applied in the field during construction or maintenance, such as at field welds, are applied under variable and frequently adverse conditions. Rain, snow, extreme cold, steep terrain, remote locations, inexperienced workers, and unsuitable job specifications often present significant challenges. In many cases where external corrosion of a pipeline has been found, it was associated with failure of the field-applied coatings at welds.
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