Inspection techniques for detecting corrosion under insulation

Corrosion under insulation is a real threat to the onstream reliability of many of today`s plants. This type of corrosion can cause failures in areas that are not normally of a primary concern to an inspection program. The failures are often the result of localized corrosion and not general wasting over a large area. These failures can be catastrophic in nature or at least have an adverse economic effect in terms of downtime and repairs. Corrosion under insulation is difficult to find because of the insulation cover that masks the problem until it is too late. It is expensive to remove the insulation, particularly if asbestos is involved. There are a number of methods used today to inspect for corrosion under insulation. The main ones are profile radiography, ultrasonic spot readings, and insulation removal. The other method now available is real time X-ray. Real time X-ray has proven to be a safe, fast, and effective method of inspecting pipe in plant operations.