Insulation, corrosion under

Corrosion under insulation is also a concern, particularly in refrigeration systems. The specification of the insulation system needs to include painting, vapor barriers, and external metal jackets (16). 

Corrosion under insulation is a major problem with carbon steels and must be taken into consideration in the RBI analysis of any plant to avoid serious failures. Several techniques are available to minimize this attack including painting, spraying with aluminum, and/or wrapping with aluminum foil. 

Covers mechanical integrity programs for piping, pressure vessels, storage tanks, and process piping, including corrosion under insulation problems... 

The degree and frequency of external inspection of equipment and piping under insulation is site specific. The API 570 Piping Inspection Code has added this note of caution The extent of a Corrosion Under Insulation Inspection program may vary depending on the local climate warmer, marine locations may require a very active program, whereas cooler, drier, mid-continent locations may not need as extensive a program. [16]... 

The Safer Piping module sums up the corrosion on piping under insulation as a problem of water ingress on piping with poor surface protection. Engineering, construction, and maintenance recommendations parallel those presented in the heading Corrosion under Insulation offered earlier in the chapter. 

Carbon dioxide (COj) corrosion Hydrogen sulfide (HjS) corrosion Preferential weld corrosion Erosion and erosion-corrosion Crevice corrosion Flange face corrosion Cavitation Dead-leg corrosion Under-deposit corrosion Microbial corrosion Oxygen corrosion Galvanic corrosion External corrosion Corrosion under insulation (CUI)... 

To start this chapter, we will look a few similar incidents. The highlights of three incidents will demonstrate the sort of repeatability that can be found over decades. These are hot work accounts, but there are other problems (tank overflows, hose failures, misdirected flows at terminals, corrosion under insulation, etc.) that have similar versions in different settings. Therefore, please pay attention to incidents that occurred earlier than the twenty-first century in later chapters, because they too have significant learning opportunities. 

Be aware and inspect for corrosion under pipe supports and corrosion under insulation. Promptly handle any deficiencies. 

Corrosion under insulation, as generally discussed in the previous pages is a genuine concern, because it can be so easily concealed. The Safer Piping - Awareness... 

Corrosion under Insulation. Corrosion under insulation (CUI), for example, is a particularly severe form of localized corrosion that has been plaguing chemical process industries ever since the energy crisis of the 1970s forced plant designers to include much more insulation in their designs [14]. 

For instance, the buildup of scale within storage tanks and piping may result in situations where corrosive agents can accumulate and accelerate a very vicious hidden corrosion process. One particular example of such conditions that became extremely important after the energy crisis of the 1970s is what is called corrosion under insulation (CUl). However, the same problem exist in maybe a less severe fashion for structural details used in the construction of a system including lap joints, gaskets, and enclosed places that cannot be accessed. 

Determining the condition of the substrate is a critical part of any condition survey. Coatings can mask some rather severe corrosion for a period of time. Corrosion under insulation (CUI) is a particular example of the development of a very severe environment that may go unnoticed until a catastrophic leak occurs. Contaminants from process or environmental upsets can be difficult to find from a purely visual standpoint. The underl5dng substrate must be accessed in some way. If it is under insulation, strategically placed inspection windows may need to be cut into the insulation or its cladding so proper inspection or monitoring can be performed on the substrate to determine its true state. 

B.J. Fitzgerald, S. Winnik 2004. A corrosion under insulation prevention strategy for petrochemical industry piping. Corrosion Management (57), 15-19. 

B.J. Fitzgerald, S. Winnik 2005. A strategy for preventing corrosion under insulation on pipeline in the petrochemical industry. Journal of Protective Coatings and Linings 22 (4), 52-57. 

---