InfraMation 2004 Proceedings

ITC 104 A 2004-07-27

Using Infrared Surveys to Locate Corrosion under Wet Insulation

David A. Hatfield

DuPont Dow Elastomers

ABSTRACT

Corrosion under insulation (CUI) is a major problem for petroleum and chemical process industries.

Historically, there have been limited options for evaluating the presence and extent of CUI. Locating corrosion

under wet insulation (CUWI) is of primary importance in the petrochemical industry. Unseen corrosion can

lead to the release of process materials and cause costly downtime. Removing insulation and examining the

equipment is very effective, but it’s costly and time-consuming. Moisture density gauges (MDG) give good

results to trained individuals, but they are cumbersome and slow to work with and require maintaining a

radioactive isotope that must have specific licensing and regulatory monitoring. I

nfrared (IR)

surveys can be

the answer

to the problem of locating CUWI in an economical, efficient way before it reaches the point of failure.

Keywords:

IR surveys, infrared, thermography, corrosion, CUWI, MDG

INTRODUCTION

A chemical plant in Kentucky has 1300 feet of 1 1/2"-diameter insulated carbon steel piping for a critical raw

material service. The insulated line is hanging in a pipe alley 20 feet off the ground. In the past, damage to the

insulation has allowed water to become trapped in the insulation. This can cause degradation to the pipes’

coating, resulting in accelerated corrosion. Since the pipe is covered by the insulation, this corrosion is not

readily visible. The site has used a moisture density gauge in the past to survey for CUWI. This has required

expertise by the inspector and the use of a man-lift to complete the survey, resulting in a process that took 3-4

days to complete.

A highly reliable and cost-effective examination technique was needed to be able to look for signs of moisture

encroachment. The site decided to test the infrared camera to see the sensitivity it would provide in surveying

for CUWI. A survey was performed with the moisture density gage and the IR camera, and the results were

compared.

IR SURVEY VERSUS MDG SURVEY FOR CUWI

Figure 1. Because the moisture density gauge must contact the surface of the insulation, the use of a man-lift

is required for pipe inspection. IR works great from ground level.