Detection of Corrosion under Insulation Using Real Time Digital Radiography

Corrosion under insulation is a major industry problem because it is difficult to detect due mainly to the insulation cover masking potential flaws and/or flawed areas. 

These flaws can cause failures in areas that are not normally a primary focus of an inspection program. Failures can be costly at best and disastrous at their worst. With the real time digital radiography (DRT) scanner, both internal and external corrosion defects on stretches of pipe can be detected while the pipe remains in service without removing any insulation. DRT system consists of a radiation source and a linear array of radiation detectors, which are designed to examine insulated piping systems ranging from 4 to 24 inches (8 to 36 inches with insulation) in diameter and up to 3 inches thick.

During the detection process, a narrow beam of radiation is projected through the pipe walls and onto the detector array, positioned on the opposite side of the pipe. As the scanner moves along the pipe, data are acquired, and a color-coded image that depicts the relative thickness of the pipe wall is generated and displayed on the monitor in real time. Rail mounted DRT scanner has the ability to scan straight piping (in the vertical or horizontal position), elbows, and tees. A circumferential scanner can also be used to examine 100% of the piping in localized areas near elbows, tees, and other suspect areas. The system is sensitive enough to detect corrosion defects as small as 0.25 inch in diameter and 0.05 inch deep

BENEFITS:

• No removal of insulation required
• Thorough and quick scan of long sections of insulated pipe via rail mounted system
• Pipes can be examined while in service
• 100% circumferential volume examination possible
• Detects corrosion defects as small as 0.25 inch and 0.05 inch deep
• Real time detection
• Capable of scanning vertical and horizontal straight pipe runs, elbows and T-s
• Capable of scanning from 4” to 24” diameter pipe (excluding insulation)
• System is compact and easy to install

Source:http://www.ihiswt.com/sites/default/files/DRT%2009092011_0.pdf