Significance and Use
5.2 Reliable and accurate examination of tube bundles is of great importance in different industries. On-time detection of flaws reduces a risk of catastrophic failure and minimizes unplanned shutdowns of plant equipment. Fast examination capability is of great importance due to reduction of maintenance time.
5.6 APR can be applied to tube bundles made of metal, graphite, plastic or other solid materials with straight and curved sections. The APR technology has been found effective on tubes with diameters between 12.7 mm [1/2 in.] to 101.6 mm [4 in.] and lengths up to 18 metres [60 feet].
5.9 In addition to detection of flaws and blockages, APR technology can be applied for assessing tube ID surface cleanliness, providing valuable information for equipment maintenance and improving its performance.
5.10 Other nondestructive test methods may be used to verify and evaluate the significance of APR indications, their exact position, depth, dimension and orientation. These include remote visual inspection, eddy current and ultrasonic testing.
1.1 This practice describes use of Acoustic Pulse Reflectometry (APR) technology for examination of the internal surface of typical tube bundles found in heat exchangers, boilers, tubular air heaters and reactors, during shutdown periods.
1.2 The purpose of APR examination is to detect, locate and identify flaws such as through-wall holes, ID wall loss due to pitting and/or erosion as well as full or partial tube blockages. APR may not be effective in detecting cracks with tight boundaries.
1.3 APR technology utilizes generation of sound waves through the air in the examined tube, then detecting reflections created by discontinuities and/or blockages. Analysis of the initial phase (positive or negative) and the shape of the reflected acoustic wave are used to identify the type of flaw causing the reflection.
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standards.