ASTM-E2479 › Standard Practice for Measuring the Ultrasonic Velocity in Polyethylene Tank Walls Using Lateral Longitudinal (LCR ) Waves
The following bibliographic material is provided to assist you with your purchasing decision:
This practice covers a procedure for measuring the ultrasonic velocities in the outer wall of polyethylene storage tanks. The practice is intended for application to the outer surfaces of the wall of polyethylene tanks. An angle beam lateral longitudinal (LCR) wave is excited with wedges along a circumferential chord of the tank wall. A digital ultrasonic flaw detector is used with sending-receiving search units in through transmission mode. The observed velocity is temperature corrected and compared to the expected velocity for a new, unexposed sample of material, which is the same as the material being evaluated. The difference between the observed and temperature corrected velocities determines the degree of UV exposure of the tank.
Scope
1.1 This practice covers a procedure for measuring the ultrasonic velocities in the outer wall of polyethylene storage tanks. An angle beam lateral longitudinal (LCR) wave is excited with wedges along a circumferential chord of the tank wall. A digital ultrasonic flaw detector is used with sending-receiving search units in through transmission mode. The observed velocity is temperature corrected and compared to the expected velocity for a new, unexposed sample of material which is the same as the material being evaluated. The difference between the observed and temperature corrected velocities determines the degree of UV exposure of the tank.
1.2 The practice is intended for application to the outer surfaces of the wall of polyethylene tanks. Degradation typically occurs in an outer layer approximately 3.2-mm [0.125-in.] thick. Since the technique does not interrogate the inside wall of the tank, wall thickness is not a consideration other than to be aware of possible guided (Lamb) wave effects or reflections off of the inner tank wall. No special surface preparation is necessary beyond wiping the area with a clean rag. Inside wall properties are not important since the longitudinal wave does not strike this surface. The excitation of Lamb waves must be avoided by choosing an excitation frequency such that the ratio of wavelength to wall thickness is one fifth or less.
1.3 UV degradation on the outer surface causes a stiffening of the material and an increase in Young's modulus and the longitudinal wave velocity.
Keywords
ICS Number Code 23.020.10 (Stationary containers and tanks); 83.080.01 (Plastics in general)
To find similar documents by ASTM Volume:
03.03 (Nondestructive Testing)
To find similar documents by classification:
23.020.10 (Stationary containers and tanks)
83.080.01 (Plastics in general)
This document comes with our free Notification Service, good for the life of the document.
This document is available in either Paper or PDF format.
Customers who bought this document also bought:
NAS-410NAS Certification and Qualification of Nondestructive Test Personnel
AWS-D17.1/D17.1M
Specification for Fusion Welding for Aerospace Applications
MIL-H-7199
Heat Treatment of Wrought Copper-Beryllium Alloys, Process for (Copper Alloys: Numbers C17000, C17200, C17300, C17500, and C17510) (Superseded by SAE-AMS-H-7199)
Document Number
ASTM-E2479-16R21
Revision Level
2016 R21 EDITION
Status
Current
Modification Type
New
Publication Date
June 14, 2021
Document Type
Practice
Page Count
7 pages
Committee Number
E07.06