ASTM E2479-16
Standard Practice for Measuring the Ultrasonic Velocity in Polyethylene Tank Walls Using Lateral Longitudinal (LCR) Waves

Standard No.

ASTM E2479-16

Release Date

2016

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM E2479-16(2021)

Latest

ASTM E2479-16(2021)

Scope

5.1 Measuring the velocity of ultrasound in materials is a unique method for determining nondestructively the physical properties, which can vary due to both manufacturing processes and environmental attack. Velocity is directly related to the elastic moduli, which can vary based on environmental exposure and manufacturing process, The L_CR method described herein is able to measure the velocity between two adjacent points on a surface and therefore is independent of the conditions on the opposite wall. Applications of the method beyond polymer tanks will undoubtedly be developed and examination may occur in the production line as well as in the in-service mode.

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 (L_CR) 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.

1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

ASTM E2479-16 Referenced Document

• ASTM E1316 Standard Terminology for Nondestructive Examinations
• ASTM E2373 Standard Practice for Use of the Ultrasonic Time of Flight Diffraction (TOFD) Technique
• ASTM E494 Standard Practice for Measuring Ultrasonic Velocity in Materials
• ASTM E543 Standard Practice for Agencies Performing Nondestructive Testing
• ISO 9712 Non-destructive testing — Qualification and certification of NDT personnel

ASTM E2479-16 history

• 2021 ASTM E2479-16(2021) Standard Practice for Measuring the Ultrasonic Velocity in Polyethylene Tank Walls Using Lateral Longitudinal (LCR) Waves
• 2016 ASTM E2479-16 Standard Practice for Measuring the Ultrasonic Velocity in Polyethylene Tank Walls Using Lateral Longitudinal (LCR) Waves
• 2011 ASTM E2479-11 Standard Practice for Measuring the Ultrasonic Velocity in Polyethylene Tank Walls Using Lateral Longitudinal (L_CR) Waves
• 2006 ASTM E2479-06 Standard Practice for Measuring the Ultrasonic Velocity in Polyethylene Tank Walls Using Lateral Longitudinal (L_CR) Waves