ASTM E797/E797M-21 PDF

Full title and description

ASTM E797/E797M-21 — Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse‑Echo Contact Method. This practice provides guidance and procedures for manual ultrasonic pulse‑echo contact measurements of material thickness from a single accessible surface, applicable to components and materials where ultrasonic waves propagate and back‑wall echoes can be obtained.

Abstract

This standard specifies the manual pulse‑echo contact technique for ultrasonic thickness measurement. It covers principles of measurement, instrument and transducer considerations, calibration using reference blocks, velocity determination, readout and A‑scan verification, unit systems (SI and inch‑pound, treated separately), limitations (including temperature and geometry), and recommended practices to achieve reliable thickness readings for corrosion monitoring, manufacturing control, and quality assurance.

General information

• Status: Published / Active
• Publication date: Current edition approved June 1, 2021; published September 2021.
• Publisher: ASTM International
• ICS / categories: 17.040.20 (Properties of surfaces); Nondestructive testing (ASTM Committee E07, Subcommittee E07.06 Ultrasonic Method)
• Edition / version: E797/E797M‑21
• Number of pages: 9

Scope

The practice provides guidelines for measuring thickness by the contact pulse‑echo ultrasonic method at temperatures not to exceed 93 °C (200 °F). It is applicable to materials in which ultrasonic waves propagate at an effectively constant velocity and from which resolvable back‑wall echoes can be obtained. The practice is primarily intended for flat or near‑parallel surfaces; it has limited applicability for non‑parallel, highly curved, or concentric geometries.

Key topics and requirements

• Principle: thickness = (velocity × transit time) / 2 (pulse‑echo round trip).
• Temperature limit: intended for use at temperatures ≤ 93 °C (200 °F).
• Calibration: requirement for one or more reference blocks (known thickness/velocity) covering the measurement range; use of “round‑number” thickness reference blocks is recommended.
• Velocity determination: guidance to obtain material sound velocity from reference blocks, tabulated values, or comparative methods (see referenced practices).
• Instrumentation: descriptions of pulse‑echo instruments, thickness readout instruments, A‑scan display use, and requirements for time‑base linearity and verification.
• Units: SI and inch‑pound units are each considered independent standards and must not be mixed.
• Limitations and applicability: notes on material inhomogeneity, surface condition, geometry effects, and situations where measurements may be unreliable.
• Quality and verification: recommended checks (A‑scan inspection, use of multiple reference blocks, probe selection, and coupling considerations) to reduce measurement uncertainty.

Typical use and users

Used by NDT technicians, inspection engineers, corrosion engineers, quality control personnel, and maintenance teams for nondestructive thickness checks on piping, tanks, pressure vessels, structural components, and machined parts. Typical applications include corrosion/erosion monitoring, dimensional verification in production, in‑service inspection, and spot checks where only one-sided access is available.

Related standards

Commonly referenced standards and practices include ASTM E317 (performance evaluation of ultrasonic pulse‑echo instruments), ASTM E494 (measuring ultrasonic velocity), ASTM E1316 (NDT terminology), ASTM E543 (agencies performing NDT), and related ASME practice SE‑797. ISO and industry guidelines on NDT personnel qualification (for example ISO 9712) and ultrasonic testing are also relevant.

Keywords

ultrasonic thickness measurement, pulse‑echo, contact method, nondestructive testing (NDT), A‑scan, calibration block, sound velocity, corrosion monitoring, thickness gauge, manual ultrasonic

FAQ

Q: What is this standard?

A: ASTM E797/E797M‑21 is a practice that describes procedures and recommendations for manual ultrasonic pulse‑echo contact measurement of material thickness from one accessible surface.

Q: What does it cover?

A: It covers measurement principles, instrument and transducer considerations, calibration with reference blocks, velocity determination, A‑scan verification, unit treatment (SI vs inch‑pound), applicability limits (including temperature and geometry), and recommended verification to ensure reliable readings.

Q: Who typically uses it?

A: Nondestructive testing technicians and engineers, corrosion and maintenance personnel, inspection and quality control staff in industries such as oil & gas, power generation, manufacturing, fabrication, and utilities.

Q: Is it current or superseded?

A: The designation E797/E797M‑21 is the 2021 edition (current edition approved June 1, 2021 and published September 2021). Users should confirm they are using the latest revision before application.

Q: Is it part of a series?

A: It is one practice within ASTM Committee E07 on Nondestructive Testing and relates to other ultrasonic and NDT practices (for example E317, E494, E1316). It is often used alongside other industry codes and ASME practices (such as SE‑797) when applied to pressure‑retaining equipment.

Q: What are the key keywords?

A: Ultrasonic, pulse‑echo, thickness measurement, contact method, A‑scan, calibration block, nondestructive testing, sound velocity, corrosion monitoring.