Thickness Measurement of Metal
(Ultrasonic Thickness Testing — UTT)

Non-destructive measurement of metal wall thickness using ultrasonic pulse-echo method — assessing corrosion-induced wall thinning in pipes, tanks, vessels and structural steel members from one side only.

Overview

What is the Thickness Measurement of Metal?

Ultrasonic Thickness Measurement uses the pulse-echo method to measure metal wall thickness from a single accessible face — without requiring access to the opposite face. An ultrasonic pulse is transmitted through the metal and the time for the echo to return from the opposite face is measured. Thickness = (velocity × transit time) / 2.

Conducted as per ASTM E797 and IS 13596, ultrasonic thickness testing is the primary method for in-service corrosion monitoring of pipes, storage tanks, pressure vessels, offshore platforms and ship hulls. Global Lab uses NABL-calibrated digital ultrasonic thickness gauges (0.5–300mm range) with appropriate transducers for all metal types.

Single-Side Access

Thickness measured from one face — no access to opposite side required.

Corrosion Mapping

Grid-based scanning produces thickness maps showing thinning zones.

0.5–300mm Range

Measures from thin sheet metal to thick structural steel plates.

All Metal Types

Steel, stainless steel, aluminium, copper, titanium and cast iron measured.

NABL Certified Reports

All results on NABL-accredited letterhead per ASTM E797.

Remaining Life Assessment

Minimum wall thickness vs design minimum — remaining corrosion allowance calculated.

Test in Action

Thickness Measurement of Metal — Site Images

UT Gauge Calibration on Reference Block

Thickness Measurement on Pipe Wall

Corrosion Map Generated from Grid Survey

Test Procedure

How the Thickness Measurement of Metal is Conducted

1

Surface Preparation

Test surface cleaned of paint, loose rust and scale at measurement points. Surface roughness assessed.
2

Gauge Calibration

Ultrasonic gauge calibrated using calibration block of same material and known thickness per ASTM E797.
3

Couplant Application

Appropriate ultrasonic couplant (gel) applied to measurement points to ensure acoustic coupling.
4

Thickness Measurement

Transducer placed on surface. Digital thickness value displayed and recorded. Grid pattern scanning performed.
5

Corrosion Map & Report

Measured thicknesses plotted on element sketch. Minimum thickness identified. Remaining life assessed. NABL report within 24 hours.

Standards & Specifications

Applicable Test Standards

Standard	Title	Scope	Type
ASTM E797	Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method	UT Thickness	ASTM
IS 13596	Ultrasonic Thickness Measurements — Methods and Procedures	UT Thickness	Indian Standard
ASME B31.3	Process Piping — Inspection Requirements	Piping Inspection	ASME
API 510	Pressure Vessel Inspection Code — In-Service Inspection	Vessel Inspection	API

Applications

Where is the CAPO Test Used?

In-service corrosion monitoring of process plant piping and pressure vessels

Storage tank floor and shell corrosion assessment — API 653 inspection

Offshore platform structural member wall thickness survey

Ship hull and ballast tank corrosion monitoring from accessible face

Structural steel corrosion assessment on bridges and industrial structures

Periodic statutory inspection of boilers, heat exchangers and pressure equipment

Why Choose Global Lab

Our Advantages

NABL Accredited ReportsLegally valid UT thickness certificates for statutory and insurance inspections.

Corrosion MappingGrid-based thickness maps identify thinning zones for targeted repair.

Remaining Life AssessmentMinimum thickness vs design minimum — corrosion rate and remaining life calculated.

Pan-India CoverageNDT teams at all 7 lab locations for industrial and infrastructure sites.

Fast 24-Hour ReportComplete thickness survey and NABL report within 24 hours.

Combined Metal NDTUTT + DPT + coating thickness as a complete metal condition assessment.

Thickness Measurement of Metal(Ultrasonic Thickness Testing — UTT)