Method and apparatus for measuring the thickness of a coated material

A method of measuring the thickness of a coated pipe comprising:

• measuring the velocity by which an ultrasonic pulse is transmitted through uncoated material from which the pipe is manufactured;
• measuring the velocity by which an ultrasonic pulse is transmitted through the coated pipe;
• determining the thickness of the coating on the pipe as a function of the difference in transmission velocities;
• ultrasonically measuring the thickness of the coated pipe;
• and,
• calculating the thickness of just the pipe by subtracting the measured thickness of the coating from the measured thickness of the coated pipe.

Apparatus for measuring the thickness of a coated material comprising:

• means ultrasonically measuring the thickness of the coating on said coated material;
• means ultrasonically measuring the thickness of the coated material;
• and,
• a processor calculating the thickness of the material by subtracting the measured thickness of the coating from the measured thickness of the coated material to determine the thickness of the material.

Apparatus measuring the thickness of a coated pipe comprising:

• means transmitting an ultrasonic pulse through uncoated material from which the pipe is manufactured and measuring the velocity by which said ultrasonic pulse is transmitted therethrough;
• means transmitting an ultrasonic pulse through the coated pipe and measuring the velocity by which said ultrasonic pulse is transmitted therethrough;
• a processor determining the thickness of the coating on the pipe as a function of the difference in transmission velocities;
• and,
• means ultrasonically measuring the thickness of the coated pipe, said processor further calculating the thickness of just the pipe by subtracting the measured thickness of the coating from the measured thickness of the coated pipe.

An instrument for measuring the thickness of a coated pipe comprising:

• a memory storing a schedule of velocity values for ultrasonic pulses transmitted through an uncoated material from which a pipe whose thickness is to be measured is manufactured, a user of said instrument accessing velocity information for a particular pipe material prior to performing a thickness measurement;
• means transmitting an ultrasonic pulse through the coated pipe and measuring the velocity by which said ultrasonic pulse is transmitted therethrough;
• a processor to which velocity information is supplied from said memory, said processor determining the thickness of the coating on the pipe as a function of the difference in stored velocity value for the uncoated pipe material and the measured velocity through the coated pipe material;
• means ultrasonically measuring the thickness of the coated pipe;
• and,
• said processor calculating the thickness of the pipe by subtracting the measured thickness of the coating from the measured thickness of the coated pipe.