Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers


Pit Gauge

Last updated: November 24, 2018

What Does Pit Gauge Mean?

A pit gauge is an industrial tool widely used to measure the wall thickness of structures like plates or pipes. With this tool, plumbers, pipeliners, warehouse personnel, fabricators and even buyers are able to conduct proper measurements to determine the degree of corrosion.

Any damage or deviation from normal measurements indicates a corrosion problem. Hence, a pit gauge is a very important tool in corrosion inspection.

Pit gauges are also known as pit depth gauges or bridging bars.


Corrosionpedia Explains Pit Gauge

A basic pit gauge has a simple lever and a pointer, whereas advanced and more accurate models may have digital readouts or analog dial indicators. Different sizes and designs of pit gauges enable corrosion inspectors to measure components of all shapes and sizes in almost all industries.

Various surface shapes and sizes require different types of pit gauges. Some bigger shapes like tanks, have gauges with parts that can be extended to cover larger surface areas. The type of tip that scans the pit varies in length and thickness, and the most common are:

  • Standard – Universal for general corrosion tests
  • Conical – Larger than standard, used when a large amount of scanning is required
  • Needle tip – For small diameter and shallow pits (very delicate)

A pit gauge is very convenient to use, as it is composed of only one movable part and precisely registers to +/- 0.0005 inches. The scale of a pit gauge is graduated in decimal and fractional inches and is capable of measuring degree of thickness from 0 to 0.625 inches. Pit gauges are available in pocket sizes, so they can be easily carried and transported.

The following equipment particularly benefits from corrosion measurement using pit gauges:

  • Pressurized equipment (boilers, pipelines, storage tanks, piping, vessels)
  • Tube-shaped products (drill pipes, casings)
  • Aircraft elements
  • Structures and bridges

Pit gauges are used to determine whether corrosion has increased. In actual settings, inspectors are continually required to conduct measurements of pit depths.



Pit Depth Gauge

Bridging Bar

Pit Gage

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