What Is IPS?

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While it might be somewhat outdated, IPS—Iron Pipe Size—is a system of measuring pipes that is still used by a number of modern pipe manufacturers and the industries that use them. As such, understanding IPS is critical to ensuring that a plumber knows how to use the system.

IPS, which is the more commonly used abbreviation for the old method of measuring pipes known as the Iron Pipe Size, is often not as well understood as it ought to be among plumbers, particularly those individuals who are new to the plumbing industry, Plumbers should, therefore, always strive to ensure that they understand how to use the Iron Pipe Size measurement system; though its use as a means of pipe measurement has been widely discontinued in modern times, it is still used in some scenarios and so, as such, it is important that a plumber knows how to read and understand Iron Pipe Size measurements.


How Does The Iron Pipe Size System Work?

During the heyday of the Iron Pipe Size (IPS) system as a means of pipe measurement, most of the pipes that were produced were made by the welding of two halves of pipe; as such, the IPS system of measurement refers to the diameter of the sealed sections of pipe. This is similar—although not identical—to the modern system of pipe measurements: the nominal pipe size, NPS, and the ductile iron pipe standard, DIPS. One of the biggest factors for the change measurement systems was the invention of ways in which the walls of pipes could be better controlled and determined, and it was at this point (in 1948, just three years after the end of the Second World War) that the DIPS first came into play.


History Of The Iron Pipe Size (IPS) Measurement System

Iron pipe size (IPS) was used widely for the measurement of pipes up until 1927, when the American Standards Association made the decision to authorize a new form of pipe measurement, which was known as the Nominal Pipe Size (NPS). Nominal pipe size was designed to standardize the size measuring methods for both high pressure pipes and low pressure pipes, and this was put into place for both wrought iron and wrought steel pipes. Despite being based quite heavily on the system of IPS, the NPS would gradually take over as the generally accepted method of pipe measurement until, after the end of the Second World War in May 1945, it became the most popular measurement method.


Where Is Iron Pipe Size Used In Modern Times

Despite being largely discontinued in modern times, Iron Pipe Size (IPS) is still used in a few aspects of modern piping. IPS is still used by some of the major PVC pipe manufacturers and understandably has a large role in legacy drawings, diagrams, sketches, and pieces of legacy equipment.


Why Do I Need To Understand IPS As A Plumber

Despite IPS being widely unused nowadays, there are still a few pipe manufacturers—primarily those manufacturers who create PVC pipes—who use the old IPS method of measuring for their pipes. As such, if you are tasked with using any of these manufacturers’ pipes, or if you find yourself working on an old property with piping that is described on the property’s diagrams and reports under the old IPS measurement system, you would benefit from understanding how the IPS measurement system works.


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