No announcement yet.

IPS thread

  • Filter
  • Time
  • Show
Clear All
new posts

  • IPS thread

    I have a AL block with a 1/2-14 ips threaded hole. Only problem is I cannot find an IPS spec anywhere. Anyone know what this stands for?


  • #2
    IPS is a straight thread (not tapered) used in plumbing. It stands for Iron Pipe Size.

    [This message has been edited by Evan (edited 05-05-2004).]
    Free software for calculating bolt circles and similar: Click Here


    • #3
      Iron Pipe Standard.

      John S.

      Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


      • #4
        Here is a chart of Iron Pipe Size.
        Free software for calculating bolt circles and similar: Click Here


        • #5
          I have delt with NPS, NPT, NPSM, etc but never heard of IPS. Thanks for the info.



          • #6
            To answer your question the hole may be assumed by industry convention to be NPT. Regardless, clarify with the customer.

            IPS (inch pipe size) relates to the outside diameter of the pipe and it's a "Nominal" dimension, that is a 1" IPS pipe is actually 1.315" OD. The nominal inch designation can be confusing. A few minutes of study of the tables will give you a general idea of a quirky system. Personally I carry a wallet card listing pipe size data.

            The IPS designation should be accompanied with the schedule number which relates to the wall thickness which is roughly proportional to the pipe diameter. The pipe most people are familiar with is Sch 40.

            Here's a link to a table:


            NPT designates "National Pipe Tread" which refers to the tapered pipe threads we are all familiar with. Many of the NPT thread designations have no counterpart in modern practice in the English and Metric systems.

            The National pipe threads designation has an interesting history that dates from the merchant size wars in the nineteenth century where the giants of the time vied for dominance etc each with their own standards. I forget who won but somebody wrote a book on the subject in the early '40's. From the confusion came the Unified Thread System and the Metric Thread system but it took two world wars to resolve the confusion and settle on universal standards to facilitate wartime interchangeability. Pipe sizes and pipe threads are but a remnent of an interesting and frustrating time in industrial history.

            Straight pipe threads are designated:
            NPSM (National Pipe Straight Mechanical),

            NPSL (National Pipe Straight Locknut), and

            NPSH (National Pipe Straight Hose).

            These standards are discussed in Machinery's Handbook and other common references.

            [This message has been edited by Forrest Addy (edited 05-06-2004).]


            • #7
              The reason for the odd pipe sizes is that they were originally iron pipe. Thats why its called IPS Iron Pipe Size. When steel began to be used, the walls of the pipe could be thinned and still have superior strength compared to the old iron pipe. However, by that time, valves and fittings were already standardized, so the bores of the pipe were made larger, leaving the OD the same as the iron pipes. That gives us the odd pipe dimensions we have today, where the nominal size has no relation to actual size.