Aside

Fittings – “It’s Just Not Fitting!”

Making Some Sense of All the Different Fittings

How do we make some sort of sense from all the different fittings? There are so many, and so many different terms of what is what.

What is a Push To Connect? What is a Quick Connect? What is a Coupler? What is a brass nipple (no, it’s not that!)?

Why does a 1/4″ pipe thread measure almost a 1/2″? Why does an 1/8″ pipe thread measure about 1/4″?

Who was the crazy person that started this mess? – and what was he/she drinking?

Let’s try to at least sort through the most common fittings used on Profitable Hobbies Engraving and Micro Sandblasting Systems.


If you have additional questions, please don’t hesitate to contact Profitable Hobbies at 1 800 624-7415.

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2 Responses to Fittings – “It’s Just Not Fitting!”

  1. Mel Joines March 5, 2010 at 7:32 pm #

    Why does 1/4″ pipe thread measure almost 1/2″ across?
    The answer is easy. Pipe size is determined bt measuring the inside of the pipe, across the diameter. So 1″ pipe is 1″ across the inside diameter, 1/4″ pipe is 1/4″ across the inside diameter. The threads are cut into the outside of the pipe wall. The different pressures that piping is designed to handle determines the wall thickness. Low pressure pipe has a thin wall, where high pressure piping has a thicker wall. To handle the higher pressures safely. And all of the piping has the same inside diameter measurement. This is why pipe threads are bigger than the measurement of the pipe.
    Tubing is measured across the diameter of the tube on the outside. So 1/4″ tube is 1/4″ across the outside diameter of the tubing. And the wall of the tubing is inside that measurement making the hole in the tubing smaller than the measurement across the diameter.
    Remember when measuring:
    Pipe is always ID inside diameter
    Tubing is always OD outside diameter.
    I hope this helps.
    Mel Joines
    was a pipe fitter in the US Navy.

  2. admin March 8, 2010 at 10:09 am #

    Thanks for the insight Mel. I figured there was some reasonable explanation.