Watching The Trades

I never would have thought that the Japanese would treat their houses as throwaway objects. I have always heard so much about what fine craftsmen the Japanese were that I always imagined that they built their houses with the same kind of care. They don’t.

The typical lifespan for a house in Japan is only 30 years and buying a used house is almost unheard of. You can read more here.

I never would have thought that rising construction cost would so quickly become a problem for governments trying to build or repair their infrastructure. Obviously, I knew that this was going to be a problem in the future because I wrote a post on the problem. But serious problems are starting to pop up now.

This article from the New York Times explains why.

If you ask an engineer a pipe is vessel and a tube is a structure. The standard measure for a pipe (i.e, the size you use to spec it) is the inside diameter because it is a vessel for transporting gas or liquids. The standard measure for a tube is measured by outside diameter because it is used for structural support.

If you ask a plumber, a pipe is any thick walled tube that can be threaded. A tube is anything that carries gas or liquids and is too thin walled to be threaded. Most plastic pipe is not threaded. However it is thick walled and that is why it is called pipe (You can also get plastic tubing).

In general, a plumber use inside diameter as the standard measures for both pipes and tubing. But Black Iron (and other ferrous metal pipes) and plastic pipes nominal size is only an approximation of the inside diameter. What’s more, the inside diameter will vary by thickness of the pipe wall (which is indicated by the pipe schedule). So a schedule 40 pipe will have an inside diameter that is almost twice as big as a schedule as a schedule 120 pipe even though they are both the same nominal size. To make matters worse, from 14” the nominal size is based on outside diameter.

To make matters even more complicated, the standard measure for annealed copper refrigeration tubing (otherwise known as ACR tubing) is always outside diameter. But this stuff is used by HVAC technicians, not your average plumber.

I don’t understand I why we all can’t be more like engineers. Do we really need a bunch of different standard measures for pipes when they are all used for transporting gas or liquids?