A plumbing inspector failed me because I plumbed the job according to the Code book. Really, that’s what happened. It seems that there are three sets of rules by which we plumb in the Memphis area: (1) the Code book, (2) the “Blue Pages,” which are Shelby County’s amendments to the Code, and (3) an unwritten body of rules I’ll call “We’ve never allowed that.”
An inspector came to my job, looked at a certain joint, and said “You can’t use a 90 there; you have to use a long sweep.” That surprised me, so I got out the Plumbing Code and showed him the pertinent paragraph and asked “What does this mean right here?” (The book specifically said that I was correct.) He was surprised by what he saw, but he repeated “We’ve never allowed that.”
I decided to call the office where the top Code guys sit. “Mr. ____ tells me I cannot use a 90 to change from vertical to horizontal.” The Code official answered “We’ve never allowed that.” I protested “But the book says it’s legal.” All he could say was “Well, we’ve never allowed that.”
So I crawled under the house, cut out the 90, and replaced it with a long sweep. Nobody ever said the world was fair.
Now knowing what code you are using but the IPC allows this 2 inch and smaller. The Uniform Plumbing Code does not allow a 90 from the virtical to the horzontal but does allow it from the horzontal to the virtical. A short sweep is allowed in both codes. The reason behind this is because of the velocity the waste is moving in the virtical pipe. When it changes to the horzontal it creates a considerable amount of turbulence if a 90 is used compared to a sweep fitting. The sweep makes a better change from the virtical to the horzontal without creating a lot of turbulence and makes the waste flow better. I hope this helps of why, there is nothing worse than an inspector saying we have allways done it this way without an explaination.
Thanks, Bill. It’s easy enough to see that a sweep would redirect the waste better than a mere 90. And I suppose four 22’s separated by at least two inches would be even better than that! I won’t argue with the headroom that’s engineered into the Code (and increased with every edition, as if sewage were evolving in its physical properties), but it’s a funny world when the inspectors have a set of rules that a plumber cannot find out about until they fail him.