Plumbing code essentials: Joints and connections

The 2018 Code Essentials series are available as valuable companions to the 2018 International Building, Residential, Fire, Energy Conservation, Existing Building and Plumbing Codes. Aimed at all user levels — including first-time users, veteran code users and other professionals such as architects, designers and contractors — these guides use a straight-forward, focused approach to explore code requirements with non-code language, allowing readers to gain confidence in their understanding of the material and build a solid foundation for learning and applying the code’s requirements.

2018 Plumbing Code Essentials

Gravity flow in drains can be impeded significantly by anything that causes excessive friction. Therefore, it is imperative that joints create a smooth interior surface free of ledges or reductions that can obstruct the flow. Additionally, fittings that properly direct the flow are necessary. International Plumbing Code Table 706.3 lists the various types of directional pattern fittings and their proper use for changes in direction. Naturally, horizontal to horizontal and horizontal to vertical changes in direction fittings with a larger turning radius are generally referred to as long-sweep bends, wyes and combination wye and eighth bend fittings. Note that a short sweep may be used in vertical to horizontal changes of direction in 3-inch or larger diameter drains, and both the quarter bend and the short sweep may be used for 2-inch or smaller fixture drains. When using International Plumbing Code Table 706.3, note that both plastic and cast iron drainage fittings have a long sweep and a quarter bend, but cast iron also has a short sweep, which is a shorter radius than its quarter bend. Do not compare the radius of bend for one type of material to another. A good rule of thumb is to consider the radius of joining two eighth bends (45 degrees) of material to be equivalent to a long sweep of the same material.

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