Is it a Wye? …or is it a Lateral?
Comments Off on Is it a Wye? …or is it a Lateral?A person from the plumbing trade walks in asking for “wye”. Meanwhile, someone with a steamfitter background calls looking for a “45-degree lateral”. Which one is heavier? Trick question — they’re the exact same fitting.
To minimize ambiguity, our company standardized terminology decades ago. A fitting consisting of a straight through-run with a single branch at a 45º angle is classified as a lateral. A fitting featuring a main inlet that divides symmetrically into two 45º outlets—forming a Y-shaped configuration—is designated as a true wye, named for its resemblance to the capital letter “Y”, just like we learned to draw in grade school.
Terminology Differences: Plumbing vs. Steamfitting
Plumbers frequently work with PVC and ABS piping systems. In catalogs from manufacturers like Charlotte®, Genova®, and others in the plastics industry, what a steamfitter would call a lateral is typically listed as a wye. While both refer to the same fitting—a branch coming off at a 45º angle—the terminology varies by trade.
Adding to the complexity, the plumbing trade refers to a 45-degree elbow as a “1/8 bend.” This is based on fractional terminology, where a 45º turn equals one-eighth of a full 360º circle.
Understanding these naming conventions is pivotal when working across trades or reviewing manufacturer specifications. Not confused enough? So, when a customer requests a “combination wye and 1/8 bend”—often shortened to “combo”—they’re referring to what we in the piping and fittings industry typically call a lateral tee.
A lateral tee is essentially a lateral fitting with a 45-degree elbow integrated (or welded) onto the branch, orienting it perpendicular to the main run.