Archive: Sep 2020

Short & Long Elbows

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Nomenclature of Elbows


A short radius elbow has a CenterLine Radius (CLR) of 1x the nominal diameter. 

     A four inch elbow (IPS or OD) has a 4” CLR.

A long radius elbow has a CenterLine Radius (CLR) of 1-1/2x the nominal diameter. 

     A four inch elbow (IPS or OD) has a 6” CLR.

A sweep elbow would be defined as any elbow outside of those parameters, typically having a CLR broader (larger) than 1-1/2 times the nominal diameter.


One of the most common errors one runs into is when a customer from one industry hops into a conversation with someone from another industry.  For instance, when a customer from the sanitary, food & dairy, biopharm community calls for a “short 90”, they are referring to a short pattern (no tangents) elbow.  But the person hearing is in the industrial market and interprets this to be a short radius 90.

“My customer is asking for a “short 90”;  what does that mean?”

When industrial customers from paper, wastewater, vacuum, chemical, etc request a “short 90” they are almost undoubtedly speaking of a short radius elbow.

When your customer in food, dairy, or biopharm phones you, the call out of “short 90” means the customer doesn’t want a tangent on their elbow.  Essentially, it is a long radius 90º elbow (CLR = 1.50x nominal diameter) with no tangents. Most often, the fitting is requested in Tube-OD.  Some customers in the sanitary field aren’t even aware that there is such a fitting as a short radius 90, despite the fact that they are made (primarily for the industrial market).

This is a classic case where not asking the right question(s) will come back to bite you a couple days after you ship out what you were certain was the correct fitting.  Take a moment to check out our webpage on Elbows (Smoothflow).  Bring your customer to the page and ask them to “point.”  It’s the ounce of prevention to avoid that pound of cure.

Is it a Wye? …or is it a Lateral?

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Someone from the plumbing trades comes in and asks for a “wye”.  Someone from a steamfitter background calls looking for a “45-degree lateral”.  Which fitting weighs more?  Trick question!  They are the same fitting.

Decades ago, our company started restricting the conversation to two terms to cull the confusion.  A straight run with a branch to one side is a LATERAL.  A fitting with a trunk coming up that splits to a 45º branch left and right is called a TRUE WYE, because it resembles a “capital letter Y” as we learned to draw it in grade school.


Plumbers work extensively with PVC and ABS.  If you look in the catalogs from Charlotte®, Genova®, or various other manufacturers in the plastics industry, what a steamfitter will refer to as a lateral, is referred to in those catalogs as a wye.

Not confused enough?  The plumbing trade calls a 45-degree elbow a “1/8th bend”;  because it turns 1/8th of a 360-degree circle.  So when a customer calls for a “combination wye & 1/8th bend” (a.k.a. “combo”) They are referring to what we call a lateral-tee.  A lateral-tee is simply a lateral with a 45-deg elbow welded to the branch directed perpendicular to the run.