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.

Comments are closed