What is the difference between a Pipe Bend and an elbow

Pipe elbows and pipe bends are both very common pipe fittings products which are used to change the flowing direction in a piping systems. Some times they are interchangeable, but not same.

A pipe bend means a piece of pipe which are bent to some angle to join two pipings.  They can be nearly any bending radius and angles . Pipe bends are commonly produced on site to meet a specific need by hot induction bending or cold bending. A elbow means a specific pipe bend as per the standard ANSI/ASME B16.9 (or EN 10253, or other pipe fittings standards). Commonly the elbows have a bending radius of 1.5D or 1D (Here the D means nominal diameter of this bend) ,which are called “Long Radius elbow (LR elbow)” or “Short Radius elbow(SR elbow)” . and the angle of an elbow is 45 degree or 90 degree usually, some times there are also custom-designed elbows which are 30 degree,60 degree ,180 degree or other angles.

The pipe bends should be as per the standard of  ANSI/ASME B16.49 which did not specific the bending radius and angle , the regular pipe bend radius are 2.5D, 3D ,5D ,7D or 8D , but it can be any other bending radius according to the design need, and bending angle can be in any degree, 5 ,10 ,15, 90 degree or any other. People said “All bends are elbows but all elbows are not bend”, it is not true . Actually “All elbows are pipe bends but not all bends are elbows”  is more reasonable.

The Feature of Carbon Steel Pipe Fittings

Pipe fittings play an important role in the connection, controlling, direction changing, streaming components collectively sealed and supporting. Carbon steel pipe fittings are main auxiliary products for the steel pipe. The key products are carbon steel elbow, flanges, steel cap, steel tee, carbon steel pipe reducer. The standards include national standard, American standard and DIN.

Carbon steel pipe fittings also called pressure pipe fittings. It is usually divided into three types:

butt class pipe fittings, socket welded pipe fittings and threaded pipe fittings. In pipe joints system, you need various sizes of steel pipe fittings due to the different pipe sizes. For example, the threaded pipe fitting is necessary for straight tube or tube section connecting. Because of the double characteristics of the tubes and mechanical elements, all pipe should belongs to the steel pipe fittings after finished the deep process of steel pipe.

The sides of the steel pipe are painted to guaranteed as the fittings or oxidation resistant metal like zinc or nickel with electroplating. But it is well-known that the out layer of steel tube is just a thin film that is easy to be damaged. Once the protective layer damaged, the steel tubes start to rust in the atmosphere. So the preservative is necessary for the carbon steel tube depending on the zinc, nickel and chromium as protective layer.