How to distinguish between pipe elbow and pipe bend?

Elbow is a standard fitting but bends are custom fabricated. In bends as the pipe is bent and there is no welding involved, there is less pipe friction and flow is smoother. ... Bend has a larger radius then elbows. Generally the most basic difference is the radius of curvature.


” All bends are elbows but all elbows are not bends.”
Infact, the pipe is bent to form an elbow.
Elbows are pre-fabricated and are firm in design.
There are issues with bends since the tickness at the bend radius reduces as we bend the pipe.
Bends typically have a minimum  radius of 1.5 times pipe radius (R). If this  radius is less than 1.5R, it is called Elbow. Reference to any international / industry standard need to be traced. 1.5, 3 and 4.5 R are the most common  radii in industry.

Sharp bends are normally called Elbows.
An elbow is also typically a sharp 90 degrees and often is a separate piece.
A bend typically flows smoother since there are not irregular surfaces on the inside of the pipe, nor does the fluid have to change direction abruptly.
The most basic difference of them is the elbow relatively short than bend, R = 1D to 2 D is elbow More than 2D is bend. In the production process, cold bends can use Bending Machine to bend by ready-made straight bend. One-time completed also don’t need second corrosion. But elbow need manufacturers make to order, to do anti-corrosion, order cycle is long. Elbow price is higher than bend. But cost performance is much higher than bend. It is well-known that bend do not have anticorrosive processing is easy damaged, but the price is cheap so are used very much in some demand which not very high engineering.

In the west-east gas transmission of course, cold bends cost is low. elbow need manufacturers make to order, needs corrosion, order cycle is long,but cold bends can use ready-made straight bend by Bending Machine to bend. One-time completed also don’t need second corrosion. The cold bend construction technology need follow oil standard .west-east gas transmission have the enterprise standard,but we can use either elbow nor bend in open area.  Enterprise warn broad customers between ness elbow and bend performance price is differ ,please carefully choose after consider it.

Bends and elbows cannot be used interchangably in piping system design ....

One of the important differences commonly ignored between bends and elbows is the change in "stiffness" of a system.

When a detailed stress analysis is performed on similar piping systems, a system with "all bends" is much stiffer than one with "all elbows". In accordance with the rules of ASME B31.1 and B31.3, the flexibility factors are significantly different

This means that the the calculated reaction forces on the system terminations (anchor points) are much higher with the system of bends than the one with elbows.

For piping systems with reaction sensitive terminations (like one with centrifugal pumps) stay away from the bends.

DIMENSIONAL TOLERANCES OF BUTT WELD ELBOWS - 45° AND 90° - LR AND 3D - ASME B16.9 -
Nominal Pipe Size1/2 to 2½3 to 3½45 to 8
Outside Diameter
at Bevel (D)
+ 1.6
- 0.8
1.61.6+ 2.4
- 1.6
Inside Diameter at End0.81.61.61.6
Center to End LR (A/B)2222
Center to End 3D (A/B)3333
Nominal Pipe Size10 to 1820 to 2426 to 3032 to 48
Outside Diameter
at Bevel (D)
+ 4
- 3.2
+ 6.4
- 4.8
+ 6.4
- 4.8
+ 6.4
- 4.8
Inside Diameter at End3.24.8+ 6.4
- 4.8
+ 6.4
- 4.8
Center to End LR (A/B)2235
Center to End 3D (A/B)3366
Wall Thickness (t)Not less than 87.5% of Nominal Wall Thickness
Dimensional tolerances are in millimeters unless otherwise indicated and are equal ± except as noted.
Note:
MSS SP-43 only covers stainless steel buttweld fittings made for use with Schedule 5S and 10S pipe and Stub Ends suitable for use with Schedule 40S pipe, as defined in ASME B36.19. The dimensions and dimensional tolerances defined in MSS SP-43 are substantially the same as those in ASME B16.9 specifications from NPS 1/2 - NPS 24. Except with regard to the outside diameter at the bevel.

Seamless steel pipe >>

Seamless steel pipe >>
Seamless steel pipe is alos called CDS pipes (Cold drawn seamless pipe).

Pipe fitting >>

Pipe fitting >>
Pipe fitting is work that involves the installation or repair of pipes or tubes. Pipes and tubes are necessary for a wide range of reasons.

Flanges General >>

Flanges General >>
A flange is a method of connecting pipes, valves, pumps and other equipment to form a piping system.

Get in Touch

Welcome to Sunny Steel Enterprise Ltd.

Sunny Steel provide a wide range of steel products as Steel pipes, Seamless tube and seamless pipes, Alloy pipes, Pipe fittings, Composite steel pipe used in the industry, construction etc.

You can get in touch by telephone, post, online or E-mail.
Please check the help section first to see if your question may be answered there.