Carbon Steel 7D Elbows are pipe fittings used in pipeline installations to connect two pipes of the same nominal diameter, allowing the pipeline to change direction at a specified angle. The most common turning angles are 45°, 90°, and 180° (U-bend).
Specification
Materials: carbon steel, stainless steel A234, A860, F304, F304L, F316 and F316L.
Thickness: SCH 5 to SCH 160.
Types: 7D Bends.
Size: 1/2 to 72 inches (DN15 to DN1,800mm).
Manufacturing Standards: ANSI, ISO, JIS and DIN.
Carbon steel elbows can be classified in multiple ways:
By Bending Angle:
45° Elbows – Used for slight directional changes in pipelines.
90° Elbows – The most common type, used for right-angle turns.
180° Elbows – Used for complete reversal of flow, also called "U-bends" or "return elbows."
By Radius:
Long Radius (LR) Elbows – Bending radius is 1.5 times the pipe diameter (1.5D). Offers lower fluid resistance and pressure drop, making them the preferred choice.
Short Radius (SR) Elbows – Bending radius equals the pipe diameter (1D). Suitable for space-constrained installations but with higher fluid resistance.
By Connection Method:
Butt-Weld Elbows – Feature beveled ends for welding. Provide the highest strength and sealing, ideal for high-pressure and high-temperature pipelines, and are the dominant form in industrial applications.
Socket-Weld Elbows – One end has a socket for pipe insertion and subsequent welding. Used for small diameters (DN80 and below) and medium/low-pressure pipelines.
Threaded Elbows – Equipped with internal/external threads for screw connections. Easy to install/remove but with lower sealing and strength, typically used for low-pressure, non-critical applications (e.g., water, air).
Flanged Elbows – Have flanges at both ends for bolting. Facilitate maintenance and disassembly but are more costly.
By Wall Thickness (Common Standards):
Sch 5s, Sch 10s, Sch 40s, Sch 80s, etc. ("s" denotes stainless steel fittings, but carbon steel also follows this numbering).
Higher numbers indicate thicker walls and greater pressure resistance.