Stainless steel elbow is a pipe fitting that connects two lengths of pipe or tubing to change the direction in piping and plumbing systems, there are common angles having 45 degree, 90 degree and 180 degree, stainless steel elbow can withstand high pressure and resist corrosion.
Elbow dimension ranges from 1/2 inch to 72 inch, Schedule in wall thickness range covers 5S, 10S, 40S, 80S, 160S, XXS conforming to ASME B16.9 and ASME B16.11.
Stainless Steel Elbow Fitting Specifications and Standards
ASME B16.9, Factory Made Wrought Butt welding Fittings
ASTM A403, Wrought Austenitic Stainless Steel Piping Fittings
ASTM A960, Common Requirements for Wrought Steel Piping Fittings
ASTM A815, Wrought Ferritic, Ferritic/Austenitic, and Martensitic Stainless Steel Piping Fittings
EN 10253-3, Wrought austenitic and austenitic-ferritic (duplex) stainless steels without specific inspection requirements
EN 10253-4, Wrought austenitic and austenitic-ferritic (duplex) stainless steels with specific inspection requirements
Stainless Steel Material
There are various stainless steels to be adapted for pipe elbow used in different applications, as we know that stainless steel exhibits excellent properties to resist corrosion, heating and high pressure, thus, stainless steel elbow is often used in critical applications.
304 and 316L are the most used stainless steel grades, they are both high chromium austenitic grades, and can be met the most cases, and other grades are available, such as, 321/321H and 347/347H. Some special alloys are usually for elbow as well, like 904L, 2205.
|WP 304||0,08||1,0||2.00||18.0 – 20.0||8.0 – 11.0||–||0,03||0,045|
|WP 304L||0,035||1,0||2.00||18.0 – 20.0||8.0 – 13.0||–||0,03||0,045|
|WP 316||0,08||1,0||2.00||16.0 – 18.0||10.0 – 14.0||2.00 – 3.00||0,03||0,045|
|WP 316L||0,035||1,0||2.00||16.0 – 18.0||10.0 – 15.0||2.00 – 3.00||0,03||0,045|
|WP 321||0,08||1,0||2.00||17.0 – 19.0||9.0 – 12.0||–||0,03||0,045|
There are also EN steel no. for opting, these equivalents include 1.4301, 1.4307, 1.4401, 1.4404, 1.4541, 1.4550, 1.4438 and 1.4539.
Elbow Length and Radius
Elbows are available in two radius types by length, Short radius (SR) and Long radius (LR), there are also other radiuses, for example, 2D, 3D and 4D.
Long Radius Elbow
Long radius elbow the radius of curvature is equal to 1.5 times the diameter of the pipe, namely, R = 1.5D, long radius elbow is used to reduce frictional force and elbow abrasion.
Short Radius Elbow
Short radius elbow the radius of curvature is equal to the pipe diameter, short radius elbow is typically installed in the limited situation and tight space, it will be giving the piping a sharper turn than a long radius elbow, However, it is a less cost option compared to LR elbow.
2D means bending radius is 2 times the nominal pipe size, in the same way, 3D means 2 times the nominal pipe size, they are long radius elbows as well, these long radius elbows not like 1.5D elbow frequently used, they are more smoother and used for specific applications.
Elbow Direction Angle
There are three common angles of elbow to use in piping system, 45 degree, 90 degree and 180 degree, these angle types are to turn fluid different into direction, including right angles and return angle, there are also other angles to use, like 60 degree and 180 degree.
45 Degree Elbow
45 degree elbow changes the flow direction to 45 degrees, it includes long radius 45 degree elbow and short radius 45 degree elbow.
90 Degree Elbow
90 degree elbow changes the flow direction to 90 degrees, it also has long radius and short radius types, 90 degree elbow is the most used elbow..
180 Degree Elbow
180 degree elbow changes the flow direction to 180 degrees.
Elbow Connection Style
According to connection style, elbow can be classified butt weld elbow, socket welded elbow and threaded elbow, butt weld elbow is commonly used type.
Butt Weld Elbow
Butt weld refers to connect pipes and fittings ends by butt welding method, it has ends in beveled to make it easy to weld, beveled ends should be conformed to requirement of ASME B16.25, plain end is offered upon request, BW elbow dimensions can be from 1/2” to 72”, BW weld elbow can be made of both seamless and welded pipe by the process of hot forming that includes bending and forming to shape.
Butt-weld fittings allow for a smooth, flush connection that provides maximum flow, is lower cost elbow, thin wall sizes can be allowed.
BW Elbow Dimensions
|NPS||OD||Center to End|
|All Dimensions to ASME B16.9, unit is in mm|
BW Elbow Weight Chart
|Approximate weights in kg, density 8 kg/dm3|
Dimensional Tolerances of Butt Weld Elbows
45° and 90° – LR and 3D elbow conform to ASME B16.9.
|Nominal Pipe Size||1/2 to 2.1/2||3 to 3.1/2||4||5 to 8|
at Bevel (D)
|Inside Diameter at End||0.8||1.6||1.6||1.6|
|Center to End LR (A/B)||2||2||2||2|
|Center to End 3D (A/B)||3||3||3||3|
|Nominal Pipe Size||10 to 18||20 to 24||26 to 30||32 to 48|
at Bevel (D)
|Inside Diameter at End||3.2||4.8||+ 6.4
|Center to End LR (A/B)||2||2||3||5|
|Center to End 3D (A/B)||3||3||6||6|
|Wall Thickness (t)||Not less than 87.5% of Nominal Wall Thickness|
Dimensional tolerances are in millimeters.
Socket Weld Elbow
Socket weld elbow has socket area at end of elbow, it can be inserted a pipe to connect together, the diameter of socket area is matching with the outer diameter of pipe.
Socket connect elbows are easier to weld than butt-weld elbows because the fitting doesn’t need to align perfectly to the pipe. Slip the pipe into the socket and weld, no beveled ends needed.
SW elbows also have 90 degree and 45 degree elbows for selecting, generally, SW elbow is used for small pipe diameter, and have three pressure ratings: Class 3000, 6000 and 9000.
Threaded elbow is similar to the SW elbow in shape, the difference is that threaded elbow has thread inside of elbow end, this type elbow is easier to install and remove, good for pipeline repair and maintenance.