Butt weld fittings are to connect pipes or fittings ends by welding. It’s a weldable steel pipe fitting that would allow to branch off, allow for change of direction of flow, attach auxiliary equipment, or reduce the size of the pipe.
In the case of forged steel butt weld fittings, you would find them to be manufactured according to ANSI/ASME B16.9. Also known by welded pipe fittings Butt weld fittings would also be referred to as welded pipe fittings. When these would be used in stainless steel and carbon steel, they would be able to offer certain advantages as compared to socket weld and threaded fittings. Whereas socket weld would only be available up to a specific size, you would find butt weld fittings to be available in sizes starting 1/2 inch to 72 inch.
Like general category of pipe fittings, Butt weld pipe fittings includes: Butt weld Elbow in 45 degree or 90 degree Butt weld Tee and Reducing Tee, Reducer, Cap, Cross
Types OF Buttweld Fittings
Pipe elbows Steel elbow is used to be installed between two lengths of pipe or tube allowing a change of direction,usually these carbon steel elbows distinguished by connection ends.
PIPE ELBOW DIMENSIONS AND SHAPES
Pipe elbows are manufactured in a wide range of dimensions (combinations of outside diameter and wall thickness, i.e. pipe schedule, following the ASME B36.10 and ASME B36.19 sizes specifications for carbon/alloy and stainless steel pipes) to fit the needs of pipelines of sizes from 1 to 80 inches and above (consult the elbows size chart for details). Generally, steel elbows below 24 inches in diameter are produced by cutting and bending seamless steel pipes, and pipe elbows of larger sizes are manufactured using welded pipes or steel plates as feedstock.
The three most common shapes for pipe elbows are the 45, 90, and 180 degrees (or return elbow), as shown in the image:
Some special types of steel elbows are:
reducing elbow: a pipe connector with an inlet and an outlet in two different bore sizes is used instead of the combination of a standard elbow and concentric reducer.
mitered elbow: large size elbow assembled by joining steel plates
DIFFERENCE BETWEEN SHORT AND LONG RADIUS PIPE ELBOW
The center to face distance of a long radius pipe elbow (see “B” in the image below) is always 1.5 times the nominal pipe size, whereas, for a short radius pipe elbow, the center to face distance (see “A” in the image) is equal to the nominal pipe size.
Example:
For a 4 inches long radius (LR) butt weld elbow, the center to face distance is 4 x 25.4 x 1.5 = 152.4 mm;
For a short radius butt weld elbow, the center to face distance is instead 4 x 25.4 x 1 = 101.6 mm. Short radius pipe elbows are available only for the 90 and 180-degree configuration (and not for the 45 degrees); instead, long radius elbows are available for all degrees.
PIPE ELBOW MATERIAL GRADES
The typical material grades for butt weld elbows are carbon steel (ASTM A234 WPA/WPB/WPC), alloy steel for power generation (ASTM A234 WP9/WP91 and other low-alloy grades), stainless steel (ASTM A403 WP304/WP 316 and so on) and, duplex/super duplex (ASTM A815 UNS S31803 and UNS S32750/32760). Nickel alloys like Inconel, Hastelloy, Incoloy are also used to manufacture pipe elbows.
Carbon steel elbows ASTM A234 WPB, WPC – chemical composition:
Grade
C
Mn
P
S
Si
Cr
Mo
Ni
Cu
V
Nb
WPB
0.3
0.29-1.06
0.05
0.058
0.1min
0.4
0.15
0.4
0.4
0.08
0.02
WPC
0.35
0.29-1.06
0.05
0.058
0.1min
0.4
0.15
0.4
0.4
0.08
0.02
Stainless steel elbows ASTM A403 304, 316 – chemical composition:
Grade
C
Mn
P
S
Si
Ni
Cr
Mo
WP 304
0.08
2
0.045
0.03
1
8.0-11.0
18.0-20.0
–
WP 304L
0.035
2
0.045
0.03
1
8.0-13.0
18.0-20.0
–
WP 316
0.08
2
0.045
0.03
1
10.0-14.0
16.0-18.0
2.00-3.00
WP 316L
0.035
2
0.045
0.03
1
10.0-16.0
16.0-18.0
2.00-3.00
Pipe bending Pipe bend can be made of variety materials,like carbon steel,alloy steel,stainless steel,low temperature steel or high performance steel,etc. Pipe Tees We can provide seamless tube tees and welding tube tees, which can also be divided into straight tees and reducing tees.Usually, the pipe tees have the same inlet and oulet sizes.
There are three main types of pipe tee, equal, reducing, and barred:
EQUAL TEE (STRAIGHT TEE)
An equal tee, otherwise called straight tee, is a butt weld fitting used to branch a pipeline, or any other pipework, at 90 degrees.
A pipe tee is defined “equal” when the bore size at the run and branch sides have the same diameter. An equal tee is therefore used to connect two pipes of the same nominal diameter. To order an equal tee, it is sufficient to provide the nominal diameter, the schedule and the material grade of the pipe tee fitting (sizes should match, of course, the dimension of the connecting pipes).
Equal tees are available in sizes from half an inch to 48 inches (or larger) and in seamless and welded execution (seamless up to 24 inches, welded for tee sizes above 24 inches).
Butt weld tees are manufactured according to ASME B16.9 (carbon and alloy) and MSS SP 43 (stainless steel and nickel alloy). For more information about the materials for steel tees, refer to this article.
REDUCING TEE
A reducing tee features a smaller bore size at the branched pipe side (generally 2/3 sizes smaller). In case a larger bore size reduction is necessary, then a reinforced branch connection (such as a Weldolet) should be preferred to prevent turbulence and have a smoother flow reduction.
The standard dimensions and tolerances of equal and reducing pipe tees are defined by the ASME B16.19 specification (carbon and alloy steel) and by the MSS SP 43 spec (for stainless steel and nickel alloys tees).
BARRED TEE
A barred tee is a special type of equal tee used for pigged pipelines (reducing barred tees do not exist, as the pig would not pass through the reduced area anyways). A barred tee features a welded restriction on the branch pipe side that prevents the pig from flowing from the run pipe into the branched pipe.
Such barred restriction is welded on the internal side of the fitting and looks like a steel cage.
Pipe cross A pipe fitting, having four openings in the same place, at right angles to each other. A pipe cross is a kind of pipe fitting. It is used in the place where four pipes meet together. The pipe cross may have one inlet and three outlets, or there inlets and one outlet. End caps End Cap, Carbon Steel cap, Stainless Steel Caps, ANSI, ISO, JIS and DIN Standards, Measures 1/2 to 56 Inches. Based on different materials, pipe caps include carbon steel cap, stainless steel cap, and alloy steel cap etc. Pipe reducer Pipe reducer are tube fittings that are widely used in a number of industries in order to providing greatest connection flexibility in connecting fractional tubes in various installations.
CONCENTRIC REDUCER
The open ends of a concentric reducer are aligned and centered one to the other. Generally, this type of pipe reducer is used to modify the bore size of the pipeline by two (maximum three) measures, to avoid an excessive pressure drop in the pipeline.
If the required size reduction is larger, a cascade of butt weld fittings (multiple pipe reducers in sequence) has to be used to have a smooth and gradual adjustment of the flow capacity of the pipeline.
ECCENTRIC REDUCER
The open ends of an eccentric reducer are in an “offset” position one to the other. Eccentric reducers are used, generally, for pipelines installed in a horizontal position (whereas concentric reducers are used for pipelines installed vertically or for the inlets of suction pumps, as top flat eccentric reducers).
TOP AND BOTTOM FLAT ECCENTRIC REDUCER
Eccentric reducers can be top flat (“TF”) or bottom flat (“BF”). The bottom flat eccentric reducer type is used for pipe-racks (the bottom of the reducer is flat and at the same level of the bigger sized run pipe), while the top flat pipe reducer type is used at the inlet of piping suction pumps as shown in the image below (this setup prevents the formation of vapor traps in the pipeline):
CONCENTRIC VS ECCENTRIC REDUCER
The key difference between concentric vs eccentric reducer is the centricity of the inlet vs. the outlet of the fitting, which is perfect for a concentric reducer and offset of an eccentric reducer.
Stub end Stub Ends are fittings used in place of welded flanges where rotating back up flanges are desired. They are also called Lap Joints and Vanstone Flared Laps. A rotating back up flange seats itself against the back surface of the Stub End.
A stub end suits the following applications:
All cases that require a rotating back flange to facilitate the bolting activities;
High-grade pipelines (stainless steel upwards): the use of stub ends reduces the overall weight of expensive materials in high-grade piping and therefore reduce the overall cost of the flanged connections (savings can be substantial for large diameter or long pipelines). For example, in a stainless steel 316 piping system, the contractor may use stainless steel stud ends (and weld them to the pipes) and carbon steel lap joint flanges (indeed the flange just supports the connection but does not come into contact with the fluid conveyed by the pipeline
It has to be noted that stud ends are becoming popular also in high-pressure applications (whereas they were used for low-pressure applications only in the past).
STUB END TYPES
Stub ends are available in three different types, named “Type A”, “Type B” and “Type C”:
The first type (A) is manufactured and machined to match standard lap joint backing flange (the two products have to be used in combination). The mating surfaces have an identical profile to permit a smooth loading of the flare face
Stub ends type B are have to be used with standard slip-on flanges
Type C stub ends can be used either with lap joint or slip-on flanges and are manufactured from pipes
ASA AND MSS STUB END
Stub ends are available in two different patterns:
the short pattern, called MSS-A stub ends
the long pattern, called ASA-A stub ends
STUB END FINISH
Stub ends can be ordered with different ends finishing:
Beveled Ends
Squared Ends
Flanged Ends
Grooved Ends
Threaded Ends (Male Only)
Coupling Fittings Coupling fittings are used for fluid conduits in which each end portion of two tubes to be connected is provided with a swaged-on adapter carrying the necessary means to connect or disconnect the tubes without disturbing the swaged-on adapter.
PIPE FITTINGS DIMENSIONS AND MATERIALS
Butt weld fittings are manufactured in a wide range of dimensions (combinations of outside diameter and wall thickness, i.e. schedule) and material grades (the most common are ASTM A234 WPB for carbon steel/alloy steel, ASTM A403 WP304 and WP316 for stainless steel wrought fittings, ASTM A815 for duplex and super duplex fittings).
Carbon steel fittings are common for pipelines and process piping applications in the oil and gas and power generation industry, stainless steel fittings are for applications where corrosion and erosion are a key issue (desalination, pharmaceutical and, food sectors).
