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Pipe Fittings


Pipe fittings are of different types.
1 )Elbows:
Used for change in direction of pipe routing.
(a)They are of 2 types
45° Elbow which can be
Short Radius Elbow, R = 1D
Long Radius Elbow, R = 1.5D
90° Elbow which can be
Short Radius Elbow, R = 1D
Long Radius Elbow, R = 1.5D
(b)According to end connection elbows can be classified as
Socket Weld : for size upto 1½’’
Butt Weld : for size greater than 1½’’ ( > 2’’ in *)
Threaded : for size upto 1½’’ in G.I. Pipes
(c)Dimensional standard
For socket weld & threaded elbows : ANSI/ASME B16.11
For bevelled end elbows : ANSI/ASME B 16.9
Thickness for beveled end fittings = Thickness of pipe
Thickness for 3000# socket weld elbows = Schedule 80 of respective pipe size.
Thickness for 6000# socket weld elbows = Schedule 160 of respective pipe size.
Thickness for 9000# socket weld elbows = Schedule XXS of respective pipe size.
(d)Pressure class for socket weld & threaded pipe fitting
It is as follows:
2000 psi or 2000 rating – used only for threaded pipe fittings
3000 psi – used only for Socket Weld pipe fitting & threaded pipe fittings 6000psi – used only for socket weld pipe fitting & threaded pipe fittings
9000psi – used only for socket weld pipe fitting & threaded pipe fittings
Socket weld and threaded pipefitting are manufactured from following forged materials
Carbon steel – ASTM A 105
Low temperature carbon steel- ASTM A 350 Gr. LF2
Low alloy steel – ASTM A 182 Gr. F11(generally used), F1, F6, F9
Stainless steel – ASTM A 182 Gr. F 304, F304L, F316, F316L, F321
Butt weld pipe fittings are manufactured from pipes
Carbon steel – ASTM A 234 Gr. WPB
Low temperature carbon steel – ASTM A 420 Gr. WPL6
Low alloy steel – ASTM A 234 Gr. WP11/WP22/WP9
Stainless steel – ASTM A 403 WP/304, 304L, 316, 316L, 321
2) Tee:
Used for taking a branch.Tee can be
Equal/straight tee – All 3 sizes are equal
Unequal/reduced tee – Branch size is always smaller
Points (b), (c), (d) and (e) are same as elbows
3 )Half coupling:
Used to take a branch upto 1½’’ size.
End connections are socket weld & threaded
Used in pipe class upto 300 rating
Points (c), (d), (e) same as elbow

4 )Reducer/expander:
Used when change in pipe size is there.
Type – Concentric Reducer – Butt Weld
Eccentric Reducer – Butt Weld
In case of Eccentric Reducer one side is tapered while the other side is straight. Here the difference in elevation of the axis exists leading to eccentricity. Its construction is like a trapezoid.
In case of Concentric Reducer both sides are tapered and the axis is also the same. Its construction is like a cone.

For E.g. if the Header Side is 6’’ then 6/2 = 3 and hence the next lower size possible is 2½’’.Hence it can be seen that reduction from 6’’ to 2½’’ is possible. Further reduction beyond 2 ½’’ is not possible. Reducers can be manufactured in small size.
Dimension standard: ANSI/ASME B16.9
Thickness is same as the pipe thickness.
Material: Same as BW elbows
5)Full coupling:
Used for pipe to pipe joint of small bore (upto1½’’)
End connections are socket weld & threaded
Dimensional standard, material and pressure class same as half coupling
6 )Weldolet:
Used to take butt weld branch for which reducing tee is not possible
Used in high pressure, high temperature pipe class from 900 rating
Dimension standard:
Header and branch size with thickness is to be specified
Forged same as elbow / half coupling
7) Sockolets:
Same as weldolet except there is a Socket weld end at branch side.
8) Caps:
Used at the end of the line for the termination of the line.
End connection: The end connections are
Socket weld }
Threaded end } Up to 1 ½”
Butt weld Above 2”
Dimension standard:
ANSI/ASME B 16.11 For SW & Threaded End
Thickness for BW caps same as thickness of pipe.
Material:Same as elbow

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