 |
Satish Lele lelepiping@gmail.com |
View this page as YouTube Video Presentation
These permit a change in direction of piping, a change in size of pipe, or a branch to be made from the main run of pipe. These are Elbows, Tees, Reducers, Caps. They are formed from plate or pipe, machined from forged blanks, cast, or
molded from plastics.
Screwed or socket-welding forged steel fittings are rated to the nominal cold non-shock working pressure of 2000, 3000 and 6000# (PSI).
Branching
There are different methods of branching. These are done by Stub-In, Weldolet, Elbolet, Latrolet, Sweepolet, Cross, Lateral, Shaped Nipple, Nipples.
Tees
Butt Weld Tee : Straight and reducing :These are used for making 90 Deg branching from the main run of pipe. Straight tees with branch same size as pipe are readily available. Reducing tees have branch smaller than the size of the pipe. These do not require reinforcing.
Stub In : It is the term for a branch of pipe welded directly into the side of a main pipe run. It is not a fitting. This is the commonest and least expensive method of welding a full size or reducing branch for pipe 50 mm NB and larger. A stub in can be reinforced.
Weldolet : It makes a 90 degree branch, full size or reducing on straight pipe. Closer manifolding is possible than with tees. Flat based weldolets are available for connecting to pipe caps and vessel heads.
Elbolet : It makes a reducing tangent branch on long radius and short radius elbows.
Latrolet : It makes a 45 degree reducing branch on a straight pipe.
Sweepolet : It makes a 90 deg reducing branch from the main run of pipe. Primarily developed for high yield pipe used in Oil & Gas transmission lines. Provides good flow pattern, and optimum stress distribution.
Cross Straight or Reducing : Straight crosses are usually stock items. Reducing crosses may not be readily available. For economy, availability and to minimize the number of items in inventory, it is preferred to use tees etc., and not crosses, except where space is restricted, as in marine piping or revamp work. Reinforcement is not needed for these.
Lateral Straight or Reducing : It permits odd-angled entry into the run of the pipe, where low resistance to flow is important. Straight laterals with branch bore equal to run bore are available in standard and XS weights. Reducing laterals and laterals at angles other than 45 degrees are usually available only to special order. Reinforcement is required where it is necessary to restore the strength of the joint, to the full strength of the pipe.
Nipples : These join unions, valves, strainers, fittings etc. Basically a short length of pipe either fully threaded (close nipple) or threaded both ends (TBE), or plain one end and threaded one end (PEO-TOE). Available in various lengths. Nipples can have grooved ends also.
Shaped Nipple : These are rarely used, but can be used for 90 deg and 45 deg or any other angle. The run is field cut using nipple as template. It needs reinforcement if it is necessary to bring the strength of the joint up to the full strength of the pipe.
Pipe to pipe connector : These are used to join threaded pipe to tube. Tube is flared inside the nut.
Tank Nipple : It is used for making a screwed connection to a non pressure vessel or tank in low pressure service. Overall length is usually 150 mm with a standard taper pipe thread at each end. On one end only, the taper pipe thread runs into a ANSI lock nut thread.
Elbows
These are of following types. Long Radius and Short Radius Elbows, Reducing Elbows, Long Radius Tangent Elbow, Returns, Bends, Mitered Elbows.
Long Radius and Short Radius Elbows : These make 90 degree and 45 degree changes in direction of the run of pipe. The elbows normally used are Long Radius (LR) with centerline radius of curvature equal to 1.5 times the nominal pipe size for 20 NB and larger sizes. Short Radius (SR) elbows with centerline radius of curvature equal to the nominal pipe size are also available. 90 deg long radius elbows with a straight extension at one end (Long Tangent) are also available.
Reducing Elbows : These are designed both to change direction and reduce pipe size. These have centerline radius of 1.5 times the nominal size of larger end. Their use eliminates one fitting (reducer) and reduces welding by one third. The gradual reduction in diameter through the arc of reducing elbow provides maximum flow efficiently, reduces turbulence and erosion and helps in maintaining pressure.
Long Radius Tangent Elbow : These are special elbows that provide a straight length at the end to accommodate a slip on flange.
Return : It changes the flow of direction in 180 deg and is used to make heating coils, vents on tanks etc.
Bends : These are made from straight pipe. Common bending radii are 3 and 5 times the pipe size. Larger radius bends can be made by hot bending. Only seamless or ERW pipe is used for bends.
Mitered Elbows : These are fabricated as required from the pipe and these are not fittings. The miters are used for pipes 200 NB and larger where pressure drop is not important and where the regular elbows are costlier. A 2-piece 90 deg miter has 4 to 6 times hydraulic resistance of the corresponding long radius elbow. A 3-piece 90 deg miter has about double the resistance. 3, 4 and 5-piece miters are normally used.
Reducers
Reducers are used to change the size of the pipeline. These are of two types.
Concentric Reducers : The centerline of inlet and outlet is at same level. It is generally used in vertical pipes.
Eccentric Reducers : The eccentric reducer is used when it is necessary to keep either the top or bottom of the line level. These are used with flat side up or down. Flat side down is used in horizontal pipes. Flat side up is used for pump suction line.
Swage
These are of three types. Concentric, eccentric and ventury type. Swage is used to connect butt welded piping to smaller screwed or socket welded pipe. In butt weld pipes it is used when greater reduction is required. Swages are of three types.
Concentric Swage : The centerline of inlet and outlet is at same level. It is generally used in vertical pipes.
Eccentric Swage : The eccentric swage is used when it is necessary to keep either the top or bottom of the line level. These are used with flat side up or down. Flat side down is used in horizontal pipes. Flat side up is used for pump suction line.
Ventury : Ventury type swage gives a smooth flow.
Cap
Caps are used to seal the end of pipe. These are ellipsoidal in nature.
Flat Closure : These are flat plates normally cut from pipe at site.
Dished Heads : These are used for large diameter pipes.
Socket Weld Fittings
Full Coupling : It is also termed as coupling and it joins pipe to pipe, or to nipple, swage etc.
Half Coupling : It is used to make side branching on large diameter pipes or vessels. It is of the same length of full coupling but has socket weld end on only one side. Shaping is necessary for the end.
Reducer : It joins two pipes with different diameters.
Cross : These are used in exceptional cases where two tees cannot be fitted. Mostly used in marine piping or during modifications.
Sockolet : It makes a 90 degree branch, full size or reducing on a straight pipe.
Elbolet : It makes a reducing tangent branch on elbows.
Swaged Nipple : It is similar to swage. These can allow two types of joining. Socket ended items of different sizes which has plain ends on either sides for insertion into socket ends. A socket ended item to a larger butt welding pipe or fitting. This type has larger butt-weld end and smaller socket weld end.
Elbows : These change pipe direction in 90 deg and 45 deg from the run of the pipe. The ends are socket weld type.
Screwed Fittings
Full Coupling : It is also termed as coupling and it joins pipe or items to with threaded ends.
Half Coupling : It is used to make 90 deg screwed connections for pipes to instruments, or for vessel nozzles. Welding heat may cause embrittlement of the threads of this short fitting.
Reducer or reducing coupling : It joins threaded pipes with different diameters. Can be made in any reduction by boring and tapping standard forged blanks.
Cross : These are used in exceptional cases where two tees cannot be fitted. Mostly used in marine piping or during modifications.
Threadolet : It makes a 90 deg branch, full size or reducing on a straight pipe.
Elbolet : It makes a reducing tangent branch on elbows.
Nipples : These join unions, valves, strainers, fittings etc., Basically a short length pipe with that have screwed ends.
Swaged Nipple : It is similar to swage. These can allow two types of joining. Screwed items of different sizes which has screwed ends on either sides. A screwed item to a larger butt welding pipe or fitting or vice versa.
Elbows : These change pipe direction in 90 deg and 45 deg from the run of the pipe. The ends are threaded internally.
Flange : This is similar to slip on flange, but has internal threads.
Latrolet : It makes a 45 deg reducing branch on straight pipe. It is welded on pipe.
Nipolet : A variant of threadolet, having integral plain nipples. Primarily developed for small valved connections.
Stub In : Not recommended for pipes with diameter less than 50 mm, due to risk of weld material entering line and restricting flow.
Bar Stock Plug : It seals the screwed end of a fitting. Also termed as round head plug.
Screwed or socket-welding forged steel fittings are rated to the nominal cold non-shock working pressure of 2000, 3000 and 6000# (PSI).
Stub In : It is the term for a branch of pipe welded directly into the side of a main pipe run. It is not a fitting. This is the commonest and least expensive method of welding a full size or reducing branch for pipe 50 mm NB and larger. A stub in can be reinforced.
Weldolet : It makes a 90 degree branch, full size or reducing on straight pipe. Closer manifolding is possible than with tees. Flat based weldolets are available for connecting to pipe caps and vessel heads.
Elbolet : It makes a reducing tangent branch on long radius and short radius elbows.
Latrolet : It makes a 45 degree reducing branch on a straight pipe.
Sweepolet : It makes a 90 deg reducing branch from the main run of pipe. Primarily developed for high yield pipe used in Oil & Gas transmission lines. Provides good flow pattern, and optimum stress distribution.
Cross Straight or Reducing : Straight crosses are usually stock items. Reducing crosses may not be readily available. For economy, availability and to minimize the number of items in inventory, it is preferred to use tees etc., and not crosses, except where space is restricted, as in marine piping or revamp work. Reinforcement is not needed for these.
Lateral Straight or Reducing : It permits odd-angled entry into the run of the pipe, where low resistance to flow is important. Straight laterals with branch bore equal to run bore are available in standard and XS weights. Reducing laterals and laterals at angles other than 45 degrees are usually available only to special order. Reinforcement is required where it is necessary to restore the strength of the joint, to the full strength of the pipe.
Nipples : These join unions, valves, strainers, fittings etc. Basically a short length of pipe either fully threaded (close nipple) or threaded both ends (TBE), or plain one end and threaded one end (PEO-TOE). Available in various lengths. Nipples can have grooved ends also.
Shaped Nipple : These are rarely used, but can be used for 90 deg and 45 deg or any other angle. The run is field cut using nipple as template. It needs reinforcement if it is necessary to bring the strength of the joint up to the full strength of the pipe.
Pipe to pipe connector : These are used to join threaded pipe to tube. Tube is flared inside the nut.
Tank Nipple : It is used for making a screwed connection to a non pressure vessel or tank in low pressure service. Overall length is usually 150 mm with a standard taper pipe thread at each end. On one end only, the taper pipe thread runs into a ANSI lock nut thread.
Long Radius and Short Radius Elbows : These make 90 degree and 45 degree changes in direction of the run of pipe. The elbows normally used are Long Radius (LR) with centerline radius of curvature equal to 1.5 times the nominal pipe size for 20 NB and larger sizes. Short Radius (SR) elbows with centerline radius of curvature equal to the nominal pipe size are also available. 90 deg long radius elbows with a straight extension at one end (Long Tangent) are also available.
Reducing Elbows : These are designed both to change direction and reduce pipe size. These have centerline radius of 1.5 times the nominal size of larger end. Their use eliminates one fitting (reducer) and reduces welding by one third. The gradual reduction in diameter through the arc of reducing elbow provides maximum flow efficiently, reduces turbulence and erosion and helps in maintaining pressure.
Long Radius Tangent Elbow : These are special elbows that provide a straight length at the end to accommodate a slip on flange.
Return : It changes the flow of direction in 180 deg and is used to make heating coils, vents on tanks etc.
Bends : These are made from straight pipe. Common bending radii are 3 and 5 times the pipe size. Larger radius bends can be made by hot bending. Only seamless or ERW pipe is used for bends.
Mitered Elbows : These are fabricated as required from the pipe and these are not fittings. The miters are used for pipes 200 NB and larger where pressure drop is not important and where the regular elbows are costlier. A 2-piece 90 deg miter has 4 to 6 times hydraulic resistance of the corresponding long radius elbow. A 3-piece 90 deg miter has about double the resistance. 3, 4 and 5-piece miters are normally used.
Concentric Reducers : The centerline of inlet and outlet is at same level. It is generally used in vertical pipes.
Eccentric Reducers : The eccentric reducer is used when it is necessary to keep either the top or bottom of the line level. These are used with flat side up or down. Flat side down is used in horizontal pipes. Flat side up is used for pump suction line.
Concentric Swage : The centerline of inlet and outlet is at same level. It is generally used in vertical pipes.
Eccentric Swage : The eccentric swage is used when it is necessary to keep either the top or bottom of the line level. These are used with flat side up or down. Flat side down is used in horizontal pipes. Flat side up is used for pump suction line.
Ventury : Ventury type swage gives a smooth flow.
Flat Closure : These are flat plates normally cut from pipe at site.
Dished Heads : These are used for large diameter pipes.
Half Coupling : It is used to make side branching on large diameter pipes or vessels. It is of the same length of full coupling but has socket weld end on only one side. Shaping is necessary for the end.
Reducer : It joins two pipes with different diameters.
Cross : These are used in exceptional cases where two tees cannot be fitted. Mostly used in marine piping or during modifications.
Sockolet : It makes a 90 degree branch, full size or reducing on a straight pipe.
Elbolet : It makes a reducing tangent branch on elbows.
Swaged Nipple : It is similar to swage. These can allow two types of joining. Socket ended items of different sizes which has plain ends on either sides for insertion into socket ends. A socket ended item to a larger butt welding pipe or fitting. This type has larger butt-weld end and smaller socket weld end.
Elbows : These change pipe direction in 90 deg and 45 deg from the run of the pipe. The ends are socket weld type.
- Latrolet : It makes a 45 degree reducing branch on straight pipe.
- Nipolet : A varient of sockolet, having integral plain nipples. Primarily developed for small valved connections.
- Stub In : Not recommended for pipes with diameter less than 50 mm, due to risk of weld material entering line and restricting flow.
- Lateral : It makes full size 45 degree branch from the main run of the pipe.
Half Coupling : It is used to make 90 deg screwed connections for pipes to instruments, or for vessel nozzles. Welding heat may cause embrittlement of the threads of this short fitting.
Reducer or reducing coupling : It joins threaded pipes with different diameters. Can be made in any reduction by boring and tapping standard forged blanks.
Cross : These are used in exceptional cases where two tees cannot be fitted. Mostly used in marine piping or during modifications.
Threadolet : It makes a 90 deg branch, full size or reducing on a straight pipe.
Elbolet : It makes a reducing tangent branch on elbows.
Nipples : These join unions, valves, strainers, fittings etc., Basically a short length pipe with that have screwed ends.
Swaged Nipple : It is similar to swage. These can allow two types of joining. Screwed items of different sizes which has screwed ends on either sides. A screwed item to a larger butt welding pipe or fitting or vice versa.
Elbows : These change pipe direction in 90 deg and 45 deg from the run of the pipe. The ends are threaded internally.
Flange : This is similar to slip on flange, but has internal threads.
Latrolet : It makes a 45 deg reducing branch on straight pipe. It is welded on pipe.
Nipolet : A variant of threadolet, having integral plain nipples. Primarily developed for small valved connections.
Stub In : Not recommended for pipes with diameter less than 50 mm, due to risk of weld material entering line and restricting flow.
Bar Stock Plug : It seals the screwed end of a fitting. Also termed as round head plug.
