Piping Elbows and Bends

Bend

A bend is simply a generic term in piping for an "offset" - a change in direction of the piping. It signifies that there is a "bend" i.e, a change in direction of the piping (usually for some specific reason) - but it lacks specific, engineering definition as to direction and degree. Bends are usually made by using a bending machine (hot bending and cold bending) on site and suited for a specific need. Use of bends are economic as it reduces number of expensive fittings. An elbow, on the other hand, is a specific, standard, engineered bend pre-fabricated as a spool piece (based on ASME B 16.9) and designed to either be screwed, flanged, or welded to the piping it is associated with. An elbow can be 45 degree or 90 degree. There can also be custom-designed elbows, although most are catagorized as either "short radius" or "long radius".

In short "All bends are elbows but all elbows are not bend"

Elbow

Whenever the term elbow is used, it must also carry the qualifiers of type (45 or 90 degree) are radius (short or long) - besides the nominal size.

Elbows can change direction to any angle as per requirement. An elbow angle can be defined as the angle by which the flow direction deviates from its original flowing direction. Even though an elbow angle can be anything greater than 0 but less or equal to 90° at a single point is not desirable. Normally, a 45° and a 90° elbow combinedly used while making piping layouts for such situations.

In order to find out the elbow angle at A, it is necessary to consider a plane which contains the arms of the elbow. If there had been no change in direction at point A, the pipe would have moved along line AD but pipe is moving along line AG. Plane AFGD contains lines AD and AG snd elbow angle (phi) is marked which denotes the angle by which the flow is deviating from its original direction.

Considering right angle triangle AGD, tan (phi) = v( x2 + z2)/y
Similarly elbow angle at G is given by : tan (phi1) = v (y2 +z2)/x

Elbow Radius:

Elbows or bends are available in various radii for a smooth change in direction which are expressed in terms of pipe nominal size expressed in inches. Elbows or bends are available in three radii,
a. Long radius elbows (Radius = 1.5D) : Used most frequently where there is a need to keep the frictional fluid pressure loss down to a minimum, there is sample space and volume to allow for a wider turn and generate less pressure drop.

b. Long radius elbows (Radius > 1.5D) : Used sometimes for specific applications for transporting high viscous fluids likes slurry, low polymer etc. For radius more than 1.5D pipe bends are usually used and these can be made to any radius. However, 3D & 5D pipe bends are most commonly used.

c. Short radius elbows (Radius - 1.0D) : to be used only in locations where space does not permit use of long radius elbow and there is a need to reduce the cost of elbows. In jacketed piping the short radius elbow is used for the core pipe.

Here D is nominal pipe size in inches.

There are three major parameters which dictates the radius selection for elbow. Space availability, cost and pressure drop.

Pipe bends are preferred where pressure drop is of a major consideration. Use of short radius elbows should be avoided as far as possible due to abrupt change in direction causing high pressure drop.

Minimum thickness requirement:

Whether an elbow or bend is used the minimum thickness requirement from code must be met. Code ASME B 31.3 provides equation for calculating minimum thickness required in finished form for a given internal design pressure

Bends and Elbows

Piping elbows and bends are widely regarded as significant parts of the piping systems and any kind of fluid conveyance. They are employed to alter the direction of either the liquid or gas in pipelines, and are important in the proper and safe routing of fluids. Here's a brief overview of piping elbows and bends:Here's a brief overview of piping elbows and bends:

Piping Elbows:

• Piping elbows are those curved fittings utilized to produce changes in the direction of the pipeline which is within a pipeline system.
• There are many types, yet the most frequently used ones are at an angle of 45 degrees and 90 degrees. There are also available other angles to fulfill the specific need.
• The described piping elbows can be manufactured from metals such as carbon steel, stainless steel, and alloys; plastics; and composites.
• Elbows are principally employed in situations when there is a requirement for the flow change by a specified angle such as turns, or for laying the pipes around something.
• They have variety; long radius elbows which have a more gradual curvature and short radius elbows which have more sharper curvature.
• Elbows are made to specification of the industry code to fit and give necessary performance in piping systems.

Piping Bends:

• Piping bends are quite like elbows in that they offer a means to change direction of flow but are more gradual than that of elbows.
• Understandably, bends can be utilized where there is a requirement for a gradual change of direction with the aim of reducing the turbulence of fluids and subsequent pressure drop.
• You can make bends out of many materials just like elbows and they are offered in several radial dimensions to suit a given design requirement.
• The term radius of a bend describe the degree of curvature of bend depending on the degree of curvature it can be categorized as long radius bend or short radius bend.
• Bends in most piping systems have to be specially made to the required angle and particular radius.
• Selecting and designing bends requires sufficient amount of attention because the bends can either make or break the effectiveness and safety of a piping system.

Consequently, piping elbows and bends are crucial elements in piping applications since they enable the alteration of the direction of the fluid flow as it passes through the pipes while at the same time meeting all the design criteria of the piping system. As a result, the decision of whether to use elbows or bends relies on the design parameters of the system and the necessary degree of fluid flow regulation and pressure loss in the pipeline. The choice and placement of the said components are important facets that define operational efficiency and reliability of the piping system.

Here is a table that summarizes the key differences between piping elbows and bends:Here is a table that summarizes the key differences between piping elbows and bends:

Piping elbows and bends are among the most useful pipe fittings and are contained in numerous piping systems. They provide a means through which pipes may be turned without necessarily bending or ‘kinking’ the pipe. This assist in avoiding leakages and other things that maybe associated along with it.

When selecting a piping elbow or bend for a particular application, it is important to consider the following factors:When selecting a piping elbow or bend for a particular application, it is important to consider the following factors:

• The type of fluid that will be flowing through the fitting: That is to say it is relative, some fluids are more sensitive to turbulence compared to others. For instance, products which are sensitive to flow such as pharmaceutical products and food products may need the use of a bend with a slow radius for minimal turbulent flow.
• The flow rate of the fluid: The operation flow rate will create an impact on the level of turbulence created through the fitting. When requiring higher flow rates it is better to employ a component with more appropriate radius of curvature that will not cause turbulence.
• The pressure drop: Thus the risk of pressure drop across the fitting depends with the radius of curvature of the fitting. Further, for the application where pressure drop is a constraint then it is required to employ a fitting having a larger value of radius of curvature.

Based on these aspects, one can be in a position to choose the right piping elbow/bend for his or her specific use.

Elbow piping

Elbow piping is a specific type of pipe fitting; its main application is to alter the direction of the pipe. Materials that can be used to manufacture elbow piping include; Steel, Stainless steel and PVC. Elbow piping is used in a variety of applications, including:Elbow piping is used in a variety of applications, including:

• Oil and gas industry: Elbow piping is applied to associated oil and gas through pipelines.

Elbow piping in oil and gas industry

• Chemical industry: Elbow piping is used to transport chemicals through pipelines.

Elbow piping in chemical industry

• Power generation: Elbow piping is used to transport steam and water through pipelines.

Elbow piping in power generation

• Food and beverage industry: Such pipes are used on elbows to pass food and beverages through pipelines.

Elbow piping in food and beverage industry

• HVAC industry: Elbow piping is used to transport air through pipelines.

Elbow piping in HVAC industry

Thus, elbow piping is an important accessory in most piping systems. It enables one to manipulate pipework where it would be inapplicable for the pipe to bend or kink. This helps to avoid seepage and the likes which in one way or the other causes damage.

The extent of preparation and installation of elbow piping should be done according to the recommended practices by the manufacturer. Since elbow piping is prone to leakages and direct collapse, it requires proper supports. In elbow piping, alignment is another factor that must be correct in order to avoid leakage or other related issues.

Here are some safety tips for working with elbow piping:Here are some safety tips for working with elbow piping:

• Furthermore, elbow piping should always be handled while wearing safety glasses and gloves.
• Understand to what pressure and temperature is the fluid going to be exposed, in the context of the elbow piping.
• Also, one must ensure that the elbow piping part is properly supported and aligned.
• When fixing, over tighten the bolts that connect the elbow piping with the pipes.
• Check the elbow piping to ensure that it requires replacement due to wear or is damaged in some manner.

Following these measures, you will be able to avoid such mishaps and occurrences of various injuries when handling elbow piping.

Difference between elbow and bend in piping

difference between bend and elbow in pipingin piping can be understood as those variants where the primary difference lies in the radius of curvature. An elbow will have a small radius of curvature as against bend which will have or may have a big radius of curvature.

As with the angles, the elbows are commonly employed in situations where there is a requirement of the change of direction. For instance, elbows are applied in pipelines for purposes of flow direction changes of the fluids.

Bends are usually applied where there is a requirement of the smooth transition from one plane to another. For instance, used in piping systems are bends which help in joining pipes of dissimilar sizes.

Here are some examples of applications where elbows and bends are commonly used:Here are some examples of applications where elbows and bends are commonly used:

• Elbows:
  • Some pipelines that alters the direction of flow of fluids
  • HVAC systems to reverse the flow of the air
  • Systems which are used to alter the direction of the flow of water in the e mainstream plumber.
• Bends:
  • Bend pipes to fit interconnect pipes of different sizes
  • HVAC systems to reverse the air circulation
  • Plumbing works to alter the movement of fluids in a given pipe network

Well, elbows are used where the turn need to be sudden and intensive while bends are used where the turn need to be smooth and gradual.

As a note, beside some differences the terms “elbow” and “bend” are often synonyms. However, it can be informative to differentiate between the two terms in order to make decisions concerning the function and usage of the different types of fittings in a specific application.

Piping bend

Pipe Bend is described as a fitting which is used to offer a change in direction in a piped line. Piping bends are normally being fabricated out of several types of metal and plastic materials such as steel, stainless steel, & PVC. Piping bends are used in a variety of applications, including:Piping bends are used in a variety of applications, including:

• Oil and gas industry: Piping bends are used for conveying oil, and/or gas through a pipeline.

Piping bend in oil and gas industry

• Chemical industry: Piping bends are used to transport chemicals through pipelines.

Piping bend in chemical industry

• Power generation: Piping bends are used to transport steam and water through pipelines.

Piping bend in power generation

• Food and beverage industry: Piping bends are used in handling foods and beverages through the pipelines.

Piping bend in food and beverage industry

• HVAC industry: Piping bends are used to transport air through pipelines.

Piping bend in HVAC industry

Bends are common elements used in most of the piping systems to assist in the delivering the fluid. They enable pipes to be turned one time, meaning that it is impossible to bend or kink the pipe. This does help to reduce leakages and other similar issues.

The variety of piping bends on offer currently may be categorized in the following manner with each having its own advantage and disadvantage; Some of the most common types of piping bends include:Some of the most common types of piping bends include:

• Sweep bends: Sweep bends differ from other types of bends in that the radius of curvature in sweep bends is not too sharp. This makes them less likely to disturb the fluid flow Within lists and if spinning fast a disc it is possible to create turbulence because the disc is actually rotating this applying centrifugal force to the the body of the fluids they are contain.

Sweep bend in piping

• Elbow bends: Elbow bends have a sharp radius of curvature. This makes them more likely to cause turbulence in the fluid flow. However, elbow bends are also more compact and easier to install than sweep bends.

Elbow bend in piping

• Long radius bends: Long radius bend pipe has a curving radius which measures more than the diameter of the pipe. They are less likely to disturb the movement of the fluid than the elbow bends are making the following a safer column profile than the bend one.

Long radius bend in piping

• Radiused bends: Sweep bends are bends with a relatively small curvature radius and greater than that of a radiused bend, but smaller than the long radius bends. This makes them a good Goldilocks of sweep bends and long radius bend since they can do the work of the two without compromising on the results.

Radiused bend in piping

When selecting a piping bend for a particular application, it is important to consider the following factors:When selecting a piping bend for a particular application, it is important to consider the following factors:

• The type of fluid that will be flowing through the bend: There are some types of fluids that become more sensitive to turbulence more than others. For instance, fragile substances as pharmaceuticals and foods may need to use sweep bends since turbulence is likely to harm the products.
• The flow rate of the fluid: Depending on the flow rate of the fluid, a certain amount of turbulence will be produced in the bend. Actually, for higher quantities of flow, it is better to utilize the bend that has the largest measured radius of curvature, because lower turbulence levels are achieved.
• The pressure drop: This means that layout of the bend and the radius of the curvature will determine the pressure drop across the bend. A decrease in pressure drop is possible when the curvature of the bend is larger, for this reason, it is advisable to apply in the process a bend with a greater radius of curvature.

Regarding the above factors, one should be able to choose the right piping bend for the specific application.

Here are some safety tips for working with piping bends:Here are some safety tips for working with piping bends:

• It is always recommended that one should wear safety glasses and preferably gloves any time he or she is handling piping bends.
• Know the pressure and temperature of the fluid that will be undergoing the piping bend.
• Ensure that location of the piping bend is adequately supported as well as is in correct position.
• However, should one be very keen on this aspect, then it is desirable not to over-screw the bolts that connect the piping bend with the pipes.
• The piping bend should also undergo regular check up for any signs of teasers or damages.
• If the following safety measures will be taken then you will be able to avoid the occurrence of accidents and injuries frequently while using the piping bends.

By following these safety tips, you can help to prevent accidents and injuries when working with piping bends.

Types of elbow in piping

As for piping systems, there are several types of elbows these are used for different purposes or changes the direction of the piping system in different measure. The type of elbow depends on qualities such as the need for angle change, space allowance and the extent to which pressure drop and turbulence are to be decreased. Here are some common types of elbows used in piping:Below is a list of typical elbow varieties that can be employed in piping:

Long Radius Elbow (LR Elbow):

• Long radius elbows have a curvature that provides a gentle change in direction.
• They are usually employed where it is necessary to change the direction of the flowing liquid gently, reducing the pressure drop and at the same time, the turbulence of the liquid downstream the bend.
• A long radius elbow, as the name indicates is an elbow pipe that has a longer radius, but the radius as far as practicality and standards are concerned lies between I and 1. Five sizes of the nominal pipe diameter.

Short Radius Elbow (SR Elbow):

• Short radius elbows are characterized by a curvier section as compared to the long radius elbows.
• They are used in cases where the application is in need of a tighter bend or due to the design requirements imposed.
• As mentioned before the nominal size of the short radius elbow is equal to the pipe diameter and so is the minimum radius of this type of elbow.

90-Degree Elbow:

• This type is the most common of all and is applied where one needs to be able to create a change of direction of ninety degrees in the pipe.
• Both, long radius and short radius versions are available for this equipment.

45-Degree Elbow:

• A 45-degree elbow is applied if the change in direction needs to be around 45 degrees on the pipeline.
• That’s why it is employed when a lower level of change is needed compared to a 90-degree elbow.

180-Degree Elbow:

• An elbow of 180-statute directs circulation in the complete opposite direction meaning that it’s an extreme turn.
• It is applied in situation where a pipeline requires a loop, in other words a 180 degree turn.

Threaded Elbow:

• Threaded elbows have threads at their ends, they are designed in such a way that they can easily be fitted on threaded pipes without having to weld them.
• They are applied mainly in such systems where the working pressure is low and the diameter of the pipe is small.

Socket Weld Elbow:

• Socket weld elbows are having socket on both ends for welding the pipes with the help of socket weld fittings.
• They are particularly employed in applications that involve high pressure and/or small bore piping.

Buttweld Elbow:

• Buttweld elbows are available in various types; they are connected to the pipes through butt-welding hence offering very strong and leak proof joints.
• They are employed in almost all types of piping services especially in high pressure and large diameter services.

Mitered Elbow:

• Mitered elbows are made of multiple pieces of pipe weld at a certain angle to make a particular angle of elbow.
• They are applied in position where standard elbow cannot give the necessary angle or radius.

Every kind of elbow has its unique utilization in piping systems and the utilization can simply depend upon the design and its uses of the particular system. Proper specification and application of elbows are very important attributes that can determine the efficiency of the piping system.