Types of tube bending depend on several factors such as quality of the material, weldability of the material, and the application purpose of the tube. Tube bending is considered a critical science. There are numerous approaches to attain desirable results.
Let’s learn about the common types of Metal pipes or Tube Bending.
Mandrel Bending Technique:
This technique is an age-old method of tube bending. It is used industrywide for numerous applications. In this method, the external wall of the pipe or tube bends, tightening the bend radius of the tube. The Mandrel is essential to prevent the tube from flattening out when pressure is applied to bend the tube. This method is utilized by the automotive, exercise equipment, and aerospace industries.
Press Bending Method:
This is one of the oldest methods used to bend tubes. It requires a bend die. The Press Bending method does not provide exact precision. Pipes bent using this technique lack internal support and are vulnerable to deformities.
Rotary Draw Technique:
This is a fairly advanced technique. The rotary draw machine is used to carry out the process of tube bending. It bends the tubes across a series of dying with constantly maintained radii. It provides detailed results. It is used for intricately detailed work like making roll cages and handrails.
Roll Bending Method:
The roll Bending method requires a particular type of machinery with three rollers known as a “jig”. It can bend metal pipes, tubes, sheets. The jig plays a vital role in bending the metal. The metal moves back and forth on the rollers until the desired shape is acquired.
Electric Tube Benders:
The Electric tube benders are used for automotive industrial applications. They are used for large-scale bending as they are powerful. These machines are highly suitable for complex bending and high volume bending.
Heavy Duty Bending:
These benders are used for specific applications. An application that demands heavy-duty benders cannot compromise with a lighter bender. These benders are the best in the market. They can bend the toughest materials and work with precision even in demanding applications. They have the perfect properties of extreme power and precision. They are often used for heavy industries like automotive, shipbuilding, aerospace, etc.
Left & Right Benders:
These benders are the most appropriate choice for multitasking. They use an amalgamation of tools and process bending of tubes in various directions. They can repeat the process endlessly. They can tackle complex processes. It is highly suitable for complex and high-volume applications.
9 facts about 5D bends
Pipe bends are used in many industries, including chemical, oil and gas, electric, metallurgy and shipbuilding. Pipe bends function as structural passageways to facilitate the transfer of substances, such as water and fuel. Some have a short radius while others have a long radius. Long radius bends give less frictional resistance and allow for less pressure drop when compared to short radius bends. When selecting the type of pipe bend, it’s important to choose one that is compatible to the application.
The Radii of Bend Pipes
Bend pipes come in all types of radii, including 3D bends, 4D bends, 5D bends, 8D bends and 10D bends. The radius in 5D bends is five times the nominal diameter. With a 10-inch diameter pipe, the radius of the centerline of the bend would be 50 inches. Pipe bending for the specified radii is both art and science. And with today’s modern machines and advanced software, pipe bending is highly precise. With the right machine, lubrication, tooling and material, achieving the perfect bend is a sure thing.
The Differences Between Bends and Elbows
Although the words bends and elbows are often used as synonyms, there are some differences. Bend is a term for any offset of direction in the piping while elbow is an engineering term. Elbows have limitations to angle, bend radius and size. Most angles are either 45 degrees or 90 degrees. All other offsets are specifically pipe bends. And while elbows have sharp corners, bends never do. The most basic different between a bend and an elbow is the radius of curvature. Bends have a radius more than twice the diameter, and elbows have a radius of curvature between one and two times the size of the pipe’s diameter. All elbows are bends, but not all bends are elbows.
Induction Bending for Creating 5D Bends
Induction bending is one of the means of bending pipes for 5D and other bends. Local heating, using high-frequency induced electrical power, is applied. An induction coil is placed around the pipe and heats a circumferential area of the pipe at a temperature between 850 to 1100 degrees Celsius. When the right temperature is reached, the pipe moves through an induction coil while an arm applies the bending force. There are many benefits to induction bending. It allows for large radii for smooth flow of fluid, reduces the number of welds in a system and fabricates bends quickly. With faster production, efficiency is ramped up. It’s also a clean process, as no lubrication is needed, and water is recycled.
Ram-type bending is an old and effective bending method for bending pipes, including 4D bends and 5D bends. This method is often used in muffler shops. It’s also one of the least expensive ways to bend pipe. A hydraulically driven ram forces the pipe against pivot blocks or rollers. Often, a ram tool is used to produce a concave surface and to prevent stretching on the exterior of the bend. The only downside is that ram-type bending is not as controllable as other methods.
Roll bending is commonly used for pipes in the construction industry. Rolls are positioned vertically or horizontally to produce very large radii. The pinch-style roll bender is one of the machine types used for roll bending. A tube feeds between the lower and upper roll to produce the wanted bend angle. Some applications may require an additional roll to guide the tube outward when the coil is being formed.
The mandrel bending pipe method is effective when the least amount of deformation is desired. The pipe is supported with a mandrel support to bend the pipe. The pipe is drawn through a counter bending die for further bending. This method of pipe bending is used in the manufacture of heat exchanger tubing, dairy tubing and exhausts like turbocharger and custom made ones. This method produces a non-deformed diameter every time.
Rotary Draw Bending
Rotary draw bending is often used for bending pipe when a constant diameter and good finish are desired. The pipe is drawn through a stationary counter-bending die onto a fixed radius former die. It’s used for roll cages, stock car chassis and other types of pipes.
Centerline Radius, Outside Diameter and Wall Thickness
Centerline radius, outside diameter and wall thickness are important variables with bending pipe methods. Plus, every pipe schedule has a nominal wall thickness. And since wall thickness can vary, any variations need to be accounted for. Other bending variables include the neutral line, outside bend radius and inside bend radius. Pipes experience spring back after bending. The harder the pipe and small the bend’s centerline radius, the more spring back, which results in radial growth. Copper pipes have less radial growth than steel pipe due to its less spring back. In pipe bending, consistency, size and quality of the weld seam matter for centerline radius, outside diameter and wall thickness. When these are right, the perfect bend can be created.
Material Used for 5D Bends, 6D Bends and Others
Common materials used for pipes and pipe bends include carbon, stainless steel, titanium, aluminum and cast iron. There are also plastic pipes of various grades. It’s important to select the right material for the right application, including the pipe fittings. Pipe fitting materials include aluminum, brass, bronze, cast iron, vitrified clay and many others. Pipe fittings must satisfy many criteria. The materials must be compatible with the fluids being transported, different pressure levels and fluctuating temperatures. Materials should also conform to certain standards like DIN, ASME, NPT and BSP. Surface finish is also important, and pipe fittings should have a corrosion-resistant property.
In some fields, the schedule 40 and schedule 80 are used for pipes. However, there are many other schedules due to increased pressure demands. The schedule of a pipe refers to its pressure rating. The higher the schedule, the higher pressure it can have. As the schedule increases, the wall thickness increases. When choosing pipe bends, it is critical to consider the schedule of the pipe. Schedule 80 is often used for heavy-duty while schedule 40 is often used for light-duty. Be sure to choose the appropriate schedule for the pipe bend, and it will be a perfect match.
3D bends are used are in 10 applications
In any project using metal pipes, there are likely to be a few places where the pipe has to go around a corner, or has to be bent to follow a certain contour. In many cases, with proper planning and a good design, these bends can be made using pre-fabricated elbows, which come in popular angles like 45 or 90 degrees and several common bend radii, typically referred to as either short or long-radius bends.
The word “tube” refers to round, square, rectangular, and oval hollow sections used for pressure equipment, for mechanical applications, and for instrumentation systems.
Tubes are designated by their outside diameter and wall thickness, which are exact measures in inches or millimeters. For tubes, the difference between the outside diameter and the wall thickness, multiplied by two, defines the inside diameter of the tube.
The most important physical properties of steel tubes are the hardness, the tensile strength, and low manufacturing tolerances.
Tubes are indicated with outer diameter and wall thickness, in inches or in millimeters.
Sometimes, however, a custom bend will be required to make the pipe fit precisely around an obstacle or to follow a curve perfectly. Pipe can be custom-bent with presses or more complex machines using one of several common methods, including ram bending, rotary draw bending, compression bending and three roll bending, among others. Separate dies are typically required for each size of pipe and each different bend radius, except on more complex machines.
So what are 3D bends and what are they for?
A 3D bend is a bend in which the radius of the curve is equal to 3 times the diameter of the pipe. It is a smoother bend than a 1.5D bend, which looks almost like a regular 90-degree right angle, but it is a sharper bend than a 5D bend, which looks like a smooth arc between two perpendicular pieces.
Here are a few of the places where you will commonly find 3D bends being used:
1. Automotive Exhaust Systems
Both manufacturer-supplied and custom exhaust systems for cars and trucks often feature a wide assortment of bends to maneuver around various obstacles on the underside of the car, such as the engine, transmission, cross-members and the fame. Most vehicle exhausts feature custom compound beds, and the fabricators generally prefer smoother curves, like 3D bends or even 5D bends, because they reduce the turbulence and back-pressure inside the exhaust system, and that can help increase an engine’s performance.
2. Automotive Roll Cages
Off-roading can be a very competitive sport, or, more simply, an expensive hobby. One of the many dangers when rock-crawling, mudding or generally pushing a vehicle beyond its limits, is the possibility of rolling the vehicle over. To prevent injury and damage to the vehicle, a quality roll cage is an absolute necessity. Many roll cages are custom formed from metal pipe, often chromoly steel, using an assortment of bends, including the common 3D bend. Each piece is bent, cut and welded together to make a complete roll cage that is both durable and aesthetically pleasing.
3. Structural Frames
3D bends are very common in structural frames of all kinds. These can range from the frames of custom automobiles, to the frames of buildings, or even airplanes or spacecraft. Often, to build a structural frame, pipe is bent, cut and welded together to make a strong skeleton, and then sheet metal is attached via screws or welds to create a completed assembly, which is both extremely strong and resistant to the elements. When built using aluminum, titanium or certain alloys, it can also be lightweight and corrosion-resistant.
Many types of furniture incorporate tubular steel and 3D bends for either structural or aesthetic purposes. Tables frequently use tubular steel legs, with bends where they meet the tabletop to provide support. Metal chairs, couches and futons with tubular frames often use similar bends to provide a nice gentle curve that is both pleasing to the eye and structurally rigid. Shelving units can also incorporate custom bends, either for decoration or for structural integrity.
The 3D bend is also quite common in fencing, for both decorative and structural uses. It is seen extensively in galvanized chain-link fencing, especially to add a gentle curve to gates and other decorative items, or in custom-designed fencing. Pipe is also used regularly in fencing for cattle, horses and other livestock, as well as for domestic pets, and often decorative touches are added that require custom bends.
In the plumbing industry, 3D bends are quite common. They are incorporated anywhere that standard elbows cannot be relied upon to bypass obstacles or to change the angle of the pipe. In pipes that contain high-viscosity liquids or fluids that require reduced turbulence, the smoother 3D bend is often preferable to sharper bends. Custom bends are used in plumbing of all kinds, from the pipes in your home, to the pipes in chemical plants, food processors or refineries.
7. Wiring Conduit
Wiring conduit is designed to protect electrical cables from the weather, accidental damage and other dangers. When wiring conduit is required on an electrical job, often it must be bent to go around corners or other obstacles. Typically, smoother curves like 3D or 5D bends are used instead of sharp curves, because it makes it much easier to fish the wire through the conduit after it is installed. Electricians usually carry their own tools to bend small-diameter conduit, though for larger-diameter versions, they may require custom bending services.
Gas and oil pipelines, like any plumbing system, often use 3D bends in many places along their lengths. Unlike typical household pipes, however, these are typically much larger, and require some serious machinery to do custom bends. Gentle bends help the high-viscosity oil flow through the pipes easier, and they help natural gas flow smoother, reducing pipe fatigue and the chance of leaks.
9. Hand Rails
An often-overlooked area where 3D bends are used is in the hand rails for stairways or walkways, as well as the safety rails used to provide handicap access. Custom bends are often used to follow curves, go around corners or to provide mounting points at each end of the pipe. Sometimes the bends are also used strictly for decorative purposes.
10. Art Projects
In many art projects, tubular steel is used to create a frame, upon which the artist builds the rest of the piece. Custom bends are often used to create gentle-flowing lines and other aesthetic features, which many times are covered up by other materials. The frame creates a strong base for the rest of the piece, and determines its overall shape.
If you have a project that calls for 3D bends, it often may not be feasible to buy the equipment to produce them yourself. The tools can be prohibitively expensive, and they require a significant amount of training and practice to operate them properly. Fortunately, there are services available that will custom-bend pipe to your exact specifications, saving you the expense and the hassle of buying your own equipment.