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Steel pipe bend

A 3D pipe bending is a pipe bend that the bend radius is 3 times the pipe outside diameter.

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Description

Steel pipe bend is a bending pipe that used to change the pipeline direction. Common use radius bend in 3D bend and 5D bend, It is similar to pipe elbow, but differently pipe bend is longer than elbow and usually manufactured for the specific needs.

So depends on different bending radius (R) to distinguish bend and elbow.
In case bending radius is more than 2 times of D (diameter), it is pipe bend. Like 3D bend, 5D bend, 6D pipe bend, 8D pipe bend.
In case bending radius in 1D or 1.5D, it is elbow. (short radius elbow 1D and long radius elbow 1.5D).

Pipe Bending Radius: 3D Bend, 5D Bend, 6D, 8D and customized
Bending Degrees: 15°, 22.5°, 30°, 45°, 60°, 90°, 180° and customized

Common Use Bends in Pipelines

3D and 5D bends are most common use in long pipelines, since they provide better efficiency in changing directions. After that is 6D and 8D bend, as the compensation to complete for small degree change.

3D Bend

3D bend radius in 3D, means the bend radius is 3 times of pipe outside diameter. For example if a 3D bend used in a 10 inch pipelines, the bend radius would be 30 inches.

5D Bend

5D bend means the bend radius is 5 times of pipe nominal diameter. It provides better smooth performance to change pipeline direction than 3D bend.

6D Bend

6D bend as one of long radius bend, bend radius “R” is 6 times of pipe diameter, in case of the same degree, it has longer length than 3D or 5D bend, but shorter length than 8D bend.

The radius become bigger, the length of the pipe bend become bigger.

8D Bend

8D bend normally is the longest radius for the common use.
Pipe Bending Machine by Hot Push Manufacturing

How does steel pipe bend made?

The pipe bend is bent by a set of bending equipment with two processes: Cold simmering and hot pushing. (Including bending, squeezing, pressing, forging, machining and etc)

Pipe Bending Machine by Hot Push Manufacturing

Insert the straight pipe into pipe bending machine, heat the pipe and use lever (installed with different dimension of mould) to bend the pipe.

Differences between Steel Pipe Bend VS Elbow

Pipe bend and elbow both for change the pipe direction, still there are a lot of differences in below aspects:

  • Bending Radius
  • Manufacturing Processes
  • Different cost
  • Application scope

Bend pipe radius

Bending Radius of Bend 3D, 5D, 8D and Elbow 1D, 1.5D

As we talked above,

  • Steel pipe bend radius: Above 2 times of D, so there are 2D, 2.5D, 3D, 5D, 6D, 7D or 8D pipe bend.
  • Steel pipe elbow radius: R=1D or R=1.5D or 2D. Below 1.5D is short radius elbow, and more than 1.5D but not over 2D is long radius elbow.

R is radius of curvature; D is (elbow or bend) pipe diameter.

Large Diameter Pipe Bend / Bending

Steel pipe bending usually required in large diameter in oil and gas pipelines, since it has better capacity to transport the material, and long pipelines will need different radius of pipe bends to be intalled in complex conditions.

Different of manufacturing processes

3D, 5D, 8D Bend: Could be bend directly from a finished pipe with cold bending processes, to different degrees.

1D, 1.5 D Elbow: Shall be made according by standard manufacture procedures, with hot finishing or hot bending, to a certain degree, 45°, 90° or 180°.

Cost different with elbow and 3D, 5D, 6D, 8D bend

So by the help of simple production process with standard 1.5D or 1D, steel pipe elbow cost is lower than bend. Pipe bend is mostly required with customized radius like 3D, 4D, 5D, 6D, 8D or degrees so the processes is more complicated than elbow and cost is higher.

Different applications scope

  • Bend: Compatible with slower liquid and lower pressure.
  • Elbow: Compatible with high pressure and rapid liquid.

Sometimes elbows must be used in narrow sections, because the radius of curvature of the elbow is small, generally 1.5D, but the pipe bend could be up to 40D.

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.

4. Furniture
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.

5. Fencing
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.

6. Plumbing
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.

8. Pipelines
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.

Methods of bends in carbon steel

While the industry provides various means for bending the carbon steel pipe to the 5D bend, heat induction is the most widely-known–but not the most popular–technique in the industry. The pipe to be bent is subjected to extreme temperature, and when at the desired heat, a mode or model in the dimensions of the 5D bends is forced through the heated pipe, causing the pipe to conform to the bend of the 5D pipe dimensions. Carbon steel is the hardest pipe material used in this manner, and heat induction is the best means to curve the carbon steel pipe into the 5D curvature.

Uses

Heat-processed 5D bend pipes are used in all oil and gas lines, and the factory testing exceeds the quality standards required by the oil and gas industry. This is an industry where quality standards can be linked to safety standards.

What You Are Buying

Customers obtain a wide range of bend geometries and total design flexibility with customized radius and angle. Qualified subcontractors carry out hot induction bending with state-of-the-art technology, giving full control of the bending process, as well as total monitoring of all bending parameters.

1) Heat Induction Bends for Oil and Gas Industry
The production of high-quality bends depends on the manufacturing process of the steel pipe that is transformed into the bend. During the hot-induction bending process, unavoidable thinning occurs. Therefore, a custom- and precision-made mother pipe must be produced in order to comply with minimum wall thickness after the bending is complete.

Heat treatment is carried out on each bend in order to achieve the required degree and mechanical properties after bending. For critical applications (such as high-strength steel, heavy wall, sour service or low-temperature) full quenching and tempering after bending is still performed as a preferred process. Machining the bend ends guarantees top tolerances of inside diameters of the pipe. We therefore ensure the bend has the minimum working strengths of the mother pipe.

World-class bending manufacturers provide high quality bending solutions for oil and gas pipelines, either onshore or offshore. The bends manufacturing and testing procedures exceed all quality standards required by the oil and gas industry.

2) Cold Bending Process

High quality bending solutions are more than critical. Cold-bending is commonly used over hot-bending because certain types of steel and metal alloys can be weakened. You cannot allow the pipes to be weakened in any way as this can lead to damage of your product, your plant, or cause risks of injury to your employees. Cold-bending is also preferred by many industries because of its affordability, with costs being less than that of heat induction.

Cold-bending 5D bends is a continuous operation where a long strip of metal, usually steel, is passed through sets of rollers, with each set of rollers performing only a part of the bend, until the desired cross-section profile is obtained. Roll-forming is ideal for producing parts with long lengths or in large quantities. Roll-Forming is also generally a lower cost process than other metal forming processes. Cold-processed bends are used in construction, water piping and as machinery parts.

Sunny Steel provides fast, dependable metal custom-bending for:

  • angle
  • flat bar
  • round tube
  • pipe
  • square tube
  • Ibeams
  • channel
  • finned tube

We specialize in bending, fabricating and testing of heating and cooling coils. We are proud of our leading reputation in the industry with our attitude of professional workmanship and on-time delivery. Some of our advantages over competitors include:

  • Fast Turnaround Times
  • Dependability
  • Outstanding Reputation
  • Custom Pipe Bending
  • Custom Oil Field Bending
  • Architectural Application Bending
  • Heating and Cooling Coil Fabrication

Sunny Steel fabricates all types and sizes of cooling coils from 1/8″ pipe to 8″ pipe and all alloys.