3D Pipe Bending

How do you calculate 3D pipe bend?

3D pipe bending is a pipe bend that the bend radius is 3 times the pipe outside diameter. The RADIUS of a 5D pipe bend is actually what is 5 times the nominal diameter. So if you had a 10″ diameter pipe, the radius of the centerline of the bend would be 50 inches. Larger numbers have smoother curves.

What size is a 3D bend?

3D Bend is bend radius 3 times of the pipe outside diameter, for example if a 3D pipe bend used in a 10 inch pipelines, the bending radius would be 30 inches. Same with elbow (1D or 1.5D), 3D bend also ranges different degrees like 45 degree, 60 Degree and 90 Degree.

3D pipe bending involves using specialized equipment and machines to form pipes into various shapes and curves along three planes. This technique is commonly used in industries such as aerospace, automotive, and construction to create complex piping systems for various applications. 3D pipe bends allow for more efficient and effective use of space while improving fluid flow and reducing the risk of leaks or breaks.

3D bends are pipe bends whose radius is three times the outside diameter of the pipe. Others are the U-bends that have a bend of 180 degrees. 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.

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.

• 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.

What is the difference between a 3R and a 3D elbow?

There is no difference between 3R and 3D.

• Both have a centerline radius of three times the nominal diameter size.
• Both have a smoother curve than an SR or LR.
• (In fittings, 3D does not refer to modeling software or screens.)

What does 3D or 6D mean for pipe fittings?

Larger numbers have smoother curves.

• Centerline radius is calculated based on diameter and number that precedes it.
• For example, a 10″ 6D has a 60″ centerline radius.
• Smoother curves are often used for applications with higher pressure, abrasion or corrosion.

Creating 3D Bends

The process involves the use of machines and mechanical force. Normally, pipe or tube bending machines are human powered, hydraulic assisted, or even pneumatic powered. The following are some of the most commonly used pipe bending processes.

Three-Roll Push Bending

This is one of the most commonly used processes. It is used to come up with bending geometrics that include multiple plane bending curves. Normally, the profile is led through a bending roll and the supporting roll or even rolls, while at the same time being pushed through the tool. The bending radius is normally determined by the position of the forming radius. This is one of the most flexible processes used in the creation of bends, for multiple radii can be actually obtained.

Rotary Draw Bending

This is one of the most precise technologies used to create 3D bends. It uses a feature called ‘die sets’ that has a constant center line radius. Rotary draw benders can be programmed to store several bend works with different degrees when it comes to bending. Technically, an IDX (positioning index table) is at all times attached to the rotary bender. This enables the operator to create complex bends that have varying planes. Rotary benders are largely used in tube bending.

Heat Induction

When it comes to this bend tubing process, an induction coil is normally placed at the bend point of the pipe. thereafter, the area is subjected to temperatures ranging from 800 to 2200 degrees Celsius. When it is hot, pressure is actually applied to bend the pipe. Finally, the pipe can be passed through cold air or water. Normally, this process is used in extremely large pipes such as gas pipes lines

Hot-Slab/Sand Packing Forming

In this process, the pipe is filled with sand and the ends caped. The pipe is then passed through a furnace with temperature of 870 degrees Celsius. thereafter, the pipe is placed on the slab and the pins set in it. You can then bent the pipe around the pins using a tool such as the winch, or you can even apply some mechanical force. The sand that is normally put in the pipe minimizes any distortion in the cross section of the pipe.

Press Bending

This will probably be one of the first processes used on cold tubing and even pipes. Normally, a die is pressed against the pipe. This will force the pipe to fit the shapes. However, this process comes with its own drawbacks since the internal area is not supported. It results in some kind of deformation and perfect 3D bends and 5D bends will not be achieved.

Why use 3D & 5d pipe bends?

Diagram of ASME B16.49 induction bend, 90° 3D Bend with Tangent lengths.

Larger radius bends offer several advantages for fluid flow in pipes. They provide smoother flow for various mediums such as water, slurry, oils, solids, and more. This reduced resistance results in improved flow efficiency compared to 1D or 1.5D bends. Additionally, longer bend radii help minimize turbulence, especially when compared to standard fittings.

When planning your piping project, it's essential to assess whether traditional 1D or 1.5D bends can effectively meet your requirements. If there are any doubts, it's advisable to consider using 3D or 5D bends to optimize your system's performance.

Constants for Pipe Bends:

ASTM

• ASME/ANSI B16.49 Factory-Made Wrought Steel Buttwelding Induction Bends for Transportation and Distribution Systems
• ASTM A403 Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings
• ISO 2851 tainless steel bends and tees for the food

JIS

• JIS B2311 Universal steel butt-welding pipe fittings
• JIS B2312 Steel butt-welding pipe fittings
• JIS B2313 Steel plate butt-welding pipe fittings
• JIS B 2321:1995Aluminium and aluminium alloy butt-welding pipe fittings

EURO

• DIN 3867 Non-soldering compression couplings – Pressure bush for butt joints
• DIN 2609 Steel butt-welding pipe fittings; technical delivery conditions
• BS 1640 Specification for steel butt-welding pipe fittings for the petroleum industry
• BS 1965 Butt welding pipe fittings for pressure purpose
• STPG38

How to Calculate a Pipe Bend?

Pipe fittings are necessary to join together pipes, or to change the direction of an existing pipe. Pipes and pipe fittings are made of a variety of materials, depending on the fluid or gas being transported. Most pipe fittings tend to be either threaded or able to slip over the pipes they connect. Whether you are using steel pipes of PVC pipes, a chemical solvent is required to create a seal between the pipe and the fittings.

Measure the required length of the pipe to be installed, keeping in mind the extra length required where the pipe will be inserted into the fitting. Mark this length on the pipe.

Bevelled Ends

The ends of all buttweld fittings are bevelled, exceeding wall thickness 4 mm for austenitic stainless steel, or 5 mm for ferritic stainless steel. The shape of the bevel depending upon the actual wall thickness. This bevelled ends are needed to be able to make a “Butt weld”.

Welding Bevel acc.to ASME / ANSI B16.9 and ASME / ANSI B16.28

ASME B16.25 covers the preparation of buttwelding ends of piping components to be joined into a piping system by welding. It includes requirements for welding bevels, for external and internal shaping of heavy-wall components, and for preparation of internal ends (including dimensions and dimensional tolerances).

Our in-hourse R&D team developed bevel ends equipment are good using in thickness 2mm to 20mm pipe fittings, guarantee high efficiency and high quality.

These weld edge preparation requirements are also incorporated into the ASME standards (e.g., B16.9, B16.5, B16.34).

ASME B16.25 (BUTT WELD ENDS)

ASME B16.25 sets standards for the preparation of the ends of components that need to be welded together.

Cut square or slight chamfer, at manufacturer’s option for :

• t ≤ 0.19” carbon steel or ferritic alloy steels
  t ≤ 0.12” austenitic alloy steels

Buttweld Fittings general

A pipe fitting is defined as a part used in a piping system, for changing direction, branching or for change of pipe diameter, and which is mechanically joined to the system.

There are many different types of fittings and they are the same in all sizes and schedules as the pipe.

ASME / ANSI B16.9 dimension

ASME B16.9 Standard covers overall dimensions, tolerances,ratings, testing, and markings for factory-made wrought buttwelding fittings in sizes NPS 1⁄2 through NPS 48 (DN 15 through DN 1200).

Tolerances of Welded Fittings

All dimensions are given in inches. Tolerances are equal plus and minus except as noted.

1. Out-of-round is the sum of absolute values of plus and minus tolerance.
2. This tolerance may not apply in localized areas of formed fittings where increased wall thickness is required to meet design requirements of ASME B16.9.
3. The inside diameter and the nominal wall thicknesses at ends are to be specified by the purchaser.
4. Unless otherwise specified by the purchaser, these tolerances apply to the nominal inside diameter, which equals the difference between the nominal outside diameter and twice the nominal wall thickness.

The ASME B16.9 pipe fittings can be used under the jurisdiction of the ASME Boiler & Pressure Vessel Code (BPVC) as well as the ASME Code for pressure piping. Referencing pressure ratings of flanges per ASME B16.5, they can be designated as Classes 150, 300, 600, 900, 1500 and 2500. The allowable pressure ratings for ASME B16.9 pipe fittings may be calculated as for straight seamless pipe of equivalent material in accordance with the rules established in the applicable sections of ASME B31 Code for pressure piping.

Design of Fittings

The design of butt welding pipe fittings made to ASME B16.9 shall be established by one of the following methods: (a) mathematical analyses contained in pressure vessel or piping codes; (b) proof testing; (c) experimental stress analysis with hydrostatic testing to validate experimental results; (d) detailed stress analysis with results evaluation.

Standard Marking

Generally, ASME B16.9 pipe fittings shall be marked to show the following details: “trademark + material grade + wall thickness + size + heat number”. For example, “M ASTM A234 WP5 SCH80 6″ 385“. When steel stamps are used, care shall be taken so that
the marking is not deep enough or sharp enough to cause cracks or to reduce the wall thickness of the fitting below the minimum allowed.

Material & Manufacture

The ASME B16.9 fittings may be made from an extensive range of mateirals covering (1) carbon and low-alloy steels in accordance with ASTM A234 and ASTM A420; (2) austenitic and duplex stainless steels in accordance with ASTM A403 and ASTM A815; (3) nickel alloys in accordance with ASTM B366; (4) aluminum alloys in accordance with ASTM B361; and (5) titanium alloys in accordance with ASTM B363.

Pipe Fittings Dimensions Tolerance as per ASME B16.9:

ASME American Society for Mechanical Engineers

This is one of the reputed organizations in the world developing codes and standards.
The schedule number for pipe fitting starts from ASME/ANSI B16. The various classifications of ASME/ANSI B16 standards for different pipe fittings are as follows:

• ASME/ANSI B16.1 – 1998 – Cast Iron Pipe Flanges and Flanged Fittings
• ASME/ANSI B16.3 – 1998 – Malleable Iron Threaded Fittings
• ASME/ANSI B16.4 – 1998 – Cast Iron Threaded Fittings
• ASME/ANSI B16.5 – 1996 – Pipe Flanges and Flanged Fittings
• ASME/ANSI B16.11 – 2001 – Forged Steel Fittings, Socket-Welding and Threaded
• ASME/ANSI B16.14 – 1991 – Ferrous Pipe Plugs, Bushings and Locknuts with Pipe Threads
• ASME/ANSI B16.15 – 1985 (R1994) – Cast Bronze Threaded Fittings
• ASME/ANSI B16.25 – 1997 – Buttwelding Ends
• ASME/ANSI B16.36 – 1996 – Orifice Flanges etc.

ASTM International American Society for Testing and Materials

This is one of the largest voluntary standards development organizations in the world. It was originally known as the American Society for Testing and Materials (ASTM).

• ASTM A105/A105M – Specification for Carbon Steel Forgings for Piping Applications
• ASTM A234/A234M – Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• ASTM A403/A403M – Specification for Wrought Austenitic Stainless Steel Piping Fittings
• ASTM A420/A420M – Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service

AWWA: American Water Works Association

AWWA About – Established in 1881, the American Water Works Association is the largest nonprofit, scientific and educational association dedicated to managing and treating water, the world’s most important resource.

• AWWA C110 – Ductile-Iron and Gray-Iron Fittings, 3 Inch Through 48 Inch (75 mm Through 1200 mm), for Water and Other Liquids
• AWWA C208 – Dimensions for Fabricated Steel Water Pipe Fittings

ANSI The American National Standards Institute

ANSI is a private, non-profit organization. Its main function is to administer and coordinate the U.S. voluntary standardization and conformity assessment system. It provides a forum for development of American national standards. ANSI assigns “schedule numbers”. These numbers classify wall thicknesses for different pressure uses.

MSS STANDARDS: Manufacturers Standardization Society

The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry is a non-profit technical association organized for development and improvement of industry, national and international codes and standards for: Valves, Valve Actuators, Valve Modification, Pipe Fittings, Pipe Hangers, Pipe Supports, Flanges and Associated Seals

• MSS SP-43 – Wrought Stainless Steel Butt-Welding Fittings Including Reference to Other Corrosion Resistant Materials
• MSS SP-75 – Specifications for High Test Wrought Buttwelding Fittings
• MSS SP-73 – Brazing Joints for Copper and Copper Alloy Pressure Fittings
• MSS SP-83 – Class 3000 Steel Pipe Unions, Socket-Welding and Threaded
• MSS SP-97 – Integrally Reinforced Forged Branch Outlet Fittings — Socket Welding, Threaded, and Buttwelding Ends
• MSS SP-106 – Cast Copper Alloy Flanges and Flanged Fittings Class 125,150, and 300
• MSS SP-119 – Factory-Made Wrought Belled End Socket Welding Fittings

Difference between “Standard” and “Codes”

Piping codes imply the requirements of design, fabrication, use of materials, tests and inspection of various pipe and piping system. It has a limited jurisdiction defined by the code. On the other hand, piping standards imply application design and construction rules and requirements for pipe fittings like adapters, flanges, sleeves, elbows, union, tees, valves etc. Like a code, it also has a limited scope defined by the standard.

Factors affecting standards

“Standards” on pipe fittings are based on certain factors like as follows:

• Pressure-temperature ratings
• Size
• Design
• Coatings
• Materials
• Marking
• End connections
• Dimensions and tolerances
• Threading
• Pattern taper etc.

BSP British Standard Pipe

BSP is the U.K. standard for pipe fittings. This refers to a family of standard screw thread types for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread. This has been adopted internationally. It is also known as British Standard Pipe Taper threads (BSPT )or British Standard Pipe Parallel (Straight) threads (BSPP ). While the BSPT achieves pressure tight joints by the threads alone, the BSPP requires a sealing ring.

JIS Japanese Industrial Standards

This is the Japanese industrial standards or the standards used for industrial activities in Japan for pipe, tube and fittings and published through Japanese Standards Associations.

NPT National Pipe Thread

National Pipe Thread is a U.S. standard straight (NPS) threads or for tapered (NPT) threads. This is the most popular US standard for pipe fittings. NPT fittings are based on the internal diameter (ID) of the pipe fitting.

BOLTS & NUTS

We are manufacturer of Flange bolts & Nuts and supply high quality

• A193 = This specification covers alloy and stainless steel bolting material for pressure vessels, Valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications.
• A320 = Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service.
• A194 = Standard specification for nuts in many different material types.

AN Here, “A” stands for Army and “N” stands for Navy

The AN standard was originally designed for the U.S. Military. Whenever, a pipe fitting is AN fittings, it means that the fittings are measured on the outside diameter of the fittings, that is, in 1/16 inch increments.

For example, an AN 4 fitting means a fitting with an external diameter of approximately 4/16″ or ¼”. It is to be noted that approximation is important because AN external diameter is not a direct fit with an equivalent NPT thread.

Dash (-) size

Dash size is the standard used to refer to the inside diameter of a hose. This indicates the size by a two digit number which represents the relative ID in sixteenths of an inch. This is also used interchangeably with AN fittings. For example, a Dash “8” fitting means an AN 8 fitting.

ISO International Organization for Standardization

ISO is the industrial pipe, tube and fittings standards and specifications from the International Organization for Standardization. ISO standards are numbered. They have format as follows:

“ISO[/IEC] [IS] nnnnn[:yyyy] Title” where

• nnnnn: standard number
• yyyy: year published, and
• Title: describes the subject

General standard

Wide variety for all areas of application