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by James Dickie on Thu, Aug 04, 2022 @ 13:08 PM
Tube bending is an essential day-to-day operation in all kinds of industrial facilities. Despite its importance, tubing systems are often constructed by trial and error with little or no planning, which inevitably leads to wasted time and material and can even affect their efficiency and safety.
Fortunately, it doesn’t take any special training or complicated math to design and build a tubing system that’s optimized for the space. However, there are some important considerations when doing any kind of tube bending:
- distance between bends
- tubing length
- number of fittings
- locations of bends and fittings
These all need to be incorporated into the design before you start.
In this post, we discuss some best practices when planning out a tubing system layout, including how to determine the distance between bends.
Plan Your Tubing Layout Before Bending
Before you start any tube bending, it’s important to plan how the system will be routed. Don’t skip this step—a little planning up front can save a lot of time, effort, and money.
Create a diagram laying out all the required directional changes, taking into account any obstacles in the space and any components that need to be installed. These will be accomplished either with bends or by connecting separate lengths of tubing with fittings, depending on the situation. The system should be as simple as possible while avoiding obstacles and remaining accessible for maintenance. A logical, efficient layout will make the system easier to maintain and minimize the risk of potential problems.
Planning out an efficient design up front doesn’t just reduce material costs and produce a more attractive design—it can improve the system’s performance and lifespan. Too many multi-radius bends produce turbulent flow, which can disrupt flow and produce vibrations that can lead to premature failure.
Tubing System Design Best Practices
When planning the layout of a tubing system, there are several factors to consider. Here are some best practices to keep in mind:
- Determine the number of fittings and length of tubing required before doing any bending or installation. Make sure to allow enough tubing to seat fully into any fittings.
- Locate connections where they can be easily accessed for ease of maintenance.
- Make sure tubing does not obstruct other equipment or instrument panels, which can make them difficult to access and cause potential safety concerns.
- Avoid running tubing at handrail or footrail heights to prevent inadvertent contact from plant personnel.
- Provide support for longer runs of tubing to reduce vibration and increase the system’s life.
The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry Suggested Spacing for Supports
|
Tubing Diameter |
Tubing Diameter |
Distance between Clamps (ft.) |
Distance between Clamps (m) |
|
3/16 to 3/8 |
4 to 10 |
3 |
0.9 |
|
1/2 to 7/8 |
15 to 22 |
5 |
1.5 |
|
1 to 1 1/4 |
25 to 30 |
7 |
2.1 |
Maximum Horizontal Pipe Hanger and Support Spacing
Nominal Pipe or Tube Size (in) |
Nominal Pipe or Tube Size (mm) |
Standard Wt. Steel Pipe |
Copper Tube |
||||||
|
Water Service (ft) |
Water Service (m) |
Vapor Service (ft) |
Vapor Service (m) |
Water Service (ft) |
Water Service (m) |
Vapor Service (ft) |
Vapor Service (m) |
||
|
1/4 |
6 |
7 |
2.1 |
8 |
2.4 |
5 |
1.5 |
5 |
1.5 |
|
3/8 |
10 |
7 |
2.1 |
8 |
2.4 |
5 |
1.5 |
6 |
1.8 |
|
1/2 |
15 |
7 |
2.1 |
8 |
2.4 |
5 |
1.5 |
6 |
1.8 |
|
3/4 |
20 |
7 |
2.1 |
9 |
2.7 |
5 |
1.5 |
7 |
2.1 |
|
1 |
25 |
7 |
2.1 |
9 |
2.7 |
6 |
1.8 |
8 |
2.4 |
|
1 1/4 |
32 |
7 |
2.1 |
9 |
2.7 |
7 |
2.1 |
9 |
2.7 |
|
1 1/2 |
40 |
9 |
2.7 |
12 |
3.6 |
8 |
2.4 |
10 |
3.0 |
|
2 |
50 |
10 |
3.0 |
13 |
3.9 |
8 |
2.4 |
11 |
3.3 |
For more recommendations for tubing support, download Swagelok’s Tube Fitter's Manual. If you run into any issues during planning, contacting an expert may be your best option
Tube Bending: Distance Between Bends
Another critical factor when tube bending is the distance between bends or the amount of straight tube between bends. Why is the distance between bends important? Tube benders require a straight section of tube to clamp the workpiece securely during the bending operation. There must be a sufficient amount of tubing material for the tool to grip to prevent the tube from slipping during the operation. Having adequate distance between bends also allows bending with lower pressure, prolonging tool life.
Offset Bends
Creating offset bends is a common operation in tube bending. Distance between bends is important here to ensure the offset provides the clearance needed to avoid an obstacle.
To determine the required distance between offset bends, first, use the offset angle (E) to determine the offset bend allowance (A) using the table below. Then, multiply the offset dimension (O) by the offset bend allowance (A) to get the offset distance (L).
L = O × A
|
Offset Bend Angle (E) |
Offset Bend Allowance (A) |
|
22.5° |
2.613 |
|
30° |
2.000 |
|
45° |
1.414 |
|
60° |
1.154 |
Quality Tubing Systems Start with a Quality Vendor
There’s a lot that goes into good tube bending—distance between bends is just one example of the factors you need to account for when planning and installing a tubing system. Edmonton Valve & Fitting supplies both tube benders and high-quality tubing to help you get the perfect bend every time. Need help achieving accurate bend angles or identifying defects? Our Swagelok-certified tube bending training can help your team perfect their technique and design, install, and maintain even the most complex tubing systems.