System design is equally critical to ensuring leak-free operation and can be cited 20% of the time when identifying the cause of fluid loss. Proper system design first involves selecting the right components to fit the application. The system designer must thoroughly examine all major considerations and how they will affect the choice of components. Once a designer looks at the application and determines which components can meet the requirements, other more subjective factors can be considered.

Correctly routing, bending and clamping tube lines is critical to system development. Failing to adhere to tube line fabrication best practices can result in a system that is inefficient and costly. By following recommended procedures, designers can help ensure a system that is leak-free.

Routing — Proper routing involves making a connection line from one point to another through the most efficient means. Routing, among all system design considerations, is perhaps the most significant and difficult.

Figure 1 shows several common routing configurations and their preferable alternative. In all instances, it is important to leave fittings as accessible as possible. Hard-to-reach joints are problematic to assemble and tighten properly as well as time consuming to service.

The ideal path should also avoid excessive strain on joints (a strained joint will eventually leak) and allow for expansion and contraction. Lines should be run straight and parallel when possible.

Figure 1

Figure 1. Proper routing of tube lines.
Select figure to enlarge.

Bending — The two most important rules to follow when fabricating a tube line are measure exactly and bend accurately (Figure 2a). A single measuring or bending error will result in a tube line that does not fit (Figure 2b) — a waste of both time and money.

Figure 2a

Figure 2a. Accurate measurements coupled with exact angles will result in a tube line that fits at all points (A-D).
Select figure to enlarge.

Figure 2b

Figure 2b. A measuring error on the second leg (B-C) resulted in a tube line that cannot fit at point D.
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Using proper tools is the best way to achieve good results. There are a number of bender types to choose from (Figure 3) for smooth, wrinkle-free bending without excessive tube flattening:

  • Hand-held lever (individually sized for tube sizes ranging from 1/8 to 1 in. and 5 to 14 mm)

  • Manual crank, table mount or vise mount

  • Hydraulically powered

  • CNC

Figure 3

Figure 3. Common types of tube benders.
Select figure to enlarge.