Instrumentation Tubing – Getting it Right

Not many people realise that the type of hydraulic and instrumentation tubing you choose is, in fact, a rather critical decision. 

Instrumentation tubing, most commonly made from mild or stainless steel, aluminium or copper, is used to connect pressure switches or gauges as well as flow monitors and valves on ventilation systems and industrial piping. These materials generally have good machinability and offer the best overall corrosion resistance which is vital for instrumentation systems that are located in corrosive environments or process harsh media. Choosing the correct tubes will thus guarantee reliability, integrity and safety.

Selecting Instrumentation Tubing Tips

It’s not just the size and length of the tube that matters, one also needs to consider how compatible the tubing material is with the media it will contain if you are to eliminate the risk of leaking, accidents and unscheduled downtime. 

System operating pressure is another important factor in determining the type and size of instrumentation tubing you should use. In general, high-pressure installations require strong materials such as steel or stainless steel.

Stainless steel instrumentation tubing is characterised by good corrosion resistance, a smooth and clean surface and high precise dimensional tolerance which reduces the risk of leaks when connecting the tubes with couplings.

Also, take into account the operating pressure. Copper and aluminium tubing is most suitable for low-temperature media whereas stainless steel and carbon steel tubing are more suited to higher temperature media. 

Always check that the instrumentation tubing you purchase is free from nicks, gouges and deep scratches, as this can interfere with sealing, especially when the tubing is used in a gas service environment.  

Along with proper tube selection, installation is a key ingredient when it comes to building reliable tubing systems.

Mixing materials should be strongly discouraged for tubing installations as dissimilar materials in contact with one another may be susceptible to galvanic corrosion. Different materials also have different levels of hardness which can adversely affect the fittings ability to seal on the tubing. Thus, stainless steel fittings should also only be used with stainless steel tubing and aluminium fittings only with aluminium tubing. The only exception is brass fittings which are used with copper tubing.

Always purchase quality tubing as it is counterproductive to purchase high quality, mechanically attached tube fittings and pair it with cheap tubing, which will only compromise the integrity of the overall system.  

Instrumentation tubes are measured by their OD (outside diameter) and can vary in size. The most common sizes are ¼”, 3/8” and ½”. Make sure you measure correctly to get the right size tubing for your tubing system.

Steelmor is the leading supplier and manufacturer of instrumentation tubing in South Africa. We stock metric and imperial sizes in all wall thicknesses from 6mm to 16mm as well as 1/8” to 1” Give us a call today on 011 747 5700 for advice and products.