SMC TU0604BU-20 Polyurethane Tubing 6 mm Blue, 20 m

Blue polyurethane tube for general pneumatic piping

TU0604BU-20 is a 20 m roll of blue polyurethane tubing from the SMC TU series, with a 6 mm outside diameter and a 4 mm inside diameter. It is the size that pushes into the one-touch fittings of 6 mm size on cylinders, valves, speed controllers and manifolds, and it is a flexible tube that is easy to route around machine frames.

The code reads TU (series), 06 (the 6 mm outside diameter), 04 (the 4 mm inside diameter), BU (the colour blue) and 20 (the 20 m roll). Changing the last field to 100 gives a 100 m roll, and the same catalogue lists black, white, red, yellow, green, clear and orange. Colours are often used to separate air lines by function, for instance blue for extension and another colour for retraction.

Technical specifications

Using it with the right fittings

Polyurethane is softer than nylon, so the working pressure given for it is lower: the catalogue gives 0.8 MPa at 20 deg C for this series, and notes that the value changes with temperature. Fittings are often rated higher than the tube, for example the SMC KQ2 one-touch fittings carry 1.0 MPa, but the system is limited by the weakest part, so the figure of the tube must be used.

The tube should be cut square with a proper tube cutter and pushed fully into the fitting. A tube that is cut at an angle or scratched on the outside can leak. Keep the bend radius at or above 15 mm: a sharper bend kinks the tube and cuts off the flow.

Care and limits

The catalogue states that this tubing is for general industrial air and water. Please consult the manufacturer for other fluids, and keep surge pressure below the maximum operating pressure, because a pressure spike can damage both fittings and tubes. Heat from adiabatic compression, or a hot surface close to the line, can lower the burst pressure and shorten the life of the tube.

For welding areas or where sparks fall on the tubing, a flame-resistant type is needed; this plain polyurethane tube is not described as flame resistant in the catalogue page used for this listing.

Keep a short spare length of the same tube on the machine for quick repairs, and label each line at both ends so that the colour code stays meaningful after a service. Before ordering, compare the tube outside diameter with the fitting it will go into, since a tube that is not the right size will not seal or hold.

Documents and quotation

The SMC tubing catalogue PDF below has the specification table, the colour code and the burst-pressure curve. Please confirm outside diameter, colour and roll length before ordering. Other pneumatic parts are listed under Automation Accessories. Seven Star LLC is an independent supplier and quotes the exact code on request.

TU0604BU-20 pressure rating by temperature

The SMC TU/TIUB catalogue gives the maximum operating pressure of the whole TU polyurethane range as a function of temperature, and the same figures apply to the TU0604BU-20. The vacuum figure is listed separately, with a note that the usable vacuum depends on the fitting the tube is pushed into.

The derating matters in Oman and the GCC. Tubing routed on the outside of a machine, close to a hot motor, or inside an enclosure in the summer can easily sit at 40°C or more, so a line that is fine at 0.8 MPa in a cool workshop is limited to 0.65 MPa at 40°C and 0.5 MPa at 60°C. Set the regulator with this in mind, or move the tube away from the heat source.

How It Works in a pneumatic circuit

Polyurethane is a flexible, elastic material, which is why the TU0604BU-20 bends easily, recovers its shape and tolerates the repeated flexing found on moving cylinders, slides and robot heads. The tube itself is only a conduit: the push-in fitting grips the outside of the tube and seals on it, so the outside diameter tolerance and a clean, square cut are what make the joint tight. The 4 mm bore gives a sensible flow for the small and medium cylinders and valves that use 6 mm fittings.

The catalogue notes that the model number is not printed on the tube body, so keep the roll label or note the code in the machine documentation for reordering.

Selection & Ordering Guide

• Size: TU0604 = 6 mm OD × 4 mm ID. Other metric sizes in the series run from TU0212 (2 mm) to TU1610 (16 mm); inch sizes are sold as TIUB.
• Colour: BU = translucent blue. The catalogue lists 29 colour variations, including black (B), white (W), red (R), yellow (Y), green (G), clear (C) and orange (YR).
• Length: -20 = 20 m roll; -100 = 100 m roll. A 100 m reel is available as a made-to-order option (suffix -X3).

If the application needs higher pressure or less elongation, a nylon tube of the same size may suit better; for welding areas, a flame-resistant tube is the correct choice. Our team can help confirm the correct ordering code.

Installation & Maintenance

• Cut the tube square with a proper tube cutter; never use pliers or side cutters.
• Push the tube fully into the fitting, then pull back gently to confirm it is held.
• Do not bend tighter than 15 mm radius; allow slack for moving parts so the tube is not stretched at the end of travel.
• Keep surge pressure below the maximum operating pressure, and avoid abnormal temperature rise from adiabatic compression, which the catalogue warns can burst the tube.
• Inspect lines on moving axes at regular intervals for cuts, abrasion and flattening, and replace sections that show wear.

Typical Applications in Oman & the GCC

The TU0604BU-20 is used for general air piping on packaging and filling machines, food and beverage lines, water treatment skids, assembly fixtures, and the pneumatic actuators found in oil and gas support equipment and building services. Colour-coded TU tubing makes fault-finding faster for maintenance teams working across many machines.

Why Source from Seven Star LLC

Seven Star LLC supplies SMC pneumatic tubing, fittings and automation components across Oman and the GCC. Send us the full ordering code, quantity and roll length to request a quote, and our team can help confirm the correct ordering code for your fittings.