When to Use This Checklist

If you are about to order Festo plastic tubing, Festo nylon tubing, or replacement air hose for a machine, this checklist is for you. It is also for the person who will have to explain next week why the line is down because the tube did not fit. I handle pneumatic component orders for a maintenance team. I have been doing it for seven years—maybe eight if you count the six months I would rather forget. I have made enough expensive mistakes to fill a spare room with learning experiences. The worst one cost about $3,200 on a single order of tubing that looked right, came in the right packaging, and still caused a week of headaches. That one pushed me to stop ordering from memory and start using a real checklist. This checklist has seven steps.

Step 1: Write Down the Operating Conditions Before You Look at the Catalog

Every tube selection starts with what the line actually does. Pressure, temperature, media, movement, and exposure. Write that down before you look at part numbers. I know it sounds basic, but a lot of the mistakes I have encountered came from people who skipped this and went straight to a catalog.

Say you need higher pressure. Festo nylon tubing is usually my first choice because it is stiffer and holds its shape. Festo polyurethane tubing is better when the tube has to flex repeatedly or route around tight corners. Both are plastic tubing, but they are not interchangeable. If you order Festo plastic tubing without saying nylon or polyurethane, you leave it up to whoever fills the order to choose for you. That is not a good position to be in.

Back in 2021, I ordered a replacement for a broken air line and wrote only PU tube on the request. The vendor sent a flame-retardant version. It probably would have been fine, but the flex life was different and it failed again in eleven months. The lesson: material grade matters as much as the OD.

Step 2: Use the Current Festo Catalog and Support Portal, Not Memory

Do not trust your memory for the part number. I have been burned by part number changes more than once. Festo has a support portal and online catalog with datasheets and CAD downloads. Use it. Searching for Festo plastic tubing there is a starting point, but then narrow by material, OD, ID, pressure rating, and color.

One thing that surprised me: a part number can look identical across product families except for one letter. That letter can change the material from nylon to polyurethane. The naked eye will not always catch it. The catalog will.

If you are replacing an existing tube and the part number is still legible on the tube or the fitting, start with that. But still verify it in the current catalog. If the number was superseded, the catalog will show the replacement.

Step 3: Verify OD, ID, and Wall Thickness — Not Just the Size

6 mm tube is not a complete specification. Put another way: 6 mm is the outside diameter, not a full spec. A thicker wall can handle more pressure but less flow. If you replace a 6 mm tube with a 6 mm tube but the ID is smaller, the cylinder cycle time can slow down. In one case, that difference showed up as a timing failure on a pick-and-place station. It looked like a sensor issue. It was a tube issue.

Use a caliper on the old tube before ordering. Measure the OD and ID. If the tube has been stretched by an old fitting, measure in a section that was not clamped. Also check the cut length. We once ordered a roll when we needed cut lengths, and the result was a coil that no one wanted to deal with because it would not lie straight. That is an easy thing to miss.

Step 4: Do Not Assume Any Tube Works With Any Push-In Fitting

This one cost us real money. In 2022, we used a generic 6 mm tube with a Festo push-in fitting. It leaked. The tube OD was 5.95 mm instead of 6.00 mm. That 0.05 mm was enough. Not all plastic tubing is made to the same tolerance. When you buy Festo plastic tubing, you are buying a product designed to work with the fitting system. That is not a marketing line. It is a tolerance thing.

I am not saying every replacement tube has to be Festo. I am saying check the data sheet for the fitting's recommended tubing range. Some fittings are more forgiving than others. Some materials, like hard nylon, seat differently than soft polyurethane. If you are using a Festo fitting, the safest path is to use the tube listed in the same catalog for that fitting.

Step 5: Ask for Total Landed Cost, Not Just Price per Meter

This is the step I wish I had learned earlier. A price per meter is not the final price. Shipping, handling, minimum order quantities, cut length charges, and documentation fees all appear later. I have learned to ask what is NOT included before I ask what the price is.

Ask what is NOT included before you ask what the price is.

It sounds backwards, but it works. A vendor that shows all fees upfront might look more expensive at first, but it usually costs less in the end. A vendor that hides fees until the invoice is the one that makes you explain to your manager why the repair cost 20% more than the PO. Transparent pricing is worth paying for.

After one rush order, I pressed submit and immediately wondered whether I should have asked for a breakdown first. The spare parts arrived on time, but the invoice had a line item that I had not planned for. My fault, but the fee was avoidable.

Step 6: If You Color Code Lines, Verify Material — Not Just the Color

Color coding is great for troubleshooting. But a blue nylon tube and a blue polyurethane tube are not the same product. Do not assume that the same color means the same material. I did exactly that once. I saw blue tube on a spare parts list and ordered the first blue tube in the catalog. It was blue. It was also the wrong hardness. The fitting did not hold the way it should have.

If the color is critical for your line, get a physical sample before ordering a full batch. At least that has been the rule that works for us. Color in plastic is tricky. According to Pantone Color Matching System guidelines (pantone.com), Delta E below 2 is a normal tolerance for brand-critical colors. But a screen color is not a plastic sample. Ask for a chip.

Step 7: Keep a Labeled Sample in Your Maintenance Store

Here is the process gap that hurt us more than once. We did not have a formal sample retention process. We would order tube, install what we needed, and throw the scrap away. Six months later, someone would ask which part number we used on line three, and no one could answer. The third time this happened, I finally created a sample bin. Should have done it after the first time.

Now we keep a 10 cm piece of each new tubing order in a labeled bin. The label says the order date, the Festo part number, the size, and the machine or line it was for. That sounds simple, but it has already saved us from ordering the wrong material at least four times in the past 18 months.

When you receive the order, do not just check the packing list. Pull one tube out and check the printed text on the tube if there is any. Many Festo tubes have part number or material markings printed along the side. If the marking is missing, that is worth a quick call before you install it.

Two Material Questions That Are Not About Tubing

Sometimes the same search brings up other plastic materials. If you are also buying a plastic sheet roll for machine guards, glazing, or custom spacers, take the same approach. Plastic sheet is not one thing. PET, PP, PE, PVC, and PTFE all look like plastic and behave differently. Check material, thickness, temperature rating, and any UV resistance you need. A plastic sheet roll is easy to buy wrong if you only judge by look and thickness.

If you are looking at the polyurethane foam market for packaging or acoustic panels, remember that PU foam is a different product family from PU tubing. They share a polymer name, but the physical properties are completely different. A foam data sheet does not tell you anything about flex fatigue or pressure rating for tube. Do not mix them up in your sourcing process.

And for the common question: is polyethylene terephthalate plastic? Yes. PET is a thermoplastic polyester and it is widely used in bottles, film, and sheet. It is a plastic, but it is not the same as nylon or polyurethane. So do not assume a PET plastic sheet roll has the chemical resistance or flexibility of a polyurethane tube.

Common Mistakes I Still See

  • Ordering by OD only. A 6 mm tube can have wall thicknesses from 0.5 mm to 1.5 mm. That affects pressure and flow.
  • Choosing the softer tube just because it is easier to route. In a hot area, nylon often lasts longer than polyurethane.
  • Ignoring static dissipative requirements in areas that need them. If the machine has a hazardous area rating, do not guess. Check the spec.
  • Letting a nearly identical part number trick you. Write the full part number down and verify it in the current catalog.
  • Not asking about minimum order quantity. A 100 m roll might seem like the best price, but if you only need 12 m, the MOQ changes the real cost.

The point is not to make ordering Festo nylon tubing complicated. It is to slow down for five minutes now instead of explaining a $2,000 mistake later. I have made these errors so you do not have to. If you take one thing from this checklist, make it this: specify the material, verify the full part number, and ask for total cost before you commit.