Are there any special stainless steel tubing cutting or installation procedures needed for SilcoTek coated tubing? Here's a handy guide to installing and maintaining inert coated tubing.
If you've ever tried to install stainless steel tubing, you know there's some technique to cutting the tube, making up connections, and making precise bends. After you get the hang of it, working with stainless steel tubing is not too difficult. The same holds true when working with SilcoTek® coated stainless steel tubing. Here are some quick tips on installing and maintaining inert, corrosion resistant silicon coated tubing.
In this blog post you will learn:
Cutting SilcoTek® Coated Tubing
The project is all laid out and it's time to start fabricating. Time to cut the SilcoTek coated tubing. You can cut inert coated tubing the same way you'd cut any stainless steel tube. Cut stainless steel tubing by using a tube cutter or a powered tube cutting wheel. Do not use a hack saw which tends to skip across the tube surface (damaging the tubing) and will tend to leave an uneven rough cut which can interfere with tube fittings and result in a leak.
Select a tube cutter designed for the size and material of tubing you're cutting. When using a pipe cutter be sure the cutting wheel is specified for cutting stainless steel and not for cutting softer metal tubing like copper, aluminum, or brass. For longest life and best cut quality select a cutting wheel that is made of hardened tool steel and is designed with a thinner profile. A hard thin tube cutting wheel will make a clean cut with the least amount of burrs. A thin profile wheel will also make tube cutting easier with less effort. Want to purchase SilcoNert, Dursan, Silcolloy, or other coated tubing, fittings or other products? You can buy coated products directly from the manufacturer.After selecting the correct tube cutter and cutting wheel you're ready to make your cut. Mark the tube as needed, and follow the following steps:
- Insert tube into the tube cutter. (rotate the cutting wheel adjuster to open the cutter)
- Align the cutting wheel on the cut mark and rotate the cutting wheel depth adjuster to apply a slight amount of pressure onto the tube surface.
- Rotate the cutter to roll the tube cutting wheel around the tube. Roll the cutter around the tubing a few times, then increase the cutting depth by slightly tightening the cutting wheel adjuster. That will push the cutting wheel into the tube a bit more. Then continue rolling the tube cutter around the tube, adjusting the wheel depth as needed. You should see a "scratch" or mark around the tube that will begin to increase in depth. When the cutting wheel penetrates the tube wall the tube will snap apart. Here's a demonstration of cutting a stainless steel tube with a tube cutter.
You're not done yet though!
For analytical service, we recommend you take steps to prevent metal particulates from entering the tube during and after cutting. After cutting the tube you should be sure to angle the cut end downward to prevent particulates from sliding further into the tube. Tap the tube end to expel the tube cuttings and blow out the tube to remove fine particulates. It's important to remove particulates to prevent flow path contamination, avoid clogging of filters, and to stop particulates from adsorbing test analytes and impacting test accuracy. Here's a quick video demonstrating cutting of SilcoTek coated stainless steel tubing using a powered tube cutter and removing particulates from the tubing.
Can I bend the tubing?
The tubing is cut, now it's time to make some bends. You can bend SilcoTek coated tubing but there are minimum bend radius limits. You don't want to kink the tubing or stretch the outer tube wall to the point that the tube stretch creates voids in the coating surface. As a guide, we recommend a gentle sweep bend of the following radius:
|Tube size||Recommended bend radius|
|1/16 inch||1in radius|
|1/8 inch||2in radius|
|1/4 inch||4in radius|
|1/2 inch||8in radius|
|3/4 inch||12in radius|
Most standard tube benders can stretch the outer wall of the tubing and have too tight a bend radius, bend the tube using a mandrel that matches the recommended bend radius.
Watch our tube bending video to learn more.
Get more information on coated tubing performance. Get our chemical compatibility guide.
Anything special I need to know about installing fittings?
To install SilcoTek coated tubing all you need to do is follow the manufacturer recommended fitting make-up procedure. Here's an example from Swagelok®. For analytical and high purity applications avoid using snoop or other liquid leak detection sprays. Use an analytical leak detector, they're available from most chromatography supply houses. Here's an example from Restek®. Fittings should also be coated to assure an inert flow path. You don't need to coat the ferrule, just the fitting body. Ferrules are not significantly exposed to the flow path in a properly made up fitting.
It's that easy! You really don't have to take many special precautions when installing SilcoTek coated tubing in analytical systems. Just follow sound installation guidelines and the system should provide fast accurate analytical results for years to come.
Be sure to pick the right coating for the application. Get our coating selection guide.
Project is installed, now clean the tubing!
Avoid using steam to clean SilcoTek tubing. Steam is usually fairly dirty, especially in refinery and chemical process industries and can contaminate an analytical sampling flow path. A nitrogen flush or rinsing with a high purity solvent will prevent flow path contamination. Here's more information on tube flow path cleaning.
OK my tubing is installed, how do I maintain SilcoTek coated tubing and keep my tubing running at peak performance?
The care of a flow path surface is probably the most important factor in determining if the overall system will continue to deliver high purity, corrosion resistance or inertness over the life of the project or process. Ignore proper coating care and we'll likely be hearing from you about troubleshooting your system for reactivity or coating failure.
To avoid that scenario, here are a few helpful tips about how to keep your coating running like a top:
1. Keep it clean.
Maintain surface cleanliness to prevent cross contamination and accumulation of reactive particulates. Clean surfaces using the best minimally invasive method. Highly abrasive or basic (pH above 8) cleaners will damage the surface. We recommend using a non polar solvent like a high purity hexane to remove hydrocarbon contaminants, and a polar solvent to remove more active compounds. Get the highest purity solvent available, lower grades will leave a film on the surface.
Remember once you've cleaned and rinsed the surface, trace remnants of the solvent may remain on the surface. We've found many solvents can leave trace amounts of adsorptive or reactive substances on coating surfaces. Always test cleaning solvents for inertness and contamination before use in high purity or analytical applications.
2. Don't get steamed.
Refiners use steam to clean or purge sample transport flow paths; however, live steam can cause silicon surfaces to become active. Live steam can also deliver particulates at high velocity to the surface, damaging the coating. As an alternative, consider sonication of components for a short duration or flushing the system with a solvent. (Note: Sonication can also damage the coating surface; avoid leaving parts in ultrasonic cleaners for more than a few minutes.)
3. Don't exceed the pH range.
Exposure to bases above a pH of 8 can erode the silicon surface. One way to tell if the surface is being eroded is to check the color of the part. If you notice the iridescent rainbow coating color changing, it's a good indicator the coating becoming thinner and is being damaged.
4. Install filters in the flow path.
Particulates can damage silicon surfaces, especially when moving at high velocity. Particles can also react with process fluids or adsorb sample compounds, contaminating the flow path. Installing fritted filters in the sample flow path will prevent system contamination and avoid potential damage to SilcoTek® coated surfaces. Worried about activity in sintered metal frits? SilcoTek® can coat metal filters, helping analysts maintain system inertness while preventing particulate contamination.
Too much to remember? Here's a coating care guide to help keep your inert coating running at peak performance.
Performance For Life
It's not unusual to find a coated part still performing at peak inertness after many, many years of service. It all depends on the severity of the environment. For critical or severe environments, it's a good idea to inventory key coated components and monitor performance over time. Depending on the process environment and use, some customers recoat components periodically as part of an overall preventative maintenance program. Others monitor performance and if they find inertness is declining due to surface damage or contamination; they'll send the used part back to us for recoating. Most likely, the part will perform well over the life of the system and won't need to to be recoated, but for critical applications it's prudent to monitor performance.
Have more questions? Go to our Frequently Asked Questions page.