Industries ranging from analytical laboratory, oil & gas exploration, refining, chemical process, semiconductor, HPLC, & bio tech should pay attention to cleaning and maintaining a stainless steel critical flowpath; because a poorly cleaned surface will impact yield, product quality, lab results, and perhaps environmental compliance.
Cleaning stainless steel in some industries can be as simple as blowing the surface off with compressed air while in other industries, like GC or HPLC chromatography, it's important to evaluate the solvent to be sure it does not leave trace contaminants on the surface which can lead to analyte adsorption or false positive results. Cleanliness is truly in the eye of the beholder.
To take full advantage of a clean flowpath, you have to clean the entire system. It's not a question of how do I clean a sample cylinder, or how do I clean stainless steel tubing or that fitting, valve or regulator. It's about cleaning the entire system for optimum performance. It does no good to clean tubing, valves and fittings in an analytical system only to discharge the contents of a dirty sample cylinder into the flowpath.
So here are a few tips on maintaining and cleaning a stainless steel surface.
Do's and Don'ts of surface maintenance.
- Set a regular surface maintenance schedule. You do equipment preventative maintenance, why not PM your critical flowpaths?
- Don't steam clean. No matter what your surface, steam cleaning is not a good idea. Particulates commonly found in live steam will deposit on your surface, contaminating your process or sample.
- Do resurface as needed. Over time roads get pot holes, paint peels, furniture needs polishing; just about all surfaces need some sort of maintenance. So the next time you're driving down that rut filled road, think of your critical flowpath. I bet it needs maintenance too.
- Don't abrade or change surface roughness. A rough surface can trap contaminants and increase unwanted surface interaction.
When to clean.
Clean more often than you think! Set a cleaning schedule and learn the signs of surface contamination. You don't need to see goop dripping out of a critical flowpath to realize it needs to be cleaned. Signs you may need to clean the surface are:
- A film or other contamination on the surface
- Loss of peak or peak distortion, poor lab results
- Calibration problems
- Process contamination
How to clean your surface.
The key takeaway? Match the solvent to the contaminant:
Use the least aggressive, most effective high purity solvent. Why risk damaging or contaminating the surface if you don't need to.
Always follow the recommended and approved safety precautions as outlined in the product MSDS, company standards, industry standards, local, state, and federal regulations when handling and using solvents.
Common effective solvents are:
Different industries have different approved cleaning methods. Research industry publications for best practices and develop your own written method to assure consistency. The Compressed Gas Association CGA G-4.1 is a valuable resource for establishing baseline cleaning criteria in a variety of industries. Here's the table of contents. Unfortunately you'll have to purchase the entire document, but it's worth it if you need to develop the best cleaning method for your application.
Here are a few other sources for cleaning and sampling best practices:
Cleaning of stainless steel:
Natural gas stream sampling:
Air analysis sampling:
High purity tubing with cleaning information from Swagelok®.
What do semiconductor processing, stack probes, analytical instrumentation and refining have in common? They all have critical surfaces that must be maintained in order to keep their processes running smoothly. What areas, to what degree, and how surfaces are cleaned and maintained vary by industry. Our coatings assure a high purity high performance surface. Take a few minutes to watch our webinar to learn how to maintain coated surfaces. You'll be glad you did.
*image courtesy of Swagelok®