On Site & Shop Passivation Services

Astro Pak has over 60 years of experience perfecting our passivation chemistries and processes.  We bring that expertise, along with our state-of-the-art equipment and highly trained personnel, on-site to your facility to perform pre-operational or maintenance cleaning and passivation on your systems and equipment.

Our highly skilled technicians and controlled environments ensure consistent quality and compliance to industry and customer-specific standards. Our proprietary Ultra Pass® passivation process is renowned for its environmentally friendly blend of high-purity ingredients, including chelants that bind with metal ions rendering them incapable of redepositing on surfaces.  As a result, the material handling requirements and other impacts on-site are greatly reduced.

Beyond that, the Ultra Pass® passivation process provides superior results, capable of producing an optimized passive layer on the surface of stainless steels, yielding unmatched corrosion resistance. Our studies have shown that the chrome to iron ratios achieved by Ultra Pass® passivation far exceeds ASME BPE recommended minimums and meets or exceeds the requirements of many industries including semiconductor, aerospace, pharmaceutical, and biotechnology.


On-Site mobilization field team

Whether you’re conducting a planned shutdown or require emergency response, Astro Pak can mobilize crews from one of our nationwide locations to your facility, utilizing a modern fleet of service vehicles, pump skids, and our chemistries and processes. We provide passivation, surface finish, and a wide range of chemical cleaning services, circulating our chemistry through your systems and equipment.


Florida Cleanroom Shop

For components, parts and sub-systems that can be cleaned out-of-place, our shops are well suited to meet your cleaning and passivation requirements. Our nationwide shop facilities deliver prompt and reliable service and features state-of-the-art equipment that can accommodate hardware of all sizes and volumes. We have dip tanks up to 40ft and overhead bridge cranes with 10 ton lifting capacity for oversized parts.


Passivation of new systems is an important part of the “start-up” phase of construction. Newly fabricated and welded piping and vessels may have a shiny appearance, but metal debris and iron oxides left behind from machining and welding can cause premature corrosion. Our cleaning and passivation solutions remove these contaminants and impart an optimized passive layer on the surface of stainless steel, thereby enhancing corrosion resistance and extending equipment maintenance intervals.


Over time existing systems may develop process application residues, rouge/rust, pitting, bioburden, scratches, and other internal or external surface conditions that can compromise product quality and equipment integrity. Our on-site cleaning, derouging, passivation, mechanical polishing and electropolishing services will restore the surface finish of operational tanks and distribution piping with minimal downtime, and eliminate the need for system revalidation.


Astro Pak has cleaned hardware and components for almost every cleanliness critical industry and application since 1959. Our studies have shown that the chrome to iron ratios achieved by our Ultra Pass® passivation far exceeds ASME BPE recommended minimums and meets or exceeds the requirements of many industries including pharmaceutical, biotechnology, space and semiconductor. Some of the world’s most prestigious institutions including JPL, Lawrence Livermore National Laboratory, MIT, and Cal-Tech have sought guidance and consultation from our subject matter experts. For cleanliness critical components our Cleanroom Services locations are ITAR certified and feature ISO 14644-1 certified Class 5, 6, or 7 cleanrooms and labs of varying sizes and capabilities. We also house an extensive library of approved procedures and meet the standards and specifications set forth by both industry regulatory bodies and private organizations. Our Cleanroom Services locations maintain AS9100 certified Quality Management Systems.


Our Engineering Services Group have a wealth of experience working on a variety of systems, designing efficient and intricate flow paths to maximize time and material costs.


We have extensive experience working with Process and Utility Piping and Tanks of varying lengths and sizes employed in a myriad of industries, systems, and applications.



Food & Beverage

Water & wastewater


We process a wide range of alloys including:

Stainless Steel, Carbon Steel, Aluminum, Copper, and Specialty Alloys

Project Showcase

Food & Beverage

Distillery Dry House


Process Vessel


Frequently Asked Questions

Most stainless steels (especially austenitic types) can be passivated, but levels of improvement vary between alloy type and quality of surface chemistry present.
Passivation removes iron and small amounts of very light rouge from the surface thus enhancing corrosion resistance. Heavier amounts of rouge must be derouged to prepare for the passivation treatment.
That depends upon the quality level desired and the sensitivity of the product process to low levels of iron or iron oxides. It also depends upon the methods used to refine the final product, including filtration, evaporation/drying, or iron’s effect on the biotech process. Generally, lightly discolored wipes or faintly visible rouge is acceptable, distinctly colored wipes or significant surface discoloration is unacceptable. Use of filtration testing to measure the amount and size of particles in the process fluids can be used as a guide to evaluate the effect of rouge coming off the surface.
By taking samples before and after the passivation treatment and testing them for chromium to iron ratio, one can quantify the quality of the passive film. The semi-conductor and pharmaceutical industry have set stringent measurable standards for systems or levels of purity.
We conduct iron readings of the solution circulating the system.  At the beginning of the passivation process, iron concentration levels start out high and gradually taper off and plateau when all the iron is removed.  Additionally, we know that 2% citric will hold in solution 1% iron (1 % iron is equal to 10,000ppm).  We typically see iron concentration levels in the 1 to 50 ppm levels in our passivation.  Our proprietary blend uses substantially higher percentages of citric to ensure that all iron is captured before the acid is exhausted.
No, only on a molecular level. Passivation enhances the chemistry of the passive layer by increasing the ratio of very stable chromium atoms to the more reactive iron atoms in the upper three to five atomic layers of the metal’s surface.
Passivation does not remove material. Passivation enhances the ability of the treated surfaces to resist corrosion.
As the pit develops, it starts out shallow and deepens but the debris inside the pit cannot be removed. The pitting process will continue until it creates a hole in the pipe or surface.
Generally speaking – No. However, one can consider that corrosion undoes passivation by attacking the passive film. Reducing environments will undo passivation and render the surface active or corroded. The passive layer is very thin (2 to 5 molecular layers) and can be eliminated by welding or polishing, by reducing environments and corrosion.
Derouging is the removal of visible iron oxides and other metal oxides from the surface. Passivation is the removal of iron or iron oxide from the surface in the passive film or top 3 to 4 molecular layer. Derouging uses stronger acids to remove large visible accumulations of iron oxides to a visually clean condition. Passivation is designed to remove the small amount of free iron from the visually clean surface.
The passive layer is very thin (2 to 5 molecular layers) and can be removed by welding, polishing, by reducing environments and corrosion.
Typical passivation process takes 8 to 10 hours in small systems and generally 12 hours for larger systems. Derouging alone can take 4 to 24 hours depending upon the condition of the surface.
Passivation enhances the chemistry of the passive layer by increasing the ratio of very stable chromium atoms to the more reactive iron atoms in the upper three to five atomic layers of the metal’s surface.
Yes. Visually the surface looks like it has spots (white, black or brown) hazing or roughness. The pits need to be sanded/polished out and electropolished. If the pits are very deep, then the surface will need to be ground, welded and then polished and electropolished.
Regular scheduled preventive maintenance and reduction of corrosive conditions – i.e reduce the use and concentration of chloride containing solutions or choose more resistant alloys where chlorides and heat are present.