Passivation
Passivation Services
Astro Pak has over 65 years of experience perfecting our passivation chemistries and processes. Our proprietary Ultra Pass® passivation process is renowned for its citric acid based blend of high-purity ingredients, significantly reducing safety and environmental risks along with financial costs associated with material handling and disposal. Moreover, it 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.
CLEANING BEFORE PASSIVATION
ON-SITE
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.
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.
Cleanroom
For cleanliness critical components, Astro Pak offers coast-to-coast Cleanroom Services facilities, featuring ISO 14644-1 certified Class 5, 6, and 7 cleanrooms and labs of various sizes and capabilities. These highly controlled environments support processes such as ultrasonic cleaning, pressure and cold shock testing, clean assembly, vacuum-sealed packaging, and cleanliness verification for particle count, TFS, and NVR.
accreditations
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.
PRE-OPERATIONAL
MAINTENANCE
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.
Hardware
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.
- Heat Exchangers
- Fillers
- Mixing Vats
- Blenders
- Churners
- Grinders
- Pasteurizers
- Bottling Equipment
- Process Columns
- Retorts
- Piping, Tubing, Hoses
- Gauges
- Sensors
- Transducers
- Valves
- Flanges
- Gaskets
- Manifolds
- Fasteners
- Filters
- Fittings
- Spools
- Vacuum Jacketed Vessels & Piping
- Pressure Vessels
- Distillation Columns
- Boilers
- Vaporizers
- Turbines
- Diffuser Grids
- Architectural Structures
- Purified Water (RO, DI, USP, WFI)
- High Purity Gas (GOX, GH2, GN2, GHE)
- Liquefied Gas (LOX, LH2, GN2, GHE)
- Oxygen
- Ozone
- Vapor Compression Stills
- Clean Steam Generators
- Water for Injection Tanks & Stills
- Sterilizers
- Autoclaves
- Lyophilizers
- Fermentors
- Bioreactors
- CIP, SIP Skids
- Chromatography Skids
- Ground Support
- High Pressure Air
- High Vacuum
- Cryogenic
- Fuel, Gas
- Lube Oil
- Hydraulic
- Hydrogen Peroxide
- Chlorine
biopharmaceutical
SPACE
Food & Beverage
Water & wastewater
semiconductor
We process a wide range of alloys including:
Stainless Steel, Carbon Steel, Aluminum, Copper, and Specialty Alloys
Project Showcase
Resources
Pickling and passivation are both chemical processes used to treat metal surfaces, but they serve different purposes and involve different chemicals. Pickling Pickling is a metal treatment process primarily used …
One of the most frequently asked questions online, “Which is better, passivation or electropolishing?” is driven by a misunderstanding of the two processes and the different roles they play. In …
Technical Summary The passivation process is a controlled chemical treatment used to remove free iron from the surface of corrosion resistant alloys, primarily stainless steel. By increasing the chromium-to-iron ratio …
FAQ
Most stainless steels (especially austenitic types) can be passivated, but levels of improvement vary between alloy type and quality of surface chemistry present. All stainless steels are alloys of iron and chromium, with most grades also including nickel. Chromium makes up at least 10% of the metal and gives stainless steel its resistance to corrosion. Some stainless steel grades include molybdenum to further enhance corrosion resistance, specifically pitting corrosion resistance.
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. Passivation is designed to remove the small amount of free iron from the visually clean 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 most commonly used data to evaluate the passive layer is the chromium-to-iron ratio and the passive layer depth, which can be measured using Auger Electron Spectroscopy (AES) and Electron Spectroscopy for Chemical Analysis (ESCA). The semiconductor and pharmaceutical industries 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. The passive layer is only a few atomic layers (about 2 to 10 nanometers) in thickness.
Passivation does not remove material. Passivation enhances the ability of the treated surfaces to resist 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.
Although the passive metal oxide film spontaneously forms in corrosion resistant and chromium-rich alloys, given the proper conditions, a new stainless steel vessel or part needs to be passivated prior to being placed into service. Fabrication, machining and welding leave behind contaminants such as metal oxides, inclusions, fabrication debris, and tramp iron, thereby compromising the metal’s natural ability to resist corrosion.