electropolishing
& mechanical polishing
Electropolishing & mechanical polishing services
Astro Pak provides mechanical polishing, electropolishing, and electrolytic cleaning of stainless steel tanks, vessels and equipment for pre-operational preparation and for remediation after installation and use. Our surface finishing processes adhere to ASME BPE and ASTM B912 standards, providing optimal Ra (Roughness Average) finishes to your equipment and vessels. We use custom-designed tooling to ensure optimal contact with intricate stainless-steel surfaces, along with proprietary chemistry, for superior results. Our surface reconditioning solutions are geared towards enhancing the cleanability and durability of your equipment.
MECHANICAL POLISHING
Mechanical polishing removes corrosion, pitting, scratches or etchings which compromise the passive layer of stainless steel, creating a low-chromium area that is more susceptible to corrosion. Mechanical polishing also smooths welds where ferrules and valves have been replaced or added. Mechanical polishing alone is often sufficient for dry product vessels. For other applications, it is most often the first step prior to electropolishing and passivation.
ELECTROPOLISHING
Electropolishing removes impurities, and other embedded contaminants, also known as the Bielby layer, which forms during mechanical polishing. The result is a smooth, mirror-like finish where residue and even single-cell bacteria, will have no place to lodge. Often, electropolishing is the final process in preparing a vessel for service. However, combining electropolishing with passivation achieves a smooth chromium rich surface with improved cleanability and superior corrosion resistance.
ELECTROLYTIC CLEANING
Electropolishing is done for a prescribed amount of time at a set current density. Electrolytic cleaning, also referred to as “electrochemical cleaning” or “electrocleaning”, is performed with the same tooling, but at a lower power and only for the amount of time it takes for the surface to be visually clean or pass a wipe test. Rouge and other metallic surface contaminants can be rapidly removed from austenitic stainless (300 series) with an ELC process. Weld color or heat tint can also be removed using electrolytic cleaning, as this process is limited to the outermost surface of the metal.
PRE-OPERATIONAL
Newly fabricated vessels and equipment may have a shiny appearance, but metal debris and iron oxides left behind from machining and welding can cause premature corrosion. Our surface finish 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.
MAINTENANCE
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 mechanical polishing and electropolishing services will restore the surface finish of operational tanks and equipment with minimal downtime, and eliminate the need for system revalidation.
ASTRO PAK ELECTROPOLISHING CAPABILITIES
| ALLOY | CAPABILITY |
|---|---|
| Austenitic Stainless Steel | Yes |
| Ferritic Stainless Steel | Small quantities, call for more info |
| Duplex Stainless Steel | Small quantities, call for more info |
| Precipitation Hardened Stainless Steel | Small quantities, call for more info |
| Nickel-based Alloys (Hastelloy, Inconel) | Call for more info |
| Aluminum | No |
| Titanium | No |
| Cobalt | No |
| Copper | No |
exterior Surface Remediation
We also help our customers with exterior surface repair including removal of rust and/or staining on platforms, handrails, etc… While product purity and quality is the main focus of FDA inspections, don’t let staining on your facility exteriors have inspectors second guessing what’s going inside your system. While we’re cleaning your product contact surfaces, make sure you ask about our exterior surface repair services. Depending on your scope of work, we can tailor a plan that addresses your specific needs via mechanical, chemical, electrolytic, and/or hand detail methods.
Resources
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 …
ASTM B912, “Standard Specification for Passivation of Stainless Steels Using Electropolishing,” establishes requirements for producing and verifying a passive stainless steel surface through electropolishing. The specification covers stainless steels in …
As we’ve written many times before in this blog, stainless steel is far more than just “corrosion resistant metal.” While it is true that its material strength and resistance to …