Descaling
DESCALING SERVICES
Descaling is defined in ASTM A380-25 as, “the removal of heavy, tightly adherent oxide films resulting from hot-forming, heat-treatment, welding, and other high-temperature operations.” Astro Pak covers descaling as defined in ASTM A380 with our pickling services
Our specific definition of descaling is the removal of mineral deposits that accumulate on metallic surfaces from hard water. Scale, per Astro Pak’s definition, is calcium or magnesium salts instead of heavy metal oxides mentioned in the ASTM A380 definition. These hard water deposits typically appear as a hard white or brownish layer. If left untreated, scale can reduce flow rates, lower heat transfer efficiency, and even lead to equipment failure.
Astro Pak provides specialized descaling solutions tailored to the system and level of buildup. Our services are performed in compliance with ASTM A380 methods, using both chemical and mechanical methods to ensure safe and thorough removal of hard water scale. Each project is closely monitored, with progress tracked and documented to validate effectiveness and ensure compliance.
Chemical Descaling
- Uses acids such as sulfamic and phosphoric acid
- Removes calcium carbonate, magnesium hydroxide, and other mineral deposits
- Safe for stainless steel, carbon steel, copper alloys, and aluminum with inhibitors
- Often followed by passivation or electropolishing to restore surface protection
Mechanical Descaling
- Applied for stubborn or heavy deposits that resist chemical cleaning
- Methods include sanding, grinding, abrasive blasting, polishing, and pigging
- Effective for localized buildup in piping, tanks, or heat exchangers
- Commonly paired with chemical descaling for complete system cleaning
Before & After: Heavy Calcium Carbonate Deposits
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 derouging, 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.
Resources
Water Treatment Pipeline Descale
A critical section of water infrastructure in Northern California required restoration to ensure reliable delivery of clean water to residential and agricultural users. Round-the-clock descaling operations restored full capacity while protecting the watershed.
Pickling & Passivation
Providing on-site pickling & passivation services to remove contaminants and enhance the corrosion resistance of stainless steel surfaces, ensuring optimal performance and longevity.
Water Wastewater
Our comprehensive range of pre-commissioning (or pre-operational) services include organic contamination and mill-scale removal, sanitization, disinfection, and passivation of piping and equipment.
Frequently Asked Questions
Descaling is the process of removing mineral deposits, such as calcium carbonate and iron oxides, that accumulate on stainless steel and process equipment over time.
Scale forms when the dissolved metals in hard water, calcium and magnesium, react with organic ions like hydroxide, carbonate, and sulfate. Higher temperature or dirtier water can speed the formation rate of scale.
Descaling can restore flow rates and heat transfer efficiency lost due to scale buildup.
Yes. When performed according to ASTM A380/A380M-17 standards and using the correct formulations, descaling is safe for stainless steels and other corrosion-resistant alloys.
Derouging removes iron oxide staining, while descaling targets mineral and hardness deposits. Both are important for maintaining system performance and cleanliness.
Descaling is not the same as passivation. Passivation dissolves microscopic metallic contaminants deposited on a stainless steel surface from unclean or improper fabrication or corrosion while descaling dissolves the calcium and magnesium compounds formed due to water hardness. Passivation enhances stainless steel’s passive oxide layer, increasing corrosion resistance while descaling restores the flowability and heat transfer capability of the scaled equipment.
After descaling, systems are typically passivated or electropolished to restore the protective chromium oxide layer and prevent future corrosion or buildup.
Tracking pH during descaling is a useful method to determine the progress and completion status of the chemical process.
Descaling, per Astro Pak’s definition, typically does not generate hazardous waste. Astro Pak pickling, or descaling per the ASTM A380 definition, generates hazardous waste.