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The Dry Ice Blasting Process
Dry ice blasting uses solid CO₂ pellets accelerated in a compressed air stream to remove fouling, scale, and contaminants from equipment surfaces. The cleaning action combines three mechanisms:
1. Kinetic impact – Pellets strike the surface, breaking the bond between contamination and substrate
2. Thermal shock – The extreme cold (-78.5°C) causes differential contraction between fouling and base material, creating micro-fractures
3. Sublimation expansion – CO₂ transitions directly from solid to gas on impact, expanding 800× in volume and lifting contamination away
Unlike abrasive blasting or chemical cleaning, dry ice leaves no secondary waste—the CO₂ sublimates completely, leaving only the removed contamination to collect. This eliminates post-cleaning washdown, reduces disposal costs, and allows faster return to service.
The process is non-abrasive when properly controlled, making it suitable for precision equipment including finned heat exchangers, electrical components, and turbine blades where surface integrity must be preserved.
A typical dry ice blasting setup requires:
CORE EQUIPMENT:
• Blasting unit – Controls pellet feed rate and air/pellet mixing. Available in single-hose (pellets + air combined) or dual-hose configurations (separate streams)
• Air compressor – Typically 185-375 CFM at 80-125 PSI for industrial applications. Must deliver oil-free, dry air to prevent contamination
• Dry ice pellets – Stored in insulated containers. Standard pellets are 3mm diameter; rice pellets (1-3mm) used for delicate applications
SITE REQUIREMENTS:
• Adequate ventilation or atmospheric monitoring (CO₂ can displace oxygen in confined spaces)
• Containment barriers to collect dislodged contamination
• Electrical power for compressor and blasting unit
• Access routes for equipment delivery
SAFETY EQUIPMENT:
• Thermal-insulated gloves for pellet handling
• Safety glasses and hearing protection
• CO₂/O₂ monitors for confined space or poorly ventilated areas
• Respiratory protection if working with hazardous contamination (NORM, carcinogens, etc.)
Setup time is typically 1-4 hours depending on site access, ventilation requirements, and safety permit complexity.
The CO₂ pellets sublimate completely upon impact, transitioning directly from solid to gas without passing through a liquid phase. This is the key advantage over water washing, chemical cleaning, or abrasive media.
WHAT HAPPENS DURING BLASTING:
• Pellets strike the surface at -78.5°C
• Impact energy and surface heat cause instant sublimation
• CO₂ gas expands 800× in volume, helping lift contamination
• Gas disperses into the atmosphere or is extracted by ventilation
WHAT’S LEFT BEHIND:
• Only the dislodged contamination – fouling, scale, coatings, or debris that was removed
• No blast media residue – No sand, grit, water, or chemical solution requiring cleanup
• No secondary waste streams – Nothing to rinse, neutralize, or dispose of beyond the original contamination
VENTILATION CONSIDERATIONS:
In enclosed or poorly ventilated spaces, CO₂ can accumulate and displace oxygen. This requires:
• Atmospheric monitoring with O₂/CO₂ detectors
• Forced ventilation or natural airflow to maintain O₂ levels above 19.5%
• Confined space entry protocols if working inside vessels or structures
The sublimation process is complete within seconds. Once blasting stops and ventilation occurs, CO₂ levels return to normal atmospheric concentration (typically within minutes to hours depending on enclosure volume).
ENVIRONMENTAL NOTE:
The CO₂ used in dry ice production is typically captured as a byproduct of industrial processes (ammonia production, ethanol fermentation, etc.) rather than being newly generated. Using it for cleaning represents recycling of existing CO₂ rather than adding new emissions to the atmosphere.
Aerial Cooler & Heat Exchanger Applications
Fouling on air-cooled heat exchangers (ACHEs), fin-fan coolers, and tube bundles acts as thermal insulation, reducing heat transfer efficiency and increasing process temperatures or compressor loads. Dry ice blasting removes this fouling without damaging delicate fin structures, enabling:
PERFORMANCE RECOVERY:
• Airflow restoration: 15-40% improvement in airflow through fouled bundles (measured via pressure drop or anemometer)
• Heat transfer recovery: 20-60% improvement in heat rejection capacity, depending on initial fouling severity
• Process impact: Reduced outlet temperatures, lower compressor discharge pressures, decreased energy consumption
WHY IT WORKS FOR FINNED EQUIPMENT:
• Non-abrasive action preserves thin aluminum or copper fins (0.2-0.5mm thick)
• Sublimation reaches between tightly spaced fins (2-4mm pitch) where brushes and water washing struggle
• No water introduction means no risk of freeze damage in cold climates or corrosion in carbon steel units
TYPICAL APPLICATIONS:
• Refinery overhead condensers
• Gas plant propane/ethylene coolers
• Compressor aftercoolers and intercoolers
• Lube oil coolers
• Transformer radiators
VERIFICATION:
Post-cleaning effectiveness is measured through thermal imaging, airflow testing, or process monitoring (outlet temperatures, pressure drop). Visual inspection alone often underestimates improvement since internal fin surfaces may appear clean while still retaining invisible films.
Yes—dry ice blasting is often faster than conventional cleaning methods and can be integrated into turnaround schedules without creating bottlenecks. Key advantages:
SPEED FACTORS:
1. No secondary cleanup required – Chemical cleaning requires rinsing, neutralization, and disposal coordination. Water washing requires drying time. Dry ice leaves only the dislodged contamination to collect—saving 4-12 hours per unit.
2. Parallel operations possible – Multiple blasting crews can work simultaneously on different equipment without sharing water supplies or chemical mixing stations. Particularly valuable when cleaning multiple ACHEs or cooler banks.
3. No cure time or dry time – Equipment can be reassembled and pressure-tested immediately after blasting. Chemical inhibitors may require hours to dry; water washing requires complete drying to prevent corrosion or freeze damage.
4. Equipment can remain in place – For ACHEs, dry ice blasting can be performed in situ without removing bundles from the frame (depending on access and fouling severity). Avoids rigging, lifting, and reinstallation delays.
TYPICAL TIMEFRAMES:
• Small ACHE (4-tube bundle): 2-6 hours
• Large refinery overhead condenser: 8-16 hours
• Compressor package (aftercooler + intercoolers): 4-8 hours
CRITICAL PATH INTEGRATION:
Dry ice blasting is typically scheduled during the equipment cleaning and inspection window, running concurrently with:
• Mechanical inspections on other equipment
• Catalyst changeouts
• Vessel internal work
• Instrumentation calibration
Because it doesn’t generate liquid waste or require permit-to-work extensions for chemical handling, it rarely becomes the limiting activity in the turnaround schedule.
Dry ice blasting is not universally superior to all alternatives—the optimal choice depends on fouling type, equipment constraints, site conditions, and operational priorities. Here’s a decision framework:
CHOOSE DRY ICE BLASTING WHEN:
✓ Substrate is delicate or precision-critical
– Finned heat exchangers (0.2-0.5mm aluminum fins)
– Turbine blades with tight tolerances or thermal barrier coatings
– Electrical switchgear, motors, or control panels
– Soft metal surfaces (aluminum, copper, brass)
✓ Water is restricted or problematic
– Cold climate operations (risk of freeze damage)
– Water-sensitive equipment (electrical gear, open motors)
– Arid regions with limited water supply
– Sites lacking wastewater treatment infrastructure
✓ Secondary waste disposal is costly or complex
– NORM-contaminated equipment (no need to dispose of radioactive blast media or rinse water)
– Hazardous fouling (lead, asbestos, carcinogens) where minimizing waste volume reduces disposal costs
– Sites with strict discharge permits
✓ Downtime must be minimized
– Turnarounds with tight critical paths
– Online cleaning of accessible equipment (some applications)
– Situations where drying time or chemical cure time would delay restart
✓ Fouling is moderately bonded, organic, or brittle
– Hydrocarbon films, waxes, greases
– Biological growth (algae, mold)
– Light to moderate corrosion products
– Dust, pollen, atmospheric soiling
CHOOSE ALTERNATIVE METHODS WHEN:
✗ Fouling is extremely hard or thick
– Heavy mineral scale (>5mm thick calcium carbonate, silicates)
– Welded slag or metallurgical scale
– Hardened concrete or refractory
→ Better option: Abrasive blasting, grinding, or chemical dissolution
✗ Equipment requires chemical passivation or coating
– Stainless steel needing re-passivation after cleaning
– Surfaces requiring phosphate conversion coatings
– Equipment needing corrosion inhibitor films
→ Better option: Chemical cleaning with integrated passivation step
✗ Tube internals with heavy deposits
– Exchanger tubes with thick scale buildup inside
– Piping with internal corrosion products
→ Better option: Chemical circulation cleaning, mechanical pigging, or hydrojetting
Return to Operation & Safety
Verification methods depend on the equipment type, contamination being removed, and industry standards. Visual inspection alone is often insufficient because residual films, internal fouling, or incomplete cleaning may not be visible to the naked eye.
VERIFICATION APPROACHES BY EQUIPMENT TYPE:
HEAT EXCHANGERS / AERIAL COOLERS:
• Thermal imaging – Compare surface temperature uniformity before and after cleaning. Hot spots indicate remaining fouling or airflow blockage.
• Airflow measurement – Use anemometer or pressure drop testing to confirm airflow restoration through fin banks.
• Process monitoring – Track outlet temperatures, approach temperatures, or heat duty after return to service.
• Acceptance criteria: Typically 80-95% restoration of design performance, depending on equipment age and baseline condition.
ELECTRICAL EQUIPMENT:
• Insulation resistance (megger) testing – Verify no conductive contamination remains on electrical components.
• High-potential (hipot) testing – Confirm dielectric strength meets manufacturer specifications.
• Acceptance criteria: Resistance values above minimum thresholds per IEEE or manufacturer standards.
NORM-CONTAMINATED EQUIPMENT:
• Radiation survey – Use calibrated gamma detectors to measure surface activity.
• Wipe testing – Collect swab samples to verify removable contamination is below regulatory limits.
• Acceptance criteria: <1000 dpm/100cm² (removable) and background levels for fixed contamination (varies by jurisdiction).
TURBINES / ROTATING EQUIPMENT:
• Borescope inspection – Verify complete removal of deposits from blade surfaces and gas paths.
• Dimensional verification – Confirm critical clearances and tolerances are maintained (not eroded by cleaning).
• Acceptance criteria: Visual cleanliness per OEM standards; no pitting, erosion, or coating damage.
FOOD PROCESSING / PHARMACEUTICAL:
• ATP swab testing – Measure adenosine triphosphate (biological contamination indicator).
• Microbiological sampling – Confirm sterility or acceptable colony counts.
• Acceptance criteria: <10 RLU for ATP; <10 CFU/cm² for microbial counts (varies by application).
DOCUMENTATION:
Cleaning verification should include:
• Before/after photographs (time-stamped)
• Measurement data (thermal images, airflow readings, radiation surveys, etc.)
• Operator sign-off and QA/QC approval
• Equipment ready-for-service clearance per site permit-to-work system
Dry ice blasting presents specific hazards that require training, engineering controls, and procedural safeguards. The primary risks are oxygen displacement, cold contact, and noise exposure.
PRIMARY HAZARDS AND CONTROLS:
1. OXYGEN DISPLACEMENT (MOST CRITICAL)
Hazard: CO₂ is heavier than air (density 1.5× air) and displaces oxygen in low-lying or enclosed spaces. O₂ levels below 19.5% cause hypoxia; below 16% can lead to unconsciousness without warning.
Controls:
• Atmospheric monitoring with calibrated O₂/CO₂ detectors (continuous or spot-check, depending on enclosure)
• Forced ventilation (blowers, exhaust fans) to maintain air exchange
• Confined space entry permits for work inside vessels, pits, trenches, or poorly ventilated structures
• Emergency evacuation procedures and rescue equipment (harnesses, retrieval systems)
• Worker training on hypoxia symptoms (dizziness, headache, rapid breathing)
2. COLD CONTACT BURNS
Hazard: Dry ice pellets at -78.5°C cause frostbite on skin contact within seconds.
Controls:
• Thermal-insulated gloves (not standard work gloves) for pellet handling
• Long sleeves and full-length pants to prevent pellet contact with bare skin
• Safety glasses or face shields (pellets can ricochet)
3. NOISE EXPOSURE
Hazard: Blasting units and air compressors generate 80-110 dBA, depending on equipment and distance.
Controls:
• Hearing protection (earplugs or earmuffs) for operators and nearby workers
• Noise barriers or enclosures for prolonged operations
• Hearing conservation program compliance (OSHA 29 CFR 1910.95 or equivalent)
4. HAZARDOUS CONTAMINATION
Hazard: Blasting dislodges contamination (NORM, lead, asbestos, hydrocarbons, etc.) which becomes airborne or settles as dust.
Controls:
• Respiratory protection appropriate to contamination type (P100 filters for particulates, supplied air for IDLH atmospheres)
• Containment barriers (plastic sheeting, tarps) to limit contamination spread
• HEPA vacuums or wet methods to collect dislodged material
• Pre-job hazard assessment and industrial hygiene monitoring
5. PRESSURE HAZARDS
Hazard: Compressed air at 80-125 PSI can cause injection injuries or eye damage.
Controls:
• Never point blast nozzle at people or body parts
• Lock-out/tag-out procedures during equipment maintenance
• Pressure relief and safety interlocks on blasting units
TYPICAL SAFETY PLAN ELEMENTS:
• Pre-job hazard assessment (JSA or SWMS)
• Atmospheric monitoring plan (O₂/CO₂ trigger levels and response)
• Ventilation calculations and verification
• PPE requirements (respiratory, thermal, hearing, eye protection)
• Emergency response procedures (hypoxia rescue, cold burns, pressure injuries)
• Exclusion zones and barricades
REGULATORY CONSIDERATIONS:
• OSHA 29 CFR 1910.146 (Permit-Required Confined Spaces)
• OSHA 29 CFR 1910.134 (Respiratory Protection)
• OSHA 29 CFR 1910.95 (Occupational Noise Exposure)
• ACGIH TLV for CO₂: 5000 ppm (8-hr TWA), 30,000 ppm (15-min STEL)
• OSHA PEL for O₂: must maintain ≥19.5% in breathing zone
When properly controlled, dry ice blasting is non-abrasive and safe for most industrial surfaces. However, improper technique, excessive pressure, or use on incompatible substrates can cause damage. Understanding the mechanisms and limits is essential for safe application.
WHY IT’S GENERALLY NON-DAMAGING:
• Soft media: Dry ice pellets have a Mohs hardness of ~2 (similar to fingernail), compared to sand (7) or glass bead (6-7).
• Sublimation on impact: Pellets disintegrate rather than ricocheting or embedding in the surface.
• Controlled kinetic energy: Adjustable air pressure and pellet feed rate allow tuning to match substrate sensitivity.
WHEN DAMAGE CAN OCCUR:
✗ Soft metals or degraded coatings
Risk: Aluminum, copper, lead, or soft alloys can erode under high-pressure blasting (>100 PSI).
Solution: Reduce air pressure to 40-80 PSI; use rice pellets (smaller, lower mass); increase standoff distance.
✗ Thermal barrier coatings (TBCs) or precision surfaces
Risk: Ceramic TBCs on turbine blades or thin organic coatings may delaminate if bond is already weakened by thermal cycling or corrosion.
Solution: Avoid blasting if coating adhesion is suspect; use low-pressure settings; test on inconspicuous area first.
✗ Brittle materials (glass, ceramics, certain plastics)
Risk: Thermal shock from -78.5°C can cause micro-cracking in thermally sensitive materials.
Solution: Avoid dry ice blasting on glass windows, certain acrylic plastics, or brittle ceramics. Use alternative methods.
✗ Extremely thin materials (<0.5mm)
Risk: Thin foils, shims, or corroded metal may perforate under direct impact.
Solution: Visual inspection for base metal condition before blasting; reduce pressure; avoid direct perpendicular impact.
SAFE APPLICATIONS (WELL-ESTABLISHED):
✓ Aluminum and copper fins (0.2-0.5mm) on heat exchangers – tested extensively without damage when using 60-100 PSI and proper technique
✓ Electrical components (motors, switchgear, transformers) – non-conductive, no water introduction
✓ Stainless steel, carbon steel, cast iron – robust substrates tolerate standard blasting parameters
✓ Turbine blades with intact coatings – used by OEMs and operators for compressor cleaning (with low-pressure protocols)
✓ Rubber gaskets, seals, O-rings – not damaged by dry ice when blasted indirectly (contamination removed from adjacent surfaces)
PRE-CLEANING ASSESSMENT:
Before blasting sensitive equipment, evaluate:
1. Substrate material and thickness – Consult equipment drawings or use ultrasonic thickness gauging for corroded areas
2. Coating condition – Perform adhesion testing (tape test, scratch test) if coating integrity is unknown
3. Existing damage – Identify cracks, corrosion, or weak areas that could propagate during cleaning
4. Trial area – Blast a small, inconspicuous section first and inspect for any adverse effects
Environmental & Sustainability
Dry ice blasting offers measurable environmental advantages over conventional cleaning methods, primarily by eliminating secondary waste streams and reducing chemical/water consumption. However, it’s important to distinguish actual benefits from marketing claims.
VERIFIED ENVIRONMENTAL BENEFITS:
✓ NO SECONDARY WASTE MEDIA
• Chemical cleaning generates spent solvents, acids, or alkaline solutions requiring treatment and disposal
• Abrasive blasting (sand, grit, walnut shells) creates contaminated media requiring disposal as hazardous or non-hazardous waste
• Water washing generates contaminated rinse water requiring oil/water separation or wastewater treatment
• Dry ice leaves only the original contamination – the dislodged fouling or debris, with no added waste volume
✓ REDUCED WATER CONSUMPTION
• Critical in arid regions or sites with limited water supply
• Avoids wastewater discharge permitting and treatment costs
• No risk of groundwater contamination from wash-down runoff
✓ ELIMINATES CHEMICAL EXPOSURE AND DISPOSAL
• Avoids toxic or corrosive chemical handling (safety benefit + environmental benefit)
• No soil or groundwater contamination risk from chemical spills
• Reduces regulatory burden (fewer hazardous waste manifests, disposal audits)
✓ USES RECYCLED CO₂
• Dry ice is typically produced from captured CO₂ that is a byproduct of industrial processes:
– Ammonia production (Haber-Bosch process)
– Ethanol fermentation (breweries, biofuel plants)
– Natural gas processing (CO₂ separation from methane)
• Using this CO₂ for dry ice represents recycling rather than generating new emissions
• The CO₂ would otherwise be vented to atmosphere or flared
IMPORTANT CLARIFICATION – NOT “CARBON NEGATIVE”:
While dry ice blasting uses recycled CO₂, it is not carbon-negative or climate-mitigating:
• The CO₂ captured for dry ice production would likely have been released to the atmosphere anyway (from fermentation or industrial processes)
• Blasting releases this CO₂ back to the atmosphere upon sublimation
• Net atmospheric impact: neutral to slightly positive (energy used for liquefaction and pelletization adds a small emissions burden)
This is still environmentally preferable to chemical cleaning (which generates waste + emissions) but should not be marketed as a climate solution.
WHEN ENVIRONMENTAL BENEFITS ARE GREATEST:
• NORM decontamination: Avoids creating radioactive wastewater or contaminated blast media
• Hazardous fouling removal: Minimizes volume of hazardous waste requiring disposal (only the fouling itself, no added media or rinse water)
• Water-scarce regions: Desert facilities, remote sites, or areas with water use restrictions
• Sites with strict discharge limits: Facilities unable to discharge wastewater or chemical rinse without expensive treatment
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For detailed technical guidance on specific applications, consult the linked whitepapers or contact Co2Blast Ltd. for site-specific engineering support.