What’s the best way to clean out a tank?

The best way to clean out a tank depends on what the tank holds, the type of deposits inside, and the surface condition required afterward. For most industrial tanks, high-pressure water jetting is the most effective and versatile method, capable of removing sludge, scale, and residue without damaging the substrate. The sections below cover methods, timing, safety, equipment, and quality standards in detail.

What methods are used for industrial tank cleaning?

Industrial tank cleaning relies on several proven methods, each suited to different deposit types and tank conditions. The most widely used approaches are high-pressure water jetting, chemical cleaning, mechanical scraping, and vacuum extraction. In practice, the most effective tank cleaning solutions combine more than one method depending on the severity of contamination and the surface preparation standard required.

High-pressure water jetting uses water delivered at pressures ranging from 500 to 3,000 bar to cut through sludge, scale, and hardened residues. It works without chemicals, generates no toxic fumes, and leaves surfaces ready for inspection or coating. Chemical cleaning dissolves organic residues and biological growth, making it useful when mechanical access is limited. Mechanical scraping is reserved for very heavy scale deposits that resist water alone. Vacuum extraction removes loosened debris and liquid waste simultaneously, keeping the work area clean and compliant with environmental regulations.

For oil storage tanks, cargo holds, and process vessels in the petrochemical and energy sectors, water jetting combined with vacuum recovery has become the industry standard. It minimises waste disposal costs, reduces operator exposure to hazardous materials, and consistently meets the surface cleanliness grades demanded before recoating or inspection.

When should you use high-pressure water jetting to clean a tank?

High-pressure water jetting is the right choice when a tank contains hydrocarbon residues, scale, rust, or old coatings that need to be removed to a defined cleanliness standard. It is especially appropriate when chemical use is restricted, when the substrate must not be damaged, or when the cleaned surface needs to be inspected or recoated immediately after cleaning.

Specific situations that call for water jetting include:

• Oil storage tanks requiring removal of sludge and hydrocarbon residue before inspection or maintenance
• Cargo holds on vessels where residue from previous loads must be fully removed
• Process vessels in petrochemical plants where scale or fouling reduces capacity or efficiency
• Tanks being prepared for recoating, where the surface must meet a specific cleanliness and roughness profile
• Environments where abrasive blasting is restricted due to dust, fire risk, or environmental regulations

Water jetting at pressures above 1,700 bar (“24,656 PSI”) is classified as ultra-high pressure and can remove even heavily adherent coatings and mill scale. At lower pressures, between 500 and 1,000 bar (“7,252 and 14,504 PSI”), it is effective for softer deposits and general cleaning without stripping intact coatings. Matching the pressure range to the application protects the substrate and avoids unnecessary energy consumption.

What safety precautions are required before cleaning a tank?

Before any tank cleaning operation begins, a thorough risk assessment and a defined set of safety controls must be in place. Confined space entry procedures, gas testing, lockout/tagout of all inlets and outlets, and verified personal protective equipment are non-negotiable starting points. High-pressure water jetting adds additional hazards that require specific precautions beyond standard confined space rules.

Key precautions include:

• Atmospheric testing: Confirm oxygen levels, flammable gas concentrations, and toxic vapour levels before entry and continuously during the operation
• Confined space entry permit: Issued only after all hazards are identified and controls are verified
• Lockout/tagout: All pipework, agitators, heating systems, and pumps must be isolated and locked out before personnel enter
• Personal protective equipment: High-pressure-rated gloves, face shields, waterproof suits, and steel-capped boots as a minimum
• Standby rescue team: A trained rescue crew must be on standby whenever personnel are inside a confined space
• Equipment inspection: All hoses, lances, nozzles, and connections must be inspected before use and rated for the operating pressure

Industry organisations set the standards that govern safe water jetting practice. In the Netherlands, SIR provides guidance and certification for industrial cleaning operations. Across Europe, EWJI publishes water jetting safety codes. In the UK, the WJA sets operator certification requirements, while in the USA, the WJTA issues recommended practices for high-pressure water jetting. In Germany, DIRV oversees safety standards for industrial cleaning. Operators and maintenance engineers should be familiar with the relevant body for their region and ensure all personnel hold current certifications before work begins.

How do you remove stubborn deposits from tank walls?

Stubborn deposits on tank walls, including hardened scale, polymerised hydrocarbons, and thick rust layers, require a combination of high pressure and mechanical action. Ultra-high-pressure water jetting at 2,000 to 3,000 bar (“29,007 to 43,511 PSI”) is the most reliable method for breaking the bond between heavy deposits and the steel substrate without damaging the base metal.

For deposits that resist water alone, the following approaches improve results:

• Rotating nozzles and spinning jets: These distribute the cutting energy across a wider area and prevent the jet from dwelling in one spot, which can cause surface damage
• Repeated passes at controlled speed: Slowing the traverse rate increases dwell time and improves penetration into thick scale layers
• Pre-soaking with water or approved solvents: Softening deposits before jetting reduces the pressure needed and speeds up the overall process
• Robotic systems with consistent standoff distance: Maintaining a fixed nozzle-to-surface distance ensures uniform energy delivery, which manual lancing cannot always achieve in confined or awkward geometries

Tank wind girders, internal bracing, and curved wall sections present particular challenges because manual access is difficult and consistent nozzle positioning is hard to maintain. Robotic crawlers with adjustable swing arms address this by keeping the cleaning head at the correct angle and distance throughout the pass, delivering predictable results even in geometrically complex areas.

What equipment is needed for effective tank cleaning?

Effective tank cleaning requires a matched set of equipment covering water delivery, cleaning tools, debris recovery, and operator protection. The core components are a high-pressure pump unit, hose reels rated for the operating pressure, appropriate nozzle assemblies, and a vacuum or recovery system to collect wastewater and debris.

For large oil storage tanks and industrial vessels, robotic systems have become an increasingly important part of the equipment set. Our MagTrack robotic crawler is a modular magnetic crawler designed for exactly this type of application. It operates on flat and slightly curved steel surfaces and can be fitted with a range of modular tools depending on the task:

• Blast Can (vacuum dome): Installed in front of the carrier for closed waterblasting, collecting both water and debris without leakage, leaving a clean and dry surface ready for inspection or coating
• Curved Blast Can: Handles surfaces with a radius of up to 3 metres (“9.8 feet”), making it suitable for smaller storage tanks and the curved contours of ship hulls
• Swing Arm: Used for open water blasting of tank wind girders and similar structures, with adjustable distance from the cleaning head to the surface
• MagTrack Mini: A compact, lightweight 2-wheel-drive crawler with a fixed blast can, suited to narrow spaces including offshore oil rigs, with a 2025-updated drivetrain and improved vacuum seal

All water jetting tools on the MagTrack platform operate at pressures up to 3,000 bar (“43,511 PSI”), covering the full range of industrial cleaning and surface preparation requirements. Alongside robotic equipment, a complete setup includes personal protective equipment for all personnel, atmospheric monitoring instruments, confined space rescue equipment, and a waste management system compliant with local environmental regulations.

How do you know when a tank is clean enough?

A tank is clean enough when it meets the specific cleanliness standard defined for its next use, whether that is reinspection, recoating, return to service, or safe entry for further maintenance work. Cleanliness is not a subjective judgement; it is measured against internationally recognised standards that define acceptable levels of rust, contamination, and surface roughness.

The most commonly referenced standards for surface cleanliness after water jetting are the ISO 8501 series for visual cleanliness grades and the SSPC/NACE standards used widely in the USA. For tank interiors being prepared for recoating, inspectors typically check:

• Visual cleanliness: No visible oil, grease, sludge, or loosely adherent scale remaining on the surface
• Surface profile: The roughness of the steel must fall within the range specified by the coating manufacturer, typically measured with a replica tape or profilometer
• Soluble salt contamination: Chloride and sulphate levels on the surface must be below the threshold specified for the coating system being applied
• Moisture: The surface must be dry and at an acceptable temperature relative to the dew point before coating can proceed

For tanks returning to service rather than being recoated, the acceptance criteria focus on the absence of residue that could contaminate the next product stored, and on structural integrity confirmed by visual or ultrasonic inspection. In all cases, a formal inspection record should be completed and signed off before the tank is closed or returned to service.

How MagTrack helps with industrial tank cleaning

When tank cleaning demands combine confined spaces, curved steel surfaces, and strict cleanliness standards, robotic technology makes a measurable difference. Our MagTrack system is built specifically for these conditions, bringing together high-pressure water jetting and vacuum recovery in a modular platform that adapts to the geometry and requirements of each job.

Here is what MagTrack delivers for tank cleaning operations:

• Closed waterblasting with zero leakage: The Blast Can vacuum dome collects water and debris at the point of impact, leaving a clean and dry surface without manual sweeping or additional recovery steps
• Curved surface capability: The Curved Blast Can handles radii up to 3 metres (“9.8 feet”), covering the full internal geometry of most storage tanks
• Reduced operator exposure: Remote-controlled operation keeps personnel out of the immediate cleaning zone, directly reducing risk in confined and hazardous environments
• Consistent standoff and pressure: Robotic control maintains the correct nozzle distance and angle throughout every pass, delivering uniform results that manual jetting cannot reliably replicate
• ATEX Zone 2 certification available: The MagTrack Mini is available as a certified ATEX Zone 2 unit, making it suitable for use in potentially explosive atmospheres such as oil storage tanks
• Modular tooling: Swap between the Blast Can, Curved Blast Can, and Swing Arm to match the specific cleaning task without changing the carrier platform

If you are looking for tank cleaning solutions that combine safety, efficiency, and surface quality, we would be glad to discuss your specific requirements. Contact our team to find out how MagTrack can be configured for your next tank cleaning project.