How do you select a tank cleaning contractor?

To select a tank cleaning contractor, focus on three core criteria: verified safety certifications, relevant industrial experience, and the quality of equipment they deploy. The right contractor should hold recognised qualifications, demonstrate a clean safety record, and use professional-grade tank cleaning solutions suited to your specific storage medium and tank geometry. Below, we answer the most important questions to ask before you hire.

What qualifications should a tank cleaning contractor have?

A professional tank cleaning contractor should hold certifications from recognised water jetting and industrial safety bodies, carry documented proof of relevant project experience, and employ operators who are trained to a verified standard. Qualifications are your first filter: they tell you whether a contractor operates within established industry norms or outside them.

Depending on where you operate, look for alignment with the following organisations:

• SIR (Netherlands) — the Dutch safety certification body for industrial cleaning professionals
• EWJI (Europe) — the European Waterjet Industry Association, which sets continent-wide standards
• WJA (UK) — the Water Jetting Association, which certifies operators and contractors in the United Kingdom
• WJTA (USA) — the Waterjet Technology Association, the benchmark for North American operations
• DIRV (Germany) — the German industrial cleaning association covering high-pressure water jetting standards

Beyond certifications, check whether the contractor has experience with your specific type of tank: oil storage, chemical, cargo hold, or potable water. Each medium carries different regulatory requirements and cleaning protocols. A contractor who has cleaned crude oil storage tanks is not automatically qualified to handle tanks containing hazardous chemicals. Ask for project references that match your application.

What equipment does a professional tank cleaning contractor use?

A professional tank cleaning contractor uses high-pressure water jetting equipment, vacuum blasting systems, and, increasingly, robotic crawlers capable of operating in confined and hazardous spaces. The specific equipment depends on the tank type, surface condition, and whether the job requires closed-circuit or open cleaning.

For standard industrial tank cleaning, the pressure range typically runs from 500 bar (“7,250 PSI”) for general washing up to 3,000 bar (“43,500 PSI”) for aggressive surface preparation and coating removal. At the higher end of that range, equipment must be robust, precisely controlled, and operated only by trained personnel.

Modern contractors increasingly deploy robotic systems for tank interiors. These crawlers can operate on flat and curved steel surfaces, removing the need to send workers into confined spaces for the most hazardous parts of the job. Key equipment categories include:

• High-pressure water jetting units — the core tool for breaking down deposits, scale, and coatings
• Vacuum blast systems (closed waterblasting) — collect water and debris simultaneously, leaving a clean and dry surface ready for inspection or recoating
• Robotic magnetic crawlers — electrically driven, remote-controlled units that work on steel tank walls without human entry
• Abrasive blasting attachments — used when surface roughness needs to be established before painting or coating
• Recycling blast systems — closed-circuit sandblasting that captures abrasive and prevents airborne particle release

Ask any contractor to specify the exact equipment they plan to use for your job, including the operating pressure range and whether the system is closed-circuit or open. This detail tells you a great deal about their professionalism and environmental awareness.

How do you assess a contractor’s safety record?

To assess a tank cleaning contractor’s safety record, request their lost-time injury frequency rate, review any regulatory inspection findings from the past three years, and verify that their operators hold current certifications from bodies such as SIR, EWJI, WJA, WJTA, or DIRV. A contractor with a strong safety culture will share this information readily.

High-pressure water jetting operations carry inherent risks. Pressures between 500 bar (“7,250 PSI”) and 3,000 bar (“43,500 PSI”) can cause severe injuries if equipment fails or operators are inadequately trained. This makes safety documentation non-negotiable, not optional.

Practical steps to evaluate safety performance include:

1. Request the safety data sheet and risk assessment for the specific job before work begins
2. Check for ATEX compliance if the tank has ever held flammable materials — equipment must be rated for explosive atmospheres
3. Verify operator training records against the relevant national or European certification body
4. Ask about near-miss reporting — contractors who track near-misses have a more mature safety culture than those who only report incidents
5. Inspect personal protective equipment (PPE) standards — high-pressure jetting requires specialist PPE beyond standard industrial workwear

A contractor who is reluctant to share safety data or who cannot name the certification bodies their operators are qualified under is a contractor you should approach with caution.

What’s the difference between manual and mechanized tank cleaning?

Manual tank cleaning involves workers entering the tank to perform cleaning operations directly, while mechanized tank cleaning uses remote-controlled or automated equipment to clean the tank interior without continuous human presence in the confined space. Mechanized methods are generally safer, faster, and increasingly preferred for large or hazardous tanks.

Manual tank cleaning

In manual cleaning, operators enter the tank and use hand-held high-pressure lances to direct water jets at the tank walls, floor, and roof. This approach offers flexibility for complex geometries and irregularly shaped spaces, but it exposes workers to confined-space risks, toxic vapours, and the physical hazards of high-pressure equipment. It also demands strict permit-to-work procedures and continuous atmospheric monitoring.

Mechanized tank cleaning

Mechanized systems use robotic crawlers, rotating nozzle heads, or remotely operated vehicles to clean tank surfaces without sustained human entry. Magnetic crawler robots, for example, adhere to steel tank walls and traverse the surface under remote control, directing high-pressure jets at pressures up to 3,000 bar (“43,500 PSI”). Closed-circuit systems collect both water and debris through integrated vacuum units, leaving a clean and dry surface.

The practical advantages of mechanized cleaning are significant: reduced confined-space exposure, faster cleaning cycles, consistent cleaning quality across large surface areas, and lower long-term labour costs. For tanks with hazardous residues or those requiring immediate recoating after cleaning, mechanized closed-circuit systems are the technically superior choice.

Should you choose a local or international tank cleaning contractor?

Whether to choose a local or international tank cleaning contractor depends primarily on the scale and complexity of your project, the regulatory environment you operate in, and the specialist equipment required. Local contractors offer faster mobilisation and regional regulatory familiarity; international contractors bring specialised technology and experience with complex or large-scale operations.

For routine maintenance cleaning of standard storage tanks, a locally certified contractor is often the most practical and cost-effective option. They understand local permits, waste disposal regulations, and can mobilise quickly when downtime is critical.

For larger or more technically demanding projects — such as cleaning tanks with hazardous residues, preparing surfaces for specialist coatings, or deploying robotic systems — an international contractor with proven technology may offer a better outcome even after accounting for mobilisation costs. Key factors to weigh include:

• Equipment availability — does the contractor have the right tools for your tank geometry and cleaning standard?
• Regulatory alignment — are they familiar with local environmental and safety requirements?
• Mobilisation time — how quickly can they be on site, and what are the associated costs?
• Track record in your sector — petrochemical, marine, and energy installations each have specific requirements
• Support after the job — can they provide inspection reports, surface cleanliness certificates, and warranty documentation?

What questions should you ask a tank cleaning contractor before hiring?

Before hiring a tank cleaning contractor, ask about their certifications, the specific equipment they will deploy, their confined-space entry procedures, how they handle waste and contaminated water, and what documentation they provide on completion. These questions separate professional contractors from those who cut corners on safety or quality.

A structured set of questions to bring to any contractor conversation:

1. Which certification bodies are your operators qualified under? (SIR, EWJI, WJA, WJTA, DIRV — depending on your location)
2. What pressure range will you work at, and why is that appropriate for this tank?
3. Will the cleaning be open-circuit or closed-circuit? How will water and debris be collected and disposed of?
4. Do you have experience with this specific tank medium (crude oil, chemicals, potable water, cargo)?
5. How do you manage confined-space entry? What atmospheric monitoring and rescue procedures are in place?
6. Is your equipment ATEX-rated if the tank has contained flammable materials?
7. What surface cleanliness standard will you achieve, and how is it measured and documented?
8. What does your waste disposal process look like, and who holds the environmental liability?
9. Can you provide references from comparable projects?
10. What documentation will you deliver on completion — inspection reports, cleanliness certificates, photographs?

A contractor who answers these questions clearly, with supporting documentation, is one who takes their work seriously. Vague or defensive responses to any of these points are a warning sign worth acting on.

How DERC Salotech’s MagTrack supports professional tank cleaning operations

We develop robotic tank cleaning solutions designed specifically for the challenges described in this article. Our MagTrack system is a modular magnetic crawler platform that addresses the core demands of professional tank cleaning: safety, surface quality, and operational efficiency.

Here is what MagTrack brings to a tank cleaning operation:

• Remote-controlled operation — reduces or eliminates the need for workers to enter confined spaces during the most hazardous phases of cleaning
• High-pressure water jetting up to 3,000 bar (“43,500 PSI”) — effective on even the most stubborn deposits, scale, and coatings
• Closed-circuit vacuum blasting — the integrated Blast Can collects water and debris without leakage, leaving a clean, dry surface ready for inspection or recoating
• Curved surface capability — the Curved Blast Can handles surfaces with a radius of up to 3 meters (“approximately 10 feet”), making it suitable for small storage tanks and ship hull contours
• ATEX Zone 2 certified option — safe for use in environments where flammable atmospheres may be present
• Modular design — a single carrier can be fitted with water jetting, abrasive blasting, or inspection tools depending on the task

With over 40 years of Dutch engineering expertise and a presence in more than 55 countries, we build equipment to both metric and SAE standards so it integrates into your existing operations without friction. If you are evaluating tank cleaning solutions for your next project or want to understand how robotic cleaning technology could reduce risk and downtime at your facility, contact our team and we will help you find the right approach.