Internal Floating Roof Tank Cleaning: Planning Access, Cribbing, Cleaning and Inspection
Written by Mike Vickers
Internal floating roof tank cleaning is not simply a conventional tank clean with an obstruction in the way. The roof changes the structural workfront, divides the vapour space, restricts equipment movement and creates inspection surfaces that must remain accessible. It also introduces planning decisions around roof landing, support, loading, anti-rotation controls, seals, pontoons, legs and access beneath the deck. Those decisions must be settled before the tank is opened, not improvised after entry.
The federal Reduction in the Release of Volatile Organic Compounds (Storage and Loading of Volatile Petroleum Liquids) Regulations, commonly cited as SOR/2025-88, adds another planning layer for applicable facilities and tanks. It is an environmental VOC-control regulation, not a stand-alone occupational ventilation standard. Its service-status, temporary vapour-control, IFR support and inspection provisions must therefore be coordinated with provincial OHS requirements, the tank owner’s engineering standards and the applicable integrity program.
For Solution Services, the practical objective is to build one execution plan that connects industrial tank cleaning, roof support, robotics, specialized fluids, vapour treatment, waste recovery and the inspector’s acceptance criteria. That integrated approach reduces workfront conflicts and makes the final condition of the tank easier to verify.
Why IFR Tank Cleaning Requires a Separate Execution Plan
An IFR creates at least two connected but operationally different spaces: the area above the roof and the restricted area below it. Conditions can vary significantly between those zones. A reading above the deck cannot be assumed to represent the atmosphere below it, particularly where product remains trapped around the rim, in sumps, beneath pontoons or against the tank floor.
The roof also changes how loads are introduced. Personnel, hoses, ducting and cleaning equipment can create concentrated or moving loads. Existing roof legs may be suitable for their design purpose but that does not automatically confirm they are suitable for the planned cleaning and inspection work. Roof condition, leg orientation, landing elevation, deck damage and potential lateral movement all need to be considered.
A credible IFR plan therefore treats the roof as a structural and emissions-control system. Cleaning, ventilation, access and inspection must be developed around its verified design and condition.
Build the Scope Around Verified Tank and Product Data
Pre-planning should begin with drawings, service history, previous findings and a site walkdown. This is where disciplined project management and MOC adds value. The plan should confirm the tank diameter and height, IFR construction, roof-leg pattern, landing height, columns, guide poles, sumps, internal piping, manways, fixed-roof openings, seals, pontoons and known damage.
The material profile is equally important. The last product, estimated heel, sludge depth, viscosity, temperature, VOC and benzene characteristics, H2S potential, pyrophoric deposits and waste classification affect almost every downstream decision. They determine whether heat or chemistry is useful, how rapidly vapours may be released, what monitoring is required and how liquids and solids should be contained and transported.
The scope should also define the required endpoint. “Empty,” “entry-ready,” “visually clean” and “inspection-ready” are not interchangeable. If the inspector needs unobstructed access to floor welds, the annular ring, roof legs, pontoons, seals and areas of known corrosion, that requirement must be translated into measurable cleaning acceptance criteria before mobilization.
Land and Support the IFR as a Structural Workfront
The owner, tank engineer or qualified roof specialist should confirm the landing method and the condition of the support system. The cleaning contractor should not assume that existing roof legs are sound, correctly oriented or adequate for every planned work activity. The review should address roof level, damaged or missing supports, expected live loads, the sequence of product removal, possible roof movement and the effect of temporary equipment.
Supplemental cribbing may be required where the planned access, roof condition or load distribution cannot be adequately supported by the normal landing arrangement. The decision is tank-specific. Engineered support should account for vertical loads, stability, lateral or rotational movement, installation access, grounding and material compatibility. Improvised wooden dunnage should not be treated as a substitute for an engineered support plan.
Solution Services can integrate reusable Delta P cribbing into IFR cleaning scopes where the engineering assessment identifies the need. The system provides a consistent temporary-support approach, can improve access beneath the roof and avoids the disposal stream created by single-use wooden dunnage. It is not a blanket requirement for every IFR. The roof condition, engineering review and planned work determine whether supplemental support is required.
SOR/2025-88 planning point
Section 61 generally requires an IFR to float on the liquid, but allows it to rest on a support structure or otherwise remain suspended for a total of up to 30 days in a calendar year, subject to a narrow exception for certain tanks 10 m or less in diameter. Applicable operators should track supported days across the full calendar year and align cleaning, inspection and repair sequencing accordingly.
Plan Isolation, Access and Rescue Above and Below the Roof
The access plan must show how personnel, equipment, ventilation ducting and waste hoses move through the workfront without blocking egress or overloading the roof. It should confirm whether the shell manway aligns with the landed roof, whether deck penetrations are usable, how personnel reach the area above and below the IFR, and which damaged or unstable areas require exclusion zones.
Isolation is more than closing valves. Connected lines, mixers, gauges, drains, heating systems, level controls and automatic transfer logic must be addressed under the owner’s hazardous-energy program. Unintended filling, pressure change or movement of the roof must be prevented. Where entry is required, the applicable confined-space code of practice, entry permit, atmospheric testing, tending-worker and rescue provisions must be established for the actual geometry of the tank.
In Alberta, Part 5 of the OHS Code requires atmospheric testing before entry, appropriate ventilation or purging where a hazardous atmosphere exists or is likely, continued mechanical ventilation when needed to maintain a safe atmosphere, and an effective rescue capability. Those worker-protection requirements remain distinct from the federal VOC-control requirements discussed below.
Recover Product and Use Non-Entry Cleaning Before CSE
The preferred sequence removes as much inventory as practicable before personnel enter. Pumpable product is recovered first. Where the material profile allows it, heat, circulation or compatible chemistry can reduce viscosity and mobilize settled material. Vacuum recovery then removes displaced product, wash fluid and solids into planned containment.
Remote equipment can extend the non-entry phase. Robotic door and roof cannons can mobilize material from fixed access points. Robotic tank sweeps can move along the floor and direct sludge toward recovery points. Robotic tank and vessel stingers can provide targeted washdown where reach and geometry permit. A robotic command centre gives operators external control, live imagery and a record of progress.
Automation must still fit the tank. Roof legs, columns, low clearance, pontoons, sumps and damaged internals may limit travel or nozzle reach. The right goal is not to force a robot into every workfront. It is to use remote cleaning for the tasks it can complete reliably, then reserve confined-space entry for the remaining detail work and inspection preparation.
SOR/2025-88: Ventilation, Vapour Control and Tank Status
Ventilation and vapour control are related but not identical. Mechanical ventilation supplies or moves air to improve working conditions and support atmospheric control. Vapour extraction moves contaminated gas from the tank. An emissions-control system is intended to capture, recover or destroy VOCs rather than simply transfer them to atmosphere. The equipment and monitoring plan must reflect the required function.
A tank-cleaning package may combine air movers, extraction ducting, H2S scrubbers and carbon filter units, continuous atmospheric monitoring and controlled discharge points. Product and wash-fluid recovery may be supported by vac truck services, while hot oilers and fluid heating can support the removal of viscous product where the approved methodology permits. Equipment should be selected from the product data, contaminant loading and required endpoint, not from tank diameter alone.
Section 7 of SOR/2025-88 creates an important distinction for an applicable tank that was previously in service. One route to “not in service” status requires its interior to be cleaned of all volatile petroleum liquid, sludge and solid petroleum material, with the internal atmosphere below 10% LEL in the absence of mechanical ventilation. A tank may be acceptable for controlled work while ventilation is operating and still not meet that federal service-status condition.
Section 43 allows an operator to use a temporary vapour control system during the period in which a tank interior is being cleaned or the tank is being emptied until the tank is no longer in service. The regulation also contains performance, monitoring and high-benzene provisions. Applicability depends on the facility, tank, product and relevant transition or deferral provisions. Operators should confirm the compliance path before finalizing the ventilation and vapour-control scope.
The practical plan should distinguish four endpoints: conditions acceptable for entry, controls required while work continues, conditions needed for inspection, and evidence supporting the operator’s regulatory service-status determination. Combining those endpoints into a single “gas-free” milestone creates avoidable ambiguity.
Clean by Zone and Align the Result With Inspection Needs
Once bulk material is removed, the final-clean plan should divide the tank into zones: floor plates, shell-to-floor weld, annular area, sumps, roof legs and sleeves, columns, underside of the deck, pontoons, rim seals, deck penetrations, ladders and internal appurtenances. Shadow areas behind supports and locations outside robotic reach should be listed explicitly.
Cleaning should progress from bulk removal to targeted washing and final detail work, with recovered material removed continuously. Inspectors should be engaged before the final wash so the cleaning team knows which seams, repairs and components require clear access. This is especially important around roof-leg sleeves, pontoon seams, seal assemblies and areas with historical corrosion.
SOR/2025-88 adds specific IFR inspection requirements for applicable tanks. Section 91 requires monthly inspection of the space above the roof, including an LEL determination under prescribed conditions. Section 93 requires inspection of the IFR and tank interior every 20 years, with scope that includes seal gaps, hatches and covers, structural defects, corrosion, seams, pontoons in defined circumstances, guide-pole components and exposed tank wall. The regulation also contains rules that determine when that 20-year period begins and when an earlier first inspection may be required.
These federal VOC-control inspections do not replace API 653 or the owner’s mechanical-integrity program. API 653 addresses the inspection, repair, alteration and reconstruction of in-service steel storage tanks. The cleaning scope should support both workstreams without implying that the cleaning contractor performs the independent integrity inspection.
Complete the Handoff and Control Return to Service
Cleaning completion, inspection completion and readiness for return to service are separate milestones. A useful turnover package records the cleaning endpoint, atmospheric results, areas not accessed, observed damage, quantities recovered, waste manifests, vapour-control records, before-and-after imagery, inspector deficiencies and temporary-equipment status.
The roof-support removal sequence deserves the same planning discipline as installation. The plan should confirm who authorizes removal, how workers and equipment are cleared, how supports are counted and reconciled, and how the roof is returned to its intended operating configuration. Temporary hoses, blinds, ventilation connections and electrical systems must be removed or reinstated under the owner’s turnover process.
Any newly discovered damage, inaccessible area or change to the work method should be captured through the agreed MOC or field-change process. That keeps the cleaning record, inspection findings and final mechanical condition aligned before filling begins.
What Good IFR Tank-Cleaning Planning Looks Like
- Roof design, landing height and condition are verified before the workfront is released.
- Support and cribbing decisions are based on engineering and planned loads.
- Access, egress, atmospheric monitoring and rescue are planned above and below the roof.
- Remote cleaning removes the maximum practical volume before confined-space entry.
- Ventilation for worker protection is distinguished from VOC emissions control.
- SOR/2025-88 applicability, supported-roof days and service-status evidence are confirmed by the operator.
- Cleaning acceptance criteria match the inspector’s actual access requirements.
- Waste, vapour-control and closeout records are retained as part of a complete turnover package.
The strongest IFR projects are not defined by one piece of equipment. They are defined by how structural support, cleaning, vapour management, inspection and documentation are coordinated. Solution Services is well positioned for this work because the same execution team can integrate Delta P cribbing, robotic cleaning, specialized fluids, heating, vacuum recovery, scrubber systems, final confined-space cleaning and project controls into one methodology.
If an IFR tank is entering an outage or inspection window, involve the cleaning team before the RFQ is locked. An early scope review can identify missing roof data, access constraints, support needs and regulatory interfaces while there is still time to manage them. Learn more about Solution Services’ shutdown and turnaround services or request a technical review of the planned tank-cleaning scope.
No. The need for supplemental cribbing depends on the roof design and condition, existing leg arrangement, planned loads, access requirements and engineering assessment. Existing legs should not be assumed adequate for all cleaning and inspection activities without verification.
For applicable facilities and tanks, it affects IFR operation, supported-roof time, inspections, temporary vapour-control options and tank service status. Section 7 is especially important because one route to “not in service” requires removal of volatile petroleum liquid, sludge and solid petroleum material and an atmosphere below 10% LEL without mechanical ventilation.
Water helps mobilize and transport solids, but excess water increases the total volume requiring recovery, trucking, separation, treatment, or disposal. A strong cleaning strategy tracks the relationship between water added and useful solids removed. The objective is not maximum flow for its own sake; it is enough controlled fluid energy to create productive returns while maintaining high solids concentration in each load.
Robotics can materially reduce entry by completing product mobilization, sludge recovery and targeted washdown remotely. However, roof legs, pontoons, columns, low clearance and shadow areas may limit coverage. Final detail cleaning and inspection preparation may still require controlled entry.
Include tank and roof drawings, landing height, support details, product history, estimated heel and sludge, hazardous constituents, access points, isolation boundaries, utilities, operating hours, waste ownership, vapour-control expectations, inspection scope, cleaning acceptance criteria and return-to-service responsibilities.