- Project report – Installing diesel tanks at the Raunheim data center
Installing diesel tanks at the Raunheim data center: five 100-cubic-metre tanks over the shoring wall into the pit
How our appointed person for lifting operations planned five tank lifts when the data center stands in the middle of town, the crane fits in only one spot – and the site gates had to come down to make room.
A data center keeps its own fuel in reserve. If the grid fails, the standby generators start, and they need diesel – not for minutes but for days. That reserve sits in tanks that are among the largest single components ever delivered to such a site: 100 cubic metres, 16 metres long, almost three metres in diameter, 16 tonnes empty.
Five of these tanks had to be placed in their prepared pit at a data center in Raunheim in March 2026. The order came through the general contractor, and Omega Mounting was booked as the Appointed person for lifting operations (AP) – in other words, not only for supervising the lift on the day of the operation, but for the complete lift planning beforehand.
That planning was the real job, because this data center stands in the middle of town. The access road is a residential street, the paths around the building were still a construction site, and below ground lie shafts and ducts no crane may stand on. The question was not whether 16 tonnes could be lifted. The question was from where.
Project profile
- Scope: Appointed person for lifting operations for five diesel tank lifts – lift plan, lifting equipment, crane positions measured and calculated with the crane hire company, lifting points on the tanks checked and recalculated, lift supervision, slinging, signalling and aligning the tanks in the pit
- Team: 1 appointed person for lifting operations from Omega Mounting
- Duration: 9 to 11 March 2026, three days on site
- Components: 5 diesel tanks of 100 m³ each for the standby power system, each around 16 tonnes empty, 16.16 m transport length, 2.90 m diameter, 3.19 m transport height
- Crane: Liebherr LTM 1650-8.1 from a crane hire company in the Rhine-Main region, for all five tanks, main boom 52.0 m, radius up to 44.0 m
- Role: Subcontractor to the general contractor, lift planning and lift supervision in close coordination with the crane company and the civil works contractor
- Location: Data center in Raunheim, Rhine-Main region
- Special feature: The gate systems had to be removed to give the crane access. The crane position then had to be dismantled again, because tanks were to be placed on that very area
- Result: All five tanks set down in position in the pit, bolted down and handed over for filling
What does an appointed person for lifting operations do – and why does a tank lift need one?
The appointed person for lifting operations (AP) is the person responsible for planning a lift. The term comes from the British standard BS 7121 and has become established on data center sites because many clients there are international. Under German law the role rests on a written transfer of duties under Section 13 of the German Occupational Safety and Health Act (ArbSchG) together with Section 13 of DGUV Regulation 1.
The decisive point: the Lifting AP is not the crane operator, and not the slinger either. The AP plans the lift, approves it and, if necessary, stops it. Most of that work happens before the day of the lift.
For this project, that meant in concrete terms:
- Preparing the lift plan – the written sequence of the lift, from delivery to the tank set down in place
- Defining the lifting equipment – which round slings, which shackles, which working load limit, which length
- Measuring and calculating crane positions – together with the crane company, for each individual tank
- Checking the lifting points – inspecting the lugs welded onto the tank and recalculating the sling geometry
- On the day of the lift: Lift supervision, slinging, signalling, aligning in the pit
The advantage for the client is that responsibility sits in one place instead of being passed between crane hire company, general contractor and supplier. If something does not fit, one person says stop – and has the documents to back it up.
Why space dictated the entire planning
The photos show it: the data center is not on a greenfield industrial estate but embedded in an established residential area. Neighbouring houses stand close by, and the access road is an ordinary residential street with trees and pavements.
A crane needs two things: an area to stand on, and ground that can take the outrigger loads. Both were in short supply.
At that point the paths around the building were still a construction site. Below them lie shafts, ducts and basement light wells – structures that cannot take the concentrated load of a crane outrigger. So crane planning began with a survey of what was there: what lies where, which areas are off-limits, which openings in the building can be used, and which surface will actually carry the load.
Only then could we say where the crane may stand. And because there were very few such spots, everything else followed from that: the radius had to reach from these positions, and that in turn determined the size of the machine.
The mistake at this point is reaching for a bigger crane. More capacity also means more weight, a larger outrigger footprint, higher outrigger loads and more space for rigging. On a town-centre site the bigger crane does not solve the problem – it makes it worse. What we needed was the machine that just reaches from the permitted standing areas.
How does a crane this size even get onto the site?
The second bottleneck was access. All-wheel steering makes a mobile crane surprisingly manoeuvrable, but it is long. Every millimetre of the turn from the street onto the site was measured.
The result was inconvenient, but unambiguous: It did not fit. The gate systems had to be removed.
You want findings like this before the day of the lift, not on the morning when the crane and three abnormal loads are waiting at the gate. In the same way we checked in advance whether the low-loaders with the 16-metre tanks could get in at all – first roughly by sketch, then calculated in CAD. Each tank arrived on its own low-loader as an abnormal load, through the residential street right up to the building.
How do you sling a 16-tonne tank that is 16 metres long?
A tank of this design is not a compact block but a long, thin-walled cylinder with dished ends. The load is spread over its whole length, and the shell is coated – a lifting accessory touching it in the wrong place would mean damage.
Simply wrapping a round sling around the shell would therefore be no solution. It would damage the coating and put concentrated stress on the thin wall – and the tank would be ruined before it ever reached the pit.
Instead, the tank manufacturer has welded four lifting points onto the crown of the tank. A sling arrangement of round slings and shackles attaches to these, spreading the load over all four points and keeping the tank level. Sling length, working load limit and sling angle are set in the lift plan – exactly the calculation work that happens before the day of the lift.
Two aspects of this are underestimated from the outside.
First, the headroom of the sling assembly. For the sling angle to be right, the slings have to meet well above the tank. The sling arrangement ends up as tall as a small house, and that height adds to the lifting height. Calculate only to the edge of the pit and you are several metres out.
Second, the sling angle itself. The flatter the slings, the higher the force in each leg for the same load. The angle is a deliberate compromise between leg force and sling arrangement height, not chance.
Why we recalculate third-party lifting points
The tank manufacturer had welded on the lifting lugs and marked them with their ratings. Checking them is still part of the AP's job – not out of mistrust, but as procedure.
Two things were checked:
- The condition of the welds. Visual inspection at every single lifting point before slinging. A tank has transport behind it, often over hundreds of kilometres.
- The sling geometry. We recalculated and cross-checked the manufacturer's figures: do the four points suit the planned sling angle, are the leg forces right, does the centre of gravity let the tank hang level?
Whoever pulls on someone else's component with the hook is responsible for that pull. The figure on the delivery note is a starting point, not an approval.
The lift: over the shoring wall into the pit
The tanks do not sit on the surface, but in an excavated pit secured with sheet piling and timber shoring. Its base is concreted and lined with a membrane, with the saddle supports sitting on top.
The sequence was the same for every tank: low-loader in position, attach the sling arrangement, check the lifting points, lift, slew over the shoring wall, set down. Setting down is the slowest part, because a 16-metre tank has to land exactly on its supports without damaging the coating or the pit lining. There is little clearance between tank and shoring wall – the photos show how narrow the gap is.
During alignment, lift supervisor and fitters face a simple problem: the crane operator cannot see the whole pit from the cab. Everything down there happens on instruction. So the AP stands where both the load and the target point are visible and guides the last few centimetres.
Why the crane position itself had to disappear in the end
The twist in this project lies in the sequence. The few areas that were suitable as crane positions were partly the very areas where tanks were to be placed in the end.
That meant the crane stood on a spot that then had to be cleared so that the next tank could go there. Each lift had to work on its own and happen in the right order – coordinated with the civil works contractor, because the tanks had to be filled once installed and bolted down.
That is the difference between a single lift and a full installation sequence. A lift takes an hour. The installation is a chain of lifts, modifications and approvals that only works if someone has thought it through from end to start beforehand.
Other trades, not named here, were on site during those three days. Coordinating with them is what made the planning so demanding – and what made everything fit without rework.
Why Omega Mounting?
We are an installation company from Rodgau in the Offenbach district and have been working on data center construction sites in the Rhine-Main region for years – with transformers, standby generators, load banks, cooling units and, as here, tanks.
What sets us apart from a plain installation crew on jobs like this is the planning that comes first. We provide the appointed person for lifting operations, prepare lift plans, specify lifting accessories, check third-party lifting points and agree crane positions with the crane hire company. On site we then guide and approve every lift.
For general contractors and crane companies, this has a practical value: they get one point of contact for the lifting operations who provides the documentation the client demands and who is on site on the day of the lift.
On this job we worked closely with the crane hire company – on projects like this, crane planning and lift planning are not done one after the other but together at the same table.
Conclusion
Five diesel tanks of 100 cubic metres and 16 tonnes each are no special load for a crane of this class. What made the job difficult was everything around the lift: a data center in the middle of town, access through a residential street, shafts and ducts below the few free areas, site gates in the crane's way, and crane positions that later became tank space themselves.
None of this was solved on the day of the lift but in the weeks before – with a lift plan, a CAD swept-path analysis, joint crane position calculations and a fully calculated slinging concept. On three days in March, every tank then landed exactly where it belonged.
Request a callback – tell us briefly what you need, and we'll come back with an honest assessment. Omega Mounting GmbH, Hügelstraße 5, 63110 Rodgau. As an installation company based in the Offenbach district, we are quickly on site in Raunheim, Frankfurt, Rüsselsheim, Kelsterbach, Hanau and across the Rhine-Main region – and work throughout Germany. Free, no-obligation callback.
Weitere Einsätze in Raunheim und unsere Anfahrt aus Rodgau: Industriemontage Raunheim.
Project photos
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About the author
Tobias Schott
Managing director of Omega Mounting GmbH, Rodgau · more than 20 years of hands-on experience in installation and maintenance
A trained mechatronics technician, working in maintenance, servicing and industrial installation since 2004 – first alongside his father, and with Omega Mounting since 2012: from overhead conveyors in Frankfurt to the crane system in a new-build hall. He plans and leads lifting operations as an appointed person (AP) in data centers and on industrial sites in the Rhine-Main region, trains and examines operators of cranes, mobile elevating work platforms and telehandlers, and is a qualified occupational safety specialist. On jobs abroad he is known as the “German Troubleshooter” – the person you call when a site gets stuck. He learned what quality means from his father, not from a manual: Made in Germany as a standard for his own work, not a label. That is why quality comes first at Omega Mounting – ahead of speed and price. The project diary shows jobs his team has planned and carried out – without client names, but with everything there is to learn from them.
Frequently asked questions
Allow about one week before the lift. In that time our appointed person (AP) checks the load data and lifting points, agrees the crane position and the crane with the crane hire company, and sets out the lifting accessories and exclusion zone in the lift plan. Missing information on the load or the ground is settled at a site visit.
As standard, we hire the mobile crane with its operator (crane hire, in the UK often called CPA hire); a contract lift is not our standard. Our appointed person (AP) and our engineering team plan and lead the lift, and our own riggers, slingers and banksmen/signallers carry it out on site. The lift plan states who is responsible for what.
Empty, a tank of this design weighs around 16 tonnes. It is about 16 metres long and has a diameter of 2.90 metres. Lifting is always done empty; filling only takes place once the tank has been set down and bolted.
With four lifting points welded onto the crown and a sling arrangement of round slings and shackles. A round sling around the shell is no alternative: it would damage the coating and concentrate stress on the thin wall. Working load limits, sling lengths and angles are set and recalculated in the lift plan for each lift – including the height of the sling arrangement, which adds to the lifting height.
Yes. The manufacturer's figures are a starting point, not an approval. The AP checks the welds at every lifting point as found on site and recalculates the sling geometry – leg forces, sling angle and centre of gravity. Whoever pulls with the hook is responsible for the pull.
Because more capacity also means more weight, a larger outrigger footprint, higher outrigger loads and more space for rigging. On a tight plot with shafts, ducts and basement light wells below ground, the bigger crane makes the problem worse. The right machine is the one that just reaches from the permitted standing areas.
Then it is measured before it arrives. On this job the swept-path analysis showed that the turn from the street onto the site was too tight, so the site gates were taken down beforehand. The same applies to abnormal loads: whether a low-loader with a 16-metre tank fits the access road is checked in CAD in advance, not tried on the day.
Yes. We provide the appointed person for lifting operations, appointed in writing, who prepares and signs the lift plan, specifies the lifting accessories, checks the lifting points and agrees crane positions with the crane hire company. Under German law the role rests on a written transfer of duties under Section 13 ArbSchG; on site it works like the BS 7121 appointed person, with a lift supervisor running each lift.
Yes, that is the normal case. On this job the tanks came from the supplier, the crane from a crane hire company and the site from the general contractor – we planned, checked and led the lift. We work both as subcontractor to general contractors and directly for crane hire and heavy-haulage companies.
The load’s weight and centre of gravity with the manufacturer’s drawing, the position and design of the lifting points, dimensions and transport condition – plus a site plan with access, possible crane standing areas and whatever lies beneath them: shafts, ducts, basement slabs. With that we check crane positions with the crane hire company, calculate slings and sling angles and set the exclusion zones. Anything missing we settle on a site visit.
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