Laser beams and BIM

How laser scanning and BIM has helped solve the logistics and structural issues of replacing two giant steel plant motors.

Jackie Whitelaw
30 March 2015

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Port Talbot steelworks, in Wales, UK, has been making steel for more than 100 years. To increase capacity and efficiency, owner Tata Steel is investing in several upgrade projects. At the hot strip mill, cold steel slabs are heated to 1250°C and rolled into shapes suitable for construction, manufacturing and automotive components.

The building that houses the hot strip mill is 1km long. Within it, the roughing mill presses the red hot steel slabs to a tenth of their original thickness as they pass back and forth through two rollers, each powered by its own giant motor. The existing motors have been operating more or less continuously since the mid-1980s and replacement with more powerful motors is now vital.

“When operating at full tilt, the new motors will draw the same amount of power as the whole town of Port Talbot, much of it reclaimed as a by-product from other operations within the plant,” explains Mott MacDonald project manager John Farrow. “This upgrade will increase the efficiency and speed of the hot mill process, contributing to an enhancement of the plant’s overall productivity and ensuring that it remains at the cutting edge of steel production long into the future.”

The motors will be transported by sea and transferred across the site by heavy lifting specialists. They will each arrive in the hot mill in two pieces that will be joined in a delicate, millimetre accurate operation; the completed units, each the size of a truck and weighing 200t, will then be lifted into their final positions.

MAMMOTH MOTORS: NO MEAN FEAT

Remotoring the operational Port Talbot roughing mill brings a number of significant challenges:

• Hundreds of drawings showing structural and equipment changes over the decades have to be co-ordinated.
• The larger, heavier motors must be assembled in a part of the mill that was never designed for such loading, posing problems for the foundations.
• The sizeable motors must be manoeuvred between existing equipment within the mill and around new auxiliary plant that will be installed to power the new motors.
• Close collaboration was required between multiple, international supply chain partners as well as a multidisciplinary design team.

As if that’s not enough, installing the upgraded motors requires a shut-down of the mill operations. “That’s a high risk strategy, as the facility is not making money while it’s closed,” Farrow observes. “Any over-run of construction work would have severe knock-on effects on the overall business.”

TECHNOLOGY-FIRST APPROACH

“From the outset, we made BIM core to our plans,” he John. “We used laser scanning of the hot mill to create interlinked 3D digital models that covered different parts of the building and process. Capturing the mill in such a way took three months, but we could then replace hundreds of drawings with a single overall, current and accurate model. This formed the basis for design and costing of civil engineering works, and gave our client’s engineering teams, our partners and the supply chain a 3D picture of the site that was precise and completely up-to-date.”

Our studies showed that the building foundations would not withstand the load of the motors during the assembly operation. Farrow says: “We’ve designed steel grillages – grids of criss-crossed beams – to form platforms upon which the motors can sit. By spreading the load across the foundation piles, we can avoid additional piling, which would be disruptive. The BIM model has enabled clash detection and co-ordination with existing structures and services.”

With each motor come scores of smaller supporting apparatus, such as hydraulic pumps, which all need a home. “The BIM environment made it easy to visualise how to phase installation,” he explains. “This eliminates physical and schedule clashes and ensures that everything will fit first time.”

CLOSE QUARTERS COLLABORATION

To fully unlock the collaborative power of the BIM models, several of Mott MacDonald’s technical experts were absorbed into the client’s project taskforce, working alongside Tata’s project delivery team and supply chain partners. “This close working relationship has been critical to smooth progress, especially as our client has expanded our role to span mechanical and electrical design responsibilities,” says Farrow.

The interlinked BIM models offer a single, reliable source of spatial information within the mill building that can be used as the basis for the whole project design. Operational mills are dangerous places to be, but the ability to interrogate the BIM model eliminates the need to put people in harm’s way and will benefit worker safety throughout and beyond the project.

A TOOL FOR DESIGN AND OPERATION

“The use of BIM as a design aid on new projects is well understood, but using the technology to better understand and operate existing facilities is less common,” Farrow comments. Once installed, the new motors will be there for the next 25 years. The BIM model can incorporate information for servicing and parts; if something goes wrong on a machine, the model could help operators locate the problem quickly and could even autonomously order replacement components.

The revenue lost during closure of the mill requires that essential maintenance shut-downs are carefully choreographed. The BIM model can be used to plan and simulate these maintenance activities, examine delay scenarios, avoid clashes and ensure resources are used efficiently.