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This year’s crane project of the year was different to most – highly complicated and technically precise, and, unusually, a maintenance job rather than a new build.
NZ Steel’s Grahame Liddle (pictured centre in beige shirt), who put his hand up to take on the job, says the plant was getting to a critical stage and the project had to be done sooner rather than later. At the heart of steel making operations, the slab making plant operates 24 hours a day, seven days a week – all steel that is made passes through this plant. Each year, it converts about 650,000 tonnes of molten pig iron into steel. “One of the biggest concerns was the interruption to business,” Grahame says. “If things went wrong, NZ Steel would suffer. The radiation shaft is suspended immediately above the converter vessel. Its function is to duct away flames and fumes during the exothermic reaction of steel making. To survive in these conditions, the equipment used has to be exceptionally tough, nevertheless, even the best technology has a finite life. The $6 million project to replace the radiation shaft was the largest single maintenance activity in NZ Steel’s history – all steel production had to be shut down for 18 days while the team tackled a job that had never been done before. This was a very high risk project for the company, with the consequences of extended delays very serious – shutdown overrun would cost NZ Steel in excess of $1 million per day in lost revenue.
“The CEO had to have faith and believe in the concept,” says Grahame. “Our balls were on the line saying we could do it. But NZ Steel didn’t limit the people we could have around us to do the job – which meant we could utilise the best 3D animation and graphics, etc.” Contracts with the main contractors and suppliers were established more than a year in advance. Engineering services were provided by Beca and Brightwater Meo, 3D graphics and animations were provided by Revisia, Fitzroy Engineering prepared and updated the radiation shaft, KraneQuip designed and built the purpose-built crane to perform the lifts and IMG Rigging developed the rigging plans and provided resources in consultation with NZ Steel’s rigging team. The radiation shaft is essentially a large water cooled duct, measuring 15 metres in length, having an inside diameter of two metres and weighing 25 tonnes. The original radiation shaft had been installed in one piece using a 100 tonne Manitowoc crane, and the building had been completed around it. Getting it out without damaging the other equipment around it was always going to be tricky, and to do so the shaft had to be cut in half. The thick layers of dust and dirt resulting from 20 years of plant operations also had to be contended with.
To do this a purpose-built, 22 tonne capacity, twin hoist overhead crane was installed above the radiation shaft. Meticulous planning of all rigging activities was required. The old and new shafts had to be lifted through four floors, the lowest 14 metres above the ground. A straight vertical lift was not an option. All rigging tasks were identified in the planning stages and detailed procedures drafted by the main rigging contractor. Draft plans were then peer reviewed by the project team. The technical expertise brought to the planning phase was crucial and the “buy in” to the idea of a technically complex job being done to the highest standards was essential. Every step of the plan was discussed with the rigging team to ensure the planners had considered all potential issues. To assist the team in visualising the tasks ahead, 2D drawings and 3D graphic models of the plant were developed. Graphic reproductions showed how progressive steps were to be made. Animation sequences were also developed for the lifts to ensure rigging plan concepts were proven well in advance. Mark Foster and Adam Hester of Revisia explain: “We created a virtual prototype of the job from start to finish, you could see how to get the shaft around corners. This way everyone involved knew exactly what would happen before it happened.”
Team members were selected based on their competencies and proven ability to work together as a team. Work was scheduled around the clock with teams of 35 people working 12-hour shifts. Working during the night meant hazards increased and a lot of extra lighting was required. As work was carried out on multiple levels at the same time, a strong commitment to communication was required to avoid serious accidents. Dedicated rigging, scaffold and crane operating teams were co-ordinated by experienced personnel from NZ Steel and IMG Rigging. This tricky project required 18 months of meticulous planning and design. This paid off though when the project was successfully completed in just 14 days – four days fewer than planned, with this early return to production estimated at $4.2 million in increased plant revenue. When receiving the award on behalf of NZ Steel, Grahame Liddle said the project was a huge success.
“Everything happened as planned, but not exactly to plan. But we had contingencies for every step, which we fell back on once or twice,” he said. “The guys on the job performed well under pressure. They’re what made it happen.” Related article: Custom made
Contractor Vol.34 No.7 August 2010 |
The project was the replacement of the gas radiation shaft at NZ Steel’s slab making plant at Glenbrook, which took place in November last year.
The key to getting it right would be in meticulous engineering work in the design and planning phases.
The replacement radiation shaft was manufactured in two pieces to enable it to be installed, then bolted together in situ.
The expectations for safety standards were very high with particular focus on falls prevention, isolation procedures and housekeeping.
“I was very surprised we won as this was a maintenance project and the award usually goes to a construction project, which are more expensive,” he told Contractor.