Slimmer, faster, cheaper3 April 2009
A new containerised gantry system developed by Hydrospex for US heavy lifting firm Burkhalter lifts 1,000t loads, and can be largely assembled from the ground without a big assist crane or guy ropes. Will North reports.
Traditional methods of lifting heavy, tall, vessels on refinery and petrochemical sites either use big crawlers, or guyed gantry systems. This requires large amounts of space, which is at a premium in these tight sites. Big crawlers are expensive pieces of kit too, something that will be more of a problem as the economy continues to founder. Transporting very heavy cranes requires large numbers of containers, and often special transport equipment or long loads. Hydrospex’s new BSET heavy lifting tower, developed initially for Columbus, Mississippi-based Burkhalter, promises to overcome all of these obstacles.
Hydrospex managing director Tjerko Jurgens says, “We looked at the market for the erection of refinery vessels. It’s been a good market, and is still going strong. Over the last couple of years, it has used very large cranes, with booms over 100m and capacities of thousands of tonnes. When you use a big crawler to lift, you also need another crawler to act as a tailing crane, or a tailing frame with a lot of SPMTs.
“In the same market 12 years ago, these jobs were being executed with big steel gantries. They still needed a big crawler to build the gantry, and a lot of guying, which takes up space on the job site.
“At the top of the market, the big cranes were the instrument of choice. Now that the market has become difficult, people are looking back to the old alternative method using steel gantries. But, the guy wires are a pain and you still need a crane with a 100m boom to assemble them. Some of our existing customers asked us to look for an alternative method.
“The first thing we decided was that it needs to be self-erecting, with no guy wires. It needs to have a skidding capability so it can be moved away from the finished vessel for demobilisation.
“The opportunity to move the design forward came in June 2008. Burkhalter had a job in the US that needed this equipment, so we accelerated the development from a study to a preliminary design. In July, we were able to give them a quote of EUR3.5m ($5m at prevailing exchange rates).”
Burkhalter president and CEO Delynn Burkhalter says, “We’d been looking at various systems that would perform the type of applications we were doing; we’d even looked at an old Cramo system. We’d used strand jacks before, but mainly for generator installations, rather than petrochemical and refinery work.
“Tjerko had the concept for a gantry system. We talked to him and his engineers, and together made some tweaks to the design.
“The main attraction of the BSET was the cost differential between this and cranes making similar size lifts: there’s quite a disparity. There are also benefits in terms of transportability and set up. Some customers may find this better for certain applications.”
The BSET is a tower and strand jack-based gantry. Traditional designs of this type use tubular steel lattice work sections to build the tower. Crawler cranes also need many lattice work sections for booms and backmasts. This imposes costs in both transport and erection.
Jurgens says, “When you dismantle a crawler crane, you end up with a lot of boom sections that take up space in a container, so you’re transporting a lot of air. With the BSET, the design uses a lot of small components that can be packed tightly together. For a ringer crane with the same capacity, you’ll need ninety containers. For the BSET, you can transport everything in just twenty containers. That cuts your transport costs.”
The BSET achieves these transport and erection savings by using small, precisely engineered, octagonal barrel sections to form the tower. Each section is small enough to be manually handled, and all of the sections needed for the tower can be tightly packed in a standard container. Assembly is performed using lift containers at the base of each tower.
Inside each lift container, there is a hydraulic mechanism to extend the barrels. Workers inside the lift container place the barrel sections into the hydraulic mechanism and bolt them together. It then lifts them through the roof of the container.
Once the barrel sections have passed through the container and the top of the hydraulic mechanism, another worker on the top of the container fits adjustable bracings. These are equivalent to the diagonal chords on a typical lattice work section. Videos on the Hydrospex website show how the system is assembled.
The system means that the majority of the erection process can be performed either inside the lift container, or on the roof, protected by a barrier. This protects workers from fall risks, and increases site safety. This is a core concern of safety-conscious refinery and petrochemical owners.
Burkhalter says, “The BSET erects itself to a predetermined height, requiring only minimal sized cranes to set the lifting girders on top of the system prior to self-erecting. That helps us in the safety engineering and planning, and is a big attraction to our customers.”
The finished system is highly compact. Burkhalter says, “It works well on a tight job site. It’s basically guy-less. That’s really one of the essential things we needed on this system. The initial design did use guys, but between us and Hydrospex we were able to mitigate the guys in most situations.”
The BSET’s tower is mounted on a skidding system, allowing it to move backwards and forwards. Burkhalter says, “It has movement in three axis: vertical, longitudinal and lateral.”
On vessel lifts, the tower can work without a tailing crane. Instead, the base of the vessel can be supported by the skidding system or by SPMTs.
The tower was developed very rapidly. Jurgens says, “We accepted Burkhalter’s order in July 2008, and the project was executed in January 2009, less than six months later. Burkhalter completed the job in four weeks. In that time they lifted two vessels, and mobilised and demobilised the system.
“The tower Burkhalter used had a capacity of 1,000t, and lifted to 60m.
We looked at the spec and designed new systems that could lift 1,600t up to 90m. The system still uses the same lift containers, strand jacks, gantries and skidding.”
Hydrospex is now offering an eight-mast system capable of lifting 2,400t to 80m. Jurgens says that the limits to the system come as much from end users as from engineering limitations: “When you go beyond 2,500t, the first question is whether there will be a job for it? The people designing refineries now are working on the basis that the biggest cranes go up to 2,500t, so they don’t go above the loads those cranes can lift. The BSET system can carry out 99% of the jobs that are out there at the moment.”
Both companies see a promising future for the new design. Burkhalter says, “We’re pursuing other leads right now; there’s a lot of activity around it and a lot of opportunities. It’s not like a mobile crane that works every week, but we hope to keep it busy.” Jurgens adds, “We’re in negotiations with two new potential customers. They want to wait until they’ve got a job ready, before they buy the equipment. We’ve had serious enquiries from Japan and Kuwait.
“We’ve been in business for 25 years this year. As we celebrate our anniversary, we want to be able show that we’re still creating innovative products, we’re still making remarkable creations. Everyone has known what we were doing with the design for a long time, but they wanted to wait to see it at work. When we launched our strand jack systems back in 1996, we had the same problem: they were impossible to sell. It was only when we got the London Eye ferris wheel and the salvage of the Kursk that recognised them as day-to-day heavy lifting tools.”