Well supported

Outrigger pads and crane mats are often overlooked, but are vital to safe lifting. Outrigger pads are used by wheeled mobiles to spread the pressure of outriggers when lifting, stopping outriggers sinking into soft ground. Crane mats are typically timbers joined together and laid down to support crawler cranes when travelling.

DICA CEO Kris Koberg outlines the reason why a good ground preparation is important, highlighting the risks of not carefully selecting ground preparation products.

“Without a geotechnical report it can be diffi cult to know if the ground beneath your crane will support the weight and pressure under your outriggers. Yet knowing this information is critical for proper lift planning and operating your crane safely,” says Koberg. “If outrigger reaction forces, ground bearing capacity or ground bearing pressures are not carefully considered, the crane could be put in an unsafe position, resulting in damage to the equipment and the load, or cause potential injuries or fatalities.”

In any case, always check the bearing strength of the ground and soil before setting up the crane. Always look for any sub-surface hazards before work begins. Make time to improve soil conditions through compaction, draining, or any other necessary improvements.

“If the ground bearing pressure is greater than the ground bearing capacity the ground will move. As the ground moves it will compress and compact to a point where it will support the pressure being imposed on it, or it will fail under the load. Unfortunately, suffi cient ground compaction may not occur prior to the occurrence of a catastrophic accident.”

According to the ASME standard B30.5-2011, outrigger pads and crane mats must have suffi cient strength to prevent crushing, bending, or shear failure. And it needs to be of such thickness, width and length as to completely support the fl oat [aka, the outrigger foot], transmit the load to the supporting surface, and prevent shifting, toppling or excessive settlement under the load.

“Knowing the outrigger reaction force for your crane and the ground strength (ground bearing capacity), are the essential pieces of information for selecting the correct outrigger pads or crane pads. Accurately sized and engineered outrigger pads safely spread the load over a larger area, thereby reducing the ground bearing pressure. The larger the area the load needs to be distributed over, the more rigid (generally thicker) the pad must be. If using materials that are not engineered such as wood, be sure to account for degradation that is caused by water, UV, insects, rotting and previous stress.”

When evaluating different outrigger pads, Koberg says, it is important to understand the material, thickness, and construction that will provide the right combination of strength, stiffness and load distribution to properly support your equipment.

Koberg explains that a stiff pad that is not as strong may break (physical failure) if a force is exerted on the pad that exceeds its limits. This can cause “catastrophic results.”

“A stronger pad that is not as stiff may defl ect under loads that exceed the combined stiffness of the pad and ground causing functional failure (excessive bending). Defl ection is the warning sign that signals the need for more foundation support due to higher loads, or softer soils,” Koberg says.

“Wood is not an engineered material; therefore the material properties of wood change with exposure to the environment, moisture, chemicals, and use.” “DICA thermoplastics and FRP materials used in making outrigger pads and crane pads are engineered materials and are not susceptible to environmental exposure, moisture, chemicals or use. These materials and pads do not deteriorate over time and do not fatigue from redundant loading. “Steel pads have high strength properties and are a known product in the crane industry. The primary drawback has always been weight, which can lead to high transportation costs.

“FiberMax crane pad technology was originally developed for vehicle bridges and is backed by extensive physical testing, FEA (finite element analysis) modeling and in field use. A fully molded bi-directional shear web internal core design allows FiberMax crane pads to safely reduce groundbearing pressures with quantifiableengineered load distribution results.

Because FiberMax Crane Pads are typically 1/3 the weight of steel pads, FiberMax crane pads frequently require one less truck and trailer per job, resulting in transportation savings every time they’re used.”

DICA’s SafetyTech and FiberMax products are engineered from top to bottom. SafetyTech outrigger pads are available in three categories; medium duty (25mm, 1in thick), heavy duty (50mm, 2in thick) and super duty (75mm, 3in or 100mm, 4in thick) and are designed for equipment typically up to 100t in capacity. As the thickness of a SafetyTech outrigger pad increases so does its ability to distribute higher loads over larger areas.

“SafetyTech Outrigger Pads are made from a proprietary engineered thermoplastic formula that provides greater stiffness and strength,” Koberg says. “That performance can be seen in our maximum rated capacities (up to 147 kg, 325,000lbs), performance based FEA modeling and in field use.”

“FiberMax Outrigger Pads are made from solid FRP (Fiber Reinforced Polymer) material and are designed to provide the performance of an 80mm (3in) thick polyethylene pad in a 25mm (1in) thick solution, making the pads almost 50% lighter. FiberMax Outrigger Pads are designed for cranes with a lifting capacity of less than 100t.” “FiberMax Mega Duty Crane Pads are manufactured from FRP as well.

However, Mega Duty Crane pads are designed with a fully-molded sandwich design that includes a bi-directional shear web internal core. FiberMax pads are engineered to provide maximum strength and rigidity for cranes with lifting capacities up to 500t. FiberMax Mega Duty Crane Pads come in thicknesses of 150mm, 170mm, 250mm and 300mm, and rated capacities of 80t, 114t, 147t and 170t respectively.”

Crane Service, a full-service crane rental and rigging company serving Colorado, New Mexico and Texas has used since 2005 SafetyTech outrigger pads with cranes rated at 75t or less. “We were frustrated by the fact that wood breaks, gets stuck in the mud, is difficult to handle, and looks unprofessional,” said Bob Warianka, business development manager.

As well as being light, SafetyTech outrigger pads feature TuffGrip handles that provide increased ergonomic safety for operators handling them. TuffGrip handles have a length specifically designed to encourage proper lifting that requires bending and lifting with the legs, without being so long as to cause trip hazards. In addition, recessed handles are a key innovation on all round SafetyTech outrigger pads. The design allows for easy rolling of larger pads which reduces lifting stress and the potential for back injuries.

“Every time we buy a new 75t or smaller crane, we buy a set of DICA outrigger pads to go with the crane. When we show up on the job site we look like professionals, not junk-yard dogs,” said Warianka.

UK based company Outriggerpads supplies polyethylene outrigger pads, spreader mats and crane mats.

Outriggerpads business development manager Charles Grizzle says: “As they are manufactured from high performance UHMW polyethylene, our pads are resistant to water, oil and chemicals, so they won’t splinter or corrode like the more traditional wooden and steel alternatives.”

“At Outriggerpads, we offer advice on the best and most efficient ways to spread the load and technical advice to determine which products are best for a job.”

Outriggerpads offers a range of products: Premium pads for the heavier loads; Hi-Viz pads for working in public spaces; Multi Mats, which is an interlocking modular system for heavy loads yet versatile enough to be used in different configurations for different loads. These mats are lightweight and better for manual handling and can be supplied with a purpose-built storage or transportation carrier.

“We also offer Ground Mats which are used for load spreading and ground protection while transporting machinery to and from site, these mats are available in two sizes,” Grizzle adds.

Antarctic mats

Scientists at a renowned Antarctic research facility are using spreader plates designed for the construction industry to stay one step ahead of the snow.

Halley VI is the first fully relocatable research station in the world. The state-of-the-art facility is segmented into eight modules raised on hydraulic legs. These legs can be individually raised to overcome the accumulation of snow, preventing the station from being buried. The legs are all fitted with giant skis, so the team can tow each module using a bulldozer, enabling Halley VI to be relocated as required. Snow levels rise by over 1m every year and the sun does not rise above the horizon for 105 days during winter. Temperatures drop to -56C and the site can be buffeted by winds in excess of 100 mph. Outriggerpads supported Halley VI by creating a bespoke product specifically designed for the research station. The 1200 x 1000 x 40mm pads weigh only 46kg each, making them easy to manually position, yet have a 30,000kg loadbearing capacity. Each pad is also stamped with a unique ID number to aid identification.

Science at Halley VI provides vital information for better global understanding of ozone depletion, polar atmospheric chemistry, sealevel rise and climate change.

Halley VI is the most southerly research station operated by BAS. It houses up to 52 people in peak summer (December to February) and a core team of 16 during the long winter, when the base is completely cut off from the rest of the world.

The station is located 10,000 miles from the UK on the 150m-thick floating Brunt Ice Shelf, which moves 400m per annum towards the sea.

Grizzle says: “Manufactured from UHMW polyethylene, the material does not splinter and has a very high resistance to vertical pressure, meaning the pads adapt to the contours of uneven terrain while still retaining their shape.

“The material also adapts to extreme temperatures making it ideal for this application. Our mats have now been sitting under Halley VI for the past year.”

Placing mats

As an international manufacturer of crane mats, the Welex group have a number of offices in the Netherlands, UK and Germany and offer a large range of crane mats or bog mats.

Welex managing director Rob Koolmees says: “Many years ago I worked in the crane and construction world and I was fascinated by the simplicity and the strength of the materials. Crane mats truly are a world apart.

“They are used in nearly every large infrastructural project around the world. Now I manufacture them myself, I feel that I make a small contribution to all these international projects, and that feels fantastic. “We offer a complete package of services. If required, we are happy to take care of national and international logistics. It doesn’t matter whether we have to unload on site, lay out the mats. The Welex group delivers more than a product: it delivers a complete solution.”

Welex Verhuur manager Sebastiaan Koolmees explains, “Our crane mats are environmentally friendly and versatile, making them ideal to work with. It’s just a combination of tropical hardwoods or 100% ekki (azobé).

“The benefit of using wood is the flexibility, because if you have steel products, they don’t bend too much as they absorb the pressure. If you drive over with tracked vehicles, the impact of two metals can demolish each other, especially if you take the heavy cranes.”

Welex offers crane mats in all sizes, varying in thickness from 7cm to 30cm.

Koolmees says that they are actively involved in the following sectors: construction, energy, pipeline construction and heavy lifting. “We deliver many thousands of crane mats for the construction of our daily utilities every year. “We have various contracts for the construction of temporary access roads to and from power stations. We are also involved in the construction of a number of wind farms.”