What in the world is “bull rigging?”
Though it might conjure images of cowboys hanging on for dear life as a bucking bull furiously tries to throw them to the ground, bull rigging is actually a technique H Brown’s experienced riggers use to move equipment within a refinery or other industrial facility.
Bull rigging is sometimes referred to as “drifting,” “Tarzaning” or “hand rigging.” Even if you’ve never heard of it, you may have encountered a situation where it was the best way (or only way) to rig a load.
When a mobile or overhead crane can’t access a load to transfer it to a crane hook, we have to get creative. We might pull the load horizontally on rollers (“skidding” or “skating”). We might build a winch and block system. Or, we might use chain hoists (designed for low-headroom applications) to move a suspended load horizontally.
That, in a nutshell, is “bull rigging.” In this case, one manually operated hoist lifts the load. The rigger will then attach the trailing hoist to an advance position.
In addition to setting up cranes and hoisting equipment and materials on construction projects, bullriggers have to select the cables, ropes, pulleys, winches, blocks and sheaves according to the weight and size of load to be moved. They have to calculate the maximum load and tension the hoists will be subjected to and make sure the load never exceeds the hoists’ rated capacities.
In addition, the rigger working these “tight squeeze” jobs has to maintain a straight line from one hook to the other in a chain hoist, never wrapping the hoist chain around the load.
A bull rigger must understand the unique load handling challenges that these lifts entail. That means doing all of the following before starting the lift:
- Estimating load weight;
- Calculating the center of gravity (C/G) and its effect on the load;
- Finding load weight distribution and identifying the share of the weight;
- Understanding tension when working with angles as well as level or off-level pick points;
- Determining the force required to pull a load up an incline plan or to hold a load back when lowering;
- Calculating mechanical advantage and associated block loading and frictional gain in a multi-part winch/block system.
We execute these kinds of lifts whenever there is limited access to the equipment we’re moving. We often encounter these restricted spaces working a turnaround project at a refinery, for example.
Bull-rigged lifts are often part of a complete engineering package that includes a critical lift plan, a safe work execution plan and other kinds of engineered lifts and transfers within a facility.
Bull rigging around 17,000 pounds of steel (via Instagram user https://www.instagram.com/rgvscaffold/?hl=en)
H Brown’s rigging professionals can plan, coordinate and perform lifting operations with jacks, chain falls and block and tackle. We can also execute winch and block operations to pull loads horizontally and vertically using winches and pulley-systems.
We take inclined planes and friction coefficients into account and always adhere to the manufacturers’ recommendations regarding the care, use and inspection of all hoisting and rigging equipment.
Do you have a rigging job in a confined space? Contact the H Brown team today. From low headroom engineered rigging solutions to heavy-haul transportation across state lines, you’ll see that we have a relentless focus on safety and an uncompromising standard of quality. Our engineered lifts give you streamlined project delivery, on-budget and on-time.