*Article for Crane Brasil magazine – Edition 63/2019
Offshore lifting involves several types of operations, such as installing cargo on the seabed, lifting equipment weighing hundreds of tons, moving pipelines tens of meters long (jumpers), etc. In them, there is almost always a predominance of dynamic forces, which can reach values up to 5 times greater than the respective static loads.
In addition, the geometry of loads and slings can be quite complex, which makes it difficult to control the force in each part, which can lead to overload and rupture, in addition to causing accidents.
For greater control of lifting and greater safety, real-time monitoring has been used more and more. It consists of the installation of sensors that measure the physical quantities of interest in lifting, mainly: force, acceleration, inclination, displacement, tension and pressure.
Weight control: For a successful lift, it is critical to determine the weight and center of gravity of the load, not only before lifting, but during planning. For this, compression load cells are used when carrying out weight control during load manufacturing. With this, the weight and center of gravity are accurately determined.
Force control on the slings: In multi-legged, or hyperstatic, leagues, the force in each leg can be monitored using tensile load cells. It is then possible to assess which of them are slack or overloaded, allowing adjustments to be made to standardize the efforts on the slings and the load.
Control of dynamic forces: Suitable sensors and data loggers can read up to 48,000 force values per second. This allows the monitoring of force peaks during operation, as well as intervening in the lift when necessary.
Acceleration control: Shock sensitive loads are monitored with accelerometers. They record shocks suffered during transport and lifting.
More and more companies have invested in lifting monitoring in order to increase the safety and effectiveness of operations. They have also applied this technology to lifting on land, obtaining excellent cost/benefit from this investment.