Lifting people with offshore cranes

*Article for Crane Brasil Ed Magazine. 59/2018

Standards establish safety requirements, lifting capacity and boundary conditions such as wave height and wind speed

Lifting people with land cranes is a controversial subject because of the risks involved and the history of recorded accidents. So much so that the manufacturers of this equipment warn in their manuals that land cranes are not designed for lifting people.

Although there are directives in some Regulatory Norms (NR), such as NR-12, there is still no complete system for lifting people that guarantees safety. The design of a specific device or the follow-up of a responsible engineer is not enough. An example of this is that most fatal accidents do not occur due to the failure of the suspended basket, but due to the failure of the crane that is moving the load, or its fall.

In the case of offshore cranes, the practice of lifting people for transshipment, that is, for boarding or disembarking from the platform, is very common and is provided for in technical operational and project standards for offshore cranes, such as API Sepc. 2C, EN 13852-1 and NORSOK R-002. They establish minimum requirements for safety devices, lifting capacity and limiting operating conditions, such as wave height and wind speed.

Lifting for transshipment is done with personnel transport baskets, which can be flexible like the Billy Pugh or rigid like the Frog Range, varying in complexity. They can be simply the basket or have a seat with a shock absorber, safety belt, floats and other safety devices. The Norwegian norm NORSOK R-002 only allows the use of rigid baskets.

The lifting of people on platforms must follow a specific project, which will include the type of crane, vessels, basket landing area, weather conditions and dynamic behavior of the set during lifting.

Although the accident rate with offshore lifts of people is lower than with land lifts, there is still a way to reduce it. The author developed a basket behavior prediction method taking into account wave height and wave period, improving efficiency in the design and execution of the lift, increasing safety and increasing the available meteorological window.