Safe working load for crane operations

Article published in the Regulator Issue 3:2015

NOPSEMA inspectors recently conducted an inspection in relation to crane operations on a construction vessel facility. The inspection identified that the facility’s active heave compensated knuckle boom crane had been overloaded on several occasions during a previously completed project specifically, the safe working load (SWL) had been exceeded.

The crane was equipped with several alarms that sound when 90%, 100% and 110% of the SWL is reached. The crane also had an overload protection system that restricts the cranes movements once the SWL is exceeded. During the inspection, it was established that on several occasions during heavy lifts the crane experienced loads in excess of its SWL, which subsequently set-off overload alarms in the crane cabin. Prior to the heavy lifts, the operator of the facility had completed lift assessments that predicted the static lift mass multiplied by a dynamic amplification factor (DAF) would exceed the SWL. The operator had also advised the crane drivers that it was acceptable to exceed the SWL.

The operator of the facility was given several recommendations in relation to NOPSEMA’s inspection findings. The findings included that the operator:

• appeared to use the cranes design capacity to justify exceeding the SWL

• chose to ignore the inbuilt crane overload alarms and continue the lift after exceeding the SWL

• did not have an appropriate understanding of the cranes certified SWL or use of DAFs

• failed to appropriately address the concerns of the workforce regarding operating the crane above its SWL.

A lift that would knowingly exceed the SWL of a crane should not be undertaken. The SWL of a crane is dependent on factors including operating conditions, configuration and position. The application of a DAF effectively reduces the maximum mass that can be safety lifted. Overloading a crane is unsafe and likely to be a breach of an operator’s general duty to ‘take all reasonably practicable steps to ensure that all work and other activities carried out on the facility are carried out in a manner that is safe and without risk to the health of any person at or near the facility’.