What a Dropped Object Is

A drilling or workover rig is a tall steel structure full of equipment. Lights, cameras, sheaves, hoses, clamps, guards and signs are fixed high on the derrick or mast. Tools are carried up to the monkeyboard. Loads swing on the crane over the pipe deck. Every one of these items is above the heads of people working below.

The oil and gas industry uses one simple definition for the hazard. A dropped object is any object that falls or has the potential to fall from its previous position.

Look at the two parts of this definition. First, any object: a heavy sheave and a small nut are both dropped objects. Second, has the potential to fall: an object does not need to fall before it counts. A light fitting held by one corroded bolt is a dropped object hazard today, even if it stays in place for another month.

This is why rig crews talk about dropped objects before anything falls. The work is to find the items that could fall and to stop them falling, not only to count the ones that did.

Why drops are a major hazard on a rig

Several things come together on a rig and make dropped objects one of its main hazards:

• Height. A derrick or mast is many metres tall. The higher an object starts, the more energy it has when it lands.
• Many fixed items aloft. Every light, camera, sign, sheave and clamp is held by fixings that can fail.
• Vibration, weather and corrosion. Drilling shakes the structure. Wind, rain, salt spray and heat slowly loosen bolts and weaken brackets.
• Moving equipment. The top drive, travelling block, pipe handling equipment and cranes move close to fixed items and can knock them off.
• People below. The drill floor, the pipe deck and the walkways around them are busy places. A falling object often lands where someone is working.

A dropped object can injure or kill a person. It can also damage equipment, for example a hydraulic line or an instrument, and start a second, larger event.