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Under sized runway beam end stoppers

Country: ---

Location: ---

Incident Date: 30 May 2022   Time: ---

Type of Activity: Lifting, crane, rigging, deck operations

Cause: Dropped objects

Function: Unspecified

What happened?:

Two High Potential events were recorded by an IOGP Member Company in 2022 due to the fall of lifting trolleys from their runway beams. Similar events have also occurred in previous years.

30/05/2022 - Angola - FPSO:The monorail beam trolley (84Kg) overran the end-stoppers and fell (5m). No persons injured.

02/12/2022 - Denmark - Platform:The lifting beam trolley (weight 172 kg) together with the chain block (weight 64 kg) slid from the runway beam and fell on the deck, 4.7 m below. No persons injured.

Figure 1: Angola 2022
figure 1

Figure 2: Denmark 2022
figure 2

Similar incidents:

  • 01/02/2019 Angola - FPSO: Outer most wheel mechanism of the trolley passed the stopper and trolley was found hanging off the end of the runway beam.
  • 11/12/2019 Denmark - Platform: Lifting beam trolley (weight 40kg) dropped from the end of the runway beam 3 metres to the deck.


Physical (4): Potential for fatality.

Material or production-related: Potential damaged to the lift equipment and/or the load.

What Went Wrong?:


For all cases, the runway beam end-stoppers failed to prevent the hoist trolleys running off the end of the beam:

  1. the end-stoppers were undersized for the beam/trolley width, or
  2. the manual hoist trolleys were oversized for the beam used.

Beam end stoppers are usually designed for defined type of trolleys (ref. manufacturer guide). When changing the type of trolley, there is a risk that the end-stop is not correctly sized for the trolley in use.

Figure 3
figure 3

Figure 4
figure 4

Immediate causes:

Manual hoist beam trolleys run beyond the limits of the fixed runway beam.

Root causes:

  • Inadequate design of the end-stopper for the beam and/or trolley in use (gap between stopper and trolley).
  • Inadequate control/use of lifting equipment.
  • Inadequate management of change when modifications are performed on the beam.
  • Inadequate inspection of fixed lifting equipment.
  • Inadequate pre-use checks (trolley beam range and end-stop effectiveness).

Corrective Actions and Recommendations:

Corrective actions:

Verification of all existing end-stoppers on fixed lifting equipment (runway beams).

Standards or good practices:

  • ISO 9927-1, Section 6.3 Functional test: Functional tests shall be carried out for the following limiting and indicating devices in order to ensure that they are functioning and calibrated correctly for safe operation: b) motion limiters and indicators;.


  1. Perform a survey of the runway beams to detect end-stoppers that do not extend to the edge of the beam. Beams fitted without end stoppers or fitted with inadequate end stoppers shall not be used and shall be marked accordingly onsite. Implement modifications of the stoppers where required so that they fit all type of trolley.
  2. The monorail on which the trolley is installed shall be checked, inspected and certified. Ensure that scheduled inspections of fixed lifting equipment include a verification of beam range and end-stoppers. Visual structural checks of the suspended trolley beam shall be done looking for deformation of the flanges and missing anchoring bolts.
  3. Ensure that the trolley is fit for the beam and properly installed according to the manufacturer instructions. Trolley drops may also result from an inappropriate beam width whereby a limited part of the wheels of the trolley is rolling on the beam. Indication of beam range is marked on the trolley.
  4. In all cases, ensure that the functional test including end stoppers effectiveness is carried out after each trolley installation. Include this test within the site procedures i.e. the lifting plans, permit to work. Do not release trolley for use without confirmation of end stoppers function.

Safety Alert number: 345
IOGP Safety Alerts


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