Diving bell clamp mating screws

  • Safety Flash
  • Published on 29 July 2005
  • Generated on 23 June 2025
  • IMCA SF 08/05
  • 1 minute read

A Member has reported the following issue discovered during a ‘routine’ inspection prior to the commencement of saturation diving activities using a bottom-mating system.

The bell mating screws and clamp nuts were found to be badly worn – one set to such an extent that the nut could actually be slid along the screw without rotating the screw.

Both the screws and nuts were inspected and appeared, visually, to be in a reasonable condition, with both sets of threads looking acceptable.

With the weight of the clamp laying on the nuts and threads, the clamp appeared to operate as it should, giving a false sense of security.

The Member involved has noted the need to strip down the clamping system, take the weight off the nuts and screws and undertake thorough checks of these components on a regular basis.

Latest Safety Flashes:

NTSB: Vessel crane contact with shore-side crane

The National Transportation Safety Board of the United States (NTSB) has published a report and an investigation.

Read more
Dropped pallet during forklift operation

A pallet containing a load weighing 500kg dropped off a flatbed truck in close proximity to a delivery driver.

Read more
Dropped object hazard: access hatch to the communication dome

During a routine scheduled safety inspection of the main mast, it was discovered that the access hatch to one of the communication domes had fallen off.

Read more
Lock out/Tag out and unauthorised electrical connections/disconnections
Read more
MAIB: Is your Lead-Acid battery safe?

The UK Marine Accident Investigation Branch has published Safety Digest 1/2025, consisting of lessons from recent Marine Accident Reports.

Read more

IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of the entire offshore industry.

The effectiveness of the IMCA Safety Flash system depends on the industry sharing information and so avoiding repeat incidents. Incidents are classified according to IOGP's Life Saving Rules.

All information is anonymised or sanitised, as appropriate, and warnings for graphic content included where possible.

IMCA makes every effort to ensure both the accuracy and reliability of the information shared, but is not be liable for any guidance and/or recommendation and/or statement herein contained.

The information contained in this document does not fulfil or replace any individual's or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.

Share your safety incidents with IMCA online. Sign-up to receive Safety Flashes straight to your email.