Diving bell clamp mating screws

  • Safety Flash
  • Published on 29 July 2005
  • Generated on 24 August 2026
  • 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:

GPS jamming and spoofing – good practice example

A Member’s vessel in the Red Sea encountered GPS jamming.

Read more
LTI – Shoulder strain when crew member was descending the stairs

A crew member sustained an injury to their shoulder as they were descending a flight of stairs into an ROV hangar.

Read more
Emergency escape hatch found blocked

Emergency escape hatch to the deck could not be opened.

Read more
Crew member sustained hand injury during lifting operations

A crew member sustained a hand injury during a lifting operation involving a main engine cylinder head.

Read more
NOPSEMA: Lifting operations dangerous occurrences and injuries

NOPSEMA has published a safety bulletin relating to lifting operations in the offshore industry.

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.