Skip to content

MSF: water based mud spill on deck

What happened?

The Marine Safety Forum (MSF) has published Safety Alert 20-05 relating to a spill of water-based mud. During routine mud transfer operations at an offshore installation the rig hose parted from the vessel’s manifold resulting in a release of approximately 2,500 litres of mud to the deck. The crew quickly stopped the transfer and proceeded to use standard SOPEP equipment on-board to contain the spill on deck and recovered the contaminated mud within an empty mud tank. The spill was entirely contained with no loss to the environment.

What were the causes? What went wrong?

The manifold is normally fitted with a hammer union connection. It was discovered after initial inspection of the vessel’s manifold that the thread between the manifold and the hammer union was found to be corroded.

Further inspection of the manifold threads determined that the threads in place were incompatible. The original manifold threads on-board the vessel were non-compliant to the standard National Pipe Thread (NPT) connection and therefore did not correctly engage. As a result, these threads did not provide an adequate seal which increased the opportunity for corrosion to occur. This led the connection, over a period of time to become weakened and resulted in the hose parting from the manifold.

What actions were taken?

  • Careful check to ensure different threads are correct and compatible with one another;
  • Regularly monitor and inspect the condition of the threads on manifolds by implementing into the vessels’ planned maintenance system (PMS);
  • Pre-use checks to be conducted as part of the wet bulk transfer checklist to incorporate visual inspections of the manifold connection threads.

Whilst in this incident there was no harm to persons or to the environment, the issue of proper management of threads, most particularly the ensuring of compatibility, is a topic that has been raised before. There have been a number of incidents some of which have had tragic consequences.

Members may wish to refer to:

Safety Event

Published: 12 June 2020
Download: IMCA SF 18/20

Relevant life-saving rules:
IMCA Safety Flashes
Submit a Report

IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of all. The effectiveness of the IMCA Safety Flash system depends on Members sharing information and so avoiding repeat incidents. Please consider adding [email protected] to your internal distribution list for safety alerts or manually submitting information on incidents you consider may be relevant. All information is anonymised or sanitised, as appropriate.

IMCA’s store terms and conditions ( apply to all downloads from IMCA’s website, including this document.

IMCA makes every effort to ensure the accuracy and reliability of the data contained in the documents it publishes, but IMCA shall 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.