Skip to content

Luff ram clevis failures

A member has reported a number of incidents in which a luff ram has parted at the clevis. The first incident occurred during a load test of a remotely operated vehicle (ROV) system. During recovery of the ROV whilst latched into the snubber, another luffing ram on the same launch and recovery system (LARS) parted in the same manner. Subsequently, during an ROV launch of the same system, the replacement starboard luffing ram parted at the clevis. There were no injuries or damage to equipment.

Clevis pictured after failures
Clevis pictured after failures
Clevis pictured after failures
Clevis pictured after failures

An investigation identified the following:

Contributory factors:

  • No evidence of anti-seize compound or other corrosion inhibitor in the rod end threads or on the rod threads;
  • Dead space between rod eye and cylinder rod allows generation and collection of moisture/condensation.

Immediate causes:

  • Excessive corrosion of each clevis (rod eye);
  • Dimensional check shows clevis to be deformed.

The company notes that root cause analysis for multiple failures is on-going; however the causes of the corrosion are in part attributable to a missed step during the service and maintenance of the cylinders.

The following actions were taken:

  • Updated planned maintenance system with manufacturer’s recommendations for inspection of cylinder rod eyes:
    • while A-frame foot is approximately 1″ from the hard stop so the luff cylinders are in tension, use a feeler gauge to determine if there is any gap between the faces of the rod eye and rod. There should be zero gap. If there is a gap, the cylinder should be removed, rod eye removed and inspected
    • the counterbalance valves should be verified that they are adjusted properly
    • perform a visual inspection of the A-frame operation to focus on cylinder timing or excessive lateral movement
    • perform visual inspection of rod eye surface for excessive signs of corrosion at point of rod entry.

Safety Event

Published: 18 January 2013
Download: IMCA SF 01/13

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 (https://www.imca-int.com/legal-notices/terms/) 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.