Failures of Diving System FMEA/FMECA
Thursday, Sep 27, 2012
Failure Modes and Effects Analysis (FMEA) or Failure Modes Effects and Critical Analysis (FMECA) are terms used more and more frequently throughout the diving industry, but exactly what is a diving system FMEA/FMECA? The purpose of a diving system FMEA/FMECA is to ensure a systematic assessment is carried out on all diving system equipment, and the support vessel interfaces to identify any areas where the system or vessel interfaces may fail due to equipment operational reliability as well as inadequate operational procedures, lack of redundancy and critical spares required for safe operation.
An FMEA/FMECA shall consider the failure of electrical, mechanical and control systems hardware as well as all supporting documentation. The FMEA/FMECA will identify any Codes of Practice that should be followed during the assessment such as International Codes and Legislation, Class Society Rules, Industry Standards and any Company Management Systems.
The FMEA/FMECA of a system shall assess the effects on different failure modes on the systems operating equipment and vessel interfaces. The failures are ranked for risk based on the probability and severity of the failure and will highlight deficiencies in the system as well as identify mitigation currently in place or required.
The FMEA/FMECA of a saturation diving system is now considered a mandatory requirement within the industry and is highlighted as such in the International Association of Oil and Gas Producers (OGP) Diving Recommended Practice Report No: 411, dated June 2008. Furthermore it is also considered a requirement under class and would be submitted to the classification society for review prior to the award of class certification.
Guidance of how a diving system FMEA should be carried out is identified within the International Marine Contractors Association (IMCA) guidance document IMCA D039 FMEA Guide for Diving Systems, dated November 2005.
IMCA D039 is intended to offer examples of a typical methodology used in specifying, performing and maintaining an FMEA for a diving system. It is intended to be reasonably short and concise, thus enabling all levels of management, dealing with the ownership or operation of a diving system, to understand their needs and responsibilities with respect to the FMEA process.
The guide is also intended to offer examples of good practice to the FMEA practitioners and to provide references to other relevant documentation which may assist them in performing a diving system FMEA.
Initiatives taken by OGP and National Hyperbaric Centre (NHC), including a recently set up task force to develop the OGP Diving Systems Assurance Process and the development of NHC Consulting have identified a growing concern with the content of Diving System FMEA/FMECA throughout the industry.
With the introduction of Diving System Assurance Audits, where all supporting documentation including FMEA/FMECA is reviewed, it has been observed that FMEA/FMECA assessments are not being carried out following the best industry practice of IMCA and the International Maritime Organisation (IMO).
Studies carried out by the NHC on behalf of OGP member and non member operators have identified failures of current diving system FMEA/FMECA such as;
• No consideration to following the guidance of IMCA D039 FMEA Guide for Diving Systems
• No consideration of the support vessel interfaces and services
• No consideration of the diving system planned maintenance system (PMS)
• No consideration as to whether the system drawings are a current representation of the system
• No reference to diving system operating and emergency procedures
• No consideration of a means of verifying the theoretical conclusion
• No consideration as to providing a final conclusion and current status of the system
Furthermore large sections of the diving systems, associated equipment and supporting documentation are being overlooked, as a result not all system failure modes are being considered and existing mitigation identified.
Developments within the industry, with the introduction of Programmable Logic Control (PLC) and automated systems, are also an area of concern as a complete failure of the PLC are often only considered rather than consideration of the various input and output signal failures of a PLC system.
During reviews of several FMEA/FMECA assessments we have identified they have not been used as a “live” document and updated as the system or system procedures are modified and changed. An FMEA/FMECA should always be regarded as a “live” document and be updated periodically when changes to the system warrant a revision.
The Way Forward
In conclusion, it would appear that the industries knowledge and experience of Diving System FMEA/FMECA, as well as guidance for carrying out the assessment and how they should be managed post assessment, is limited.
Therefore further guidance as well as a general awareness of FMEA/FMECA should be provided and should include a more in depth guide as to the competence of the team tasked with carrying out the study. Reviews carried out should also only be carried out by persons competent who have the technical and operational knowledge of diving systems as well as knowledge of the FMEA/FMECA process to do so.
The industry should now acknowledge that carrying out an FMEA/FMECA is not a one man job but should be carried out by a team, all experienced within the disciplines required to provide technical and operational support of the diving system to be assessed.
Current diving system FMEA/FMECA assessments should now all be reviewed by a competent team to ensure that they have been carried out correctly following the guidance of IMCA D039. It should be ensured all diving system related equipment and supporting documentation has been considered and that modifications carried out since the initial assessment have been captured.
Since identifying the issues discussed in this article, National Hyperbaric Centre (NHC) have now assembled a team of skilled individuals with the technical and operational experience to provide the industry with the support required to carry out and review FMEA/FMECA assessments.
Source: National Hyperbaric Centre