CSB report on Macondo – any new insights?

9 June 2014

More than 4 years after the initial event, the US Chemical Safety Board (CSB) has published some results of its investigation. Is there anything new to learn from their 2-volume Report, with 2 more volumes still to come? My judgement is a qualified ‘Yes’, depending on your awareness of deep water drilling technology and also your geographical location (those in UK, Norway, Australia, and perhaps some other places, will find mainly reinforcement for what they know and do already rather than new ideas).

Macondo explosion

CSB are particularly skilled at explaining technical aspects of accidents with great illustrations and summary videos, and Macondo is no exception. A good animated video is available to supplement their written words, and the illustrations within the reports are also very helpful in explaining the complex details of how the subsea blowout preventer (BOP) is intended to operate and how, in contrast, some elements failed.

How much of this detail is new is harder to judge. Immediate comments from other parties involved suggest there is very little – but of course some of them have opposed CSB’s involvement from the start (Transocean took legal action, and that case is still not finally decided), so perhaps such comments are unsurprising? I did find the following of interest:

1. CSB judge that the drill crew did activate the BOP and close in the well. But by then there was so much gas in the mile-high riser above the BOP that their actions were too late to stop the blowout. For me that raises an issue about why the diverter valve wasn’t preset to dump overboard – did no one in Transocean or BP realise how large the continuing release would be if a kick was detected late? The Volume 1 report is silent in that area.

2. Apparently there were two separate wiring errors in the BOP control pods. According to CSB these must have been introduced after the Cameron factory acceptance test, but they remained undetected in the subsequent Transocean routine testing – which complied with industry standards, rather than being linked to an equipment-specific assessment of possible failure modes.

3. CSB suggest an alternate explanation for what caused the drill pipe to move off-centre, and thus for the BOP rams not to shear it. This is a complex technical issue, way beyond my competence to judge which theory is best. But what CSB also do is challenge the rather simplistic commitment to require two sets of pipe shear rams instead of one, by identifying some scenarios where both rams would fail (Volume 2, section 6.2.1). When you realise from the Volume 2 report how much ‘doubling up’ there already was in the BOP design and the failure modes that were still possible, an alternative approach based on LOPA (Layer of Protection Analysis) seems much sounder – and indeed is what CSB advocate.

This leads on to what I suggest are the most significant parts of the CSB report – their review of ‘good practice’ offshore regulatory approaches in UK, Norway and Australia for major hazards (potential multiple fatality scenarios). They demonstrate by comparison of key wording in the respective national legislation that even the post-Macondo US regulatory regime fails to fully consider the robust management and verification systems needed to ensure such risks are ALARP, as required in UK, Norway and Australia. Indeed the concept of ALARP is still not accepted in US, with compliance to defined legislative and industry standards, etc. being the expectation, rather than facility-specific consequence and risk studies, leading to the identification of ‘safety critical elements (SCEs)’ with required performance standards. Having lived with such process in UK since at least the mid-1990s, it’s salutary to realise how far the current US approach still is from such a standard (also relevant for onshore major hazards, as CSB mention, referencing their recent reports into some refinery accidents).

CSB deliberately not tried to repeat areas that have already been thoroughly covered in earlier investigations so, for example, there is nothing about events after the initial release. In Volume 2 they examine the BOP operational failures in great detail, using the ‘bow-tie’ tool to demonstrate the barriers. I judge some of this to be a bit weak – for example they treat technical, organizational (process) and operational (people) barriers separately, whereas in practice every barrier includes elements of all three. The OGP Guide on Asset Integrity has a sounder approach.

The CSB investigation process is perhaps ponderous and extremely slow, but it is thorough. So I recommend that all OSH professionals who are involved with major hazards watch the video and read (or skim) the Overview Report plus Volumes 1 and 2, as they’ll almost certainly learn something new. The initial public responses I’ve seen indicate CSB still have some way to go in ‘winning friends and influencing people’, in the US offshore sector at least. But perhaps Volumes 3 (reviewing current US regulations and enforcement) and 4 (organisational leadership and culture) will have further valuable insights? Let us hope we can read them soon!

Ian Waldram, CFIOSH

9 June 2014