The Chevron Richmond Refinery Fire, Aug 6 th 2012

Transcription

1 The Chevron Richmond Refinery Fire, Aug 6 th 2012 November 2013 Lessons to be Learnt John Evans, g3baxi Partnership

2 A Preface Trevor Kletz ( ) 2 The best way to reduce risk is to avoid the hazard. What you don t have can t leak. Trevor was instrumental in instituting the HAZOP concept (50 years old this year) He also was among the first to propose techniques such as High Integrity Protection systems as alternatives to relief valves He was a proponent of the primacy of inherent safety over protection systems

3 Chevron statement regarding CSB Video 3 We also note that the CSB has released an animation with respect to the events of August 6, After we previewed the animation, we strongly urged the CSB not to release it. We informed the CSB that the animation contains numerous, material factual inaccuracies, the impact of which is to oversimplify, and in some instances trivialize, decisions that were made on that day. The animation also focuses on the actions of specific individuals, which we believe has the effect, surely not intended, of demeaning the challenges faced by the responding personnel. The reasons behind the incident are far more complex than depicted in the animation and we are disappointed with the CSB's decision to go forward with this unfair depiction. One must have some sympathy with this view, above all to recognise that one learns from accidents in the full awareness that emergency decisions are never made with complete knowledge. At key points in the animation we should put ourselves in the position of the individuals and ask what we would have done.

4 Incident in Detail Courtesy CSB website 4

5 Chevron Richmond - the Incident 5 Failure of a side cut in the Crude Distillation Unit (CDU) Ignition of a vapour cloud Caused by corrosion Consequences, CDU out of action for months (may still be in this state) Major damage to unit Fortunate that no one was killed 15,000 people sought medical attention with breathing complaints CSB investigation State of California Investigation Planned refinery expansion on hold This presentation takes a lot of information from the CSB interim report, some of the conclusions and analysis may be disputed.

6 Chevron Investigation 6 Measurements in 2002 indicating thinning were not documented properly to guide future inspections Information from industry experts concerning the processes leading to failure and means of guarding against such failures, including component by component inspections, was not shared effectively 2011 inspections during major maintenance did not include all components vulnerable to sufidation corrosion After discovery of leaking pipe, the response teams did not recognise the risk of rupture and fire.

7 CSB Investigation 7 Currently at Interim Report stage Concludes the cause of the release was due to sulfidation corrosion Identifies weaknesses in: Inspection Hazard assessment Application of the inherently safe principle Weaknesses in Management of Change

8 Results from the Metallurgical Investigation 8 Anamet, Feb , found:- The 8 4-sidecut was schedule 40 carbon steel from the 1970 s. 8 samples of 8 line taken, 5 samples from 12 including samples from 12 pipe replaced in Nominal thickness 8 line in, of 12 line 0.4 in Sulfidation corrosion (leading to iron sulphide, FeS) Wall thinning correlates to low silicon content (<0.1%) Tensile and hardness testing OK Thickness from in to in (cf a 1p coin is 0.06 in thick, thus from 5 x 1p s to x 1p s, or approximately the same as a business card) 8 samples showed 75% with 1/3 rd wall loss, 25% with 2/3 rd wall loss pipe was as fitted, 2/3 rd of other pipe had 40% wall loss. Wall loss strongly linked to Si content.

9 Rates of Corrosion with Silicon Content 9

10 Susceptibility of US Refineries to Sulfidation 10 In the mid 1980s, pipe manufacturers began to simultaneously comply with all three manufacturing specifications (ASTM A53B, ASTM A106, and API 5L) when manufacturing carbon steel piping. The majority of carbon steel piping purchased following this time period likely has a minimum of 0.10 wt. % silicon content. Over 95 percent of the 144 refineries in operation in the U.S., including the Chevron Richmond Refinery were built before 1985

11 Inspection Techniques 11 One must inspect low silicon steel (in fact all steel, but Low Si in particular) Inspection generally is done on elbows and fittings which are usually the bits of the low Si pipework made of higher Si steel There were no condition monitoring locations on the section of pipework that failed Even where accelerated corrosion was identified, on the 52 line in 2002, this was not followed up (will PMI pick up low Si?) And yet.. Chevron employees have authored industry papers on sulfidation corrosion and had significant influence in the development of the industry sulfidation corrosion recommended practice, API RP 939-C. This recommended practice, first published in 2009, was developed under Chevron leadership. So the expertise is in house.

12 Corrosion Rate Influences 12 Corrosion rates may be quite complex As pipe wall loses thickness it may flex more, promoting crack growth and further corrosion Change in composition will alter corrosion rate Change in process P/T conditions

13 Move to Processing Sourer Crudes 13 From the CSB report

14 Management of Change 14 Source: CSB interim report

15 Pinhole Corrosion? 15 Corrosion is characterised by pinhole pitting Sulfidation corrosion has caused severe fires and fatalities in the refining industry, primarily because it causes corrosion over a relatively large area, so failures tend to involve ruptures or large leaks rather than pinhole leaks. It can be insidious in that moderately high corrosion rates can go undetected for years before failure. Finally, process changes that increase the temperature or sulfur content can creep up over time and multiply corrosion rates so that what was thought to be a low corrosion rate system becomes corrosive enough to fail before the increased corrosion rate is recognized. Chevron s measurements on the pipework around the crude unit indicated an increased rate of corrosion with a change to higher sulphur crudes

16 Consequences of Release 16 The release from the full bore rupture of the pipe was a cloud that partially vapourised;

17 Consequences of Release 17 Why would a diesel type fuel, not collect as a pool? Distillation unit reflux lines will always have their process fluids at their boiling points These fluids are also at pressure and at height, so have potential energy They may have other dissolved components in them Note also: as their vapour pressure is high (they are boiling) they will be above their flash point The natural state of this liquid on release will be a mist Long chain hydrocarbons have higher flame speeds and are more prone to deflagration and detonation (diesel engines don t need spark plugs)

18 Human Impact 15,000 health complaints is probably one of the highest from an industrial accident, especially a non-lethal one, but.. which refinery is Chevron Richmond? A 18 (the red line represents a distance of 1 km) (images courtesy Google Earth) B C

19 Other Refinery Fires Caused by Sulfidation 19 The Chevron refinery fire is not the first to be attributed to sulfidation as a cause. There are also: Chevron El Paso 1988 & 1993 Chevron Pascagoula 2002 Chevron Salt Lake City 2007 Chevron Richmond (shelter in place alert) 2009 Silver Eagle Woods Cross, Utah (damaging 100 homes) 2011 Regina Canada 2012 bp unit in Cherry Point, Washington

20 The State of Refineries in the US 20

21 US Industrial Process Safety Regulation Issues 21 West, Texas Lack of knowledge and oversight of AN safety AN stored on pallets No deluge systems Plant siting a cause of the high fatality rate Kleen Energy Connecticut Gas blows in buildings? Inability of the authorities to enforce common sense safety practices Gas blows are still legal, though they are banned in Connecticut

22 What is a Gas Blow 22

23 The State of Refineries in Europe 23 KPMG report 2012 Over supply Competition from newer refineries As it was a market report it did not mention high sulphur fuels or the age of plant. Margins are lower even with FCC to monetise low value feeds Refineries are only an accident away from being a tank farm

24 EU Refineries on the Edge 24 Grangemouth Petroplus: inc. Reichstett and Coryton, both now tank farms ConocoPhilips Wilhelmshaven (tank farm) EU refineries might be one industrial dispute, or fire, away from a change of use. Such events can have local political impact They can also affect the economics of downstream industrial enterprises such as petrochemical plants

25 Conclusions 25 This fire was caused by a problem that can affect every refinery over a certain age It is hard to detect using standard techniques, even by industry leaders Response to early indications and replacement is the only cure Sensitivity to corrosion stressing mechanisms should feature in inspection programs It is difficult to distinguish between minor and major consequences caused by corrosion leaks. Precautionary shutdowns may be needed (though transients can also cause problems) Consequences may be vastly different to those that the refinery plans for and fire fighting equipment may be lost Aged refineries are a world wide problem, operators need to be aware of their heritage, and regulators need to be aware, too. Some argument to say they are better regulated outside the US (remember it is the same multinationals who operate them)