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Document: Letter from Chevron refinery manager

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Letter from the Chevron refinery manager in Richmond explaining the company's decision to pick the chromium alloy called 9 chromium over another type of stainless steel material.

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									                                                      Nigel Hearne            Chevron Richmond
                                                      Refinery Manager        Chevron Products Company
                                                                              841 Chevron Way
                                                                              Richmond, CA 94801
                                                                              Tel 510 242 4400
                                                                              Fax 510 242 3515
                                                                              Nigel.Hearne@chevron.com




November 19, 2012

Mr. Bill Lindsay
Richmond City Manager
450 Civic Center Plaza
Richmond, CA 94804

Dear Mr. Bill Lindsay,

We are writing with respect to the letter from the U.S. Chemical Safety and Hazard Investigation
Board (“CSB”) to you, dated November 17, 2012.

In the aftermath of the August 6, 2012 fire at the Richmond Refinery, Chevron U.S.A. Inc.
recognizes that numerous parties are interested in not only the factors that gave rise to the
incident, but also the steps that we are taking to prevent a recurrence. For these reasons, we have
been open and transparent with respect to our incident investigation and our plans to repair
damaged piping and other process equipment in the No. 4 Crude Unit. We initially met daily
(now weekly) with interested governmental agencies to discuss the proposed work. During these
discussions in early October, we first communicated our plans to replace all carbon steel piping
in high temperature sulfidation (“HTS”) service within the fire-damaged area with a 9 chromium
alloy (“9Cr”).

As an initial matter, we agree with Richard Mitchell that the City of Richmond’s scope of review
of the repair work is limited to the ministerial issuance of permits pursuant to Title 24 of the
California Code of Regulations, which includes the Building, Fire, Mechanical, and Electrical
Codes. Permits for process equipment, including for process piping in hydrocarbon service, are
reviewed by the Fire Marshal for adherence to the National Fire Protection Association’s
Flammables and Combustible Liquids Code (NFPA 30) to ensure that the selected equipment is
approved for use in the proposed service under applicable industry standards. We understand,
additionally, that in this instance the City has an interest in a transparent explanation of the
factors underlying Chevron’s decisions on material selection. We are confident we have made
the right decision, considering all the technical factors, in selecting 9Cr as the material of repair
for this service.

We appreciate the CSB’s acknowledgement of our excellent cooperation and our willingness to
meet to further explain the technical basis for our decision to utilize 9Cr. We would hope that
such a meeting could occur early this week so as to avoid any delays in the project that might
November 19, 2012
Page 2

force the layoff of the men and women performing the work, especially given the upcoming
holidays. In the interim, we wanted to provide some preliminary information with respect to our
selection of 9Cr.

As the entity responsible for assuring the safe operation of the Richmond Refinery, Chevron
strives to continually improve its performance and considers inherently safer systems when
appropriate. As part of these efforts, we take material selection decisions very seriously.
Selecting materials for process units is a complex process that necessitates consideration of
multiple factors, including operating conditions (particularly temperature), operating history,
process chemistry, velocities and other flow conditions, local unit conditions, potential unusual
operating conditions, and turnaround considerations. In making these decisions, Chevron and its
technical experts consider all possible damage mechanisms and the ability to monitor the
equipment against those damage mechanisms. A focus in material selection on only a single
damage mechanism may inadvertently shift the risk to another potential failure mode. There also
often is not a clear cut answer because each material has its own unique advantages and
disadvantages.

For the purposes of the repair project, Chevron recognizes that both 9Cr and 300-series stainless
steel would be an appropriate material for the service.1 Our analysis, however, indicates that 9Cr
provides the greater reliability and predictability.

As observed by the CSB, its “letter focuses principally on the issue of preventing sulfidation-
related corrosion failures and does not examine other factors or potential failure modes that could
influence pipe selection” (emphasis added). Chevron, however, considered these other factors
and failure modes when selecting 9Cr over 300-series stainless steel. Of greatest concern to
Chevron was the susceptibility of stainless steel to stress corrosion cracking (“SCC”) from
chlorides and polythionic acids. SCC, which can lead to leaks and piping failures, can be
difficult to detect and less predictable. We therefore viewed the benefits of 300-series stainless
in providing somewhat increased sulfidation protection as outweighed by the cost of introducing
additional risks.

The CSB acknowledges in its letter that it does not have information regarding the cost of 9Cr
versus 300-series stainless steel with respect to the repair project. Nonetheless, we want to
emphasize that material cost did not drive our decision. In fact, on an installed basis, 9Cr piping
is more expensive than 300-series stainless steel because the 9Cr piping has to be post-weld heat
treated. We selected 9Cr because we believed in this instance, after taking into account technical
issues and potential community sensitivities about carbon steel, that 9Cr was the appropriate
material.

In closing, it is important to avoid the false notion that “alloying up” is always the answer. A
reasoned, technical basis must underpin the decision to ensure that one is not simply trading one

1
    We also would note that carbon steel is used throughout the industry and continues to be suitable for service with
    an appropriate inspection program. As we have previously indicated and in light of the potential for low silicon
    carbon steel components, we are inspecting every carbon steel component exposed to HTS corrosion conditions.
November 19, 2012
Page 3

corrosion risk for another that, like SCC, may be even harder to detect. The material selection
decision then must be supported with a robust inspection program to monitor for any corrosion
and other potential damage.

We look forward to discussing these issues with you in more detail. If you have any questions in
the interim, please contact me.

Sincerely,




Nigel Hearne



Cc:    Hon.Rafael Moure-Eraso, Ph.D., U. S.Chemical Safety Board
       Mr. Mike Smith, United Steelworkers Local 5
       Mr. Kim Nibarger, United Steelworkers International Union
       Ms. Ellen Widess, CalOSHA
       Mr. Jack Broadbent, Bay Area Air Quality Management District
       Hon. Jared Blumenfeld, U. S. Environmental Protection Agency

								
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