API BULL 939E-2008
Identification@ Repair@ and Mitigation of Cracking of Steel Equipment in Fuel Ethanol Service (FIRST EDITION)

Standard No.
API BULL 939E-2008
Release Date
2008
Published By
API - American Petroleum Institute
Scope
Usage of fuel ethanol as an oxygenate additive in gasoline blends is increasing both in the United States and internationally. This document discusses stress corrosion cracking (SCC) of carbon steel tanks@ piping and equipment exposed to fuel ethanol as a consequence of being in the distribution system@ at ethanol distribution facilities@ or end user facilities where the fuel ethanol is eventually added to gasoline. Such equipment includes but is not limited to: ?? storage tanks@ ?? piping and related handling equipment@ and ?? pipelines that are used in distribution@ handling@ storage and blending of fuel ethanol. However@ data for pipelines in ethanol service is limited and caution should be used when applying guidelines from this document which have been derived mainly from applications involving piping and tanks in ethanol storage and blending facilities. SCC of other metals and alloys is beyond the scope of this document as is the corrosion of steel in this service. It is realized that SCC of steel in fuel ethanol is a topic where knowledge of the subject is actively growing through documentation of recent experience and through research in progress. This document deals with handling of cracks in existing equipment and reduction of SCC occurrence in new equipment as a result of exposure to fuel ethanol. It includes guidelines for carbon steel construction materials@ including their fabrication@ inspection and repair to help assure safe and reliable operations. This document is based on current engineering practices and insights from recent industrial experience and research. Older equipment may not conform exactly to the information contained herein@ but this does not imply that such equipment is being operated in an unsafe or unreliable manner. It is also recognized that facilities may vary and may need to be modified depending on specific operating conditions@ inspection and maintenance experience. Each user company is ultimately responsible for its own safe and reliable operations. The steels referred to in this document are defined by the ASTM designation system@ or equivalent steel grades contained in other recognized codes or standards. Welded construction is considered the primary method of fabrication in equipment exposed to fuel ethanol. Terminology used herein is given in Section 3.



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