**2.2 Documented cases of SCC in fuel ethanol**

Research carried out by the American Petroleum Institute (API) has shown that SCC of steel in fuel ethanol environment is a subject matter where awareness of the issue is growing dynamically as a result of documentation of experiences and research works in progress. Findings by API point out that documented catastrophes of ethanol process equipment dates back to no less than the early 1990s. Establishments undergoing what they contemplate as cases of SCC in fuel ethanol have been stimulated to confirm these issues through appraisal and documentation of service conditions, along with metallurgical examination of the failed or cracked components.

The appearance of cracks caused by other cracking environments is similar to SCC cracks of steel in fuel ethanol. Instances of SCC in steel equipment exposed to fuel ethanol are presented in **Figures 2**–**4**. The cracks are characteristically branched and may possibly be transgranular, intergranular or mixed mode.

Both transgranular and intergranular cracking may well occur in laboratory testing subject to the composition of ethanol. However, greater number of cracks documented from field failures display intergranular cracking. While analyzing a field catastrophe, intergranular cracking suggests ethanol SCC, but transgranular or mixed mode cracking might likewise be present [16].

Instances of SCC of steel components in fuel ethanol have been conveyed in the following kinds of equipment in gasoline blending facilities and fuel ethanol distribution:


The blend of low cost and strength brands carbon steel as the principal material of construction for equipment used in the conveyance, handling and storage of fuel ethanol [16]. Generally, carbon steel is thought as compatible with fuel ethanol from the perspective of corrosion since its corrosion rates are characteristically low. On the other hand, the corrosion rate can occasionally escalate with agitation, the presence of contaminants, and the level of dissolved oxygen content of the ethanol. In the API program, the field corrosion rate measurements in fuel ethanol point out that the corrosion rates of carbon steel were typically very low.

*Structural Integrity of Materials in Fuel Ethanol Environments DOI: http://dx.doi.org/10.5772/intechopen.86383*

**Figure 3.** *Photograph of cracked steel elbow welded to the flange [17].*

#### **Figure 4.**

*SCC failures showing (a) SCC in steel tank bottom, (b) SCC in steel air eliminator vessel, (c) leak in piping resulting from a crack adjacent to the weld, (d) multiple crack initiations and through-thickness propagation in piping [8, 16].*
