Anchor corrosion: causes

Anchor corrosion may be caused by chloride leaching Ifom PVC pipe sleeves or tape used for debonding purposes in high temperature apphcations. This can be avoided by specifying polyethylene or polypropylene sleeves or tape. 

Refractory flaws can also be caused by the frequency of temperature cycling, the rate of temperature drop, and the amount of temperature drop, which can lead to thermal shock or structural flaws from thermal expansion differences. Where monolithic linings are used, anchors attach the refractory material to the shell. Those anchors can experience failure from mechanical stresses, metal fatigue, or corrosion, leading to gaps between the refractory shell and the lining. Any gap impacts heat transfer and can initiate other types of refractory failure, such as slag corrosion because of heat buildup at those sites. 

In addition to loss of the platinum, the carlxm support that anchors the platinum crystallites and provides electrical coimectivity to the gas-diffusion media and bipolar plates is also subject to degradation. In phosphoric acid fuel cell, graphitized carbons are the standard because of the need for corrosion resistance in high-temperature acid environments [129], but PEM fuel cells have not employed fully graphitized carbons in the catalyst layers, due in large part to the belief that the extra cost could be avoided. Electrochemical corrosion of carbon materials as catalyst supports will cause electrical isolation of the catalyst particles as they are separated from the support or lead to aggregation of catalyst particles, both of which result in a decrease in the electrochemical active surface area of the catalyst and an increase in the hydrophUicity of the surface, which can, in turn, result in a decrease in gas permeability as the pores become more likely to be filled with liquid water films that can hinder gas transport. 

Corrosion of steel base plates and anchors in footings of supports Caused by stray current discharge into the groimd at elevated rail sections... 

Provide for sufficient flexibility of piping to prevent pipe movements from causing overstressing and failures from stress corrosion cracking of pipe materials or anchors, leakage at joints, or detrimental distortion of connected equipment through excessive thrusts and movements ... 

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