Saline muds

Their polarizability increases in saline muds and their current efficiency markedly decreases e.g., for the alloy galvalum III in Table 6-3, from 2550 A h kg to 1650Ahkg- . 

Temperature is of particular importance to the performance of anodes, especially when anodes are buried. Anodes may often be used to protect pipelines containing hot products. Thus temperature effects must be considered. Figure 10.14 illustrates the effect of temperature on different anodes in hot saline mud. Al-Zn-In anodes experience greatly reduced capacity in open seawater at temperatures above 70°C (down to 1200Ah/kg at 100°C) and in seabed muds in excess of (900 Ah/kg at 80°C). At... 

Fig. 10.14 Capacity-temperature relationships for anodes covered with saline mud (after...

Zinc anodes have also experienced problems at elevated temperatures in saline mud, suffering intergranular decohesion at approximately 70°C. Later work by the same authors showed the threshold for damage to be ca. 50°C. The material is not recommended above 40°C" although special zinc based materials for temperatures exceeding 50°C have been developed ... 

The presence of HjS (from bacterial activity in anaerobic saline mud, for example) can result in a significant decrease (16%) in capacity and loss of operating potential for Al-Zn-ln anodes... 

K.P. Fischer, Cathodic protection in saline mud containing sulfate-reducing bacteria. Mater. Performance 20 (1981) 41-46. 

K.P. Fischer. Cathodic protection criteria for saline mud containing SRB at ambient and higher temperatures. Paper No. 110, Corrosion 1981, NACE, Houston, TX, 1981. 

Eischer KP (1981) Cathodic protection criteria for saline mud containing SRB at ambient and higher temperatures. Paper No. 110. CORROSION/81, NACE International, USA de Romero ME, Parra J, Ruiz R, Ocando L Bracho M de Ricon OT, Ramero G, QuinteiD A (2006) Cathodic polarisation effects on sessile SRB growth and iron protection. Paper No. 06526. CORROSION 2006, NACE International, USA... 

Cathodic protection in saline mud and soils to protect steel and aluminum structures such as tanks and piping was used for corrosion control in the Caribbean Islands. The conditions encountered with saline mud and sands are unique to these areas and lend themselves to specialized application of galvanic and impressed current corrosion control. ... 

Electrolyte resistivity can vary from clean seawater at 20.5 ohm-cm. to saline mud of 300-500 ohm-cm. to brackish water conditions with resistivity up to 5,000 ohm-cm. 

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