In the future...
* Use a corrosion inhibitor in the fuel.
* Check for galvanic corrosion. Were there dissimilar metals in the system, even not directly attached to the tank? Avoid brass valves and the like.
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ASTM D975 (this is the basis diesel standard) Appendix X2.7.2: Fuel Storage Conditions:
Copper and copper-containing alloys should be avoided. Copper can promote fuel degradation and may produce mercaptide gels. Zinc coatings can react with water or organic acids to form gels which rapidly clog filters.
Caterpillar installation guidance.
http://pdf.cat.com/cda/files/3375312...EBW4976-04.pdf
Material. Black iron pipe is best suited for diesel fuel lines. Steel or cast iron valves and fittings are preferred.
CAUTION: Copper and zinc, either in the form of plating or as a major alloying component, should not be used with diesel fuels. Zinc is unstable in the presence of sulfur, particularly if moisture is present in the fuel. The sludge formed by chemical action is extremely harmful to the engine’s internal components.
Cummins installation guidance.
https://www.cumminspower.com/www/lit...0_p115-132.pdf
Diesel Fuel Piping. Diesel fuel lines should be constructed from blackiron pipe. Cast iron and aluminum pipe and fittings must not be used because they are porous and can leak fuel. Galvanized fuel lines, fittings, and tanks must not be used because the galvanized coating is attacked by the sulfuric acid that forms when the sulfur in the fuel combines with tank condensate, resulting in debris that can clog fuel pumps and filters. Copper lines should not be used because fuel polymerizes (thickens) in copper tubing during long periods of disuse and can clog fuel injectors. Also, copper lines are less rugged than black iron, and thus more susceptible to damage.
Note: Never use galvanized or copper fuel lines, fittings or fuel tanks. Condensation in the tank and lines combines with the sulfur in the diesel fuel to produce sulfuric acid. The molecular structure of the copper or galvanized lines or tanks reacts with the acid and contaminates the fuel.
Yanmar manual
http://www.mackboring.com/DAN/files/...0329PM63nj.pdf piping is specified as rubber or steel (page 9).