Chemical compatibility of sealing materials
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Product: Welded needle valve with graphite packing seal. Medium: Phosphated grease. Question: Is the chemical compatibility suitable when phosphated grease comes into contact with graphite packing?
We know that graphite exhibits excellent corrosion resistance in the vast majority of corrosive environments, including hydrochloric acid at its boiling point, dilute sulfuric acid, hydrofluoric acid, phosphoric acid, alkaline solutions, and organic solvents. Only strongly oxidizing agents such as nitric acid, concentrated sulfuric acid, bromine, and fluorine can destroy it. Phosphoric acid is a medium-strength acid with a certain degree of ionization, but materials are fully resistant to it. According to the \"Corrosion Data and Material Selection Handbook\" compiled by Zuo Jingyi and others, such materials can resist corrosion at any concentration, and their temperature resistance can reach the material’s heat tolerance limit. Therefore, contact between phosphate esters and graphite fillers does not cause damage.