The temperature instability of the chemical has to be such that it breaks down at the temperature needed to release phosphoric acid. The program performs poorly at low temperatures. Iron phosphate scale breaks off in high velocity areas and becomes a foulant. If the crude slate suddenly changes and there is not enough reactive sulfur to sustain the production of iron sulfide, the phosphoric acid has minimum ability to react with the base metal. Naphthenic acid competes with the phosphoric acid to react with the iron sulfide. If the acid content in the crude increases, it can react directly with the iron sulfide and increase corrosion.

The temperature instability of the chemical has to be such that it breaks down at the temperature needed to release phosphoric acid. The program performs poorly at low temperatures. Iron phosphate scale breaks off in high velocity areas and becomes a foulant. If the crude slate suddenly changes and there is not enough reactive sulfur to sustain the production of iron sulfide, the phosphoric acid has minimum ability to react with the base metal. Naphthenic acid competes with the phosphoric acid to react with the iron sulfide. If the acid content in the crude increases, it can react directly with the iron sulfide and increase corrosion.