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Teflon steel lining elbows are pipe fittings that use stainless steel or carbon steel as the metal substrate and PTFE as the lining material. This structure's elbow is very resistant to corrosion and can withstand the erosion of a wide range of chemical media, including as strong acids, strong bases, organic solvents, and more.
link:https://www.ttptfe.com/steel-lining-ptfe-pipes-and-fittings/steel-lined-ptfe-90-big-elbow.html
Steel lined PTFE 90°big Elbow