"PTFE and SS316L Contact"

Question:

"I am carrying out a corrosion test to replicate a situation within a subsea hydraulic system. I must have a submerged contact between the test piece and the rig. I do not want to initiate crevice corrosion and have found some evidence that hydrophobic materials such as Teflon would be a good choice to make this contact. Does anyone have any experience/knowledge on this to prevent a separate experiment? I have also read of instances that rubber bands are used to cause crevices but in some cases no corrosion occured under the band. I have seen diagrams of the Teflon washers used for the ASTM testing and wondered if the answer lay in the design. Perhaps the instances where crevice corrosion did not occur in the rubber band experiments was due to how tight the band was around the specimen. How might a needle like contact perform under some pressure?"

Answer:

ASTM crevice corrosion tests commonly use Teflon washers to simulate crevices in the corrosion test procedure. I would personally use recognized test procedures such as those detailed in ASTM. With regard to crevice corrosion, the results are particularly dependent on crevice geometry. This geometry could include the crevice material tightening procedure.

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