Which of the following statements is true about the R suffix?

• A. It implies the electrode is for stainless steel uses.
• B. It implies nothing about testing.
• C. It designates that the electrode meets the requirements of absorbed moisture testing.
• D. It implies the electrode is not to be used with AC.

Answer: (C)

The R suffix on an electrode classification indicates a moisture-related requirement. Specifically, it designates that the electrode meets the requirements of absorbed moisture testing. This matters because moisture in electrode coatings can release hydrogen into the weld, increasing the risk of hydrogen-induced cracking and poor weld quality. The R suffix signals that the electrode has been evaluated for how much moisture it can absorb and that it complies with the standard for moisture control. It doesn't relate to stainless steel usage, it isn't saying there’s no testing, and it doesn’t specify AC versus DC usage—those aspects are determined by other parts of the classification.