🔍 Key Concepts

• Boiler water chemistry and how it affects metal surfaces at tube ends • Difference between corrosion from combustion byproducts versus corrosion from water-side treatment chemicals • Where pinhole leaks typically form when water chemistry is out of balance

💭 Think About

• Is this damage more likely to come from the fireside (gas/soot) or the waterside (boiler water) of the tubes? • What effect do very high alkalinity or oxygen scavenger chemicals have on metal at points of stress, such as tube ends rolled into drums or headers? • Which of these conditions is specifically associated with caustic attack or chemical attack at seams and joints rather than general surface fouling?

✅ Before You Answer

• Identify whether pinhole leaks at tube entries are usually a waterside corrosion issue or a fireside fouling issue • Recall which treatment condition is linked with caustic gouging/pitting at stressed areas like tube ends • Eliminate any options that mainly relate to deposits on the gas side of tubes rather than the water side