There are two primary methods of reducing crevice corrosion risks:
Eliminate small gaps which might trap electrolyte and lead to stagnation
Keep electrolyte flowing freely or at high enough rates to prevent stagnation
However, a range of factors can influence both overall risk levels and the severity of the corrosion’s progression once underway:
Crevice types: Metal to metal and metal to nonmetal crevices will typically behave differently.
Metal composition: Alloys will offer different levels of crevice corrosion resistance. In many cases, the same alloys which exhibit strong pitting corrosion resistance also offer improved crevice corrosion resistance.
Physical crevice characteristics: Everything from gap size to the depth and surface texture in and around the crevice can influence corrosion risk and progression.
The use environment: Piping systems with ample room for electrolytes to circulate and with higher flow rates tend to resist crevice corrosion better. This is because there are fewer pockets of unmoving electrolyte and even when electrolyte might be trapped, higher flow rates help to exchange trapped electrolyte with fresh quick enough to avoid the initiation of corrosion.
However, the following are good starting points that are likely to impact a range of piping systems and use cases:
Use solid, non-absorbent gaskets where possible
Use butt weld joints instead of bolted or threaded joints for new equipment
Use continuous welding or soldering to eliminate crevices in lap joints
Use alloys rated higher by ASTM G48 standards for increased resistance to crevice corrosion
Ensure complete vessel drainage where possible and design any non-draining areas to allow sufficient solution flow to prevent stagnation