What determines the type of bolts used to reassemble an exchanger after maintenance?

• A. The service of the exchanger
• B. The color of the bolts
• C. The operating temperature
• D. The material of the shell

Answer: (A)

Bolt selection when reassembling an exchanger after maintenance hinges on the service it will perform. The service describes the actual conditions the bolts must withstand—what fluid or gas is inside, whether it's corrosive, the temperatures it will encounter, and the pressures involved—plus how the assembly will experience thermal cycling during operation. Those environmental and mechanical demands determine the appropriate bolt material, coating, strength, and heat treatment to maintain a reliable seal and prevent issues like corrosion, galling, or loosening. In short, the service defines the conditions the bolts must endure, which is why it guides bolt choice. Colors don’t affect performance, and while temperature and shell material can influence requirements, they’re part of the broader service context rather than standalone determinants.