Which of the following is NOT a common stressor for pressure containers?

• A. Thermal
• B. Chemical
• C. Electrical
• D. Mechanical

Answer: (C)

Pressure containers are designed to handle stresses that directly affect the vessel walls: temperature changes that cause expansion or contraction (thermal stress), chemical attack from contents or corrosive surroundings (chemical stress), and external forces or impacts (mechanical stress). Electrical effects don’t impose a direct structural load on the container itself in the same way; they’re more about ignition risks or heating from electrical sources rather than a fundamental stress that can cause wall deformation or failure. So, electrical is not a common stressor for pressure containers.