Which pressure vessels are considered outside the scope of the applicable code?

Pressure vessels that are considered outside the scope of the applicable code generally include those that are not designed primarily for pressure service or do not fall under the definitions and criteria set forth in relevant industry codes and standards. Economizers, heaters, tanks, and other pressure vessels might not be subject to the same rigorous oversight as other high-pressure systems, particularly if they are not under significant pressure or don't operate within specified thresholds defined by codes like ASME or others.

In this context, the other types of systems mentioned have more stringent regulations typically due to their operational pressures and the potential hazards they pose. For instance, compressors and boilers are well-defined within applicable codes as they operate under high pressures and are crucial for safe operation and public safety. Similarly, heat exchangers and reactors are more likely to be regulated due to their complex interactions and safety requirements under pressure. Storage vessels for hazardous materials are also subject to specific regulations directly related to safety and environmental concerns, reinforcing their necessity to comply with industry codes. Thus, the focus on ensuring safety in high-pressure environments shapes the way these various equipment types are categorized concerning regulatory compliance.