What could be a potential outcome of not using a pressure-relief device?

Not using a pressure-relief device can lead to over-pressurization, which is a serious safety hazard in systems that store or handle pressurized liquids or gases. Pressure-relief devices are essential components that protect tanks and piping systems by allowing excess pressure to escape safely. Without this device, pressure within the tank can build up to dangerous levels, potentially leading to tank failure, leaks, or even explosions. This failure not only poses a significant risk to safety but can also lead to environmental contamination and costly cleanup efforts. Therefore, the potential outcome of failing to employ a pressure-relief device is indeed over-pressurization, making it critical for safety and operational integrity in any installation or retrofitting of underground storage tanks.