Which statement about entering into a tank which has been sealed for a long time is TRUE?

Entering a tank that has been sealed for a prolonged period requires careful consideration of safety protocols due to potential hazards such as toxic gases, lack of oxygen, or other atmospheric contaminants. The correct answer highlights the importance of frequent testing of the atmosphere within the tank to ensure that it is safe for personnel to enter.

Safety testing may involve checking for oxygen levels, flammable gases, and toxic substances, and this must be done continuously or at regular intervals before and during entry. This practice is essential in preventing accidents and ensuring that workers are not exposed to harmful conditions.

In contrast, the other statements reflect unsafe practices. It is never safe to enter a confined space like a sealed tank without prior inspection, as the atmosphere could be hazardous. Visual checks alone are insufficient, as they do not guarantee that the air quality is safe to breathe. Additionally, dismissing the need for gas detectors is highly dangerous, as these devices are critical for identifying unseen and potentially lethal gas concentrations. Therefore, thorough atmospheric testing is the only acceptable and safe course of action.