Safety pad

A safety pad is the positive pressure margin of inert gas maintained in the cargo tanks of an oil or chemical tanker to keep air out and the atmosphere below the flammable range. The inert gas system holds tank oxygen content at no more than 8 percent by volume and a positive pressure, so any leak is outward and the vapor space cannot support combustion. SOLAS Chapter II-2 Regulation 4 requires inert gas systems on tankers above the relevant size, and the pad is kept through loading, the loaded passage, discharge, and tank cleaning. Loss of the pad or rising oxygen halts cargo work until the atmosphere is restored.