Before welding can be performed on a cargo tank that carried flammable products in US ports, what must be obtained?

Welding on cargo tanks that previously held flammable products necessitates a strict adherence to safety protocols due to the inherent risks associated with flammable vapors that may still exist in the tank. Obtaining a certificate from a certified marine chemist is crucial in this context. This certificate ensures that the atmosphere within the cargo tank is safe for welding, confirming that there are no flammable vapors or other hazardous conditions that could lead to an explosion or fire during the welding process.

The marine chemist performs the necessary tests to assess the tank's atmosphere, ensuring that it meets safety requirements before any hot work, such as welding, is permitted. Without this certification, there is a significant risk of ignition of residual flammable materials, endangering not only the workers performing the welding but also the integrity of the vessel and nearby personnel.

Other options, while important in their own right, do not specifically address the core requirement of confirming a safe working environment for welding operations in flammable environments, highlighting the specialized role of marine chemists in this critical process.