What feature is now required in ASME tanks that wasn't mandatory before 1983?

The requirement for Overfill Protection Devices (OPD) in ASME tanks was established to enhance safety measures for the storage and handling of hazardous materials, particularly liquid fuels like propane. Prior to 1983, there was a lack of standardized measures to prevent dangerous overfills during the transfer of liquids into storage tanks, which could lead to spills, leaks, or even explosions. The introduction of OPD as a mandatory feature aimed to mitigate these risks.

The OPD serves as a critical safety mechanism that automatically shuts off the flow of liquid when a tank reaches a certain fill level, thus preventing overfilling. This helps to ensure not only the safety of workers and the surrounding environment but also compliance with regulatory standards. The mandatory nature of OPD reflects the commitment to improving safety practices in the industry, which ultimately benefits both operators and the public.

Other features such as pressure gauges, automatic shut-off systems, and additional insulation may contribute to safety and efficiency but do not specifically address the critical issue of overfilling in the way that OPDs do, making their prior implementation less standardized before 1983.