Just in case you weren’t sure, in 49 CFR 195.2 the Office of Pipeline Safety makes it clear that any “tank used to relieve surges in a hazardous liquid pipeline system” is considered a breakout tank and therefore falls under DOT jurisdiction. This is the case even if EPA also regulates the tank, such as at a refinery. So, if a regulated pipeline uses your tank for operational pressure relief surges, you have a breakout tank.
In addition to the applicable general pipeline safety requirements, breakout tank requirements include

• Design and construction (195.132)
• Repair, alteration and reconstruction (195.205)
• Impoundment, protection against entry, normal/emergency venting or pressure/vacuum relief (195.264)
• Pressure testing (195.307)
• Protection against ignitions and safe access/egress involving floating roofs (195.405)
• Overpressure safety devices and overfill protection systems (195.428)
• Inspection (195.432)

Not sure if your plant tanks are regulated? RCP can do a jurisdictional determination and help ensure that your breakout tanks are in full compliance with DOT requirements as needed.