Answer: Thanks for the question Dirk! No, you cannot turn a 407 into a 412 certification. A 412 trailer has to be built to that certification; it must be built to ASME code and carry a U-Stamp on the plate. Unlike the 407, all material that goes into the 412 vessel must have papers certifying it meets the proper specifications. The trailer must also be rubber lined to handle hydrochloric acid. Even though some of these trailers are aluminum, the majority of them are made of steel.