The use of stainless steel tanks in the winemaking process first began in the 1950’s and besides the ever popular use of wood in the form of wine barrels is still the most common storage vessel seen at a winery. They have many advantages over other types of containers, leakage for one and temperature control for another. Temperature control is of high importance to winemakers both during the fermentation process and throughout the rest of a wine’s life. But what about the role of a tank (stainless steel or otherwise) in the compliance area of winemaking? Wineries are required to mark all of their storage containers that are larger than 100 gallons in capacity. The specific information they are required to put are them are: unique serial number,&  info on it’s current use. The unique serial number, usually called a tank number must be permanently marked onto the tank, along with the tank’s total capacity. The current use requirement refers to a placard of some sort that identifies the product currently inside the tank. This is most often the lot or blend number of the must, juice or wine in it. So if a TTB agent were to walk up to the tank they would easily be able to view and identify the tank’s number and what product was currently in it. The other area in regards to their tanks that wineries are required to maintain is an accurate form of measuring the gallons that are stored in their tanks. This is where it can get interesting when measuring a tank that is partial. (for example the tank has a 10,000 gallon capacity but only has 7,580 gallons in it.) A TTB agent would want the winery to be able to show them how they came up with that volume. This would have been done by taking either a “dry” or “wet” measurement inside the tank, then either using a formula based on the tank’s geometry or by viewing a chart unique to the tank to come up with the 7,580 gallon number. However, winemaking is really not an exact science and tank measurements are most definetely not. The laws of physics play out against them. Depending upon many factors, primarily temperature the volume inside a tank will rise and fall so getting an “exact” measurement is not very realistic. The TTB has generally come to accept this over the years and many “discussions”. Regardless of the regulations, wineries do want to keep accurate measuring formulas or charts for all their tanks. Afterall, they are always going to want to know just how much they have of any given blend, variety group or sum total.