The Spec Sheet Is a Summary, Not a Specification
Both tanks are 304 stainless steel. Both are one thousand liters. Both have a sixty-degree cone and a cooling jacket. On paper they are the same tank.

In the cellar they behave differently. One holds temperature within half a degree. The other swings two degrees during active fermentation. One cleans in forty minutes. The other needs an extra caustic cycle to pass an ATP swab. One produces beer that tastes the same every batch. The other produces beer that tastes different every batch and nobody can explain why.

The difference is not in the headline specifications. It is in the details that do not fit on a marketing sheet.

The Weld Is the Tank
A fermentation tank is a collection of stainless steel plates welded together. The weld is not a seam between two good pieces of metal. The weld is the metal. If it is not fully penetrated, if it is not shielded from oxygen during the weld, if it is not passivated afterward, it will corrode. The corrosion starts as a microscopic pit and grows into a leak, or worse, into a harborage point for bacteria that no amount of CIP can reach.

Orbital TIG welding creates a consistent, fully penetrated weld with minimal heat distortion. Manual TIG can match it if the welder is skilled and the procedure is followed. The problem is that manual welding quality varies from welder to welder and from Monday to Friday.

Ask for the weld procedure specification and the welder qualification records. A manufacturer who has those documents ready takes welding seriously. A manufacturer who does not is hoping you will not ask.

The Surface Finish Is a Hygiene Specification
The interior surface should be polished to Ra 0.4 micrometers or better. A rougher surface has microscopic peaks and valleys that protect bacteria from cleaning chemicals. The difference between Ra 0.4 and Ra 0.8 is invisible to the eye. Both look like polished stainless steel.

But the Ra 0.8 tank requires longer CIP cycles, higher chemical concentrations, and more frequent manual cleaning to reach the same level of sanitation. Over a year, that difference adds up to thousands of dollars in chemicals and labor, and a higher risk of a contaminated batch.

Ask for the surface finish measurement. If the supplier cannot provide it, the surface has not been measured.

The Cooling Jacket Geometry
The jacket is a layer of stainless steel welded to the outside of the tank through which glycol flows. Its design determines how evenly the tank cools.

A dimple jacket has spot welds that create turbulence in the glycol flow. A half-pipe jacket uses a spiral pipe welded to the tank surface. A full-coverage jacket covers the entire tank body and cone.

For most fermentation, a dimple jacket on the body and cone is sufficient. For precise lager fermentation or frequent crash cooling, a full-coverage jacket provides more uniform temperature control and faster cooling. A tank with body-only cooling creates a temperature gradient that stresses yeast and produces inconsistent flavor.

Ask for a drawing that shows the jacket coverage area. The jacket design is not always visible in a photograph.

The Manway You Will Notice Every Day
The manway is the door through which a person enters the tank for inspection and manual cleaning. It needs to be large enough to pass through comfortably and positioned so the entire interior is accessible.

A manway that is too small or poorly placed means every inspection is a struggle and every manual cleaning is incomplete. It is not a feature anyone notices when buying. It is the only feature anyone notices after the first month.

The Small Parts That Fail
The sample valve, the racking arm, the pressure relief valve, the CIP spray ball, the gaskets, the clamps. These are the parts that fail. They are also the parts where manufacturers cut costs.

A sample valve that does not seal leaks beer. A racking arm that is not adjustable cannot be positioned above the yeast. A pressure relief valve that is not rated correctly is a safety risk. A spray ball that does not rotate does not clean.

Ask about the brand and specification of every small part. A manufacturer who uses known industrial components expects the tank to last.

Want to know if the fermentation tanks you are considering will actually perform in your cellar? We review tank specifications against your beer styles and production schedule. Leave a message below with the tank specifications you are considering, and we will send you a technical evaluation.