How Assmann Builds a Better Tank
Assmann has manufactured crosslinked polyethylene tanks since 1980 using a process that prioritizes quality over speed at every stage. Three manufacturing decisions define the Assmann difference.
Unshielded Molds for Uniform Wall Thickness
In the polyethylene tank industry, mold shielding has become standard practice. Manufacturers wrap and weld layers of sheet metal around the outside of their molds to reduce heat transfer from the oven environment. This speeds up the production cycle and reduces cost per unit. It also introduces uneven heat distribution across the mold surface, which produces variation in wall thickness throughout the finished tank.
Assmann does not shield our molds. Every surface of every mold is exposed to even, convection-based heat throughout the entire molding process. Our large rotational ovens turn end-over-end, receiving heat from an adjacent stationary furnace. The oven shape and foil design are engineered to create optimum airflow and uniform heat distribution throughout the mold from start to finish.
The result is a tank wall that is genuinely uniform in thickness at every point in the structure. That uniformity is a structural quality. Consistent wall thickness means no thin spots where stress concentrates under load, and no areas where chemical permeation is more likely over time.
Gradual Cooling for Complete Crosslinking Throughout the Wall
The crosslinking process in XLPE does not end when the mold exits the oven. Covalent bonding between polymer chains continues after the heat source is removed, and how the mold is cooled in that post-oven period determines whether the crosslinking completes throughout the full depth of the wall or stops short near the surface.
Many manufacturers use rapid cooling methods to reduce cycle time. Assmann uses separate cooling chambers with very high-volume air movement to ensure gradual, controlled cooling of the mold and the part inside. This allows the crosslinking process to complete throughout the entire tank wall before cooling finishes.
A tank that is crosslinked throughout its full wall thickness is a more resilient product than one that is crosslinked primarily at the surface. The difference shows up in chemical resistance, in structural performance under sustained load, and in how the tank holds up through years of real-world service.
ISO 9001:2015 Certification and Independent Testing
Assmann is the first and only polyethylene tank manufacturer to achieve ISO 9001 certification, which we have held since 1997. ISO 9001:2015 is a quality management system standard that requires every element of the production process to be documented, monitored, and traceable. Every Assmann tank has its own quality control and routing card linking it to its date of manufacture, raw material lot numbers, and processing times. Our products undergo ultrasonic thickness, gel, and impact testing at our in-house laboratory.
Assmann is also NSF certified for chemical storage. NSF International requires extensive product testing and material analysis, and undertakes a complete evaluation of product development before certification is granted. Both certifications require ongoing compliance and independent auditing.
Built for the Chemicals That Demand the Most
Assmann crosslinked polyethylene tanks are designed for chemical storage applications where consistent wall integrity and long-term performance are non-negotiable. The chemicals Assmann tanks are built to store include sodium hypochlorite, hydrochloric acid, sodium hydroxide, sulfuric acid, hydrofluoric acid, ferrous chloride, hydrogen peroxide, peracetic acid, liquid ammonium sulfate, and many others.
Each of these chemicals places specific demands on the storage tank. Sodium hypochlorite is a strong oxidizer that requires airtight fittings and a wall material resistant to degradation under prolonged exposure. Hydrochloric acid is highly corrosive and demands consistent wall integrity throughout the tank structure. Hydrofluoric acid is colorless, highly corrosive, and consistently in demand across refrigerant, herbicide, and pharmaceutical applications.
The uniform wall thickness and complete crosslinking that result from Assmann’s manufacturing process are what allow these tanks to meet those demands over their full service life, which is measured in years and decades, not in production cycles.
Assmann maintains a full library of chemical storage guides covering specific storage requirements, venting, fittings, and compatibility. These guides are available at assmann-usa.com/solutions/applications/ (https://assmann-usa.com/solutions/applications/).