Custom Tanks: Built to Your Specifications with Unmatched Experience

What you want is what we deliver.

For over 135 years, CB Mills (Chicago Boiler Company) has been designing and manufacturing high-quality custom steel tanks and ASME pressure vessels in the United States. From simple storage tanks to complex ASME-certified reactors, our team delivers solutions that combine safety, performance, and craftsmanship.

Unmatched Fabrication Capabilities

Our facility is equipped to handle a wide range of custom tank projects, with fabrication space that supports vessels up to 12 feet in diameter and 40 feet in length. Whether vertical or horizontal, we design and build tanks with ASME Section VIII, Division 1, S, U, and R Stamps, ensuring the highest safety and compliance standards.

We work with a full spectrum of materials and alloys, including:

• Stainless steels (304 or 316)
• Carbon steel
• Low alloys
• Nickel alloys
• Duplex
• Monel
• Inconel
• Hastelloy
• Clad construction

From one-off fabrications to large-scale production runs, CB Mills has the experience, expertise, and equipment to deliver the right solution.

Applications & Tank Types

Our history includes the design and fabrication of:

• Reactors
• Open-Top Mixing Tanks
• ASME Pressure Vessels
• Mixing Tanks
• Storage Tanks
• UL-Certified Tanks
• API

Custom Features & Options

We offer a variety of design options and tank accessories, including:

• Flanged nozzles or threaded openings
• Manways
• Internal drop tubes
• Insulation rings
• Attachment tabs and lugs
• Integrated cleaning equipment and process controls (available upon request)

Why Chicago Boiler Company?

Since our beginnings in the 1890s as a boiler repair shop, Chicago Boiler has evolved into an industry leader in custom tank fabrication. Our focus has always been on quality, customer service, and continuous improvement — building process equipment that meets the unique demands of our customers while ensuring long-term reliability.

The result: custom tanks engineered for your needs, backed by over a century of proven expertise.