Why Is Purity Non-Negotiable?

Brazed Aluminum Heat Exchanger Change-Out at a Pharmaceutical Supply Air Separation Unit

Maddox Industrial Group (MIG) performed a brazed aluminum heat exchanger (BAHX) change-out on an air separation unit (ASU) in the Midwest that produces high-purity nitrogen for a major global pharmaceutical manufacturer. An internal leak within the heat exchanger was compromising product purity, requiring replacement of the exchanger core to restore the unit to separation and return it to service.

Why Is Purity Non-Negotiable?

Air separation units serving pharmaceutical and other high-purity industries must consistently deliver gases that meet extremely tight purity specifications. Even small deviations can lead to contractual penalties, production disruptions, and risks to downstream manufacturing processes. 

At the heart of every ASU is the brazed aluminum heat exchanger. When an internal leak develops, gas streams can cross-contaminate, allowing air to enter the nitrogen stream and reducing product purity. In applications where purity is critical, restoring the heat exchanger is essential to returning the entire plant to reliable operation. 

The Challenge: Restoring a High-Purity Nitrogen System

The ASU had developed an internal leak within its brazed aluminum heat exchanger, allowing air to migrate into the nitrogen stream and causing product purity to fall below specification. Rather than attempting an in-place repair, the decision was made to replace the heat exchanger core to ensure long-term reliability and restore the unit's performance.

Working inside a cold box presented additional challenges, including confined-space conditions, precise alignment of the replacement core, and weld quality requirements. There was no room for error. 

The Maddox Solution

MIG mobilized its experienced field team to perform the heat exchanger core change-out during a planned outage. ONCe the existing core had been removed, the team carefully fit, aligned, welded, and pressure tested the replacement core to ensure it integrated seamlessly with the existing system. Every weld and test was completed to meet the strict quality standards required for high-purity nitrogen service.

As one of the few contractors in the United States offering end-to-end field and shop maintenance, testing, and repair of brazed aluminum heat exchangers, MIG also holds an NBIC "R" Stamp certification. This specialized expertise enabled the team to execute the change-out efficiently while maintaining full code compliance throughout the project.

The Result

Working around the clock over a 10-day turnaround, MIG successfully completed the core replacement and testing, allowing the unit to return to full production. With the new core installed, the ASU once again met the required nitrogen purity specifications, restoring reliable operation for the pharmaceutical supply chain.

Why MIG?

• Specialized expertise in BAHX and cold box maintenance

• Complete field and shop BAHX services

• NBIX "R" Stamp certified

• More than 40 years of high-purity industry experience

• Goal Zero Safety culture with confined-space and cryogenic expertise
  
  

Frequently Asked Questions

Q. What is a brazed aluminum heat exchanger (BAHX)?

A brazed aluminum heat exchanger is a critical component inside an air separation unit (ASU). It cools and separates atmospheric air into high-purity gases such as nitrogen and oxygen. Its compact design provides efficient heat transfer while supporting the low temperatures required for cryogenic gas production.

Q. What happens when a brazed aluminum heat exchanger develops an internal leak?

An internal leak can allow gas streams to cross-contaminate, reducing product purity. In nitrogen production, this can allow air to enter the nitrogen stream, causing the gas to fall below required purity specifications and affecting plant performance.

Q. Why replace the heat exchanger core instead of repairing it?

When product purity and long-term reliability are priorities, replacing the heat exchanger core is often the preferred solution. A new core restores the integrity of the system and helps return the air separation unit to reliable operation.

Q. What makes the brazed aluminum heat exchanger replacements challenging?

BAHX replacements are performed inside the ASU's cold box, where technicians work in confined spaces and must precisely align, weld, and pressure test the replacement core. These projects require specialized experience and strict adherence to quality and safety standards.

Q. What service does MIG provide for brazed aluminum heat exchangers?

Maddox Industrial Group provides field and shop maintenance, testing, repair, and replacement services for brazed aluminum heat exchangers. With more than 40 years of experience and NBIC "R" Stamp certification, MIG supports customers with specialized expertise in high-purity and cryogenic applications.

For more information download our Case Study below: