NEWS | March 18, 2021

Innovation aids carrier maintenance efforts: Automating heat exchanger cleaning process improves critical path work

By Max Maxfield, PSNS & IMF Public Affairs Puget Sound Naval Shipyard & Intermediate Maintenance Facility

A team of innovators at Puget Sound Naval Shipyard & Intermediate Maintenance Facility spearheaded an effort to automate the process of cleaning heat exchanger tubes during aircraft carrier availabilities that proved so successful, the process is being exported to other carrier maintenance locations.

Prior to the process change, mechanics would spend many hours working in wet and cramped conditions handling high-pressure water lines to manually position and feed the hydro-lance equipment through up to 60,000 individual tubes that are part of the heat exchangers used on Nimitz-class aircraft carriers. Now, a robotic system, comprised of a control box, a positioner, and a feeding device, controls the high-pressure hydro-lance to clean the tubes, with a mechanic controlling the system from a distance via a touchscreen tablet.

Previously, the process of cleaning the heat exchangers and inspecting the tubes was one of the longest strings of work done during the availability. These long strings of work that govern the overall time it takes to complete an availability are referred to as critical path work.

“This process often resulted in a large amount of re-work, as many of the tubes were not cleaned on the first attempt to the level required to support the new inspection methods,” said Mike Gonzales, an assistant product line manager with Code 1040, Propulsion and Auxiliary Product Line. “When I was managing this work during a fiscal year 2018 carrier availability, even though the shop employees were working so hard at it, I noticed it was going rather poorly in terms of efficiency. I began searching the internet for ‘automated heat exchanger tube cleaning’ and similar phrases.”

After moving from Code 300, Operations, to Code 1040, specifically to work on the needed process improvement, Gonzales began collaborating with James Calverley, a senior mechanical engineer with Code 260.5, Steam Plant Cleanliness, Steam Plant Lay-up, & Condenser Branch.

“James was identified as the engineering lead for the same efforts, so we began collaborating on potential solutions,” Gonzales said. “At some point during the first few months of our research, we got put in contact with Jeff Brimhall (PSNS & IMF Technology Insertion manager with Code 1000I) as a potential person to help us bring new technology into the shipyard.”

Code 1000I, the Technology Insertion Product Line, helps shops and codes bring new technologies and tooling into the shipyard by navigating traditional roadblocks, including safety, security, cybersecurity, procurement, funding, and other issues. They also help find new technology solutions when a need exists but the solution is not clear. They also serve as the command’s liaison to the Navy’s various innovation organizations and outside organizations.

Calverley knew he and Gonzales would not be able to tackle such a large improvement effort by themselves, so he suggested they find subject matter experts at technology insertion who could help them work the overall problem.

“I knew the process of condenser cleaning and inspection could be improved, but I wanted buy in from all parties involved,” Calverley said. “I went into initial meetings with project management with the goal of initiating a lean event.”

Eventually, Code 1000I began working with people from several shops and codes, to look how they could improve heat exchanger cleaning. Shane Trepasso, general foreman, Shop 38, Marine Machinery Mechanics; Jericho Bautista, IT specialist, Code 109, Information Technology and Cyber Security Office; and Matt Warner, marine machinery mechanic, Shop 38, were enlisted in the effort.

“There were two companies proposing hydro lancing solutions that included automation and / or remote controls,” Calverley said. “In 2019, I ran several informal tests with Matt Warner before we ever had any robotic equipment. This testing was used to inform a challenge to the Naval Sea Systems Command technical requirements, and how the requirements didn’t account for variations in system configuration.”

This testing was performed on tubes from retired heat exchanger equipment.

According to Calverley, improving the process was aimed at making it more effective from the outset as well as making it safer. After looking at several possible solutions, the team narrowed their choices down to two solutions.

PSNS & IMF eventually decided to move forward in cooperation with the National Center for Manufacturing Sciences, with a solution from Terydon, a private industry company. The project team has refined the process and have worked with the company to greatly improve the heat exchanger cleaning and inspection process.

According to Calverley, after developing and refining the process over the course of five maintenance periods, the new automated heat exchanger cleaning and inspection process has resulted in significant savings in time and labor, including:

• The new automated cleaning process has reduced the duration of initial tube cleaning by 83 percent (from six total weeks of time from start to finish, to one week for one particular heat exchanger).

The new process has reduced the duration of re-work by 86 percent (from two continuous weeks of mechanics on tools to two days).

• The new process reduces the labor needed to clean the heat exchangers by over 65 percent (from total 2,050 man-hours of labor to under 700 man-hours of labor).

• The amount of re-work needed to reduce fouling by going back and re-cleaning has been reduced from a best case 10 percent re-cleans to a current worst case 0.25 percent re-cleans.

• PSNS & IMF also engineered improved safety processes to help reduce the chance of a near-miss situation becoming an injury.

The savings in man-hours and overall time dedicated to heat exchanger cleaning have been so significant, the process is now being used at other locations as well.

“So far PSNS & IMF has taken delivery of a set of the equipment that is being moved from location to location to support West Coast work in Bremerton, San Diego, as well as Japan,” Gonzales said. “Norfolk Naval Shipyard is starting the process to obtain the same equipment with some upgrades that we’ve identified for them. Japan will also be obtaining a set of this equipment to keep onsite.”

The heat exchanger cleaning and inspection improvement process is one very successful example of the potential throughout PSNS & IMF, but probably not the last successful innovation to originate here.

“We are working to expand efforts and take on more and more of these projects as a shipyard,” said Ryan Marson, a cell manager with Code 1000I. “We see the potential of great gains going forward, not only here at PSNS & IMF, but for the entire NAVSEA enterprise.”

Because naval vessels of several classes use heat exchangers, the team expects this technological solution could be adapted for use on a variety of ships.

“I will be thrilled when this is deployed to every class of ship where it gives us an advantage in the safety, duration, and cost of cleaning heat exchanger tubes,” said Gonzales.