A Virgina Class submarine rising out of the ocean, similar to the type of submarine that would require the hydraulic submarine test stands discussed in this article.

Redesigning and Modernizing Hydraulic Test Stands for Submarine Accumulators

Naval submarine at sea surface during sunset

When a New England manufacturer with over four decades of experience producing submarine parts for the US Department of Defense needed help replacing and upgrading a test stand for hydraulic accumulators, they turned to the experts at Devine Hydraulics. Following a three-year journey to develop new, custom hydraulic equipment, DHI recently fabricated and installed a top-of-the-line 100hp test stand that—with proper preventative maintenance and upkeep—will facilitate more efficient and accurate testing for years to come.

The customer has a long and well-respected history producing parts for submarines, but their needs have grown over the years and their existing test stand was long overdue for replacement, due to both the size and lack of modern features the existing equipment offered. The client asked Devine Hydraulics to design and manufacture custom hydraulic equipment that would meet their needs so that they could optimize their operations and continue to meet the rigorous standards required of military suppliers.

The client manufactures accumulators, a component that stores energy. Specifically, in the units they build, the accumulator opens a hatch using a nitrogen-charged hydraulic cylinder. When the hydraulic valve is opened, the pressurized nitrogen forces the hydraulic oil back into the reservoir and actuates the hatch. 

Reducing Risk and Adding New Digital Features 

The first hurdle to overcome was the redesign of the equipment, which had not kept pace with the increasing demands of the industry as technology evolved. The original power unit had always been undersized for their needs; It had been upgraded over the years, but when a larger pump was added, the motor was forced to run at around 130% of capacity to keep up. The new machine also needed to incorporate modern features, such as cycle counting, digital readouts, and touchscreen controls.

The company’s former owner had delayed or postponed maintenance and neglected a number of small preventative tasks that led to serious long-term problems. When the new owner came in, they quickly recognized the need to invest in the system to reduce the likelihood of unanticipated system failure and remain in total compliance with DoD regulations. Especially if they were going meet the needs of the new Columbia-class series of submarines that were recently ordered by the US Navy.

The old test stand required an employee to watch a counter and manually stop the equipment when the correct number of cycles was reached. The upgraded system uses a digitally-controlled cycle counter, which automatically stops the test when it has reached the number of cycles the specific test activity requires. This new technology upgrade helps eliminate distractions during testing procedures, ensures consistency, and reduces the risk of human error. 

Hydraulic System Upgrade Considerations Beyond Size Come Into Play

The upgraded system came with a significantly larger footprint– literally twice the size of the old test stand. A secondary pump was added for static testing purposes, which takes the accumulators to 4500 psi, 150% of the working pressure of 3,000 psi, and holds it for a period of time. With more powerful pumps and motors, our engineers observed early on in the project that the increased noise level could be a serious issue. While the customer had anticipated equipment that would require more physical space, they hadn’t realized that the machinery would be louder and hadn’t considered the impact the noise could have on its operators.  To reduce the excessive noise, DHI’s hydraulic engineers recommended incorporating sound-deadening material into the machinery housing.  

The interior and exterior of the new custom hydraulic test stand were finished with special anti-corrosive paint, providing additional protection to ameliorate damage for years into the future.

Professional Oversight Is Vital to Installing Hydraulic Equipment Safely

The hydraulic machine installation was a challenge, given its weight of a little over 7,000 pounds, which the client’s forklifts struggled to load. Next, it was set in place to mark it, drilled for anchor bolts to secure it, and installed the machine. The electrician wired the machine to the prewired disconnects and power unit. A chiller was set up outside and anchored to keep the working environment and machinery at an optimal testing temperature.

It took approximately eight hours to complete the wiring, then DHI could begin testing. We found that the incoming power phasing was incorrect, but a few minor adjustments allowed the startup to go smoothly. The equipment ran as expected, as it had been thoroughly tested before installation at DHI’s facility. We trained the client on how to use the equipment and made sure to answer any questions that they had, a phase that is often overlooked in new machine installation.

One of our “unofficial KPIs” regarding customer satisfaction was met just a few weeks later when the client inquired about pricing and availability for an identical unit.

Is your company using outdated hydraulic equipment? Contact us today to learn how Devine Hydraulic’s custom hydraulic engineering can help you solve problems before they begin.

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