Designing Rotary Unions for Maximum Uptime

Few maintenance tasks are more frustrating than shutting down an entire machine to replace a worn-out part. Yet many rotary unions are designed with that outcome in mind. The difference between routine maintenance and costly downtime often comes down to design choices made early in the project. Here’s how custom and standard rotary unions can change that equation.

Preventing Machine Downtime

Many off-the-shelf rotary unions require the entire machine to be disassembled for a straightforward seal replacement, resulting in a full production stop for routine maintenance. Custom rotary unions built with a modular design approach keep machines running longer by making maintenance a simple, scheduled process.

DSTI connects what’s available and what the application demands, so the rotary union is not the reason the machine goes down. We review the application’s pressure, speed, media, and duty-cycle requirements before providing recommendations.

Modifying Standard Unions for Specific Needs

• Standard Fit, Optimized Performance: When a standard DSTI series (GP, LT, SCS) closely meets the application requirements, we can incorporate targeted modifications to maximize performance without the lead time of a fully custom design.
• Effective Stock Mods: How we modify standard unions to meet unique needs:
  • Material Swaps: These can be modified to meet chemical and temperature requirements. Available materials include carbon steel, stainless steel, Inconel, brass, bronze, chromoly, titanium, and aluminum.
  • Seal Swaps: These can be modified to function with different types of media to increase life, lower torque, and extend temperature ratings.
  • Porting & Mounting: Connection sizes, mounting configurations, and housing and shaft dimensions can be modified to fit your current envelope.
• The Goal: Quick, cost-effective adjustments to proven designs help achieve specific performance targets faster and at lower cost. When you're already halfway there, DSTI delivers a tailored solution built on proven technology to get you the rest of the way.

Custom Engineering to Meet Project Goals

• Blank-Slate Design: If you need a fully engineered design, we can do it. With over a 1,000 custom projects completed across defense, aerospace, oil and gas, food and beverage, factory automation, and more, we have experience engineering a ground-up solution for applications where failure isn't an option.
• High-Performance Maintenance Features: Every part is designed for longevity and ease of maintenance.
  • Modular Construction: Components can be designed for direct access without removing the housing from the machine. Used in both defense and industrial applications, this enables field repair and service without full unit disassembly.
  • Life-Extending Materials: DSTI selects alloys, coatings, and seal materials to extend service life to meet expectations. In oil and gas applications, specialized shaft plating helps reduce maintenance frequency and operating costs.

Industry Applications for Custom Rotary Union Solutions

• Automation & Robotics: Custom rotary unions fit directly into rotary index and dial tables, with each solution built for the machine and its duty cycle.
• Oil & Gas: Our engineers build custom rotary unions to handle high pressure, high vibration, and harsh media in offshore, subsea, and land-based environments.
• Food & Beverage: The SCS Series features food-grade seals, 316 stainless steel construction, and an FDA-compliant design for CIP systems, and it can be modified for washdown, chemical compatibility, and connection requirements.
• Defense: Custom rotary unions for defense support military vehicle hydraulic systems, radar cooling, and training and simulation equipment, all calculated and tested to meet or exceed stringent military specifications.

The DSTI Advantage: In-House Lifecycle Control

From design and seal selection to Performance Verification Testing (PVT), every step of the process takes place at DSTI. That includes CNC precision machining, assembly, performance verification, and Factory Acceptance Testing (FAT), along with the required documentation from the start of the project.

Whether the design is a modified standard or a fully custom solution, DSTI verifies the performance requirements before production begins.