Engineering Better Connections: Why Couplings Matter in Ingredient Handling

In any powder ingredient handling system, the equipment used to join tubing sections together — known as couplings — might seem like minor details. But ask any plant engineer with a leaky connection or a blown clamp and they’ll tell you a different story.

Using the right tube couplings keeps your lines properly aligned and free of internal obstructions. Let’s break down the major problems with conventional couplings, including how much they could be costing you, and share what you should use instead.

Couplings That Work With Tubing, Not Pipe

First, let’s set the semantic record straight. Why do we say ‘tube’ instead of ‘pipe’? In common industrial conversation, the terms ‘pipe’ and ‘tube’ are often used interchangeably, but they’re technically defined and specified differently.

Tube is typically described by its outside diameter (OD) and wall thickness, which makes OD-based tubing ideal for applications where precise fit, alignment, or connection to other components is critical. 

Pipe, on the other hand, is defined by a nominal pipe size (NPS) and a schedule, where the schedule indicates wall thickness and pressure capability rather than exact dimensions. 

Despite these differences, many systems — especially in material handling, processing, and structural applications — use pipe and tube in similar roles, leading engineers, suppliers, and operators to casually use the terms as synonyms. Understanding the distinction helps ensure proper specification and performance, even when the terminology overlaps in practice.

The Problems With Conventional Couplings

Some conventional couplings used in powder handling systems originate from other industries such as plumbing, hydraulics, or structural piping. These couplings were not originally designed for fine powders, dust-tight operation, frequent disassembly, or hygienic processing environments

As a result, they often prioritize pressure rating over cleanability, ease of alignment, or grounding continuity. When repurposed for bulk ingredient handling, these couplings can introduce leakage points, misalignment, exposed threads, and areas where dust or product residue can accumulate. These pain points are magnified in regulated industries like food, pharma, and chemical processing. 

1. Conventional couplings leak under pressure.

Over time, vibration or minor misalignment degrades the sealing surface, leading to air and product leaks. In powder handling systems, leaks also create fugitive dust, raising housekeeping demands, safety risks, and regulatory exposure.

Do you know how much your leaks are costing you? For example, a 1/16” leak operating at 100 PSIG might cost you $1,259 a year for that single, small leak! Here’s the formula we used to calculate this.

Annual Cost of Leak = Leakage Rate (Cubic Feet per Minute) x Kilowatt/CFM x Operating Hours x Cost/KH per Kilowatt Hour)

Annual Cost of Leak = 6.5 CFM x 0.18 kW/CFM x $0.1345/kWh x 8,000 hours x = $1,259 

And that’s not all. Note that this cost does not include additional costs such as:

• Lost product
• Dust collection load
• Cleanup labor
• Increased wear on blowers and compressors

2. Conventional couplings are difficult to install or align.

Conventional couplings often require:

• Multiple tools
• Trial-and-error alignment
• Independent hangers or supports
• Skilled installers to avoid leaks or tube deformation

Poor alignment may introduce internal ledges, turbulence, and product hang-up points that degrade conveying efficiency and complicate cleaning. Installation variability also makes system modifications or retrofits more time-consuming and error-prone.

AZO’s solution: AZO couplings are designed for quick, repeatable assembly with built-in alignment and integrated mounting support, reducing both installation time and long-term maintenance effort. The standardized coupling geometry promotes organized tubing layouts by allowing tubing lines to be installed in very close proximity to one another without compromising access. This creates accessibility for ease of service in the system design.

3. Conventional couplings compromise hygiene.

Many conventional couplings use exposed threads, grooves, or uneven gasket compression that create crevices where powder, fines, and moisture can accumulate. In food, pharmaceutical, and chemical environments, these hard-to-clean points can:

• Risk product retention
• Complicate cleaning validation
• Increase allergen or cross-contamination risk
• Trigger audit findings or corrective actions

AZO’s solution: Our couplings use a smooth, flush internal profile and a continuous sealing surface that minimizes crevices and supports hygienic design principles.

4. Conventional couplings require additional hardware for continuous grounding.

While continuous grounding is common in bulk handling systems, many conventional couplings require separate grounding straps or bonding hardware to maintain electrical continuity across tube joints. These add installation complexity, additional components to inspect, and potential failure points over time.

AZO’s solution: Our couplings integrate grounding directly into the coupling design by maintaining metal-to-metal contact between the tubing and coupling halves, eliminating the need for external grounding hardware while supporting explosion prevention strategies.

Common Coupling Types

In bulk material conveying applications, the most commonly encountered coupling types include compression-style couplings and ring-grip couplings.

• Compression couplings (e.g., Morris coupling) use clamping force to secure and seal tubing ends. While functional, sealing performance and alignment consistency can vary depending on installation technique and operator experience.
  
  
• Ring-grip couplings (e.g., Tuf-Lok-type) mechanically bite into the tube wall, providing very high axial load resistance. However, they are labor-intensive to install, difficult to reposition, and less suitable for frequent disassembly.
  
  
• Grooved couplings (e.g., Victaulic style) are excellent for liquids and fire protection, but are not optimized for powder conveying where hygiene, grounding, smooth internal profiles, and frequent access are critical.

AZO’s solution: Our couplings are engineered specifically to overcome these limitations by combining precise alignment, pressure stability, ease of installation, and hygiene in a single integrated design.

Choose Couplings Built for Bulk Ingredient Handling

AZO couplings are cast from high-grade aluminum and engineered specifically for vacuum and pressure conveying systems up to 5 bar (with axial protection). That means:

• No leaks at system seams
• No misalignment during install
• No failure in upset conditions

AZO Coupling Features:

• Self-supporting: Functions as both connection and structural support
• Electrically conductive: Mitigates static buildup in powder environments
• Food-grade sealing: Includes a polyurethane seal ring compliant with FDA 21 CFR 177.1680
• Rust-resistant hardware: Stainless or mild steel fasteners for long service life
• Modular system compatibility: Designed to integrate seamlessly with AZO conveying components and accessories

COUPLING COMPARISON CHART

How AZO Couplings Work

The AZO coupling consists of two die-cast halves that clamp over adjacent tube ends. A sealing gasket sits in between to create an air- and dust-tight connection. When bolted together, the coupling aligns the tube sections and locks them in place. 

The maximum permissible absolute conveying pressure for tubing lines without axial protection is 0 - 2.5 bar. With axial protection, the maximum permissible absolute conveying pressure increases to 0 - 5 bar. This gives the plant and operators peace of mind that the coupling will not fail, even in the event of high pressures developing in the system due to upset conditions.

AZO coupling assembly is straightforward:

1. Deburr both tube ends and remove the chips.
2. Install the gasket and ensure a tight fit.
3. Place the coupling halves over the joint.
4. Insert and tighten nuts and bolts.

Note that with coated steel tubes, the tube ends must be uninsulated at the contact area to ensure an electrically conductive connection. With this design, AZO couplings eliminate much of the guesswork and labor associated with typical clamp-and-hanger setups. 

Why Replace Your Whole Plant With AZO Couplings?

If you're running a high-throughput, dust-sensitive operation, replacing legacy couplings with AZO's system will deliver measurable improvements:

• Improved Safety: Designed for both low- and high-pressure conveying, minimizing the risk of blowouts or dust leaks during both normal operation and upset conditions.
• Faster Installs: Pre-aligned cast design with built-in fastening
• Regulatory Compliance: Grounded, food-safe, and explosion-mitigation ready
• Cleaner Operations: No gaps for residue, dust, or microbial harborage
• Easier Maintenance: Tool-friendly bolts and easy disassembly for cleaning or reconfiguration
• Adaptable: Available for a variety of tube diameters for both U.S. Customary and Metric systems

AZO couplings are already being integrated into new builds and retrofit projects across food, pharma, and chemical manufacturing. Whether you're planning a greenfield installation or replacing worn connections one line at a time, our team can help specify the right solution.

Contact us to start the conversation and get your system sealed, secured, and future-ready.