When it comes to setting up or maintaining a piping system, understanding the differences between PVC pipe couplings and pipe unions is essential. Both are fundamental PVC pipe fittings, but they serve distinct purposes and have specific applications. At 247Garden, we offer high-quality ERA SCH40 and SCH80 fittings, ensuring your projects are equipped with reliable components. Let’s delve into the differences and appropriate uses of pipe couplings and unions.

The Basic Differences

Pipe Couplings:

  • Purpose: Couplings are designed to join two lengths of pipe together or to connect a pipe to a swedge. They are typically used to extend the length of a pipeline.
  • Types: There are several types of couplings, including threaded, butt-welded, and socket couplings.
  • Applications: Couplings are essential when the pipeline exceeds the standard length of a single pipe (commonly 4m or 6m). They ensure a seamless extension of the pipeline.

Pipe Unions:

  • Purpose: Unions are meant for easy assembly and disassembly of parts of a piping system, such as steam traps or control valves. This makes maintenance and replacement more convenient.
  • Types: Unions come primarily in threaded and socket varieties. The unique feature of a union is its ability to unscrew with threads, making disassembly straightforward without moving the entire pipe.
  • Applications: Unions are generally used on threaded pipes with smaller diameters. For larger diameters, flanges are often preferred due to their ease of disassembly.

Practical Applications

  • Couplings: In high-pressure situations, couplings are the go-to choice. They provide a robust connection that can withstand significant pressure, making them suitable for demanding environments.
  • Unions: Unions excel in low-pressure scenarios and are ideal for systems that require frequent maintenance. Their threaded connections are typically used in public engineering applications where pressures are less than 10 kg.

Choosing the Right Fitting

When deciding between a coupling and a union, consider the following:

  • Pressure Requirements: For high-pressure systems, couplings offer the durability needed. Unions are better for low-pressure systems where ease of maintenance is crucial.
  • Pipe Diameter: Smaller diameter pipes benefit from unions, while larger pipes often require flanges or couplings.
  • Maintenance Needs: If your system needs regular maintenance or part replacement, unions provide the flexibility to disassemble without disrupting the entire system.


Understanding the specific roles and applications of pipe couplings and unions ensures that your piping system operates efficiently and reliably. At 247Garden, we supply top-notch ERA SCH40 and SCH80 fittings, designed to meet a wide range of needs. Whether you require durable couplings for high-pressure environments or convenient unions for easy maintenance, we have you covered.

For more information or to explore our extensive range of pipeline products, feel free to contact us. We look forward to assisting you with your piping needs.