How to Connect Galvanized Round Pipe: A Complete Guide

Galvanized round pipe is widely used in various applications, including water supply systems, due to its durability and corrosion resistance. One of the most common methods for joining galvanized round pipe is threaded connection, also known as screw-threaded coupling. This method is typically used for pipes with a nominal diameter not exceeding 100 mm and a nominal pressure below 1 MPa.

Types of Pipe Threads for Galvanized Round Pipe

Pipe threads, like pipe fittings, come in two main types: tapered (conical) and straight (cylindrical). When manually threading galvanized round pipe, tapered pipe threads are commonly used, as shown in Figure 16.

Key Thread Specifications:

· Working length (L1): The distance from the pipe end to the reference plane.

· Thread tail (L3): The remaining thread length beyond the working section.

· Reference plane: A designated cross-section where the tapered thread’s diameter matches that of a straight thread of the same size.

· Taper angle: 1°47′24″ (with a taper ratio of 1:16).

· Tooth angle: 55°.

Both straight and tapered pipe threads share the same pitch and technical requirements. Threads can be cut using a pipe threading die or a lathe.

Common Threaded Connection Methods for Galvanized Round Pipe

There are three primary ways to connect threaded pipes:

1. Straight female thread + Straight male thread

2. Straight female thread + Tapered male thread

3. Tapered female thread + Tapered male thread

The last two methods provide a tighter seal, making them the preferred choices for galvanized round pipe connections.

Sealing the Connection

To ensure a leak-proof joint, a sealing material must be applied between the external (male) and internal (female) threads. The most commonly used sealants are hemp fiber and white lead paste. Here’s how to apply them:

1. Wrap a thin, even layer of hemp fiber along the threaded section.

2. Apply white lead paste over the hemp fiber.

3. Screw the fittings together.

Important: Avoid letting excess sealant enter the pipe, as it may cause blockages. After tightening, clean off any excess material for a neat finish.

Benefits of Using Hemp Fiber & White Lead Paste:

· Sealing: Prevents leaks in pressurized systems.

· Anti-corrosion: Protects the threaded section of the galvanized round pipe from rust.

Conclusion

Properly connecting galvanized round pipe using threaded joints ensures a secure and long-lasting installation. By choosing the right threading method and sealant, you can maintain both functionality and durability in your piping system. Whether for water supply or other applications, understanding these techniques is essential for reliable galvanized round pipe connections.