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3D Welding Requirements for Tubes & Fittings
“3D” in welding refers to the three key dimensional requirements for a weld joint before welding: Distance (Gap), Diameter (Misalignment), and Degrees (Angular Misalignment). Controlling these ensures a smooth, clean, and strong weld.
| Welding “D” | What It Means | Requirement / Why It’s Important |
|---|---|---|
| Distance (Gap) | The space between the two tube ends inside the fitting. | Must be very small (e.g., ≤ 1/16 inch or 1.5 mm). A large gap causes the weld to sag inside the pipe, creating a rough surface where bacteria can hide and grow. |
| Diameter (Alignment) | How perfectly the two tubes line up with each other. | Must be nearly perfect (e.g., ≤ 10% of wall thickness). Misalignment creates a step inside the pipe, causing turbulence, poor drainage, and possible biofilm formation. |
| Degrees (Angle) | Whether the two tubes are perfectly straight and not bent at an angle. | Must be almost zero (e.g., ≤ 0.5 degrees). Angular misalignment creates an uneven internal surface and poor flow, leading to areas where water can stagnate. |
In short: The goal of 3D welding is to create a joint that is as smooth and continuous on the inside as the original pipe. This prevents bacterial growth, allows complete drainage, and ensures water purity for pharmaceutical applications. It is typically achieved with precise cutting tools and orbital welding, which provides a consistent and repeatable weld.
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