The importance of preparation in welding cannot be emphasized enough. In all industries that involve welding pipes, tubes, or other structures, a strong weld is the indicator of quality and reliability. Joint machining followed by surface cleaning is the initial step in preparation for the high attribute weld result.
Ensuring the accurate cut of the weld joint and cleanliness of the metal surface and weld environment during GTAW forms the weld with high mechanical strength, is pure and clean, and has a lower risk of premature failure. Let us look at the essential preparation techniques, which are the basis of excellent tube welding.
Prerequisites of Tube Welding
Different welding techniques are applicable when welding tubes— GTAW and GMAW being the primary choices. However, the checklist has multiple steps to address before selecting these techniques and commencing the actual welding process. The starting point is the selection of material.
Stainless steel, carbon steel, and aluminum are among the metals most desired for making tubes. The selection of the welding process is made based on the metallurgical properties of the material. Once the material selection is made, it is essential to prepare the joint for welding, which depends on how thick or thin the tube wall is. V-groove can be prepared for tubes with thicknesses over 3mm. The joint preparation is better done by machining than manually.
Once the tube edge is machined, the surface needs cleaning to remove any dust or oxides. This is especially important for stainless steel tubes as they are primarily used in applications that value high sanitary specifications. However, it is equally essential to maintain the cleanliness of the weld surface for other materials.
Let’s take a detailed look at the surface preparation prerequisites in tube welding.
The Importance of Surface Preparation Measures
When preparing the metal surface for welding, it is important to understand the sensitivity of different metals to various contaminants.
- Hydrogen is highly soluble in molten aluminum. During welding, a lot of hydrogen may dissolve in aluminum and get trapped during solidification, initiating the issue of porosity.
- Oxygen may react with carbon steel to cause oxidation.
- Contaminants such as grease, oil, or moisture make austenitic stainless steel more prone to hot cracking.
Most of these issues point toward the importance of pre-weld cleaning. Tubes require exterior and interior cleaning to prevent contamination from invading the weld pool and creating defects. The following are some effective ways of surface preparation—
- Specks of dust from metallic grinding or from the environment may contaminate the weld pool. Compressed air is an effective way to remove them from the metal surface.
- Grinding provides a better result when removing rust, paints, and coatings from the metal surface.
- Pure ethanol can be used as a solvent to break apart the chemicals on grease and oils on the metal surface.
- For metals like stainless steel, electropolishing is the best way to dissolve any contaminants and smooth out burrs from the metal surface. The smooth surface is especially important for sanitary applications to eliminate the chances of bacteria breeding.
The metal is set to yield a pure and strong weld through effective preparation. However, shielding the weld pool is equally essential during the welding process so that no other contaminants can compromise the weld quality.
Surface Preparation for Welding Improves Quality
As mentioned earlier, surface preparation is only effective if the welding process involved can protect the weld pool during the action. So, when welding the tubes, such as those made of stainless steel with high purity standards, GTAW is the choice to go for. It is because GTAW effectively shields the weld using inert gasses like argon or helium to protect the molten pool from external inclusion.
For tubes of different thicknesses, AMI provides a range of clean, closed weld heads that can isolate the weld area from the external environment. Weld heads like – and — help produce a completely fused, pure, and defect-free weld.
When the effective surface preparation for welding meets high-quality weld heads and welding machines with excellent weld optimization ability, the welding of the tube is sure to have the best of attributes.
Arc Machines, Inc. with decades of experience and expertise, supports manufacturers in achieving their desired weld quality with its wide range of orbital welding solutions. For product inquiries, contact sales@arcmachines.com. For service inquiries, contact service@arcmachines.com. Arc Machines welcomes the opportunity to discuss your specific needs. To learn more about surface preparation for welding tubes, contact us. Arc Machines looks forward to providing the equipment and services your project needs.
