TPI January 2024

High tolerance, precise weld preparation for tubes and pipes used in aerospace By technical writer Del Williams on behalf of Tri Tool Technologies

Mr Belle. “In other cases, the Inconel’s outer layer may harden too quickly in response to machining, resulting in an imperfect shape for the Inconel.” “Of course, advanced alloys are very expensive, so getting the weld prep right the first time is absolutely critical,” added Mr Belle. To properly shape, cut and work with Inconel, the machinist must understand its properties and how to compensate for its limitations. Specialised facing and cutting equipment with tool bits are often required. “Without all of these components, machining pipe and tube made of advanced materials can become a major bottleneck in the aerospace manufacturing workflow,” said Mr Belle. Prepping for welding Although manual welding techniques are still utilised, particularly for larger pipes, most welding is performed by semi-automated orbital welding machines with closed weld heads. To create the weld, a generated arc is rotated mechanically 360° around the pipe or tubing in a continuous process. Orbital welding is prized in aerospace for producing reliable, high quality, repeatable welds that

The challenge is only increasing as the aerospace industry utilises lighter and stronger materials such as Inconel and other nickel superalloys to improve fuel efficiency and reduce the weight. In addition, pipe and tube welds are subjected to unprecedented high pressures, cryogenic temperatures and intense environmental stresses such as vibration and thermal cycling. “Aerospace companies are pushing the boundaries of what can be achieved every day. As a result, they are utilising more advanced materials for piping and tubing, often with smaller diameters, thicker walls and more complex joint geometries than even ten years ago,” said Chris Belle, CEO of Tri Tool Technologies. Founded in 1972, Tri Tool Technologies is a leading provider of machining tools, custom engineered solutions and on-site services for the aerospace, defence, power generation, oil and gas, life sciences and semiconductor industries. To minimise or eliminate weld failures for these critical applications, the key is achieving very consistent, high quality weld prep every single time, said Mr Belle. “The more inconsistent the machining, the more weld process challenges you will have, potentially resulting in weld failures. Unfortunately, materials such as Inconel only increase the chances of joint misalignment, poor prep angles and contamination,” explained Mr Belle. Inconel is an alloy composed of 58 per cent minimum in all weights of nickel with significant chromium and molybdenum. It is resistant to oxidation, corrosion and scaling in high-temperature environments and so is an ideal material for use in rockets and spacecraft. However, its toughness also makes it incredibly difficult to machine. “It is not unheard of for cutting and shaping tools to be broken or deformed when used on Inconel,” explained However, installing or replacing piping and tubing is no small challenge. Aerospace welding is a delicate process that demands precision. Prepping pipe and tube for welding requires very precise, repeatable machining of the ends to very tight tolerances. The cutting and bevelling can create no contaminants and must achieve a specified surface finish. The work is often performed in confined spaces such as tube racks or the wings of an airplane. Like the arteries, veins and capillaries of the human body, extensive piping and tubing systems deliver essential gases and liquids to critical equipment and systems within space and aircraft, as well as to critical infrastructure such as launch pads.

Tri Tool Technologies’ 300STS is a lightweight, portable facing machine for weld preparation on autogenous welding

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TUBE PRODUCTS INTERNATIONAL January 2024

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