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Perfect Welding

Key Operating Factors in Mechanized Cladding


5/4/2020 / US
Fronius has been supplying high-quality cladding systems for decades and has become a technology leader in the oil and gas industry. An overlay welding system of the latest generation is the High-Performance Pipe Cladding System, launched in 2018, which allows welding speeds up to 170 cm/min, depending on different values. Its speed is four times faster than the previous Fronius Pipe Cladding system. However, some technicians believe the deposition rate is the major value when selecting a cladding system. Why this is not the case and why the deposition rate is not the only important factor when choosing a cladding system is explained by the internationally renowned cladding expert Alipour Kaveh.
High-Performance Pipe Cladding Cell, front view.
High-Performance Pipe Cladding Cell, front view.

This interview was originally published by Oil & Gas Innovation Magazine.

Oil & Gas Innovation: “Mr. Alipour, would you briefly introduce yourself, please? And why did you join Fronius?”

Alipour Kaveh: “My background is mechanical engineering, materials science, and metal composites. I have 20 years of professional experience in the oil and gas industry. Fronius I have known since 2002, and we bought the first Endless Torch Rotation Cladding System from Fronius in 2006. Last year we started cooperation to support them in the development of new cladding systems and validate all cladding processes based on the requirements of API 5LD and ARAMCO specifications. I do not yet see the end of the line for possible innovations.”

Oil & Gas Innovation: “There are opinions that the deposition rate is the major parameter when selecting a cladding system. Do you agree?”  

Alipour Kaveh: “For overlay welding, the mechanical properties of the backing steel should be maintained after the cladding process as well as the quality of the deposited weld metal as per requirements of API 5 LD, API 6A, and also NACE. In order to achieve proper weld metal along with maintaining mechanical properties of backing material, therefore the heat input formula will be the main player in the overlay cladding process (ASME Sec. IX; QW-409): Heat Input = Voltage x Ampere x 60 / welding speed.

Oil & Gas Innovation: “Can you explain in detail?”

Alipour Kaveh: “As per the above formula, if welding speed increased up to 5 times because of obtaining a high deposition rate, therefore Voltage and Amperage should be increased at the same time otherwise sufficient bond integrity cannot be achieved with low heat input. In this case, if Amperage or Voltage increases to maintain the amount of heat input, then penetration will be extremely high during the cladding process.”  

Oil & Gas Innovation: “Therefore, the deposition rate is not a major item of evaluating and selecting a cladding machine because it is to achieve per high-speed cladding without sufficient bond integrity. But other parameters and related proportions are to consider as well. Is it right?”

Alipour Kaveh: “Yes, you are right. Fronius Welding Automation developed and manufactured the High-Performance cladding system based on the concept of the heat input formula to increase the deposition rate along with increasing the welding speed, current, voltage and maintaining sufficient heat input during the cladding process with a special gas mixture and a unique shape of the tungsten electrode. The company developed a cladding procedure with this concept as per the requirement of API 5LD to achieve minimum clad thickness in two layers (3.4 mm) and increasing deposition rate more than three times with two torches and twin wire.”

Oil & Gas Innovation: “And the welding speed…?”

Alipour Kaveh: “The welding speed increased from 40 Cm/min to 170 Cm/min (4.25X), heat input in the first layer is 315 J/mm, Hardness of HAZ is equal to the Hardness of base metal, Fe content is less than 5% on 1.5 mm below minimum overlay thickness for Alloy 625. After the cladding process, the mechanical properties of the backing material remain unchanged.”

Oil and Gas Innovation: “Let me summarize: when selecting cladding systems, it is not the deposition rate, but the system´s true performance which is the most important and comprehensive point?”

Alipour Kaveh: “Yes, this performance is to evaluate by the results of Destructive Tests and Inspection Report (PT) on the test coupon cladded with this cladding machine.”

Oil and Gas Innovation: “What destructive tests and inspections did they carry out on the High-Performance Pipe Cladding systems from Fronius Welding Automation?”

Alipour Kaveh: “They did the following tests: Macro Examination (Checking Base Metal, HAZ and Weld Metal), Chemical Analysis (Base Metal and Weld Metal), Corrosion Test (Detecting Susceptibility to Intergranular Corrosion in Weld Metal), Side Bend Test (Checking open defect on Base Metal, HAZ, and Weld Metal and bonds integrity), Hardness Test as per the requirement of API 5LD and NACE, Charpy Impact Test (Base Metal, HAZ and Weld Metal), Flattening Test (Checking Ductility, Soundness of Weld Metal and Bonds Integrity), Tensile Test (Checking Tensile of Base Metal after Cladding Process) and last but not least Inspection Report of Penetrant Test on As-Welded surface. DNV.GL. supervised all these tests. The approved test results are available upon request.”

Oil and Gas Innovation: “What do you expect from your future with Fronius Welding Automation?”

Alipour Kaveh: “The future of the oil and gas market in the Middle East will be dependent on the Gas export instead of oil export in the new decade. Therefore major players in the oil and gas industry decided to take gas from offshore within the next ten years to become market leaders in the gas export business. As per the above discerption and because of sour gas in this region, there are huge demands for cladding and spooling activities, and this opportunity is the future of Fronius for acting and securing cladding and welding market at least for the next ten years.”

Oil and Gas Innovation: “Mr. Alipour, thank you for the interview.”




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