TPT July 2011

T echnology U pdate Orbital tube- to-tubesheet welding AXTON Incorporated, located near Vancouver, Canada, has been manufacturing heat exchangers and other industrial equipment since the 1980s.

and this includes orbital tube-to-tubesheet welding. While the company had some previous experience with orbital welding, they gladly accepted the opportunity to refresh their skills by having an AMI factory trainer come to their facility to train their lead welders. Axton is a truly international company that exports a significant amount of their production to countries outside of Canada including Mexico, Africa and others worldwide. Industries served include mining, oil and gas, chemical, acid manufacture, petrochemical, power, transportation and pulp and paper. They are currently fabricating a large stainless steel exchanger for export. The tubesheet on this unit has 990 tubes 1¾" (44.45mm) diameter with a wall thickness of 0.084" (2.1mm). The vessel is 50ft (15.24m) long and 140" (3.55m) in diameter with tubesheets on both ends. The model 227 weld power supply is microprocessor controlled and stores weld programs, or schedules, consisting of all the programmable weld parameters in the power supply memory. The operator enters the program each time the power supply is turned on. The weld schedule specifies

primary and background amperage, travel speed (rotation), pulse times, wire feed speed and other parameters. Thus, if other factors such as tube end preparation, cleanliness and purge flow are constant, there is a very high degree of repeatability from weld to weld. The weld head features a chill follower linked mechanically to the torch that is spring loaded to the ID of the tube. This causes the torch to maintain a constant distance from the tube OD even when there is some degree of ovality in the tubes. The chill follower as well as the entire torch block is water cooled, which removes heat from the ID of the tube. This allows the application of additional heat to the weld resulting in better penetration without melting through the tubes. The power supply’s arc gap control (AVC) enables the torch to maintain a constant distance between the tungsten electrode and the weld joint. The welding operator may make small changes in the AVC setting during the day to adjust for changes in ambient temperature or humidity. Axton Incorporated – Canada

Its list of projects includes the structural engineering and fabrication of the Vancouver 2010 Cauldron for the Vancouver 2010 Olympic Games. Axton was restructured in 2002-2003 and at that time the owners decided to update some of their operations. After careful consideration they purchased a Model 227 orbital welding power supply and Model 6 orbital tube-to-tubesheet weld head from Arc Machines Inc in California, USA. Although orbital welding is generally considered to be welding of tube or pipe, orbital welding is defined as “machine or automatic welding in which the arc rotates around a stationary weld joint”

Email: axton@axton.ca Website: www.axton.ca

Acid fume extraction system ARVIND Anticor Ltd manufactures and exports industrial fume extraction systems and fume gas exhaust systems. Anticor ‘FES’ is designed to offer the highest collection or removal efficiency. All equipment is fabricated using quality thermoplastics and fibreglass. The company’s services cover conceptualisation to design, selection of anti-corrosive plastics materials for construction, manufacture, procurement of purchased items such as pumps, motors, instrumentation and control, supply, erection, commissioning and handing over with guarantees for quality and integrity of the supplies and performance of the system conforming to specified parameters. The most important basis for calculations is the determination of the exhaust air volume with fume capture and the resistance and losses of air. Process tanks have inbuilt fume exhaust slot incremental duct section to have uniform exhaust all over the length, thus creating a fumeless atmosphere near the tank. The fume extraction system is offered

with scrubber facility. The exhaust system meets all regulatory environment standards, and the system is suitable for pickling mild steel, stainless steel and other non-ferrous tubes and pipes. The fume extraction plants can be used not only in encapsulated pre-treatment plants but also for lateral suction channels on pickling tanks as well as process tanks. Arvind Anticor Ltd – India Website: www.picklingplant.com

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J uly 2011

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