TPT January 2007

P rogress in W elding T echnology, E quipment & C onsumables

Orbital welding assists volume increases in tube fabrication

Orbital welding equipment provides advantages including strength, integrity, corrosion resistance, low distortion and residual stresses, crack-free deposition, superior mechanical properties, and excellent weld seam quality. Polysoude, France, the manufacturers of orbital welding equipment, have found an increasing popularity in Europe for automated tube and pipe welding, especially for stainless steel tubing applications.

This efficiency drive was particularly the case for CMI’s heat exchanger business for the high purity and power generation industries. This type of process equipment involves the manufacture of small diameter, thin wall, stainless steel tubing ranging from ½" to 3", in materials including titanium, duplex stainless steel, and Inconel. The largest pipes have just 6" diameters. In all of these instances, smooth welds are necessary to prevent contamination and eliminate the possibility of corrosion at the weld joints, not only in pharmaceutical applications, but also in other process industries. The company researched ways in which it could consistently weld these small diameter, thin wall tubes at an accelerated pace to keep up with increasing demand. A contract from a large pharmaceutical client stipulated the use of orbital welding within a clean room environment on all of the The manufacture of pharmaceutical products is highly regulated, and the regulations are unusually strict. Weld quality is critical and the final product can be contaminated by microbial growth and other external contaminants. The company adopted the guidelines from the European Hygienic Engineering & Design Group (EHEDG), which addresses these concerns, describing the optimal interior finish, joint shape, form, design, and material. Deciding upon orbital welding for all of its process industry projects, CMI constructed a clean room for the pharmaceutical project, purchased its first orbital project’s tube welds.

› Automated orbital tube-to-tubesheet welding

Most thin-wall welding is carried out without filler wire, except for the medium-wall tubes used in petrochemical installations, in which filler wire is used. Because welding parameters are programmed into the power supply control unit, all parameters are achieved consistently and maintained at maximum rates, and every weld is identical. CMI Enterprise, a tube fabricating shop serving the pharmaceutical, cosmetic, and chemical industries, requires just this type of weld quality. Due to a growth in orders for the petrochemical, pharmaceutical and process industry, the company has had to become increasingly efficient. fi (Below) a standard TIG/GTAW open weld head with wire, and (below right) automated orbital tube-to-tube-bend welding

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J ANUARY /F EBRUARY 2007