Ty Roberts, plant manager: Traceability is key to our success.

Welders use a backing rim on the bottom of a Type 304 stainless steel cylinder to maintain the circumference during welding.

Earl Murphy, a 12-year veteran, grinds on a "hat" covering a tank.

Like a boxer in training for a big match, the Roberts Company, Winterville, N.C., constantly works to perfect its competitive stance. The firm scores in the pharmaceutical and chemical processing markets by finding new electrodes to join corrosion resistant alloys, then developing the weld procedures needed to use them.

This design and build firm learned that developing weld procedures for new corrosion resistant alloys generates the know-how to offer customers alternative alloys to trim costs or to boost performance while staying within the welding codes.

"Our market niche is corrosion applications requiring alloys," says Kelly Wyrough, director of sales and marketing for the 300-employee firm. "We follow the development of new alloys in research labs and mills worldwide and determine how to transfer the metallurgical information into weld procedures."

Mark the trail
Plant manager Ty Roberts says project traceability supports the company's success. The company uses a detailed work-in-progress procedure that includes data on materials, welders, and key inspection approvals. They log heat numbers from the mill, and segregate materials during fabrication to minimize contamination.

While the work-inprogress procedures keep work flowing and provide reports that keep customers up-to-date, the company's welders carry the burden of responsibility for the quality of their work.

The firm's welders qualify to weld a wide range of alloys—from nickel and chromium molybdenum to copper and cobalt—in its 70,000-sq.-ft. shop.

Besides training welders to help them to keep their welding skill levels high and improve their performance, weld training extends from the shop floor to the offices. "We cross-train our sales, engineering, estimating and drafting people," says Wyrough, "so they understand what is takes to make a good weld."

To weld that variety of alloys the firm stocks dozens of gases. Roberts says the company does research on gases to minimize discontinuities. "We find tips at seminars on selecting MIG gases or how the percentage of argon or CO2 effects a weld. For example, one supplier suggested using 99.9 percent argon to eliminate moisture-related problems in the tanks."

NDE saves money
During the welding stages, the firm uses radiographic inspections and ultrasonic tests to satisfy code and customer requirements, to find weld metal and base metal discontinuities, and lamination issues.

Roberts applies non-destructive visual and liquid penetrant tests to minimize the need for pressure tests of high purity vessels. and to shorten production schedules. One of the shop's ASNT or AWS certified inspectors typically performs final NDE inspections of all welds.

Inspectors use a variety of equipment including dry/wet MT equipment, such as Parker Research DA200 and DA400 MT and an EPD Technology Corp. B3 helium leak detector. The company has hydrostatic pressure testing equipment rated at 3,000 PSIG maximum, and also uses a Class 10,000 clean room for assembly and testing of high purity components.

Life extension: six months to 20 years
Roberts' expertise with corrosives help it to offer better solutions. For example, it recommended the replacement of a vessel made of carbon steel, that was lined with rubber and brick used to process sulfuric acid, with a vessel made from a newly developed, silicon-based, austenitic stainless steel. The change in materials extended the vessel's life from six months to 20 years.

Roberts continues to hone its skills in finding and applying new alloys to minimize corrosion. For more information call: The Roberts Company 252-355-9353 Fax 252-756-7018, or www.robertscompany.com

Exceeding the Challenge Quality Assurance Manager Glen Blanchard makes a "project "traveler on his computer. When the bid came in for an ASME Section VIII, Division 1, Code Stamped Heat Exchanger, that required welding tubes of a highly corrosion resistant alloy to a 1.50-in. thick, duplex stainless steel 2205 tube sheet, Quality Assurance Manager Glen Blanchard jumped at the welding engineering challenge. The tubes were of SEA-CURE, an ASME P-Number 10K Group 1 base metal. The job would require developing and qualifying to ASME Section IX a new welding procedure for joining P-No. 10H to P-No. 10K base materials, and qualifying welders. Blanchard saw another issue: "The specs called for autogenous welding, rather than using a filler metal. But we also needed to address the possibility of making repairs with filler metal. So we had to find and qualify a filler metal of similar corrosion resistance." The SEA-CURE tubes, a SA-268-S44660 (P-No. 10K) seamless material, were 0.75-in.diameter with a 16 Birmingham Wire Gage (BWG) (0.065-in.) thickness. When a vendor sent two 6-in. pieces of the tubing, the stage was set to start the ASME Sec. IX WPQR (welding procedure qualification record). "The butt welded WPQR Coupon," says Blanchard, "automatically qualifies fillet welds of unlimited size per ASME Section IX. That satisfied the tube-to-tube sheet 'seal welding' requirements." Blanchard began the final research prior to initiation of WPQR qualification. The SEA-CURE material, a highly corrosion resistant alloy, was not available in filler metal form. His search for a matching alloy for the filler metal resulted in a nickel alloy of AWS Classification ERNiCrMo-4 because of its similar corrosion resistance characteristics. He experimented with shielding gases, knowing the propensity of the "Duplex Stainless Steels" to deplete the nitrogen alloying element in the weld pool. He decided to add 2-percent nitrogen into the argon used in the shielding and backing gas. To qualify two welders, the company had each welder use the gas tungsten arc welding process for the fusion root and 0.035-in. diameter wire for the remainder on two coupons. "They welded half and half in the 5G position on each coupon," Blanchard says. One coupon was for the required full section tension test and one was for the required root and face bend tests. Within a week, Blanchard had established the weld procedure with and without filler metal, had two welders qualified for the materials, thicknesses, positions, and process for the ASME Sec. VIII, Div. 1 "U" Stamped Heat Exchanger, and the Roberts Company got the job.