Sub Sea Services AS is a family-owned fabricating operation in Stavanger, Norway, large port city that thrives on business activities in the North Sea in oil industry. Since 1990, Sub Sea Services has been offering services and specialized products for the global offshore oil-exploration industry. Because of the extraordinary demand from that sector, and to satisfy their own quality and productivity standards, Sub Sea Services earlier this year invested in a new, advanced manufacturing process: welding and finishing pipe assemblies and components with TIG hot-wire technology supplied by Polysoude (www.polysoude.com). Polysoude develops orbital welding processes and equipment that it supplies worldwide.

QUALITY AND EFFICIENCY

“Pipes and systems used to convey crude oil or natural-gas energy sources at high speed and at high pressure demand high levels of investment,” explained Weld Shop Manager Otto Henning Sulen, outlining the technological requirements and financial considerations for the firm's manufacturing processes. “The sand and other abrasive minerals, as well as corrosive media that also are conveyed during exploration, make it necessary to use the highest-quality pipe materials that are available.

“To control costs and preserve resources, we finish the internal walls of our components using deposition welding,” Sulen said.

In Sub Sea Services' deposition welding process, Inconel™ (an the extremely hard and wear-resistant material) is melted onto carbon steel tubular products. Carbon steel is cost-effective and easy to process, according to Sulen, and the computer-controlled, six-axis TIG hot wire makes the production process particularly efficient and effective. Sub Sea Services has just 50 employees, but it is able to manufacture niche products — such as the remote-controlled, interchangeable, modular slip joint for pipes installed on drilling platforms worldwide — on schedule and to consistent quality standards.

“Quality and delivery times are given the highest priority in our organization,” Sulen said, pragmatically. “For manufacturing, this means that the availability of the production equipment we use must be extremely high. For my particular area of responsibility, the equation is really very simple: if the welding system breaks down, there is no product!”

HIGH-TECH IN MIND

The decision to invest millions into manufacturing equipment was not an easy one for the fabricating company. A variety of equipment manufacturers were invited to present their technology. Finally, a local technical consulting firm, TEMA, contacted the Polysoude representative in Holland, Kees Meurs. From that point, everything progressed quickly:

“We found the automated welding solution that we had in mind: High-tech equipment … not exactly cheap, but of the highest quality, and both robust and appealing in design,” Sulen recalled. “It was not least the people there, competent and reliable, that tipped the scales in their favor. Outstanding technology and quality has always cost more. And, we have decided to invest in the best.”

Thanks to much shorter production cycles, the new process increased productivity significantly for both joint and deposition welding. In turn, this has allowed Sub Sea Services to achieve 50-80 percent greater Inconel application levels than it had done previously. And, the increase in process quality is reported to be 30-40 percent. “This also makes it possible for us to meet the specifications more closely,” Sulen reported. “For example, the melt level of the carbon steel parent metal is consistently below three percent, which is what makes it so hardwearing.”

QUALITY DEMANDS STANDARDS

The range of materials processed by Sub Sea Services extends from X60, X65, X70 to AISI 4150, 4140, and 8630, and on to low-carbon steel F22. Pipe components from 1,000 to 1,500 mm long, with diameters of 150 to 1,000 mm are manufactured.

For its customers, the manufacturer meets every required standard and specification, whether the DNV (Det Norske Veritas, the world's leading institute for the technical monitoring of offshore installations) or the IPE (Implementation of design-related requirements in Production and Erection), as well as ASME (American Society of Mechanical Engineers.)

Sub Sea Services' quality procedures are certified to ISO 9000; the proof of quality is granted following in-depth hardness and flexion tests, as well as material grinding. That the welders in Stavanger will have all the necessary qualifications and undertake ongoing training is taken as a matter of course.

Smiling, Sulen notes that his welders and machine supervisors were initially very skeptical of the new technology: “It was of course a natural human reaction in the face of something new … Once they had thoroughly familiarized themselves with the machines, automated welding, and the deposition process, they became hugely enthusiastic. They are also proud to be given responsibility for the new technology. This is because they have witnessed their own high levels of productivity and the consistently high quality. They also see the value they then bring to the company, and that fills them with pride.”

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Inconel is a registered trademark of Special Metals Corp.