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Resistance Seam Cladding September 13, 2011 David Workman Senior Engineer, Resistance and Solid-State Welding Email: [email protected] Phone: 614.688.5244 Resistance Seam Cladding for Linepipe – Background CRA pipe ─ 316 SS or High-Ni alloys CRA is becoming critical ─ Gas applications with CO2 and Cl ions ─ Fluid applications with H2S ─ Abrasion resistance Very expensive as a solid pipe Clad CRA pipe ─ Reduced cost per foot of piping system ─ Steel substrate with 2- to 3-mm clad layer CRA cladding methods are: ─ Roll bonding ─ Metallurigical bonded ─ 50% of market ─ Mechanical bond ─ Plastic deformation of CRA ─ 30% of market Other clad processes: explosion and arc cladding Dia (mm) Wall (mm) Clad t (mm) Base Mat'ls Price $/m Price $/m Mech Clad Margin $/m Price $/m Arc Clad Margin $/m Price $/m Roll Clad* Margin $/m 150 19 3 $303 $900 $597 $1,964 $1,661 $1,742 $1,439 350 19 3 $835 $2,150 $1,315 $3,976 $3,141 $4,402 $3,567 Why Resistance Seam Clad? Shorter turn time (reduced WIP) Faster production rate Simple parts configuration Flexibility to alter pipe or CRA on the fly Lower cost $/per foot less than other metallurgical cladding processes (estimated $1150/foot at 150-mm diameter) Comparatively low capital investment Ability to use DOM pipe Flat Plate Trials – EWI Project No. 51549GTO Trials between flat steel plate and 1- to 3-mm CRA clads Thermal analyses associated with the process evaluated Clads showed up to 100% bonding Surfaces were flat to within 100 μm Improved thermal profiles seen with thinner clad layers Shear test failed in base metal Proof of concept established Weld Quality when Applying CRAs to Steel Pipe with RSeWC Full-face bonding observed during testing Shear tests failed consistently in the clad Adaptation to pipes showed better than 90% bonding No dilution seen on the sectioned pipe samples Tracking and surface quality being addressed by improved tooling Metallographic Sections Narrow fusion zone apparent between CRA and Pipe Free of voids Fusion zones overlap to create continuous welded interface Process Adaptations to Round Pipe – EWI Project No. 52864IRD Adaptation of deep reach seam welding system ─ 200-kVA transformer ─ Dedicated tooling for pipe positioning ─ Flood cooling integral to the process Steel pipe ~10-mm wall × 350-mm diameter Inconel 625 liner rolled from sheet stock ~2-mm thick Process adapted to the deep reach welding frame ─ Lower speeds and currents Functionality of the Welding System Water cooling to protect wheels Process adaptations for specific welding system Industrial level cleaning of pipe for joining Demonstrated overlays to create continuous attachments Minimal residual heat from the process Minimal disruption to clad surface Wheel designs to minimize disruption of external pipe surface How is it Applied to Line Pipes? DOM pipes can be used or welded pipes Internal pig is used to transfer force and current through the pipe section without compromising pipe wall Normal high current Resistance seam welder is used to drive the system Systems can be ganged to run multiple heads simultaneously 40-foot section very easily managed in production setup Why Does it Work? The welding process is laid out to confine fusion zone to the CRA –Pipe ID interface ─ Proprietary surface preparation techniques Resistance seam welding is an established process for joining similar material thickness parts Solidification of fusion zone occurs under welding force applied by wheels to create sound microstructure Process is self regulating Welding force maintains fit-up between CRA and Pipe ID Modeling of Thermal Profile in Joint 1600 Temperature (C) 1400 1200 1-mm, 16.7-kA 1.8-mm, 16.7-kA 1000 3-mm, 16.6-kA 800 600 400 0 0.2 0.4 0.6 0.8 Fractional Distance Through the CRA 1 1.2 Speed Effect on Thermal Profile in Joint 1600 Temperature (C) 1400 1200 1000 50-mm/min, 6.9-kA 800 100-mm/min, 9.7-kA 300-mm/min, 16.7-kA 600 400 0 0.5 1 Distance Through CRA (m m ) 1.5 2 State of Technology Shown to meet or exceed user quality specifications for flat plate applications Round pipe applications require significant equipment investment to reach quality level of flat plate trials ─ To date results are above required levels ─ Further improvements are expected with tooling enhancement Cost analysis shows that the process is lower cost than competitive technologies Questions? David Workman Senior Engineer, Resistance and Solid-State Welding Email: [email protected] Phone: 614.688.5244