Hybrid Fiber Laser GMAW-P Pipeline Welding

Pipe lay rate is, in most instances, controlled by root pass welding speed. Cutting the pipeline right of way time for cross-country, or barge days for offshore, has significant cost impact on pipeline welding costs. With this in mind, EWI has been working on both high speed mechanized single sided GMAW solutions and hybrid laser arc welding (HLAW) for root pass welding without backing. Fiber lasers are a critical enabling HLAW technology for pipelines in that they have proven field deployed ruggedness in other applications, and 25% electrical efficiency, neither of which is offered by previous laser types.

EWI is completing the work scope for a $460K DOT PMHSA project, the first half of which was cost-matched with a $230K joint industry project (JIP). This $690K work scope has taken this from a literal ‘pipe dream’ to an alpha prototype capable of welding pipe girth welds at 80 in/min (2 m/min) for each weld head for the root pass with single side only welding, and capable of +/- 2 mm hi-lo mismatch. This capability was demonstrated outside in a simulated welding tent to 40+ industrialists and NRC inspectors, with all utilities supplied externally from EWI’s building. Two full girth weld root passes were made on 36-in. (0.9 m) diameter X80 pipe using the traditional double down welding technique preferred for onshore linepipe welding. Start/start and stop/stop overlaps were developed and showed good integrity.

The welding system was developed using standard M450 COTS equipment from CRC-Evans integrated with Fronius power sources, modified by CRC and EWI to accept first a 4 kW (in the JIP) and then a 10 kW IPG Photonics fiber laser and laser optics package in the DOT work. The nature of the COTS equipment is such that integration of the two processes for starting sequence and power ramping coordinated with travel motion was developed on Lincoln i400 power sources. The integration of the Fronius power sources does not allow full integration of these sequences at present.

HLAW work conducted on X80 and X100 linepipe showed that properties suitable for API 1104 qualification could be met for conventional service, and that hardness limits for sour service were off by only 18 HVN on X100 linepipe welds made with ER100S-1 consumables. The DOT project scope continues in the final phase to develop toughness data for X80 and X100 linepipe.

The major scope elements for future work on a beta prototype to be developed for pipe trench demonstration are a sturdier bug and band system with payload limit suitable for the heavier weld head, full integration of the stop start sequence for high quality overlaps, and full integration of seam tracking capability suitable for HLAW operation rather than GMAW-P only seam tracking. For cross-country pipelines, a candidate system is CRC-Evans’ P600 bug and band system. For offshore S-lay and J-lay applications, 5G and 2G operations are of predominant interest.

EWI is now announcing formation of a new JIP to develop, integrate, and test the beta prototype system. For more information on the JIP scope, launch date announcement, or other applications you may be considering for HLAW, contact Jon Jennings at jjenning@ewi.org or call 614.688.5144 or contact Ian Harris at iharris@ewi.org or call 614.688.5131