Kinder Morgan Energy Partners; Sempra Pipelines & Storage, a unit of Sempra Energy; and, ConocoPhillips jointly developed the Rockies Express (REX) Pipeline project. The pipeline was constructed in three phases:

* The 528 km REX-Entrega section across Colorado; * REX-West, which runs 1,147 km from Colorado to eastern Missouri; and, * The recently completed REX-East portion, which stretches from eastern Missouri to eastern Ohio.

The REX-West section was completed in early 2008, after receiving Federal Energy Regulatory Commission authorisation in April 2007. REX-East finalised construction and was placed into service on 12 November 2009. Following the completion of REX-East, the pipeline has the capability to transport up to 1.8 billion cubic feet (Bcf) of natural gas per day.

Each region along the 2,735 km pipeline route offered unique challenges for the construction of the pipeline. The majority of the route passed through mountainous terrain – starting in the Rocky Mountains and extending to the Appalachian Region – which brought with it significant technical challenges.

The REX-Entrega and REX-West pipeline routes cross the Rocky Mountains and much of the REX-East route also covers mountainous terrain, which presented the project’s crews with a variety of construction issues. However, the crew successfully managed to move the project forward without delay.

Most of the REX Pipeline was constructed along existing pipeline corridors. Much of the terrain was already level and ready for the pipe stringing and trenching in preparation for pipelaying, Mr Fore said, however construction crews faced a variety of landscape and geographical challenges as the pipeline construction progressed eastward along the route into the Appalachian Region on the REX-East Pipeline route.

Welding to schedule

New technology was employed to ensure that pipeline construction proceeded smoothly.

REX was designed with a construction schedule that favoured automatic field welding. The automatic welding equipment – provided by CRC Evans of Houston, Texas, and RMS Welding Systems of Nisku, Alberta – was a large part of how the construction proceeded in such an efficient fashion.

The automatic welding systems enabled a very high level of productivity that exceeded 100 welds per day for the mainline pipelay. Additional project pace was gained by the establishment of ‘mini pipe gangs’, which were capable of laying up to 20 joints of pipe per day. The mini gangs were ideal to lay pipe in the rough terrain encountered on the project.

The welding work was completed using cutting edge components.

Tie-in welds were made with Hobart welding wire, Trimark Flux Core and Fab Shield X80, which is a special wire produced to weld the high strength X80 pipe used. Once the welding was completed, each joint was checked carefully by the onsite scanning technology. Weld integrity was ensured by using ultrasonic weld inspection systems to scan 100 per cent of the field welds for defects.

The system used was an analog to digital conversion unit, but an innovative ‘phased array’ weld inspection system, provided by UT Quality of Texas, was also used on the pipeline. The totally digital system was first qualified in the US for the REX-West project. By allowing the system to be less complex and highly accurate in weld interpretation, REX saw more robust results.

REX Director of Community Relations Allen Fore said “The REX Pipeline was constructed using the latest technology in all aspects of the construction process, but the biggest asset was the skilled and experienced workers employed on the project.

“The pipeline construction process is often compared to a sort of moving assembly line and during peak construction efforts, there were thousands of construction workers on the pipeline spread.

“The innovative technology employed ensured that the pipeline was built in the safest and most efficient way possible – and will maintain the integrity of the pipeline in the future,” said Mr Fore.