The Department of Transportation's (DOT) agency overseeing pipeline safety allowed the bulk of the western portion of the Rockies Express Pipeline (REX), known as REX-West, to go into operation last month despite certain concerns related to welds on the system, according to documents filed at FERC.

"These concerns are primarily in regard to procedures used to repair welds during construction," REX told the Federal Energy Regulatory Commission in a project update, which was filed in early January. Defective welds can cause the release of natural gas from pipeline systems. The gas will either be released into the atmosphere with no incident or can trigger an explosion if a source of ignition is present. Most such leaks often occur in remote areas and therefore do not result in blasts, according to experts.

"Cooperating with the requests of PHMSA [DOT's Pipeline and Hazardous Materials Safety Administration], REX expects to excavate and reinspect numerous weld locations following the commencement of service at lower pressure to confirm the safe condition of the line. These locations remain to be determined based on welds that have been repaired and areas determined to be of higher risk due to the potential of excessive external forces," REX said [CP06-354].

"As agreed with PHMSA, REX [placed] the pipeline in service to a 72% level of the lowest specified minimum yield strength (SMYS) of the pipeline design. The 72% design level is 1,332 psig. It is expected that upon completion of further assessment and any related corrections, the pipeline operating pressure would be increased to the maximum allowable operating pressure of 1,480 psig (80% of the lowest SMYS). REX will not increase the pressure of the line without further consultation and agreement with PHMSA," the pipeline said.

"There were some tests done and we [expressed] come concerns with some of the welds. We asked [Rockies Express] to do another test. The company agreed to conduct an excavation," said PHMSA spokesman Damon Hill. "I don't know if this has been done yet."

As for how many welds are involved, he said "I'm not sure if it's two or three or 10 or 20."

Despite this, PHMSA believes REX-West is safe, Hill noted. "We feel that when we granted Rockies Express' petition [for a special permit to operate at 80%] that the pipeline was safe to operate."

Allen Fore, a spokesman for REX, downplayed the seriousness of the PHMSA's concerns. They were requests for "normal, routine inspections of welds. We are certainly complying with them," he told NGI. "We have met or are in the processing of satisfying all of the [agency's] concerns" with respect to the welds on REX-West. He further said "there's been no effect on the in-service of the line" as a result of the weld inspections.

The PHMSA has no further issues with the pipeline "that I'm aware of," Fore said.

On Jan. 12, interim service with capacity of about 1.4 Bcf/d began on approximately 500 miles of REX-West from the Cheyenne Hub in Weld County, CO, to the ANR Pipeline delivery point in Brown County, KS (see NGI, Jan. 14). The remaining 213-mile section of REX-West will continue eastward to Audrain County, MO, and is expected to be in service in late February, at which time capacity will increase to about 1.5 Bcf/d (see NGI, Jan. 28). Construction on REX-West, which encompasses 713 miles of pipeline, began in late spring of 2007.

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