Transco-Mears Recoat Project - North Carolina
Mears Group Inc. successfully completed a recoating project consisting of 11,000 feet, roughly two miles, of a various large diameter live natural gas transmission pipelines, 30, 36, and 42-inch, stretching from Lexington, NC to Mooresville, NC. Mears, contracted by Williams Gas Pipeline – Transco, began the project on March 26 with a 36-man crew and five Williams’s personnel. This included four excavators and a manual dig crew with each excavator. The gas line is Williams’ main transmission line which runs from Alabama to the East Coast. The project was a joint effort between Williams and Mears. The challenging facet of this project was the fast paced production, which required crew members to work in tandem to what is typically a slow paced project, to a faster paced project. Both sides adapted quickly to turn the project into a success and the systematic, or assembly-line approach, was a key factor in the efficiency of the project.
Recoating is extremely important and is part of maintenance on any pipeline. This particular pipeline was live; in essence, the pipe still contained gas with a pressure of over 750 pounds per square inch (psi) while being worked on. The approach that Mears used to sand blast the pipe was twofold. The first process was the automatic line travel sandblast system, which is fully-owned and patented by Mears. The other system was hand held double nozzle sandblasters. Having both of these systems allowed Mears and Transco the flexibility to achieve very high production rates. And, production rates of almost twice as much as a single nozzle, with the use of the hand held dual units. Putting it into perspective; in a typical recoat project, a one nozzle hand held sandblaster will sandblast at a rate of 15 feet an hour. Using a double nozzle sandblaster, sandblasting is at a rate of 30 feet an hour. When using the automatic line travel sandblast system, sandblasting is achieved at a rate of 60 feet an hour. This automated system can sandblast pipelines up to 36-inches in diameter.
The automatic line travel sand blasting equipment, which can clean the pipe to a near white blast at over 1 linear foot a minute on all pipe up to 36-inches, has the capability of sandblasting to any company’s specifications from pure white to gun metal gray. It also delivers a high quality surface at speeds unsurpassed than by the manual sandblasting method. You can adjust the oscillation and travel speed depending on the pipe conditions and anchor pattern required. Anchor pattern requires that the surface of the pipe has the right texture for the coating to adhere.
For small sections and pipe larger than 36 inches in diameter, Mears utilized hand held double nozzle sand blasters. The Mears crew was able to sandblast the pipe around 80 to 100 feet per day. This is exceptionally more efficient over the old method of the single nozzle sandblaster in which many other companies use.
“Working closely with Gary Price, chief inspector for Williams Gas Pipeline - Transco, enabled both Mears and Williams to effectively plan an approach that was systematic and eliminated any potential problems,” said Jay Fluharty, project manager for Mears Group.
With this systematic approach, a 50 foot ditch was carefully excavated leaving some dirt around the pipe. The remaining dirt was dug out by hand with careful execution and strict procedures. Then, Mears’ crew members dug around the pipe with hand tools. This took approximately 10 hours to clear a 125 ft. section of the pipe. This process had to be done to the entire 11,000 feet of pipe for recoating. From there, brass hammers were used to remove the old coating. “The crew faced an interesting challenge” said Mike McCann, superintendent for Mears. Working in hot and humid conditions with temperatures reaching as high as 120 degrees Fahrenheit in the ditch was no “cake walk.” The crew took extra precautions while working these sweltering conditions.
Next, the automatic line travel sand blasting equipment or the hand held double nozzle sandblasters are used to prepare the surface of the pipe, depending on the length and size of the pipe. Next, the pipe undergoes inspection. If all goes well, then new coating is applied to the pipe. Concern of overspray from the recoating process was addressed since some of the locations of the project were in close proximity to residential areas. Mears and Transco created an effective method of tarping the areas that protected the homes and eliminated any overspray produced by the recoating. This added measure kept the project moving smoothly and efficiently, while eliminating any potential problems to the landowners.
After the surface preparation was completed, the pipe was inspected, information documented and an adequate number of mils of coating sprayed on to the pipe. The newly coated pipe was then inspected and prepared to be backfilled. After the 50 foot ditch is back-filled, the crew then skips 45 feet and begins the process all over by digging another 50 foot ditch. The key to the process is having a crew perform each process as an assembly line. As the 50 foot ditch is dug, another crew is digging the next ditch. Behind the digging crew will be the sand blasting crew, and so on. Once the crew reaches the end of the pipeline, the process is repeated and the 45 feet sections are excavated, sandblasted, inspected, recoated and back-filled. The purpose of doing it in sections is to keep the pipeline from flexing at any point.
According to Fluharty, “There were three important steps we took in this project. We worked closely with Gary Price to plan this systematic approach. We effectively communicated with the landowners and moved quickly through those areas, which gave them confidence with the gas company. And, because of the diversity of our equipment, we were able to apply an effective system that kept the project moving swiftly and provided flexibility. In the end, we were in and out of each location without any problems.”
Backfill and clean-up ranged from fields, woods, horse pastures and front yards of residential areas. This stage of the project created a challenge for the crew. Williams took the lead by working with the landowners and the crews to accomplish the desired results and keep the project on schedule. This final stage of the project requires a great deal of consideration and care to yield the best results and a successful completed project.
Backfill and clean up are a very important part of the recoating projects on pipelines. “The ground will be all that anyone sees when we are finished, and after a time will be mostly what the landowners remember about our recoating project. With the long distance transmission system that we have which stretches thousands of miles, it traverses through an almost countless number of properties from Texas to New York,” stated Bill Deaton, project manager for Williams. He went on to say that maintaining a stable right of way means that pipelines have good compaction around them and while that contributes to the continued safe operation of their pipelines, it also allows them to have good relations with the landowners.
The recoating project was successfully completed in September of 2007. With the teamwork between Williams and Mears, this project was a prime example of great efficiency, with the use of the automatic line travel sand blasting equipment and the hand held double nozzle sandblasters. Using these sandblasting systems, executing the project efficiently and working in a systematic approach achieved the results desired on this recoat project. In a typical recoat project, the pace and time frame are double as compared to this particular project, which was fast paced and effectively planned out from start to finish.
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