August 2017, Vol. 244, No. 8
Features
Samalayuca-Sasabe Pipeline Looks to Bring Power to North Mexico
The Samalayuca-Sasabe project’s main objective is connecting the federal gas network to the northern states of Chihuahua and Sonora in order to supply energy to the power-generation plants located in the north and northeast of Mexico.
According to the work schedule, the project is expected to start operations next April with a $916 million total investment. This is one of the most important projects in recent years in terms of energy integration at a national level.
The Federal Electricity Commission (CFE) commissioned the construction to a consortium formed by Mexico-based Grupo Carso and the Spanish company, FCC, through a venture called AFIG (CICSA 45%, FCC Industrial 45% and Nuova Ghizzoni SPA 10%), which includes the 390-mile (630-km), 36-inch gas pipeline, a temporary dynamic discharge valve (DDV) between 10-15 meters and a strip of 5 meters on each side of the duct shaft. As of July, the completion rate is at 21%.
The project travels through the states of Chihuahua and Sonora, supplying natural gas to the point of delivery for a future connection to the Agua Prieta Natural Gas Transportation System and the existing Sásabe- Guaymas Gas Pipeline, both located in the state of Sonora, along with the San Isidro-Samalayuca Gas Pipeline. The work is an administrative concession under operation, management and maintenance through a contract signed between CARSO and the CFE.
From a technical point, one highlight of the project is the geological and topographic diversity of the region. Chihuahua’s terrain is typically desert and offers few complications for excavation, whereas the Sierra Madre Occidental contains a high water table that might complicate transportation of heavy machinery during the rainy season.
In the state of Sonora, again the area is mostly comprised of desert with the presence of some pastures. Another challenge is the considerable difference in altitude of the path, with the highest point of the mountain range 1.4 miles (2,250 meters) and its lowest point 1 mile (1,600 meters).
The pipeline will start southwest of Ciudad Juárez, (Chihuahua) and end at Pitiquito (Sonora), where it will be interconnected to the Compression Station in Ciudad Juárez. The gas will be transported from its reception point in Ciudad Juárez to the delivery point in the town of Sásabe. The route of the gas pipeline runs through 17 cities, 12 of which are in Sonora and five in Chihuahua.
The Samalayuca-Sasabe will have a transportation output of 472 MMcf/d of natural gas at a maximum allowable operating pressure of 1,440 psig and a temperature between 10°C and 50°C. For this reason, a 36-inch API 5L carbon steel pipe with a 15mm wall thickness has been implemented. The pipeline includes 23 sectioning valves (MLV), six of them with pneumo-hydraulic drive and 17 with electric motor drive, and 10 traps for maintenance and internal inspection of the pipeline.
The steel tubes forming the conduction are joined by electric arc welding by both manual and automatic processes. However, the implementation of the CRC automatic welding allowed large yields to reach 2,000 linear meters per day of welded pipe.
All of the pipeline’s welded joints are subjected to non-destructive tests to ensure quality. This is done through radiographic methods or ultrasound, as the case requires. The protection against corrosion is double: passive by fusion-bonded epoxy (FBE) coating and activated by cathodic protection by printed current.
Due to railway lines along the pipeline, engineers plan to construct 18 overpasses, most of which will rely on horizontal drilling.
Starting in Juárez, the first of the project’s five segments runs 171 miles (275-km) to the city of Janos. In addition to the 175-km of pipelines, 11 mainline valves will be installed in this segment. Segment 2 continues to the 192-mile (310-km) point of the pipeline in Agua Prieta, Sonora. This segment runs across the mountains that divides the two federal states, and due to the rugged terrain, specialized personnel were contracted.
Segment 3 continues to the 260-mile (418-km) mark, also in Sonora. It is a 67-mile (108-km) segment, comprised of three geological areas and irregular topography mixing light mountain terrain with semi-desert geology.
Segment 4 runs to the 295-mile (475-km) point in Imuris, Sonora, with a stretch of (57-km) through mountains and some valleys.
Finally, Segment 5 arrives in the village of Pitiquito, Sonora. It is a section containing desert and semi-desert terrain. Pitiquito is where the measurement and regulation station to the final pipeline interconnection will be located.
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