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Lectrus Provides Several Walk-In, Gas-Insulated Switchgear Enclosures to Alliance Refinery

Over the past decade, Lectrus has designed and built several prefabricated electrical enclosures for gas insulated switchgear on oil and gas projects around the globe.


Over the past decade, Lectrus has designed and built several prefabricated electrical enclosures for gas insulated switchgear on oil and gas projects around the globe. ConocoPhillips Alliance Refinery in Belle Chasse, Louisiana, is one example of the company’s capabilities to construct fully integrated, custom walk-in electrical enclosures for premium, medium voltage switchgear.
Located on the Mississippi River 25 miles south of New Orleans, the Alliance Refinery has a crude oil capacity of 247 million barrels per day (MBD) and primarily produces transportation fuels, such as gasoline, diesel fuel and jet fuel. The majority of the refined products are distributed to customers in the southeastern and eastern United States through major common-carrier pipeline systems and by barge.
Each of these robust, walk-in, NEMA 3R metal switchgear enclosures contained Siemens Type 8DA, 34.5kV extendable, fixed-mounted circuit-breaker gas insulated switchgear (GIS), designed to replace the outdated air insulated switchgear (AIS) at the refinery’s substations. Residing in a Class 1, Division 2 hazardous environment, all equipment (including each HVAC unit) had to meet NFPA 496 requirements. In addition to the GIS equipment, each enclosure contained transformers, electrical panels, panelboards, automatic transfer and disconnect switches, and lead calcium batteries. Final building dimensions were as follows:

  • Substation 5A: 13ft x 39ft; 56,000 lbs (2010)
  • Substation 5C: 13ft x 49ft; 78,000 lbs (2012)
  • Substation 5D: 16ft x 54.5ft; 104,000 lbs (2013)

Each switchgear enclosure was engineered to meet the following design loadings: 140 mph wind; 50 psf roof; 250 psf floor; and 400 lbs/linear foot wall. In addition, the deflection tolerance over the width of the base was 0.2 inches (0.5 mm, or L/960), which was necessary to meet the strict installation tolerances associated with GIS equipment. Proper installation of GIS equipment requires the room to have certain dimensions (including a ceiling height of 11 feet) and the floor to be level to +/- 0.001 in/in (1mm/m). Prefabricated GIS enclosures are preferred by engineers and end users in the oil, gas, and mining industries for the following reasons:

  • Compact Design – A substation using GIS is typically 10-20% the size of a conventional AIS substation.
  • Extremely Long Life – GIS equipment predict expected lifetimes of 50 years or more.
  • Increased Safety – All-round, gas-tight cast aluminum busbar housing provides maximum safety for personnel under all operating and fault conditions.
  • Enable Low Temperature Installations – Rather than limit to -5 degrees Celsius in outdoor installations, GIS equipment installed in a walk-in, NEMA 3R enclosure can be installed below -30 degrees Celsius without using unique SF6 mixtures.
  • Protection of the Environment – Sulphur hexafluoride (SF6) insulates 3 times better than air, is non-toxic and non-flammable, has a very small leakage rate (less than 0.1% per year) and does not damage the ozone layer. Additionally, the encapsulated GIS design has a very low noise emission.

The design of each switchgear enclosure complied with several Process Industry Practices (PIP), the International Building Code, the National Electric Code, and was stamped by a Professional Engineer registered in the State of Louisiana. Each structure contained the appropriate HVAC equipment to provide safe and efficient operation of all equipment in a pressurized environment. Because of the installation environment, the Lectrus Severe Duty Paint System was used which features excellent resistance to corrosion when exposed to a salt fog for over 4,000 hrs ASTM B-117. This coating system, manufactured for Lectrus by DuPont, has proven resistance to chemicals such as: sulfuric acid, hydrochloric acid, nitric acid, toluene, cyclohexane, gasoline, and others. Lastly, all non-welded structural connections used stainless steel bolts and fasteners.

For more information about Lectrus and our extensive electrical and mechanical integration capabilities, please visit


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