Oneok Partners, LLP

Oneok operates several flares in the Willison Basin of North Dakota. The pilot gas for these flares is typically gas from the compressor station. This gas is not dry and the flare pilot lines experienced freeze up issues in the winter. Oneok evaluated several options and decided to pursue utilizing propane gas as the new pilot gas source. Oneok required enough propane storage on a site to achieve a refill frequency of 14 days or more. The system must provide propane gas at adequate pressure under all anticipated site conditions.

EAPC designed the new propane offloading station, storage and transport systems. Since the system would be installed at multiple sites around North Dakota, two designs were developed. The first design utilized a single 2000 gallon propane tank and the second utilized two 1000 gallon tanks. For either design, the tanks were insulated and the lower portion heat traced to ensure the propane would be at adequate pressure on extremely cold winter days.

EAPC provided detailed design and engineering services for the new propane pilot gas systems. Applicable codes used for the design of the system included NFPA 58 and API 2510. EAPC evaluated various options (pump and vaporizer, catalytic heater, heat tracing, etc.) available to ensure the propane gas pressure would be sufficient under all design conditions. Tank sizing was evaluated and selected based on the refill frequency and commonly available stock tank sizes. Structural pads were designed for the new tank and the offloading station and bollards placed to protect equipment from damage. EAPC also defined electrical items such as heat tracing and instrumentation.