SOP S1-6230

Procedures for Abnormal Operating Conditions in LNG Storage and Distribution

• Abnormal conditions are controllable conditions that could cause a safety issue but have not reached an emergency level.
• Taking an LNG storage tank out of service for maintenance or repair requires a written detailed procedure.
• Warming and cooldown procedures are necessary when an LNG storage tank requires maintenance or repair and has been out of service, respectively.
• FNG LNG storage tanks are operational year-round, and warming or depressurizing them requires a detailed written procedure.
• Abnormal operating conditions may exist if Distribution Pressure exceeds its Maximum Allowable Operating Pressure (60 psi).
• Distribution Pressure at Site #1 is typically operated at 45-50 psi, well below the MAOP of 60 psi.
• Gas detection procedures are in place for levels between 25% and 50% LEL and levels over 50% LEL.
• The ESD system automatically shuts down all valves tied to the ESD system when gas detectors reach 50% LEL.
• Flame detectors activation due to fire requires following SOP 1112 - Fire Protection Plan.
• False detections caused by low temperature, glaring sun, or other causes require specific steps outlined in the procedure.
• Polypropylene glycol is used in the system and requires proper PPE and ventilation in case of accidental release.
• Good engineering practice suggests changing the filter element in Master Meter Dry Gas Filters at half of its collapsible differential pressure of 12.5 PSIG.