Operators of natural gas pipeline systems routinely reduce line pressure and discharge gas from pipeline sections to ensure safe working conditions during maintenance and repair activities.
A Pipeline Gas Blowdown System is used to quickly and safely remove gas from a blocked-in pipeline section. The Blowdown system allows an operator to quickly remove the gas from a large section of pipeline for repair or maintenance. The Blowdown system removes the moisture from the gas and reduces the blowdown noise to 85 dB A at 100 feet. A control valve on the inlet reduces the pressure of gas flow through the high efficiency separators, and a silencer reduces the exit noise level.
EN-FAB, Inc. has developed a modularized trailer unit for pipeline gas blowdown. The design provides for:
- Reduction of all possible pressures
- Measurement of gas flow rate
- Separation of gas, liquids, and solids
- Reduction of operating noise to a permissible level
- Removal of distasteful gas odorants utilizing a deodorizing medium
These trailers are designed for movement along difficult terrain and can be camouflaged to blend into the surroundings. Trailer design meets local transportation requirements.
Main Components
- Two (2) High efficiency separators
- Two (2) Pressure / Flow Control Valves
- Two (2) 8” RF Orifice Plate Holders
- One (1) Vent Natural Gas Blowdown Silencer
- Two (2) Pressure Indicating Controllers
- Two (2) Differential Pressure Indicating Controllers
- CO2 Fire Extinguisher System
- Two (2) Nitrogen Supply Assemblies
The system is designed for portability along the pipeline to selected sites for cleanup, blowdown, and maintenance requirements.

Typical Process Conditions
- Gas Flow Rate96 MMSCFD
- Gas Specific Gravity.60 to .65
- Inlet Gas Temperature.60 to .65
- Inlet Gas Pressure65 deg F
- Outlet Gas Pressure1200 psig to Atmos.
- Liquid Water RateAtmospheric
- Liquid Hydrocarbon Rate0 Gal/Day
- Overall Noise Level1.0 Gal/Min (Max)
- Blowdown Separators EfficiencyNot to exceed 85 dba @ 100 feet
- Remove 98% of all the entrained liquid particles 6 microns and larger at design flow rate.

