Regulator Freeze Protection-Natural Gas Essay Example
Regulator Freeze Protection
MICHAEL W. GILLIS P. ENG
GROUP LEADER, MEASUREMENT AND PROCESS CONTROL ENGINEERING
ATCO PIPELINES
Introduction
In the transportation of natural gas from wellhead to consumer, service conditions will be encountered which may cause the gas and equipment used to regulate and control pressure to experience freezing conditions. Ignoring these design considerations will result in reduced facility reliability and increased operating and maintenance costs.
Regulator or control valve freeze off at pressure reducing stations, resulting from the cooling effect of pressure reduction, can cause serious operational and safety problems. The freeze off can result in the regulator becoming inoperable causing a potential loss of pressure control or even result in the loss of service to downstream customers. Clearly, regulator freeze off is an operating condition a natural gas transportation pipeline or distribution utility wants to avoid. Awareness of the causes and effects of freezing conditions and methods of avoiding these conditions will result in more reliable, cost effective facilities and reduced risk of failures and safety hazards
The Effects of Regulator Freeze Off
The effects of regulator freeze off and its associated conditions are numerous and can be.
divided into two categories. Those resulting from a freeze off within the gas stream, either in the main body of the regulator or within pilot/controller piping, and the effects on the external regulator/valve body, station piping and foundations.
The freeze off can occur in the small diameter instrumentation and control piping or the orifice within the pilot rendering the regulator inoperable. Depending on the regulator or control valve type and it’s action, the regulator failing to respond to a downstream condition will either overpressure or fail to adequately supply the downstream demand. In the case of a frozen orifice within a controller, the inability to vent the
MICHAEL W. GILLIS P. ENG
GROUP LEADER, MEASUREMENT AND PROCESS CONTROL ENGINEERING
ATCO PIPELINES
Introduction
In the transportation of natural gas from wellhead to consumer, service conditions will be encountered which may cause the gas and equipment used to regulate and control pressure to experience freezing conditions. Ignoring these design considerations will result in reduced facility reliability and increased operating and maintenance costs.
Regulator or control valve freeze off at pressure reducing stations, resulting from the cooling effect of pressure reduction, can cause serious operational and safety problems. The freeze off can result in the regulator becoming inoperable causing a potential loss of pressure control or even result in the loss of service to downstream customers. Clearly, regulator freeze off is an operating condition a natural gas transportation pipeline or distribution utility wants to avoid. Awareness of the causes and effects of freezing conditions and methods of avoiding these conditions will result in more reliable, cost effective facilities and reduced risk of failures and safety hazards
The Effects of Regulator Freeze Off
The effects of regulator freeze off and its associated conditions are numerous and can be.
divided into two categories. Those resulting from a freeze off within the gas stream, either in the main body of the regulator or within pilot/controller piping, and the effects on the external regulator/valve body, station piping and foundations.
The freeze off can occur in the small diameter instrumentation and control piping or the orifice within the pilot rendering the regulator inoperable. Depending on the regulator or control valve type and it’s action, the regulator failing to respond to a downstream condition will either overpressure or fail to adequately supply the downstream demand. In the case of a frozen orifice within a controller, the inability to vent the