The heart of the gas transportation operation is the pipeline control system. The Nord Stream overall pipeline control system comprises the following functions:

• Pipeline parameter monitoring
• Pipeline pressure regulation
• Pipeline pressure safeguarding
• Telemetry and telecommunications
• Pipeline leak detection
• Fire and gas detection and protection
• Emergency shut down

A short introduction to each is given in following sections.

Pipeline Parameter Monitoring

Besides pressure monitoring, pipeline transportation system instrumentation continuously measures temperature, gas flow and gas composition at the inlet and the outlet.

These data are transmitted online via the Nord Stream SCADA (supervisory control and data acquisition) system and are continuously evaluated to ensure that all contractual requirements and nominations are fulfilled, to identify unexpected changes at an early stage and to ensure that design limits of the pipeline are not violated. For this purpose pipeline application software (PAS) will be used that allows detailed simulation and forecasting of the operating conditions in the pipeline.

The SCADA system displays the pipeline operating parameters at the main control room in Zug and the two landfall facilities, as well as at other locations where such information is required, i.e. Portovaya Bay Compressor Station control rooms, Greifswald Receiving Terminal control rooms.

In case a design limit is approached the system will automatically generate a pre-alarm to allow corrective actions. In case the design limit is reached, despite corrective actions, the safety function of the system will automatically initiate further corrective actions that ensure that the pipeline stays in safe operational mode.

Pipeline Pressure Regulation

The pressure regulation system ensures that the pipeline is always operated within its normal operating envelope while fulfilling the contractual transportation obligations.

The pressure regulation system of the Nord Stream pipeline will automatically alert the Nord Stream operator in Zug if the normal operating limits of the pipeline system are approached, so that corrective actions such as adjusting the gas flow can be initiated. These activities are coordinated by Nord Stream operators in Zug to ensure reliable and safe transportation of the nominated gas volumes. Besides, the manned control rooms of the upstream and downstream operators automatically receive the alerts of the Nord Stream pressure regulation system online to facilitate communication and coordination of corrective actions.

The Portovaya Bay Compressor Station upstream and the Greifswald Receiving Terminal downstream also control the pipeline pressure and gas flow rate. These facilities have their own independent control and monitoring systems.

Pressure Safety System (PSS)

The PSS ensures that the pipeline cannot be operated outside its design limits in case the pressure regulation fails. The PSS is a redundant fully automatic system that is independent of the main control room in Zug and cannot be manipulated manually.

The pressure safety system will automatically close the pipeline inlet in the event of the pipeline system approaching the limit of its normal operating pressure envelope. Thereby over¬pressurisation is avoided in case the Pipeline Pressure Regulation fails and steps to adjust the operating conditions are not taken in time and the pipeline pressure continues to rise.

Telemetry and Telecommunications

The pipeline system communications infrastructure will permit fast, reliable and secure exchange of data (telemetry) and voice messages (telecommunications) between the various facilities and control rooms, some of which are separated by significant distances.

Pipeline Leak Detection

A main focus for gas transportation is the safety of the pipeline. Thus considerable effort has been undertaken during design and construction to minimize the risk of pipeline failure. Therefore the probability of a gas leakage during the lifetime of the pipeline is extremely low. Although such an event is highly unlikely to occur, Nord Stream will install a leak detection system to allow fast reaction. This system is based on continuous monitoring and evaluation of data from flow rate and mass balance measurements.

If the leak detection system detects a major leak, appropriate actions will be initiated immediately. The alert is sent via the Nord Stream supervisory control and data acquisition (SCADA) system.

Fire and Gas Detection and Protection

The landfall facilities in Russia and Germany will have local fire and gas detection and protection systems, as is standard in the oil and gas industry.

Emergency Shutdown

The landfall facilities in Russia and Germany will have local emergency shutdown and safety systems, again as is standard in the oil and gas industry. The systems will be triggered in the case of an emergency such as fire. The gas volume in the pipeline will then be automatically separated from the landfall facility by closing the main valve (emergency shutdown valve). Additionally the landfall facility will be isolated from the upstream or downstream facility and automatically depressurized by releasing the gas via dedicated vents in a safe location to minimize the gas volume in the respective area. The underlying principle here is to stop the supply of gas to a fire.

Emergency Response

For the extremely unlikely event of a gas release, a pipeline emergency response plan (PERP) will be in place. Its details will be developed in close cooperation with all relevant authorities. The PERP will contain the first actions to be taken. A main activity is the communication of fast and correct information to affected parties. Nord Stream will therefore agree with the relevant authorities on how to distribute information and issue warnings as quickly as possible. All points of contact and possible further actions will be defined.

Also an agreement on how Nord Stream can quickly receive the necessary permits to evaluate the damage and carry out the necessary repair activities will be in place.

The emergency response centre will be located at Nord Stream’s headquarters in Zug and operated by Nord Stream core staff.