Operations monitoring

The system inspection is divided into the following areas: 

• Inspection of pipeline routes
• Auxiliary facilities
• Pipeline leakage tests
• Cathodic corrosion prevention

During its inspection of the operating company, the Federal Pipelines Inspectorate (FPI) examines whether the organisation and the skills of the employees meet the stringent requirements placed on the operation of such pipelines. In concrete terms, for example, it conducts emergency drills in order to test the operator’s reaction capability, emergency organisation and teamwork with the public emergency services.

Regular inspections of the operational regulations of individual operators ensure that they are systematically capable of responding, e.g. in emergency situations. The key aspects of operational regulations are: organisation, responsibilities, description of the operator, description of the systems and information regarding incident prevention.

Cathodic corrosion prevention

Cathodic (or active) corrosion prevention is a technical process in which a potential reduction of corrosion is achieved with the aid of a cathodic current. At the level of around - 850 mV (which is referred to as the cathodic protection potential for a normal soil), the electrochemical corrosion process is almost entirely hold. The corrosion speed is reduced to a virtually negligible level of less than ten micrometer (0.010 mm) a year.

The FPI inspects cathodic corrosion prevention systems every three years (performance checks). During this procedure the precise settings and thresholds for the operator's periodical function inspections are also specified.

The inspection of the cathodic corrosion prevention systems are carried out according to the "C1 Guidelines for planning, execution and operation of cathodic protection of pipelines" of the Swiss Society for Corrosion Protection, SSCP.

Inspection of pipeline routes

All pipelines have to be visually inspected by their operators at least every two weeks. These inspections may be carried out on foot, by car or by helicopter.

An FPI inspector accompanies these inspections every three years, which primarily focus on the following questions:

• Are there any new buildings or other structures belonging to third parties in the protection area of the pipeline?
• Have any changes taken place concerning the use of the site which could affect the pipeline in any way?
• Are there any indications of topographical occurrences (e.g. landslides) along the pipeline route?
• Do the route markings still match those specified in the regulations?
• What is the condition of special objects/components such as sections running across roads, tunnels, pipeline bridges, etc.?

Auxiliary facilities

The terms "auxiliary facilities" refer to all components of a pipeline system that are not deemed part of the pipeline itself. Namely:

• Valve stations
• Pressure reducing and metering stations
• Compressor stations
• Pump stations

The FPI is required to inspect these facilities on an annual basis. Depending on the type of the facility, there are very different checkups to be carried out. Here are listed the principal inspections and controls which roughly have to be conducted:

• General condition
• Access to protection zones
• Internal and external piping
• EX zones
• Protection against falling trees
• Function test of the most important equipment and fittings
• Function test of safety equipment and verification of settings
• Tanks (e.g. preheating) and filters related to corrosion
• Condition of buildings, escape routes, fencing

Leakage test

Pipeline transporting fuels in liquid form habe to be subjected to an annual leakage test under the supervision of the FPI. This requirement applies to all pipelines that transport oil or oil products such as kerosene, petrol, diesel, etc.

Since these pipelines are almost always installed underground, visual inspections are normally not possible, and volume comparison measurements are unsuitable since they do not offer the required degree of accuracy.

This means that different procedures have to be applied, depending on the configuration of the pipeline or system. The pressure-volume method yields the most accurate information regarding pipeline tightness. Here a pipeline is blocked on both sides and the pressure and temperature are recorded over a period of 24, 48 or 72 hours. This timeframe depends on the accuracy of measurement, especially of the temperature.

If it is not possible to shut down a system for one or several days, the pressure-jump procedure can be used. Here the short-term pressure development in a pipeline is measured at different pressures and the readings are then compared. This procedure is used, for example, for the supply pipelines at Geneva and Zurich airports.

Another method that can be used is the pressure differential measurement, which is applied in systems where two identical pipelines run parallel to one another.