Procedure and apparatus for monitoring a pipeline

The invention relates to a method for monitoring one of several pipelines existing pipeline network to Transport petrochemical liquids or gases after Preamble of claim 1 and a device according to the Preamble of claim fifth

is for the transport of environmentally hazardous media famous pipe, which concentrically of two arranged mutually corrugated metal pipes and is the gap between the tubes by pressure or vacuum monitored is. (DE-C-21 64 814)

Although this pipe an unseen damage case with highest excludes probability is where legal provisions are missing, for reasons of cost emaciated pipe used. Such under the Tradename "Flexwell suction line" available conduit consists of a corrugated metal tube, on which a extruded plastic sheath is seated. Also, in this Pipe is a two-layer pipe (Metal corrugated pipe plastic pipe), but monitoring is not provided here.

When the monitored pipe is usually the Monitoring pressure higher than the maximum delivery pressure of Medium. This is intended entry of the medium into the

Interstitial space and penetration into the Monitoring apparatus and possibly escaping from the pumped medium can be avoided at this end. at Gas stations are the feed lines during operation under a pressure of max. 3 bar. By simultaneous closing several nozzles can also pressure surges of up to occur 14 bar. For this case would have the regular Monitoring pressure min. 5 bar, lead in fact to 16 bar be adjusted. In the known pipe of two corrugated metal pipes, of which the inner moreover still wearing armor, these pressures are almost easily. For pipes whose inner and outer tubes from a less stable material, such as plastic exist, these would either burst (outer tube) or collapse (inner tube). Measures the mechanical stability the material for the inner and outer tubes to increase, would drift considerably in height the cost.

From US-A-4,450,711 is a method for monitoring a of a plurality of individual pipe portions composite pipe is known, each Pipe section of an inner tube and the Surrounding the inner tube to form an annular gap outer tube consists. In the annular gap a flushing medium is continuously circulated and analyzed. In case of damage on the interior and / or outer tube, the amount of the circulated detergent increases and due to damage in the annular gap occurred medium expelled.

The present invention is based on the task of aforementioned method for monitoring a pipeline Transport petrochemical liquids or gases indicate which of the at any time, a check Protective effect of the outer tube reliable reports, a uncontrolled discharge of the pumped medium preclude the formation of explosive mixtures in prevents interstitial space and a suction and Forward this ignitable mixtures avoids it altogether. Moreover, the method is particularly Pipe components made of materials such as low strength be plastic tubes applicable.

This object is achieved by the characteristics of claims 1 dissolved and 5 detected features.

By constantly monitoring the pressure in the interstitial space between inner and outer tubes of the individual Pipe sections of the pipeline network can both damage the inner and the outer tube for each tubing string to be reported separately. are Minor damage to the inner tube not detectable by this method may. The Circulating the gas in the interstitial space and bypassing the gas to probe reports certainly a claim on Inner tube.

While the interstitial space constantly pressure-monitored, with Except for the period where the gas is circulated, the second Action - checking by the sensors only in certain periods, such as every 60 minutes durchgeführt.Wird reported a case of damage, in any case, the plant will off.

The invention is based on the in the figures 1 to 3 Exemplary embodiments shown schematically explained.

In the figure, 1 is the scheme of the monitoring system for a consisting of line 1, line 2, line 3 and line 4 System for delivering petrochemical liquids, eg a petrol station shown. The forming each strand Conduit consists of an inner tube, an outer tube and a monitoring room.

The interstitial space of each strand is a Supply line Z₁, Z₂, Z₃, Z₄ and a line L with a Pressure generator GF connected. In the embodiment, the Pressure generator GF a nitrogen-filled gas cylinder. At However, the location of the gas cylinder can also be a conventional pump to step. With a reducing valve RV, the monitoring pressure be precisely adjusted and read on a manometer M will. Such systems are known per se and are for continuous pressure monitoring of the monitoring space of monitorable pipes.

In the inlets Z₁, Z₂, Z₃, and Z₄ are pressure switch D₁, D₂. D₃ and D₄, Solenoid valves X₁, X₂, X₃ and X₄ and sensors S₁, S₂. S₃ and S₄ provided. In addition, in the line L is a Another sensor S_c provided. In the line L are further comprising a gas pump P, a pressure vessel and a DB Another solenoid valve Z. is in a bypass line B Another solenoid valve C located.

The sensors S₁, S₂, S₃, S₄ and S_c it is about Sensors that indicate the presence of hydrocarbons find and share.

To check the inner tube for leaks, periodically all solenoid valves X₁, X₂, X₃ and X₄ with the exception of Solenoid valve, which for in the feed line to the checked strand is, briefly closed. Simultaneously, the gas pump P runs for a certain short Time. The equipment must be connected so that in this Period, the alarm function of the corresponding pressure switch D₁. D₂, D₃ or D₄ is disabled. The extracted gas of Interstitial space - usually nitrogen is preferred - is compressed in the pressure vessel DB, a limit indicator G2 by switching off the gas pump P the maximum Compression pressure in the pressure vessel DB limited. The max. Compression pressure is a function of the size of the Pressure vessel DB, the volume of the interstitial space of Level of monitoring pressure etc. optimized. Of the Cut-off time for the gas pump P is at the latest reached when the pressure measured at the limit switches G1 to a value of 0.2 bar above atmospheric pressure has fallen. Occurs an alarm event, each in the same manner Another strand tested. In this way it can be determined which strand is damaged.

After completion of the respective tests that opens otherwise closed solenoid valve C in the bypass line B to the Pressure equalization between the pressure vessel and the respective DB checked strand allow. Until carried Surge (circuit z. B. over timing) remains the Gas pump P and the alarm function of the respective pressure switch D₁, D₂, D₃ or D₄ disabled. Only then is when the pressure drops in train an alarm can be triggered. For smaller Systems where the size of the pressure vessel DB no problem represents, the monitor mode could all strands be extended - simultaneously - rather than individually.

During the pumping operation, a portion of in the Monitoring space located gas through the inlets Z₁. Z₂, Z₃ and Z₄ at the sensors S₁, S₂, S₃ and S₄ bypassed. If this gas hydrocarbonaceous, saith corresponding sensor, and it can be determined that is present in the corresponding strand an inner tube damage. In this case, the system must be shut down or the faulty train are decommissioned. If there is no Damage report on, the solenoid valve C again closed and the pressure monitoring cycle is again set, that is, by opening the solenoid valves X₁ to X₄ of the Monitoring pressure in the line L, the supply lines Z₁ to Z₄by and in the monitoring area of ​​the strands 1 to 4 Surge again. The sensor S_c is for the case required that one of the sensors S₁ to S₄ fails.

In the figures 2 and 3 pipes are in the side Section shown for which the inventive method is particularly suitable.

2 shows an inner tube 1, which from a corrugated Metal tube consists of an outer tube 2 made of a surrounded extruded plastic tube. The interstitial space 3 extends here in the form of a helix between the inner tube 1 and outer tube 2. Between the inner tube 1 and the outer tube 2, a metal foil is not shown may be provided, the when a copolymer with the outer tube 2 whose Extrusion bonded. This metal film increases the Pressure resistance of the outer tube 2 and prevents Diffusion of gas through the plastic tube.

If it is in the inner pipe 1 around an annularly corrugated metal tube, the outer tube 2 at its should Inside have a profile, to provide a continuous Monitoring room 3 needs.

In Figure 3, consists of both the inner tube 10 and the Outer tube 20 made of extruded plastic tubes by a helical spacer 40 concentrically with each other are maintained, and thereby the interstitial space 30 between be prepared.

Also in this pipe construction, it may be advantageous to not shown metal foils in the construction of both the Inner tube 10 and to provide for the outer tube 20th

The spacer 40 may be omitted if the inner tube 10 and / or the outer pipe 20 at its side facing the adjacent tube facing surface profiling z. B. in the form of having longitudinal ribs.