Catalog excerpts
DEHN protects Pipelines Cathodic Corrosion Protection Solutions
Open the catalog to page 1DEHN protects pipelines
Open the catalog to page 2DEHN protects pipelines from overvoltage interferences Pipelines operate under high pressures. If they are additionally loaded, the pipeline material, for example steel, quickly reaches its limit. In extreme cases, heavy corrosion can cause failure in the pipeline, resulting in leakage which may cause enormous material and environmental damage. Therefore, the condition of the pipeline must be continuously monitored during operation. Particularly any kind of corrosion must be immediately spotted throughout the complete pipeline. Passive corrosion protection is achieved by coating and...
Open the catalog to page 3Cathodic corrosion protection solutions 1 BLITZDUCTOR® VT KKS ALD 75 2 BLITZDUCTOR® VT KKS APD 36 3 Isolating spark gap EXFS 100 4 EXFS Coaxial connection box NAK SN4631 5 VCSD 40 IP65 6 DEHNventil® modular 7 Isolated lightning protection system with HVI®technology from DEHN 3
Open the catalog to page 5High-voltage lines are possible sources of interference voltages for pipelines Pipelines influenced by interference voltage Since pipelines are widely distributed and highly networked, they are often influenced by interference voltages from various sources of interference such as traction power supply systems, high-voltage lines, earth faults and lightning effects. Interference voltage means non-system voltages which can also occur in the form of transient, temporary or longduration overvoltage depending on their duration. They can enter a system, for example an insulated pipeline, by means...
Open the catalog to page 6Electric railways Electric railways produce galvanically injected stray currents which enter the pipeline via the ground through defects, thus changing the potential of the pipeline by means of interference voltages. High-voltage lines High-voltage lines generate electromagnetic fields which are injected into parallel pipelines and often occur in the form of permanent interference voltage. Earth faults An earth fault causes a potential gradient area in the surrounding soil whose potential affects pipelines located in this area. This potential gradient area thus spreads over to the...
Open the catalog to page 7The smart d.c. decoupling device VCSD 40 IP65 limits long-duration, temporary and transient overvoltage. Long-duration a.c. voltages are limited to a preset value by the d.c. decoupling device (voltage-controlled smart decoupling device) without influencing the required d.c. potential. Such overvoltage of a given duration or voltage level activates the correct limiting of the VCSD which are assigned to the relevant overvoltage and discharge it to earth without negatively affecting the cathodic protection potential on the pipeline (d.c. potential). The effects of dangerously high overvoltage...
Open the catalog to page 8Limitation behaviour of VCSD 40 IP65 as a function of time mhransient overvoltage is limited to values < 1.25 kV (duration: up to 1 ms). mhemporary overvoltage is limited to values < 940 V depending on the duration (duration: 1 ms up to 200 ms). I^Long-duration overvoltage is limited to values between 3 and 50 V a.c. (freely adjustable) (duration: > 200 ms). Functional description A single component is not enough to efficiently limit overvoltage. VCSD 40 IP65 from DEHN evaluates different sensor signals via a control unit, thus coordinating the interaction of the individual functional units...
Open the catalog to page 9Protection of cathodic protection rectifiers In case of impressed current cathodic protection, the required protective current is produced by a mains-powered rectifier and fed into the protection object, for example the pipeline, via impressed current anodes. Modern rectifiers additionally feature a control device which detects the protection potential of the pipeline against a reference electrode (e.g. Cu/ CuSO4 electrode) and automatically sets the optimal cathodic protective current. A cathodic protection system mainly consists of: • Cathodic protection rectifier for the protective...
Open the catalog to page 10Protection solution for protective currents up to 12 A Protection solution for protective currents between 12 A and 60 AMDEHNventil® 2P Modular type 1 + type 2 arrester with a high discharge capacity ensures easy replacement of protection modules without tools and protects power supply systems. Transient: 50 kA (10/350 ps) and 50 kA (8/20 ps) Follow current extinguishing capability: 100 kArms Type 1 + Type 2 arrester for cathodic protection systems protect the sensor measuring circuit. Transient: 7.0 kA (10/350 ps) and 40 kA (8/20 ps) Temporary: 20 A rms Type 1 + type 2 arrester for...
Open the catalog to page 11Protection of insulating joints and flanges Insulating joints and flanges are used to electrically (galvanically) isolate cathodic protection pipeline systems against system earth or to divide high voltage interfered pipelines into individual pipeline sections. Cathodic protection systems are electrically isolated until the dielectric strength of the insulation of the insulating joint / flange is reached. The dielectric strength of insulating joints can be exceeded by overvoltage resulting from a lightning strike to exposed parts of a pipeline system or the effects of short-circuit currents...
Open the catalog to page 12lightning strike earth fault / shortcircuit current insulating flanges earth electrode earth electrode earth electrode stray currents caused by electric railways pipeline insulating joint EXFS 100 / EXFS 100 KU Isolating spark gap • EXFS 100 spark gap certified according to ATEX (94/9/EC) and IECEx • Safe use in Ex zone 1/21 and 2/22 • Suited for non-sparking connection to pipelines, insulating flanges or insulating joints in hazardous areas • High a.c. discharge capacity, low sparkover voltage • Suitable for protecting insulating joints or flanges tested to class 2 / 2.5 kVrms • Transient:...
Open the catalog to page 13Protection of field instruments The surge immunity of field devices such as pressure or temperature transmitters complies with the common requirements of the EMC standards, but is not sufficient for most overvoltages caused e.g. by lightning strikes. The transmitters are often destroyed and dangerous sparking could lead to significant danger and damage in a potentially explosive atmosphere. The function of surge protective devices from DEHN is to repeatedly discharge overvoltage without sparking and to simultaneously protect the electronics of the transmitter. The Yellow/Line series from...
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