Insulating separation point
Isolation separation points are electrotechnical protective measures to interrupt the metallic conductivity of a pipeline or a system of cathodic corrosion protection . The insulating separation points are z. B. used in gas, oil, district heating or water pipelines .
Basics
The task of an insulating separation point is to isolate electrical voltages that occur in metal supply networks. This is particularly necessary for critical media such as gas, oil, kerosene, etc. Systems such as compressor stations , tanks, etc. must also be protected from high voltages in order to avoid damage. The scope of functions for insulating separation points ranges from pure insulation to reducing the voltage within the separation point.
Types
Insulating flange
The standard insulating flange is the simplest variant of an insulating separation point. It is mounted between two pipe ends of a pipeline and insulates the two ends with a non-conductive, insulating layer of hard paper or epoxy fiberglass fabric between the two flange ends . The screw shaft is insulated by sliding over a sleeve and the screw heads and nuts by a washer made of insulating material, usually GRP or Duroplast (Duromer). The disadvantage of this simple insulation is that the voltage is only prevented from flowing further in the pipe network. Due to their construction, insulating flanges should only be used above ground. The maximum mechanical resistance depends on the insulating washer. The strength of the screws can rarely be used by more than 20%. The operators of the systems very often tighten the screws because they loosen due to the creep relaxation of the insulating washer. In addition, the bending stiffness is low, since the flange screw connections mean that there is no self-contained component.
The improved insulating flange (Suckut system) has been known for decades. The insulation of the screw shaft and the use of steel and insulating washers with the largest possible area have been optimized. This system allows a screw utilization of up to 40%. The insulating flange consists of a thick ring made of hard paper.
Both versions have the disadvantage that the insulating components, which can hardly be mechanically stressed, are very heavily loaded on one side and relax due to the flange blade inclination when the flange is screwed on.
The high-performance version patented by Hardorp, Lannewehr, Lehmer, Thomsen uses rings, similar to loose flanges, as insulating and pressure rings to create the largest possible area to absorb the screw and pipe forces. In addition, the flanges can be prevented from tilting by creating a block position on the sealing surfaces. This system allows the full use of the screw strength and thus leads to the most mechanically resistant insulation system. Due to this construction, the system is considered technically tight in the long term, does not have to be checked and maintained regularly and can be installed underground. Newer designs from the licensee ISOflanges GmbH allow installation, like a fitting, as a flanged version or as a version with pipe ends for welding.
All versions can be equipped with protection against unintentional bypassing and an isolating spark gap.
Insulating piece
Also isolating coupling. The insulating piece is a fully welded (monobloc), force-fit component, which provides a high level of flexural rigidity. The tension is held within the component at an insulating point made of hard paper or epoxy fiberglass fabric from jumping over to the other side. The disadvantage of the insulating piece is that, at high voltages, the insulation inside the fully welded insulating piece burns, a carbon thread is created and thus becomes electrically conductive. As a result, the insulating piece is irrevocably defective and must be replaced.
Insulating piece with ring spark gap
The insulating piece with ring spark gap is the intelligent variant of the insulating piece. The voltage from 5 kV within the insulating piece is reduced via an internal ring spark gap. The two components of the insulating piece are isolated from each other by hard paper or epoxy fiberglass fabric. However, there is an uninsulated dead space between the left and right components, in which a small nose surrounds the spark of the overvoltage in a ring around the insulating piece until the energy is dissipated. This prevents internal damage to the insulating piece or surrounding components in the event of voltage peaks. The advantage of the ring spark gap lies in the fact that it is maintenance-free and the fact that the insulating piece can withstand high voltages. This cannot damage the insulating piece. The insulating piece with ring spark gap was invented and patented in 1986 by Franz Schuck from Steinheim / Germany in Swabia.
literature
- Ulrich Bette, W. Vesper: Pocket book for cathodic corrosion protection. 7th edition, Vulkan Verlag, Essen 2005, ISBN 3-8027-2932-3 .
- Günter Wossog (Ed.): Handbook of pipeline construction. 2nd edition, Vulkan Verlag, Essen 2003, ISBN 3-8027-2723-1 .
- Bernhard Naendorf (Ed.): Gas pressure regulation and gas pressure regulation systems. 3rd edition, Vulkan-Verlag, Essen 2010, ISBN 978-3-8027-5621-4 .