Since the reform and opening up, the market sustained and stable development of China s socialist economy, the cause of gas pipeline
in the urban construction is becoming more common. Become increasingly important for the construction and protection of the gas pipeline
project, a matching pipe insulation flange increasingly common. How to find a good insulation properties, low cost insulating flange is
particularly important, This paper describes a new, low cost, using the new flexible insulating flange.
The structure and characteristics of an old insulation flange
Old-fashioned type I constitute insulating flange installation of flange insulation between the two butt welding a flange gasket and
tighten the connecting bolts on the installation of the insulating sleeve composed of insulated bolt gasket. Flange insulation gasket
materials used oil resistant rubber asbestos sheet, neoprene panels, fabric-based neoprene rubber sheet and Teflon materials. Insulated
bolt sleeve and bolt insulation pads made of high strength phenolic cloth laminated board and pressure piping production. Its
characteristics are: steel, insulation performance and stability, the need for specialized installation of specialized installation
location, and high cost.
2 new insulating flange development
Old insulation flange structure of the applicable type of improvement. For the low pressure of city gas distribution projects in the
city gas distribution projects (PN ≤ 2.5MPa), the pipe network pressure PN ≤ 0.4MPa characteristics improve. Use steel flat flange in
the pipe network distribution works instead of butt plane flange, flange insulation gasket with PTFE, oil resistant rubber asbestos
films, neoprene material, the fastening bolt insulation kits and insulation pad will be two to one, and reduce the insulating sleeve
made half of the overall high-strength insulation pad. Will wear a set of pads steel flange bolt holes to be expanded to be able to wear
insulated sleeve pad; in order to ensure the aperture sets of pad suitable for the requirements of the original steel flanges with
bolts, so they made a special role in the steel flange assembly became the new insulating flange. It can be installed separately, can
also be installed together with the connection valve; which saves the cost of the project, saving on-site installation position is a
simple application of a new type of insulating flange, and the cost is particularly low.
3 insulation principle and performance
The working principle of insulating flange, insulating flange insulation gaskets and high-strength insulating pad electrical insulation
performance of insulating flange on both sides of the electrical insulation work. Engineering practice, the insulation flange insulation
performance of the relevant requirements of the insulating flange design technology provisions (SY/T0516--1997), and the buried steel
pipeline cathodic protection parameters test methods (SYJ23- 86) methods for testing, test results show that: the resistance value of
the insulating gasket and fastening bolts of the insulating sleeve pad between the surface of the insulation work to meet the regulatory
requirements.
4 The use of
Such insulating flange during cathodic protection, transmission and distribution network Louchuang valve Department and the need for
potential fragmentation (District) isolation of buried pipe valve wells. Buried transmission and distribution network of the slice
(District) isolation can be more clearly grasp the cathodic protection of the (district) of each piece of pipe network; to evaluate the
cathodic protection fragmentation (area), and processed for different cathodic protection ; when the adjacent slices (area) protection
potential of the same (or similar) and to the protection of potential requirements, the available cross-bar on both sides of the
insulating flange connected to the unified protection; when the adjacent slices (area) protection potential difference and fail to
protect the potential requirements of on-chip (area), can reach less than the protection of the potential requirements of on-chip
(District) special handling to meet the requirements until later contiguous run.
(5) applicability
Produced in the ways of insulating flange oil and gas Tanaka pressure PN ≥ 2.5MPa long distance pipelines, stations, etc. used in
insulation flange is still applicable. Just a special flange to flange into a corresponding level to use exactly the same.
6 Conclusion
(1) the new type of insulating flange structure, applicability, and low cost.
(2) It applies not only to the city gas distribution projects in the electrical insulation isolation; but also for long-distance
pipeline, set gas pipeline transmission and distribution stations, the need for electrical insulation isolated places.
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