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In this case, it would need to design and install an inflation compensation device in certain length of the pipe to avoid bending or breakage due to extension or shrinkage. Generally, the compensation device is a kind of ¡°U¡± style inflation elbow pipe or corrugated pipe. Of course it will make the land for laying the pipe, cost of the project and implement time increased.
Electric Introduction to the technologies for pipe
The pre-stress technology for pipe is a kind of new technology that can save the construction land, accelerate the construction progress and reduce the construction cost. The application of this technology has been successfully used in western countries for many years, and some domestic companies had used it as well. There is no need to install inflation compensation device for long distance transferring pipeline by using this technology. China already set up such a regulations in the year of 1998 ¡°The Technology Regulations for Direct Burying Heating Supply Pipes in Cities¡± £¨ CJJ/T81-98 £©
Introduction to electric heating pre-stress technology for pipe
The technology is suitable for long distance heating supplying pipeline or crude oil transferring pipeline which is outdoors, directly buried underground and heat preserved ones. The application of this technology will make the pipeline have some pull and extension during construction; the pipeline should be heated by a kind of specific electric heating unit. The heating unit, in a standard casing for indoors or outdoors use, contains electronic controllers and the power unit. The size and weight depends on the power needed (from 150KW to 350KW on stationary units).
Field of Application
The heating units can be installed at any accessible and free selectable place outside of the pipeline. There is a choice between stationary and mobile units depending on the application - in case
1. The pipe must be hold constantly at a high temperature
2. The pipe must be started from the beginning or after a standstill
3. The pipe needs to be heated during standstill.
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