Have you ever worked on sewage pipes installed in an overhead manner? Please inquire about the quality of the textbooks and the pump station issues.
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The company has a project related to the sewage pipeline network in the chemical industrial park. The management committee requires that these pipelines be installed above ground (we strongly advised the owners to bury them, but they refused); they also want these pipelines to be mounted on the same supports as the steam pipelines in the park. However, it is required that they be buried underground when passing through the factory and roads. Questions: 1. Material issue with the overhead pipes; they are installed on the same supports as the steam pipes, and since the steam pipes are made of steel and have large spans, the spacing between the supports is also large. If I choose PE pipes for my sewage system, I will need to add many small supports or use steel beams. Additionally, owners should not use steel pipes with flange connections. Are there any other materials that would be more suitable? Are there welded steel pipes available, along with a process that allows for automatic internal anti-corrosion treatment? If only PE pipes can be used, which type of PE pipe is preferable? What are the material and manufacturing standards? 2. There are many factory gates and roads, as well as numerous points where overhead and underground installations meet; how should pump stations be located? 3. The sewage pipeline network consists of various smaller branches that converge into main pipes leading to the treatment plant; for this type of overhead installation, what are the technical considerations? 4. The location is in the north, where temperatures drop to below minus 30 degrees in winter; therefore, insulation and heat tracing are necessary. The owner particularly wants to use steam for heating. What is the best method for providing heat in this case? If electric heating is used, how should the transition points between overhead and buried installations be handled?
No matter what material the plastic pipe is made of, it will sag and age over time, and must be replaced regularly. Lined pipes can be used; they are available off-the-shelf or can be fabricated on-site, with low production costs. For the outer pipe, welded pipes or thin-walled pipes can be used, while a regular PP pipe suffices for the inner pipe. In this way, it’s fine to bury the pipeline or install it above ground; however, in areas with low temperatures, the above-ground section might freeze. Insulation or heating can be applied to the above-ground part, and insulation is a more reasonable and cost-effective option, requiring only a one-time investment. Because heat tracing also needs to maintain insulation.
Plastic lining inside steel pipes necessarily requires flange connections, but the owner disagrees, arguing that flange connections have too many potential leakage points. Is using a stainless steel tube suitable? Just insulation is definitely not enough; the temperature is too low. It’s necessary to use both insulation and heat tracing. With so many pipes that need to be converted from above-ground to underground in this kind of setup, does that mean many pump stations are required? I asked someone, and he said that a pump station has to be installed for every burial – that doesn’t seem very practical
The key is who’s paying. Using plastic pipes necessarily precludes heat tracing, as steam or electric heating will cause the plastic pipes to melt and perforate. Stainless steel pipes are certainly an option, but they should also have flange connections to minimize the number of joints as much as possible. As for pump stations, the designers can calculate how far apart pumps need to be installed, based on head, flow rate, and resistance.
This post was last edited by “Life Played a Joke” on July 22, 2015, at 16:29. The management committee paid for it. They told the property owners that the investment and operating costs were very high, but the owners didn’t care; they just wanted it to be carried out. Can heating the PE pipe by placing it between insulation layers also cause damage to the pipe? Why does stainless steel also need flanges? Can’t we use welding? Mainly, it comes down to our design: it’s easy to calculate for submersible pump stations. But there are many variations in overhead and submersible types – how do we calculate those?
It is possible to check the heat resistance specifications for various types of plastic pipes. It’s mainly the contact points. I’ve never seen heat tracing pipes in the middle of the insulation layer.
We would like to use stainless steel pipes, welded ones – is that possible?
Of course, it’s possible to avoid using flanges as much as possible and go straight for welding. Flanges are used for connection at special locations.
One more question: how should the heat tracing at the transition points between buried and above-ground installations be handled, and how should pump stations be designed and configured?
When using steam tracing, a trap is required to remove water vapor. It’s easier to handle the sections that are above ground level; a trap should be installed at regular intervals. Traps must also be installed where buried pipes emerge above the ground surface. As for installing pumps, considerations must also be given to preventing freezing. I’m not a professional designer, so I’m not quite sure how to calculate it exactly. I’m sorry.
You’ve already been of great help, thank you!