Selection of piping materials
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Using 20# steel to transport deionized water at 0.8 MPa and 80°C results in a large amount of scale formation, while using 304 stainless steel is somewhat wasteful. Does anyone have any good materials that can be used for transporting warm water at 0.8 MPa and 80°C?
Reply to 1# feibiao101: You can try using a plastic tube
Ordinary plastic pipes cannot withstand temperatures of 80 degrees. If the diameter is small, PPR or PB pipes could be considered, but I suspect there will be issues with pressure resistance, given that the pressure involved is 8 kilograms. Steel-reinforced plastic composite pipes can be considered; they are resistant to pressure and corrosion, and have no issues with temperature as well.
There is nothing wrong with the plastic pipes themselves; in many cases, they are glued together, and leaks occur when exposed to heat. Where is ionized water used? It’s still under pressure; if possible, divide the water into two parts – one under pressure and one not – and then choose the materials accordingly
Use PPR pipes, as they are resistant to high temperatures and pressure; they’re just a bit more expensive
This post was last edited by nglcx2003cn on 2011-7-3 17:08. What is your deionized water used for? Isn’t it better to use stainless steel pipes? It is indeed possible to use plastic composite pipes with a steel framework on the upper floor, but the price is likely not much lower. It would be better to use carbon steel pipes and then coat them with something like PO (although coating them with PTFE is expensive). Nevertheless, it can be said that the cost of such coatings, along with the costs of manufacturing and installation, is probably similar to that of stainless steel pipes. If you really want to save money, I have another good idea for you: you can use transparent plastic hoses for the piping, secure them with steel pipes on the outside, and create flange surfaces by using gas cutting to form flanges.
It is best not to use 20# steel for hot water, as scaling occurs severely. Plastic pipes and composite steel pipes are also not recommended, as they are difficult to weld and prone to leaks. Taking everything into account, stainless steel, which requires a large initial investment but is easy to install and durable, is the best choice.
Reply to 4# buerkuaile: Steel-reinforced plastic composite pipes are not bonded together, but rather welded using electrothermal fusion; thus the joints are extremely reliable, so please rest assured. As mentioned below, the price of steel-reinforced plastic composite pipes is likely to be high. Indeed, their production cost is higher than that of ordinary carbon steel pipes, but it is lower than that of pipes with plastic lining; moreover, they are very convenient to use, as the pipes can be cut on-site as needed.
Actually, I’m quite interested in the uses of water at 8 kilograms and 80°C. All materials are chosen based on their intended use; if the process requirements dictate it, 304 tubes are the best choice. If the process requirements are not high, 20# will suffice. 8 kilograms and 80°C are enough to render many materials unusable.
If the resistivity of deionized water is particularly high, it is advisable to use CPVC.
I suggest 304 is better – it’s an investment that will yield benefits for life. Water at 80 degrees Celsius causes severe scaling and rapid corrosion. PP pipes can also be used; the conditions mentioned by the original poster are fine. GB4217-2008 is worth considering as well.