Issues regarding the use of 20 steel in GB8163 and GB3087
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Today, a construction company replaced 3087 material with 8163 in the straight sections of the square compensators installed in two D426*9 superheated steam pipes (with a design pressure of 1.3 Mpa and a design temperature of 300°C) during construction. I ordered them to remove it and redo the work. Each square compensator consists of 2 1.5DN elbows and 4 4DN bent elbows, totaling 10 welds. However, after checking the relevant standards again, I found that both materials meet the requirements. Am I wrong? The labor cost alone for installing these two compensators is nearly 5,000 yuan. I’m very confused and hope someone can help clarify this. If other sources are cited, please indicate their origin.
How are the design pressure of 1.3 Mpa and the design temperature of 300°C determined? Normally, the pressure shouldn’t be this high at this temperature, right? The saturated vapor pressure at 200 degrees is already 1.5 MPa; I’m not quite sure about this. Condition 8163 should be fine; 5310 can also be used, with material 20G.
Reply to 2# yguang: Sorry, the design pressure is 1.43 Mpa; it’s superheated steam
The 8163 pipes used in petrochemical plants are fine; I’m not sure about their use in other industries.
Hehe, no problem. For our ethylene process, the design pressure and operating pressure of the medium-pressure steam are 1.1 Mpa, with an operating temperature of 290 degrees; the design pressure is 1.61 Mpa and the design temperature is 300 degrees. We use 20 in this case#
There’s no problem using superheated steam at 300 degrees. But if the design calls for 3087, it’s not wrong to ask them to make the changes!
In the power generation industry, 8163 is rarely used for steam pipelines; steel pipes of type 3087 are more suitable for medium and low-pressure boilers. 8163 is generally used more often for water pipelines
In my opinion: 1. Since the materials used by the construction party are different from those specified in the design, it should be the supervisor who takes care of this issue; it’s not appropriate for the design team to directly point out their mistakes and demand changes from them. But small projects are another matter ； 2. From a design perspective, the requirements for material inspection in these two standards are too similar. In principle, they can all be used. 3. There are many issues that can arise on site; as the designer, it is sometimes necessary to take cost considerations into account (to save money for the client). Most construction companies still don’t want to keep making changes. If it can be confirmed that there are no problems, there’s no need to worry too much about trivial matters; this also helps to maintain good relations with the construction party, and such relations are quite important in a construction project. This is just my personal opinion; please feel free to criticize and point out any shortcomings!
These two are pretty much the same; low voltage can basically serve as a substitute
GB3087-2008 (Seamless Steel Tubes for Low and Medium Pressure Boilers) refers to hot-rolled and cold-drawn (rolled) seamless steel tubes made of high-quality carbon structural steel, which are used for manufacturing superheater steam tubes, feedwater tubes in various low and medium pressure boilers, as well as superheater steam tubes and arch brick tubes in locomotive boilers. The representative materials are 10# and 20# steel. In terms of material, 3087 is better than 8163. The original poster’s decision was correct.