Can Q235B be used at 0 degrees and 5 degrees? At atmospheric pressure, with water as the medium
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Can Q235B be used at 0 degrees and 5 degrees? At normal pressure, with water as the medium, GB150 specifies that Q235B can be used at temperatures ranging from 20 to 300 degrees. Does this mean that Q235B cannot be used at 0 degrees or 5 degrees?
It can be used; many low-temperature industrial applications are already using it
The specification states that the operating temperature range for Q235B is 20–300 degrees; so, is it not in compliance with the specifications when it is used at 0 degrees? Is there any **basis for it?
Atmospheric pressure equipment can be used just fine for holding non-toxic, non-explosive, non-corrosive substances that are not subject to regulatory controls, such as water; it is widely used in practice. Experts who insist on seeking standards are nothing but pedants.
\"Code for Design of Steam and Water Piping in Thermal Power Plants\" DL/T5054-2016: This code recommends that the operating temperature range for Q235B material be 0℃ to 300℃. **Standard \"Low-alloy high-strength steel\" GB/T 1591-2018: The operating temperature range for Q235B material is 0°C to 350°C.
GB150 specifies 20-300 degrees, so which standard should be followed in this case?
The temperature range of 20 degrees to 300 degrees mentioned in GB150 refers primarily to the design temperature for Q235B material used in pressure vessels. If your application environment involves pressure vessels, then you should follow the GB150 standard. For temperatures below 20 degrees, although GB150 does not explicitly cover 0 degrees and 5 degrees, in practice the suitability of the material at such temperatures can be determined by conducting low-temperature impact tests and other relevant performance evaluations. If the test results meet the safety and performance requirements, it can be used in theory, but it is necessary to ensure that the corresponding verification and approval processes have been completed. In summary: - When designing pressure vessels, it is preferable to follow the provisions of GB150. - When used at special temperatures (such as 0 degrees and 5 degrees), additional material performance tests and risk assessments are required to ensure compliance with safety standards. - Sometimes it may also be necessary to refer to or obtain approval from regulatory authorities or third-party certification bodies. .
The specifications are too unrealistic – the minimum temperature is set at 0 degrees, and it’s completely normal for the temperature to drop below 0 degrees in winter. Experts with their own agendas keep insisting on this, preventing the industry from moving forward
In fact, it’s no problem to use 235B for such non-pressure-bearing grooves. I’ve worked with ammonia-based refrigeration systems before; in those systems, the evaporator was mounted in a brine tank. The lowest temperature of the chilled water was -5°C, and the brine tank was made of ordinary carbon steel plates. It’s worked fine for over twenty years; if the bottom plate leaks, it’s just a matter of repairing and welding it. The insulation layer does require attention; the valves are covered with iron sheeting and filled with expanded polyurethane, which provides both insulation and moisture resistance. Salt water tanks are often lined with polystyrene foam boards, resulting in poorer moisture resistance. Polystyrene pipe shells are selected for pipes based on their outer diameter; they are inexpensive and easy to install. There are also those made of glass wool and rock wool, which have good fire-resistant properties; the downside is that they are sensitive to moisture.