Low-temperature impact issues in low-temperature equipment
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Recently, I was working on a low-temperature device with an operating temperature of -40°C; the customer also specified -40°C as the design temperature. For safety reasons, I set the temperature for the low-temperature impact test at -55°C (the material used is 09MnNiDR). As a result, my supervisor asked me why I didn’t conduct the low-temperature impact test at the design temperature I explained to my supervisor that, in theory, the design temperature should be 0–10 degrees lower than the operating temperature; however, the value used here is the same as that, with no safety margin. So I made some adjustments to the requirements for the raw materials. Every time I worked on low-temperature equipment, my supervisor criticized me, saying that I was setting too high standards, which annoyed me. I’ll just follow the supervisor’s decisions – it’s my signature on the documents, and I’m the one who will take responsibility ； Don’t carry it out; just wait for the day when you have to leave. This whole situation... Let’s discuss what temperature level is reasonable for a cryogenic shock
Why -55 and not -45, -48?
Any of the temperatures you mentioned will work fine; it’s not a matter of having to reach a specific temperature. What I mean is that a safety margin should be maintained. If I follow my supervisor’s advice, I can use 16MnDR as the material, but is it good to use a material that has to operate continuously at its temperature limit? Just like gaskets, it will fail over time if used in this manner
That makes sense:lol:lol
How did the operating temperature become the same as the design temperature? It seems that the designed temperature should be -55.
-50 should be enough; of course, using -55 will also work just fine.
If the design temperature on the drawing is -40°C, then your supervisor is correct. But, \"operating temperature -40, and the customer also specified -40 for the design temperature\" – there should be a problem with that. According to the regulatory requirements, the client who commissions the design should provide operating parameters rather than design parameters; the design parameters shall be determined by the designer. Customers may not be very familiar with the regulations regarding tolerance limits, and the designer should point this out when signing the contract or agreement. It is possible that the customer has already included a margin for operating temperature, so the design temperature was set to be the same as the operating temperature.
For low-temperature impact testing, the design temperature can be used; of course, it is also possible to set a higher requirement. The 09MnNiDR material should have no problem with low-temperature impact at -55 degrees Celsius
This post was last edited by sztlc on 2015-11-25 08:51. I have a question: for low-temperature equipment in Xinjiang, should 16MnDR or 09MnNiDR be used? One of our devices has manway sections made from 16MnDR; it is used in Xinjiang and has been in use for over half a year. Cracks appeared near the longitudinal seams of those manway sections. The material itself was found to be fine, so I’m not sure what caused the issue. I think the stress has not been completely eliminated, but we carried out stress-relief heat treatment before leaving the factory. My analysis is that either the manhole spool cannot be made using the rolled type (480*14), or the material should be 09MnNiDR.
Could you tell me the specific operating temperature, pressure, medium, and purpose of the equipment? Xinjiang is very large, so the environmental temperatures vary from place to place there.