Several questions regarding materials on the heat exchanger drawings——Seeking help from beginners
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1. In the material list for the heat exchanger assembly diagram, there are 20MnMoⅢ wire loops and 16MnⅢ reinforcement tubes. What does the ‘Ⅲ’ after 16Mn and 20Mn mean? 2. What does 3 mean in the nut M42X3? 3. Double-ended stud M24X250-B – what does B stand for? I’m just starting to work with these things and don’t understand anything. I sincerely ask for anyone’s help; thank you! ! ! !
Ⅲ probably means a grade 3 forging; I’m not sure what that 3 refers to. B should be a type B stud, right? I’m not sure if what I said is correct. This post was last edited by bin*an on 2009-2-16 at 16:51.]
For items 2 and 3, you can find the answer by looking up the standards directly
1. Ⅲ represents grade III forgings； 2. 3 indicates a regular fine-thread with a pitch of 3 mm ； 3. B refers to the Type B studs specified in JB/T4707-2000 \"Equal-length double-ended studs\".
I’ve also learned it; I’ll leave a note for easy reference later；
1. Ⅲ represents grade III forgings； 2. 3 indicates a regular fine-thread with a pitch of 3 mm ； 3. B refers to the Type B studs specified in JB/T4707-2000 \"Equal-length double-ended studs\".