Issues with gaskets for fasteners on container flanges in U-tube heat exchangers?
Thread Content
After reviewing NB_T 47020～47027-2012 on pressure vessel flanges, gaskets, and fasteners, it seems that for vessel flange fasteners, studs and nuts are sufficient. But it was also found that many of the container flanges for the low-temperature heaters in our company previously used soft aluminum washers made of 8A06 material. Does anyone know what the reason for this was? Or which standard should be consulted regarding this issue?
Using fastener washers is a practice adopted by the manufacturer itself, and it is not a requirement specified by standards. In fact, washers are rarely used for static equipment. Once, for a device we built for foreigners, the design did not include washers; the workshop kindly added flat washers and spring washers, but the foreigners were not grateful and demanded that they be removed.
The poster should just follow the standards – not all nuts require washers. As required by standards.
I happened to encounter such a problem these past two days. After checking some information, the prevailing opinion is that it’s better not to use washers, as washers are relatively soft and can make it difficult to tighten things properly ； The spring pad is even more useless, as it softens quickly under impact loads and temperature effects. However, in the case of stainless steel flanges paired with high-strength nuts such as 30CrMo, it is probably better to use hardened flat washers.
Thank you all for your replies. Indeed, in design, one encounters many specific issues for which no standards can be found; it’s probably due to a lack of experience: lol
There are only two situations involving washers that I encounter in design: one is the connection between the frame of mixing equipment and its flanges, and the other is the swivel bolt structure used in quick-release equipment. I haven’t encountered any others.
The standard does not require the use of washers......
With more Shanghai Chuan, many long-standing problems have been resolved.