I need to hold/lock two flanges together in such a way that I can lock the mechanism preventing someone else from separating the flanges (with some form of a key).

I realize this isn't specifically a car maintenance question, but I figure this audience would be the best suited to pointing me in the right direction.

Unfortunately there are no holes in the flanges and I can not add any.

I suspect a tool or clamp must exist that would meet these needs but I can't seem to find anything, or more likely don't know what key words to use when searching.

Can anyone suggest tools or how to find such a device?

  • 2
    Probably need more details or a picture of exactly what you need, but probably you will have to have something fabricated or custom welded .
    – john D.
    Jun 29, 2016 at 1:26
  • Assuming the device is for anti-tamper only and not meant to be any part of the flange connecting assembly, look for "lock-out tag-out" devices for blind flanges. They are like a clam shell and use a keyed lock or padlock. Jun 29, 2016 at 5:29
  • @JimmyFix-it Thanks for the suggestion. I looked into that and although it is a great idea for anti-tamper, I'm looking more for something that will actually prevent someone from separating the two flanges, rather than just knowing that they were separated. If I could find something a c-clamp vice grip that I could lock in the closed position, that would be the right concept. Unfortunately, I can't lock the vise grips closed. Even something like a c-clamp, if I could drill a hole through the threads and put a padlock in there, it would work, but I'm not sure if it would still be solid.
    – Eric B.
    Jun 29, 2016 at 17:27
  • Do you need to be able to separate the flanges later? If not, what about riveting or welding?
    – Dan A.
    Jun 29, 2016 at 20:52
  • How large are the flanges? how tamper-proof does it have to be, like just inconvenient deterrent or robustly secure? Jun 30, 2016 at 3:37

1 Answer 1


If the application allows, you could use something like a V band clamp with an anti tamper nut. Although it wouldn't 'lock', using a fastener with an obscure head would essentially require a 'key'.

There are also V band clamps that use a male fastener, which would give you even more options for fasteners that require obscure tools to remove.

  • Thanks! Turns out that led me to exactly what I needed to get the job done.
    – Eric B.
    Jul 4, 2016 at 13:53

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