I could walk around Amsterdam all day with a 6" cross section piece of tubular metal and nobody would bat so much as an eye. And I have multiple suitcases large enough to put a 1 meter segment of that pipe in (inches, meters...).

Even the larger:

https://en.wikipedia.org/wiki/Davy_Crockett_(nuclear_device)

would easily fit, and those suitcases even have wheels so it would not look all that heavy to someone not lugging it.