If they find the pipes on you, you'll probably be asked what it is, so tell them it's an incense burner or something (calling it a pipe would be ok if you were 18, but since you're under 18 they might confiscate it as tobacco paraphanelia posessed by a minor or some bs like that). That's your best bet.

And like everyone said, DON'T smoke out of it before you go through customs, because if it has weed resin in it you'll be busted.