In this paper, we study typical ranks of 3-tensors and show that there are plural typical ranks for m\times n\times p tensors over R in the following cases: (1) 3\leq m\leq ρ(n) and (m-1)(n-1)+1\leq p\leq (m-1)n, where ρ is the Hurwitz-Radon function, (2) m=3, n\equiv 3\pmod 4 and p=2n-1, (3) m=4, n\equiv 2\pmod 4, n\geq 6 and p=3n-2, (4) m=6, n\equiv 4\pmod 8, n\geq 12 and p=5n-4. (5) m=10, n\equiv 24\pmod{32} and p=9n-8.