(*Let's say this is your list*)
list = {{2, 15, 22}, {4, 13, 27}, {3, 17, 29}, {5, 18, 29}, {3, 11, 25}, {2, 17, 11}, {2, 24, 13}};
In[2]:= Flatten[
Cases[list, {a_, b_, c_} :>
If[b < c, Table[{b, c}, {a}], Table[{c, b}, {a}]]], 1]
Out[2]= {{15, 22}, {15, 22}, {13, 27}, {13, 27}, {13, 27}, {13, 27}, {17,
29}, {17, 29}, {17, 29}, {18, 29}, {18, 29}, {18, 29}, {18,
29}, {18, 29}, {11, 25}, {11, 25}, {11, 25}, {11, 17}, {11,
17}, {13, 24}, {13, 24}}
Or you can also write:
In[3]:= Flatten[Cases[list, {a_, b_, c_} :> Table[{b, c}, {a}]],
1] /. {x_, y_} /; x > y -> {y, x}
Out[3]= {{15, 22}, {15, 22}, {13, 27}, {13, 27}, {13, 27}, {13,
27}, {17, 29}, {17, 29}, {17, 29}, {18, 29}, {18, 29}, {18,
29}, {18, 29}, {18, 29}, {11, 25}, {11, 25}, {11, 25}, {11,
17}, {11, 17}, {13, 24}, {13, 24}}