drilled into gas pipe

[ttt tiling]

I stick them in with tile adhesive , sorted

 

[steve-tiler]

I've used pinkgrip and it works well, easier and quicker than drilling holes.

 

[CJ]

I buy the type with a strong double sided sticky foam on the back.

 

[macten]

Stick em with rapid tile adhesive too when on concrete.
Rock solid in an hour or so.