How to clip a piton

When clipping a piton, try to flip the carabiner so the spine is against the rock. The gate opening can be down (center) or up (right). Doing this aligns force along the spine of the carabiner, the strongest orientation.

If you clip with the carabiner gate facing the piton hole, the carabiner can be sometimes levered in strange ways, and could potentially even break under a heavy load. In the photo on the left, we can see this happening a bit. Depending on the style of carabiner and piton placement, this can be more or less pronounced.

And, if you find that the carabiner is being loaded in a way that you don't like no matter what you try, you can thread a sling or cordelette directly through the piton hole. Of course, avoid doing this if the piton hole is chewed up, as it might damage your sling.

Below are two examples from the German Mountain and Ski Guides Association (“Verband Deutscher Berg und Skiführer” or “VDBS”).

You can see more interesting VDBS approved anchors at this article.