A good method to seal a baseboard to stop an existing draft

If your leaking problem is from loose fitting window sashes or a poor fitting door, the simplest and cheapest method would be to purchase some self-adhesive foam weather stripping. This rolled product can be easily installed at the bottom of a window or around the outside edge of the door frame. Select the smallest size that will help seal the gaps, then just peel and stick. Too large and you may have difficulty closing the door etc.

Another good window treatment is the clear plastic window film like the 3M Indoor Window Insulator that mounts to the frame of the window. Use a hair dryer to "stretch" the film, thus sealing any air leaking in around the sides or through poorly glazed panes.

All these products are cheap and available at any hardware store or box store like Lowe's or Home Depot. Stay warm!

I would personally use Loctite PL Polyurethane Concrete Crack & Masonry Sealant, which will adhere well but still provide a degree of flexibility as your pipe moves within the brick. It's grey, but you can also mix in a little concrete dust or dirt to give it that "I'm not shiny caulk, honest!" look.

The PL product should be available at your local home improvement stores. (Homer's or Lowe's or Ace or whomever.)