The Tritium Laboratory Karlsruhe (TLK) was commissioned with tritium in 1994 and since then has continuously improved its infrastructure and has expanded its experimental activities. With a fully closed tritium cycle and the license to handle 40 g of tritium TLK is an almost unique experimental facility. More than 10 glove box systems with a total volume of about 125 m3 are operated to house experiments and infrastructure facilities on an area of more than 1000 m2. Today TLK has about 23 g of tritium on site. The paper describes the closed tritium loop of the TLK infrastructure and its links to different experiments. Some experience gained during operation of TLK is also presented.