A seal for sealing a gap in a combustion apparatus of a gas turbine between a first side and an opposite second side. The seal includes a steel strap with a flat shape and a first metal web with a flat shape attached to the steel strap on the first side and a second metal web attached to the steel strap on the second side. Thereby the seal has a seal thickness with at least the steel strap plus the first metal web plus the thickness of the second metal web, wherein the seal thickness is at most 0.2-times of width of the seal. The new seal has an Omega shape of the second metal web, which is therefore attached on both sides with a flat shaped portion to the steel strap.