1. A system for assembling an exhaust after-treatment assembly having a plurality of exhaust after-treatment blocks, each of the plurality of exhaust after-treatment blocks disposed adjacent to at least one other exhaust after-treatment block, and including one or more catalyst substrates, each of the catalyst substrates including a first face, a second face, and a plurality of side faces, the system comprising:at least one flange member configured to surround the one or more catalyst substrates in each of the plurality of exhaust after-treatment blocks, about the side faces; and
a locking arrangement comprising:
one or more clips on the at least one flange member and disposed in a plane parallel to at least one of the first face and the second face; and
a bracket member configured to engage with the one or more clips in the at least one flange member of each exhaust after-treatment block of the adjacent exhaust after-treatment blocks,
wherein the bracket member comprises a gasket attached to a back surface of the bracket member such that the gasket provides a seal joint when the bracket member is engaged with the one or more clips of the at least one flange member of each of the adjacent exhaust after-treatment blocks.