A pipe mixer for an aftertreatment system is described for mixing of a reductant and exhaust gas. The pipe mixer comprises a hollow body having a first end and a second end, the body surrounding a mixing channel; an injector mount positioned at the first end of the body; perforations provided on the body for entry of exhaust flow into the mixing channel; directional elements positioned on the body for directing exhaust flow towards the injector mount, the directional elements being positioned between the first end and the perforations wherein each directional element comprises an inlet formed on the body for entry of exhaust flow and a guide provided on an internal surface of the body, the guide having an outlet for exit of exhaust flow.