A method for revamping a melamine purification section of a high pressure melamine plant comprising: a quencher fed with a first melamine-containing stream, which is a raw melamine melt, from the synthesis section and an aqueous solution comprising ammonia and carbon dioxide, wherein melamine is dissolved and off-gas are extracted; a stripper fed with a second melamine-containing stream from said quencher and with a stripping medium, wherein purified melamine is obtained and vapours are extracted, said vapours being added with a stream of water once extracted from the stripper; a first heat exchanger, wherein the vapours added with said stream of water are at least partially condensed by heat exchange with an aqueous solution comprising ammonia and carbon dioxide, providing a condensed stream; an absorber fed with said condensed stream and a carbonate solution and providing an aqueous solution comprising ammonia and carbon dioxide, which is at least partially used for condensing the vapours in said first heat exchanger, heated in a second heat-exchanger and recycled to the quencher, said method being characterized by installation of a line for at least partially feeding a stream of water, possibly added with ammonia, to the first heat exchanger for condensing said vapours; installation of a line for at least partially sending the water leaving said heat exchanger to the quencher; installation of a line for at least partially exporting the aqueous solution provided by said absorber from the purification section of the plant; discontinuing the line for feeding said aqueous solution to the first heat exchanger, for subsequent feeding to the second-exchanger and recycle to the quencher; discontinuing the line for adding said stream of water to the vapours extracted from the stripper; discontinuing the line for introducing the carbonate solution into the absorber. a quencher fed with a first melamine-containing stream, which is a raw melamine melt, from the synthesis section and an aqueous solution comprising ammonia and carbon dioxide, wherein melamine is dissolved and off-gas are extracted; a stripper fed with a second melamine-containing stream from said quencher and with a stripping medium, wherein purified melamine is obtained and vapours are extracted, said vapours being added with a stream of water once extracted from the stripper; a first heat exchanger, wherein the vapours added with said stream of water are at least partially condensed by heat exchange with an aqueous solution comprising ammonia and carbon dioxide, providing a condensed stream; an absorber fed with said condensed stream and a carbonate solution and providing an aqueous solution comprising ammonia and carbon dioxide, which is at least partially used for condensing the vapours in said first heat exchanger, heated in a second heat-exchanger and recycled to the quencher, said method being characterized by installation of a line for at least partially feeding a stream of water, possibly added with ammonia, to the first heat exchanger for condensing said vapours; installation of a line for at least partially sending the water leaving said heat exchanger to the quencher; installation of a line for at least partially exporting the aqueous solution provided by said absorber from the purification section of the plant; discontinuing the line for feeding said aqueous solution to the first heat exchanger, for subsequent feeding to the second-exchanger and recycle to the quencher; discontinuing the line for adding said stream of water to the vapours extracted from the stripper; discontinuing the line for introducing the carbonate solution into the absorber.