A shell-and-tube stripper for carbamate decomposition and ammonia recovery from a urea solution comprises a bundle of heated tubes. The tubes are fed with the urea solution and carbon dioxide as a stripping medium, with the urea solutions forming a liquid falling film on the internal surface of the tubes and the carbon dioxide forming a counter-current gaseous flow. The tubes comprise an externallayer made of super austenitic or super duplex stainless steel and an internal layer made of zirconium, the internal layer reaching temperatures higher than 220 DEG C.