Abstract: A buckstay system is described comprising horizontal buckstays for the walls of a steam generator, for example in plural vertically space assemblies tied with vertical buckstays, in which a buckstay extends generally horizontally across each wall such as to form a connected pair with an adjacent buckstay at each corner; an elongate tie bar formation extends across each wall such as to form a fixedly mounted pair with an adjacent tie bar formation at each corner; an anchor assembly associated with each buckstay and providing engagement means by which each buckstay engages with a respective tie bar; and each horizontal buckstay is split to comprise at least two rigid elongate buckstay elements mounted together to be relatively slideable in a buckstay longitudinal direction.