The purpose of IEC 63132-4:2020 is to establish, in a general way, suitable procedures and tolerances for the installation of a vertical Kaplan or propeller turbine. This document presents a typical assembly and whenever the word "turbine" is used in this document, it refers to a vertical Kaplan or propeller turbine. There are many possible ways to assemble a unit. The size of the machine, design of the machine, layout of the powerhouse or delivery schedule of the components are some of the elements that could result in additional steps, the elimination of some steps and/or assembly sequences. It is understood that a publication of this type will be binding only if, and to the extent that, both contracting parties have agreed upon it. This document excludes matters of purely commercial interest, except those inextricably bound up with the conduct of installation. The tolerances in this document have been established upon best practices and experience, although it is recognized that other standards specify different tolerances. Wherever this document specifies that documents, drawings or information is supplied by a manufacturer (or by manufacturers), each individual manufacturer will furnish the appropriate information for their own supply only.