A ready-to-install kit for constructing equipment for carrying out maintenance and/or inspection operations inside a tank having an upper wall provided with an opening, said kit comprising: - a set of elements intended to form a support column of an articulated arm, said set comprising: - at least one extension element (8a, 8b, 8c) having a first end provided with a first attachment member and a second end provided with a second attachment member, - a first column end element carrying said articulated arm, said first column end element having an end provided with an attachment member capable of interacting with the first attachment member of an extension element (8a, 8b, 8c) in order to fix the first column end element to an extension element (8a, 8b, 8c); - a second column end element having a first end provided with an attachment member capable of interacting with the second attachment member of an extension element (8a, 8b, 8c) in order to fix the second column end element to an extension element (8a, 8b, 8c) and a second end carrying a fastening flange arranged to fasten the column to the periphery of the opening; and - an installation assistance flange, comprising securing members intended to interact with the periphery of the opening in the tank, said installation assistance flange being equipped with a first temporary fastening member (13a, 13b), wherein the extension element (8a, 8b, 8c) and the first column end element are each fitted with a second temporary fastening member capable of interacting with the first temporary fastening member (13a, 13b) of the installation assistance flange so as to provide a temporary fastening of the first column end element and of the extension element (8a, 8b, 8c) to the installation assistance flange, during the installation of the ready-to-install kit. - a set of elements intended to form a support column of an articulated arm, said set comprising: - at least one extension element (8a, 8b, 8c) having a first end provided with a first attachment member and a second end provided with a second attachment member, - a first column end element carrying said articulated arm, said first column end element having an end provided with an attachment member capable of interacting with the first attachment member of an extension element (8a, 8b, 8c) in order to fix the first column end element to an extension element (8a, 8b, 8c); - a second column end element having a first end provided with an attachment member capable of interacting with the second attachment member of an extension element (8a, 8b, 8c) in order to fix the second column end element to an extension element (8a, 8b, 8c) and a second end carrying a fastening flange arranged to fasten the column to the periphery of the opening; and - at least one extension element (8a, 8b, 8c) having a first end provided with a first attachment member and a second end provided with a second attachment member, - a first column end element carrying said articulated arm, said first column end element having an end provided with an attachment member capable of interacting with the first attachment member of an extension element (8a, 8b, 8c) in order to fix the first column end element to an extension element (8a, 8b, 8c); - a second column end element having a first end provided with an attachment member capable of interacting with the second attachment member of an extension element (8a, 8b, 8c) in order to fix the second column end element to an extension element (8a, 8b, 8c) and a second end carrying a fastening flange arranged to fasten the column to the periphery of the opening; and - an installation assistance flange, comprising securing members intended to interact with the periphery of the opening in the tank, said installation assistance flange being equipped with a first temporary fastening member (13a, 13b),