Abstract: The invention relates to enclosures (1) for gas-insulated medium-voltage or high voltage apparatuses. A connection portion (4) between a first end (20) of the first enclosure tube (2) and a mating machined second end (30) of the second enclosure tube (3) has a gas-escape path (L) running from the inside (6) to the outside (7) of the enclosure tubes (2, 3). According to the invention, the gas-escape path (L1) is shaped to have a first segment (L1) running along an at least partially axial direction of the enclosure (1) and being equipped with least one sealing ring (5; 5a, 5b). In addition, a slim ring-like snap-on bracket (9) can be used. The direct machining of the mating enclosure ends (20, 30) allows to omit conventional flanges. The partially axial orientation of the gas-escape path (L) allows to provide plural sealing rings (5; 5a, 5b) in series in the gas-escape path (L).

Abstract: The invention relates to a modular and compact arrangement (200) of three phases (A, B, C) of a gas-insulated apparatus (100), that is suitable for placement inside a tunnel or a pipe (106) or another confined space. According to the invention, the three phases (A, B, C) are arranged in a triangle or side-by-side on a fixation part (103, 104) which includes a roller system (105; 105a, 105b, 105c, 105d). This allows the insertion of such a three-phase assembly (100) into confined spaces such as pipes or tunnels (106), without the need for access by workers or machinery. Furthermore, the present disclosure relates to a method for assembling and installing such a three-phase arrangement (100) into the confined space (106).