INSULATION STRUCTURE, LEAK INSPECTION METHOD FOR INSULATION STRUCTURE, AND SHEATH HEATER

PROBLEM TO BE SOLVED: To provide an insulation structure capable of surely detecting a micro gap that may cause dielectric breakdown, during or after plant operation, a leak inspection method for the insulation structure and a sheath heater.SOLUTION: The insulation structure comprises: a metallic cylindrical sheath tube 11; a heater 12A that is an insulated body to be inserted into the sheath tube 11 in an electrical non-contact state; an insulation part 13 that is formed by filling a gap between the sheath tube 11 and the heater 12A with an insulation material (e.g., MgO or the like); a seal part 14 that is provided in the sheath tube 11 and seals a housing port of the heater 12A; a heater terminal 15 that is connected with an end portion of the heater 12A; a connector 16 which fixes the heater terminal 15 to an end portion of the sheath tube 11; a nozzle 18 with check valve that is provided in a connector 16 and is a gas introduction part for introducing a gas body 17 from the outside; and a gas guide path 19 for guiding the gas body 17 that is introduced from the nozzle 18 with check valve, into the sheath tube 11.SELECTED DRAWING: Figure 1 【課題】プラントの運転中又は運転後において、絶縁破壊の原因となる微小なすき間を確実に検出することができる絶縁構造体、絶縁構造体のリーク検査方法及びシーズヒータを提供する。【解決手段】金属製の筒状のシース管１１と、シース管１１内に電気的に非接触状態で挿入される被絶縁体であるヒータ１２Ａと、シース管１１とヒータ１２Ａとの間に絶縁材料（例えばＭｇＯ等）を充填してなる絶縁部１３と、シース管１１に設けられ、ヒータ１２Ａの収納口を封止する封止部１４と、ヒータ１２Ａの端部と接続されるヒータ端子１５と、ヒータ端子１５をシース管１１の端部に固定するコネクタ１６と、コネクタ１６に設けられ、外部からガス体１７を導入するガス導入部である逆止弁付ノズル１８と、逆止弁付ノズル１８から導入したガス体１７をシース管１１内部に導入するガス案内通路１９と、を具備する。【選択図】図１