JP2004347045A

JP2004347045A - Expansion joint for stainless steel tube

Info

Publication number: JP2004347045A
Application number: JP2003145744A
Authority: JP
Inventors: Susumu Hotta; 侑堀田; Katsuyoshi Omura; 勝良大村; Shigeyuki Matsumoto; 茂行松元
Original assignee: NOORA ENGINEERING KK
Current assignee: NOORA ENGINEERING KK
Priority date: 2003-05-23
Filing date: 2003-05-23
Publication date: 2004-12-09

Abstract

<P>PROBLEM TO BE SOLVED: To provide an expansion joint for a stainless steel tube capable of preventing a clearance specific to the stainless steel tube from occurring by absorbing, at a joint portion, the extension/retraction of the tube by heating and earthquake. <P>SOLUTION: A large diameter socket is directly formed at one front end part of the stainless steel tube by elastic processing and a tilted flange part is formed at the tube end part of the socket side steel tube to keep airtightness by tightening the tilted flange part of the socket steel tube together with a wedge type packing in the radial inner side by a retaining fitting. The dimensional ratio of the depth length of the socket side steel tube from the tube end to the liquid contact face of the packing to the dimension of the clearance between the outer diameter of the socket side steel tube and the inner diameter of the socket side steel tube is maintained at less than 100 which does not cause crevice corrosion specific to stainless steel. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、継手部分で熱や地震による管の伸縮を吸収でき且つステンレス鋼特有のすき間腐食が起こらないステンレス鋼管用の伸縮管継手に関する。
【０００２】
【従来の技術】
ステンレス鋼管は、鉄管やアルミ管に比べて耐食性および機械強度に優れているので、今日では、プラント配管、建築設備の給水管、給湯管、空調配管および水道用小径配管などの分野で多用されている。また、最近では生活環境の悪化に伴って敷設済みの配管が短期間で腐食しやすく、このために建築設備の排水鋳鉄管や水道用ダクタイル鋳鉄管に代わって、これらの分野にもステンレス鋼管のニーズが発生している。
【０００３】前記のような新分野で使用される配管継手には、継手部分で熱や地震による管の伸縮を吸収できることが必要であり、さらに作業性を高めるために、排水鋳鉄管や水道用ダクタイル鋳鉄管のように、流体が上流から下流に向かう方向や圧送の流れ方向に向かって一方の管端部を受け口に差し込んで接続する構造の継手が求められている。このため、従来のステンレス鋼管接続で用いられていたねじ継手、工事現場において特殊工具でプレスや拡管によって接続するメカニカル式継手、公知のフランジ式継手などを前記の分野に転用することはできない。
【０００４】例えば、一方の管端部を受け口に差し込んで接続する構造の継手をステンレス鋼で製造すると、ステンレス鋼特有のすき間腐食を起こして漏水事故が発生することが懸念されるため、現在まで具現化していない。排水鋳鉄管のように、ステンレス鋼製の継手を鋳造によって製造すると、肉厚になって素材コストがかなり高くなり、しかも従来の鋳鉄品と同様に重くなって、運搬および作業効率が低下してしまう。
【０００５】
【発明が解決しようとする課題】
薄肉のステンレス鋼管であっても、排水鋳鉄管や水道用ダクタイル鋳鉄管のように、一方の管端部を受け口に差し込んで接続する構造の継手を製造し、この際にステンレス鋼特有のすき間腐食を起こさない態様にすることが絶対に必要である。また、従来の鋳鉄品と同等の性能を有する管継手を、薄肉のステンレス鋼管の管端を利用して塑性加工によって直接成形できると、製造および運搬コストならびに作業効率の点で非常に望ましい。
【０００６】本発明は、ステンレス鋼特有の問題および鋳鉄製の継手に関する前記の問題点を改善するために提案されたものであり、薄肉のステンレス鋼管であっても、ステンレス鋼特有のすき間腐食を起こさない伸縮管継手を提供することを目的としている。本発明の他の目的は、従来の鋳鉄品と同等の性能を有する管継手を薄肉のステンレス鋼管から直接成形できる伸縮管継手を提供することである。
【０００７】
【課題を解決するための手段】
ステンレス鋼管に関する最近の研究成果によると、ステンレス鋼はすき間が生じれば必ず腐食するわけではなく、この腐食には、すき間の間隔と奥行き深さに関係することが判明してきた。つまり、ステンレス鋼管について、管継手の実用上のすき間の範囲においては、奥行き深さがすき間の間隔の１００倍を超えると急に腐食が発生しやすくなり、１００倍未満であると、腐食が殆ど発生しないことが実験で証明されている。
【０００８】したがって、本発明に係る伸縮管継手では、すべての管サイズの継手に関して、差し込み側鋼管の管端からパッキンの接液面までの奥行き長さと、差し込み側鋼管の外径と受け口側鋼管の内径とのすき間距離との寸法比率を、ステンレス鋼特有のすき間腐食を起こさない１００倍未満の関係を維持させる。本発明は、リング状のパッキンを用いて薄肉のステンレス鋼管を密に接続する管継手であり、該管継手は、排水鋳鉄管や水道用ダクタイル鋳鉄管と同等の性能を有している。
【０００９】本発明に係るステンレス鋼管用の伸縮管継手は、ステンレス鋼管の一方の前端部に塑性加工によって大径の受け口を直接成形する。受け口側鋼管の管端部に傾斜フランジ部を形成することにより、押さえ金具によって受け口鋼管の傾斜フランジ部をくさび形パッキンとともに半径方向内方へ締め付けて気密性を保っている。受け口側鋼管の内周面に関して、パッキン位置よりも後方で傾斜フランジ部の近傍に、環状溝または並行の環状突条を設けて止め金具のスナップリングを保持すると好ましい。また、好ましくは、受け口側と反対側の差し込み側鋼管に関して、管端の近傍に抜け止め用の環状凸部を設けることにより、差し込み側鋼管が抜け始めて後退すると、該環状凸部がシール用パッキンまたは止め金具の側面に接触して停止させる。
【００１０】本発明の他の構成について、ステンレス鋼管用の伸縮管継手は、受け口側鋼管の後方内周面に環状溝または並行の環状突条を設けてパッキンを保持してもよい。この場合、受け口側と反対側の差し込み側鋼管に関してパッキン位置よりも後方に抜け止め用の環状凸部を設け、この環状凸部と係合する止め金具を受け口側鋼管の管端部に取り付ける。本発明のさらに別の構成について、ステンレス鋼管用の伸縮管継手は、受け口側と反対側の差し込み側鋼管の外周面に並行の環状突条または環状溝を設けてパッキンを保持してもよい。この場合、差し込み側鋼管に関して後方の環状凸部またはパッキンと係合する止め金具を受け口側鋼管の管端部に取り付ける。
【００１１】前記の止め金具は、受け口側鋼管の管端にフランジ部を形成した際に１対のルーズフランジまたは半円筒形の半割り体であると好ましい。受け口側鋼管の管端部に環状溝または並行の環状突条を設けた場合には、この個所でスナップリングを保持させてもよい。また、この管端部に雄ねじ山を刻設したならば止めナットも使用可能である。
【００１２】
【発明の実施の形態】
本発明に係る伸縮管継手１において、受け口鋼管２の傾斜フランジ部７は、塑性加工によって大径の受け口５を直接成形する際に同時に形成できる。フランジ部７の傾斜角度は、図１に示すような約３０度が一般的であるけれども、３０度から増減させることも可能である。伸縮管継手１では、主たる使用部品がパッキン８であり、残りの部品は、押さえ金具である１対のルーズフランジ１０，１１（図１〜図３）や締め付けバンド２６（図６）などにすぎず、全体的なコストが低くて経済的である。
【００１３】本発明で用いるパッキンは、例えば、硬質ゴム、皮、フェルト、プラスチック製であり、銅，鉛，軟鋼のような金属パッキンであってもよい。矩形断面のパッキン８（図１）は、傾斜フランジ部７と対応する面取り９を有し、該面取りがあるのでくさび形になり、前記の押さえ金具によって半径方向内方へ締め付けて気密性を保つことができる。
【００１４】本発明で用いるパッキンは、一方の側端面に三角形状の切り込み６０を設けたパッキン５８（図７）でもよい。パッキン５８は、切り込み６０によって上下方向に圧縮させやすく、図７に示すように、鋼管３６と受け口６９との間に挟み込むことが可能である。また、流体圧の上昇によって、シール面に押し付けられる力が強くなり、密封力を増す効果もある。パッキン５８が他方の内端縁に面取り６２を有することにより、鋼管３６の差し込みが可能となる。
【００１５】伸縮管継手１において、抜け止め部として環状凸部１８（図２）を形成する。この環状凸部の代わりに、環状リング２１（図４）を溶接したり、前端部２３（図５）をテーパ状に拡げてもよい。環状凸部１８は、円周方向に直線状、間欠的または部分的に形成すればよい。この環状凸部は、差し込み側鋼管の外周面と密接するパッキン８の側面と接触するならば比較的低くてよい。一方、スナップリング４２（図３）または６６（図７）と接触しうる場合には、該スナップリングの内径に合わせて比較的高くすることを要する。止め金具が１対のルーズフランジ７５，７６（図９）や半割り体９４（図１０）であれば、環状凸部の高さは任意に設定できる。
【００１６】図３に示す実施例では、スナップリング４２を環状溝４０に嵌めて固定しているが、該環状溝の代わりに並行の低い環状突条を設けてもよいことは明らかである。これは、図７に示すパッキン５８またはスナップリング６６でも同様である。図９に示すパッキン９０では、並行の環状凸部８６，８８の代わりに環状溝を設けてもよい。
【００１７】前記の止め金具は、受け口側鋼管の管端にフランジ部７４を形成する場合には、１対のルーズフランジ７５，７６や半円筒形の半割り体９４であると好ましく、またはドーナツ板（図示しない）を直接フランジ部７４または受け口９２に溶接したり、ボルト止めしてもよい。受け口側鋼管の管端部に環状溝６４（図７）または並行の環状突条を設けると、この個所でスナップリング６４を保持できる。図示しないけれども、この管端部に雄ねじ山を刻設したならば、止めナットも使用可能である。
【００１８】伸縮管継手１は、建築設備や食品工場などの排水管、建築設備の配管全般、水道用配水管などに使用される比較的口径の大きいステンレス鋼管の接続に用いると好ましい。伸縮管継手１は、薄肉のステンレス鋼管用であるので、該ステンレス鋼管の一方の前端部に塑性加工によって大径の受け口を直接成形でき、管径を変えるためにブッシングやニップルを取り付ける手間を省略できる。
【００１９】
【実施例】
次に、本発明を実施例に基づいて説明するが、本発明は実施例に限定されるものではない。図１には伸縮管継手１の実施例を断面で示している。
【００２０】管継手１は、通常、同径である薄肉のステンレス鋼管２，３を接続する。一方のステンレス鋼管２の前端部には、塑性加工によってより大径の受け口５を直接成形する。ステンレス鋼管２は、受け口５の管端部において傾斜フランジ部７を設け、該フランジの傾斜角度は約３０度である。
【００２１】管継手１において、例えば、ステンレス鋼管２，３は厚さ２ｍｍであり、その外径は１１４ｍｍである。受け口５の外径は１２３ｍｍであると、差し込み側鋼管３の外径と受け口５の内径とのすき間距離Ｄは２．５ｍｍになる。一方、差し込み側鋼管３の管端からパッキン８の接液面までの奥行き長さＨが約８０ｍｍであると、この奥行き長さＨはすき間距離Ｄの約３２倍であるから、当然、１００倍未満の関係を維持している。
【００２２】リング状のシール用パッキン８は、硬質ゴムまたはプラスチック製である。パッキン８は、前方の外周縁を面取りした矩形状の横断面を有し、面取り９の傾斜角度は約３０度である。押さえ金具は１対のルーズフランジ１０，１１である。一方のルーズフランジ１０は、その内径が受け口５の外径よりも僅かに大きく、前方の内周縁を傾斜角約３０度で面取りする。他方のルーズフランジ１１は、その内径が鋼管３の外径よりも僅かに大きく、その外径はフランジ１０のそれと等しい。
【００２３】管継手１を組み立てるには、鋼管２の受け口５にあらかじめルーズフランジ１０を装備しておく。次に、差し込み側の鋼管３にパッキン８およびルーズフランジ１１を装備してから、受け口５に差し込み、ルーズフランジ１０，１１を複数本の締め付けボルト１２で締結する。この結果、ルーズフランジ１０，１１によって傾斜フランジ部７とともにシール用パッキン８を半径方向内方へ締め付け、受け口５の管端に密着させて水密性を保持する。
【００２４】管継手１は、奥行き長さＨとすき間距離Ｄとの寸法比率が約３２倍で１００倍未満であるため、ステンレス鋼特有のすき間腐食を起こすことがない。管継手１は、差し込み側鋼管３が前後動可能であることにより、継手部分において熱や地震による管の伸縮を吸収できる。管継手１では、フランジ１０，１１がいずれも自由に回転できるルーズ式であるから、止め金具が継手本体と一体に鋳造された排水鋳鉄管や水道用ダクタイル鋳鉄管に比べて施工性が良好である。
【００２５】図２には伸縮管継手の変形例を示し、図１の伸縮管継手１における差し込み側鋼管３が抜け出る蓋然性を回避する。管継手１４では、差し込み側鋼管１６の前端面の近傍に、抜け止め部として環状凸部１８を形成する。環状凸部１８は、差し込み時において鋼管１６に関してパッキン８よりも前方に位置する。環状凸部１８は、鋼管１６を回転しながら内側からの塑性加工によって浅く成形すればよい。
【００２６】管継手１４は、建設設備の排水管のように内圧は通常掛からないけれども、接続個所にスラスト荷重などが働き、差し込み側鋼管１６が抜け出すおそれがある接続個所に設置する。差し込み側鋼管１６が抜け始めて後退すると、環状凸部１８がシール用パッキン８の側面に接触して停止し、該鋼管の抜け出しを効果的に阻止する。
【００２７】図３に示す管継手３４では、差し込み側鋼管３６の前端面の近傍に比較的高い環状凸部３７を形成するとともに、受け口側鋼管３８の内周面において、パッキン８つまり傾斜フランジ部７の位置よりも後方且つ近傍に環状溝４０を設け、該環状溝内に縮径可能なスナップリング４２を嵌めて保持する。受け口側鋼管３８に関して、環状溝４０は、差し込み時において差し込み側鋼管３６の環状凸部３７より前方に位置する。
【００２８】スナップリング４２は、リング状のバネ板であり、完全な円環状ではなくて一部を切り欠いているために縮径可能である。このため、スナップリング４２を縮径して環状溝４０に嵌めると、該スナップリングと鋼管３６の外周面との間に若干の間隙が生じる。
【００２９】管継手３４を組み立てるには、鋼管３８の受け口４４にあらかじめルーズフランジ４６を装備しておく。次に、差し込み側の鋼管３６にスナップリング４２，パッキン８およびルーズフランジ４８を装備してから、受け口４４に所定深さ差し込み、弾性のスナップリング４２を縮径して環状溝４０内に嵌め込む。ルーズフランジ４６，４８を位置合わせしてから、比較的長い複数本の締め付けボルト５０で締結する。
【００３０】管継手３４は、接続個所にスラスト荷重などが働いた際に、差し込み側鋼管３６が抜け始めて後退すると、環状凸部３７がスナップリング４２の側面に接触して停止し、該鋼管の抜け出しを阻止する。管継手３８は、管継手１４（図２）のようにシール用パッキンで抜け防止するのではなく、スナップリング４２によってより大きな抜け出し阻止力を得ることができる。
【００３１】管継手３４は、高耐震性として大きい伸縮性および抜け出し阻止力が要求される配管について適用できる。管継手３４は、水道用配水管のように内部流体の圧力が高い場合に好適である。
【００３２】図２または図３に関して、差し込み側鋼管用の抜け止め部として、環状凸部１８，３７の代わりに図４または図５のような加工を行ってもよい。図４では、鋼管２０の外周面に沿って環状リング２１を溶接する。図５では、鋼管２２の前端部２３をテーパ状に半径方向外方へ拡げている。
【００３３】また、パッキン８の押さえ金具は、図１から図３に示すルーズフランジの代わりに、図６に示すようなルーズ式締結用バンド２６で締め付けてもよい。図６において、リング状のパッキン２８は、前後の外周縁２９，３０を面取りした矩形状の横断面を有し、両面取り角度はおのおの４５度である。リテイナ３２は、横断面が４５度に屈曲した環状プレートからなり、その内周面がパッキン８の外周面と接触し、傾斜内周面がパッキン２８の外周縁３０と接触する。リテイナ３２は、パッキン２８を成形するときに一体化してもよく、またはパッキン８と分離していてもよい。
【００３４】締結用バンド２６は、リテイナ３２の傾斜外周面および傾斜フランジ部７の外周面と接触するように、前後方部が４５度傾斜したほぼＵ字形断面の環状プレートである。締結用バンド２６は、軸線と直角に配置した１本または２本の締め付けボルト（図示しない）で締結することができる。
【００３５】図７に示す管継手５２では、受け口側鋼管５４における受け口後方の内周面に環状溝５６を設けてシール用パッキン５８を保持する。パッキン５８は、ほぼ矩形状の横断面を有し、半径方向に弾性圧縮しやすいように一方の側端面に三角形状の切り込み６０を設け、且つ他方の内端縁に面取り６２を形成する。また、受け口側鋼管５４の管端部にも環状溝６４を設け、該環状溝内に縮径可能なスナップリング６６を嵌めて保持する。
【００３６】一方、差し込み側鋼管３６に関して、パッキン位置よりも後方に、抜け止め部として環状凸部３７を設ける。抜け止め部である環状凸部３７は、止め金具であるスナップリング６６と係合すると、鋼管３６の抜け出しを阻止する。管継手５２では、鋼管３６の差し込み時にパッキン５８を損傷しないように、鋼管３６の管端面における切断バリを入念に取り、さらにテーパ状の面取り６８を行うと好ましい。テーパ状の面取り６８の代わりに、管端部を多少すぼめる加工を行ってもよい。
【００３７】管継手５２において、例えば、ステンレス鋼管３６，５４は厚さ２ｍｍであり、その外径は１１４ｍｍである。受け口外径は１２３ｍｍであると、差し込み側鋼管３６の外径と受け口の内径とのすき間距離は２．５ｍｍになる。一方、差し込み側鋼管３６の管端からパッキン５８の接液面までの奥行き長さが約５０ｍｍであると、この奥行き長さはすき間距離の約２０倍であるから、当然、１００倍未満の関係を維持している。
【００３８】管継手５２を組み立てるには、鋼管５４における受け口後方の環状溝５６に、あらかじめリング状のパッキン５８を嵌めておく。次に、差し込み側の鋼管３６において、環状凸部３７よりも後方にスナップリング６６を装備してから、受け口６９に所定深さ差し込み、弾性のスナップリング６６を縮径して環状溝６４内に嵌め込む。
【００３９】図８に示す管継手７０では、図７におけるスナップリング６６と環状溝６４の代わりに、受け口側鋼管５４の管端にフランジ部７４を成形し、止め金具として１対のルーズフランジ７５，７６を用いる。ルーズフランジ７５は、その内径が受け口７２の外径よりも僅かに大きく、且つルーズフランジ７６は、その内径が鋼管１６の外径よりも僅かに大きく、両者の外径は等しい。
【００４０】管継手７０を組み立てるには、鋼管５４の受け口７２にあらかじめルーズフランジ７５を装備しておく。次に、差し込み側の鋼管１６にルーズフランジ７６を装備してから、受け口７２に所定深さ差し込み、ルーズフランジ７５，７６を複数本の締め付けボルト７８で締結する。
【００４１】図９に示す管継手８０では、受け口側鋼管８２の管端にフランジ部７４だけを成形し、止め金具として１対のルーズフランジ７５，７６を用いる。一方、差し込み側鋼管８４の外周面に並行の環状凸部８６，８８を設け、両環状凸部の間でパッキン９０を保持する。
【００４２】管継手８０を組み立てるには、鋼管８２の受け口９２にあらかじめルーズフランジ７５を装備しておく。次に、差し込み側の鋼管８４の環状凸部８６，８８間にパッキン９０を取り付け、ルーズフランジ７６を装備してから、受け口９２に所定深さ差し込み、ルーズフランジ７５，７６を複数本の締め付けボルト７８で締結する。
【００４３】図１０では、図８および図９で用いるルーズフランジ７５，７６の代わりに、止め金具として半円形の半割り体９４，９４を用いる。半割り体９４はＵ字形の横断面を有し、中間底壁の内径はフランジ部７４の外径、一端壁の内径は受け口９２の外径且つ他端壁の内径は鋼管８４の外径よりも僅かに大きい。半割り体９４，９４は、受け口９２のフランジ部７４に被せてボルト９６で締め付ける。ボルト９６は、通常、軸心対称に２本配置する。
【００４４】
【発明の効果】
本発明に係る伸縮管継手は、すき間の間隔と奥行き深さとの寸法比率が１００倍未満であるため、ステンレス鋼特有のすき間腐食を起こすことがない。一方、現状の排水鋳鉄管および水道用ダクタイル鋳鉄管では、既に配管の腐食や水道水の汚染などの問題が顕在化しており、この分野においても、本発明によって耐食性が優れ且つ安全性の高いステンレス鋼管の適用を可能とするものである。
【００４５】本発明の伸縮管継手では、薄肉のステンレス鋼管に対して適用するため、塑性加工によってステンレス鋼管の一方に大径の受け口を直接成形でき、且つ傾斜フランジ部、環状凸部、環状溝、管端フランジなどの成形も容易である。このため、作業現場で管接続を簡単に達成でき、経済的なステンレス配管システムを提供するものである。
【００４６】本発明の伸縮管継手は、差し込み側鋼管が前後動可能であることにより、継手部分において熱や地震による管の伸縮を吸収できる。この伸縮管継手において、シール用パッキンの締め付けまたは抜け止め金具として１対のルーズフランジを適用すると、これらのフランジはいずれも自由に回転して位置決めできるから施工性がきわめて良好である。
【図面の簡単な説明】
【図１】本発明に係る伸縮管継手を示す概略断面図である。
【図２】伸縮管継手の変形例を示す概略断面図である。
【図３】伸縮管継手の第２変形例を示す概略断面図である。
【図４】差し込み側鋼管に関して、管端の近傍に設ける抜け止め部の変形例を示す部分断面図である。
【図５】抜け止め部の別の変形例を示す部分断面図である。
【図６】パッキンの押さえ金具の変形例を示す概略断面図である。
【図７】伸縮管継手の第３変形例を示す概略断面図である。
【図８】伸縮管継手の第４変形例を示す概略断面図である。
【図９】伸縮管継手の第５変形例を示す概略断面図である。
【図１０】差し込み側鋼管の止め金具の変形例を示す概略断面図である。
【符号の説明】
１伸縮管継手
２受け口側鋼管
３差し込み側鋼管
５受け口
７傾斜フランジ部
８シール用パッキン
１０，１１ルーズフランジ
１２締め付けボルト[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an expansion joint for a stainless steel pipe that can absorb expansion and contraction of the pipe due to heat or an earthquake at a joint portion and does not cause crevice corrosion peculiar to stainless steel.
[0002]
[Prior art]
Since stainless steel pipes have better corrosion resistance and mechanical strength than iron pipes and aluminum pipes, they are widely used today in fields such as plant piping, water supply pipes for building equipment, hot water supply pipes, air conditioning pipes, and small diameter pipes for water supply. I have. In addition, recently installed pipes are susceptible to corrosion in a short period of time due to the deterioration of the living environment.Therefore, stainless steel pipes have been used in these fields instead of drainage cast iron pipes for building equipment and ductile cast iron pipes for water supply. Needs are occurring.
[0003] The pipe joints used in the above-mentioned new fields need to be able to absorb expansion and contraction of the pipes due to heat and earthquakes at the joints. Like ductile cast iron pipes, there is a demand for a joint having a structure in which one end of a pipe is inserted into a receptacle and connected in a direction from the upstream to the downstream or in a flow direction of the pumping. For this reason, screw joints used for conventional stainless steel pipe connection, mechanical joints connected by a special tool at a construction site by pressing or pipe expansion, and well-known flange joints cannot be diverted to the above fields.
[0004] For example, if a joint having a structure in which one end of a pipe is inserted into a receptacle and connected is made of stainless steel, there is a concern that a corrosion characteristic of stainless steel may occur and a water leakage accident may occur. Not embodied. When stainless steel joints are manufactured by casting, such as drainage cast iron pipes, the wall thickness increases and the material cost becomes considerably high, and as with conventional cast iron products, it becomes heavy, and the transportation and work efficiency is reduced. I will.
[0005]
[Problems to be solved by the invention]
Even thin stainless steel pipes, such as drainage cast iron pipes and ductile cast iron pipes for waterworks, manufacture joints with a structure in which one end of the pipe is inserted into the receptacle and connected, and at this time, the unique corrosion of stainless steel It is absolutely necessary to have an embodiment that does not cause In addition, it is highly desirable to be able to directly form a pipe joint having performance equivalent to that of a conventional cast iron product by plastic working using the pipe end of a thin stainless steel pipe in terms of manufacturing and transportation costs and work efficiency.
The present invention has been proposed to solve the problems inherent in stainless steel and the above-mentioned problems relating to cast iron joints. Even in a thin stainless steel pipe, the crevice corrosion inherent in stainless steel can be prevented. An object of the present invention is to provide an expansion joint that does not cause a rise. Another object of the present invention is to provide an expansion joint capable of directly forming a joint having performance equivalent to that of a conventional cast iron product from a thin stainless steel pipe.
[0007]
[Means for Solving the Problems]
Recent research on stainless steel pipes has shown that stainless steel does not necessarily corrode when a gap is formed, and that this corrosion is related to the gap spacing and depth. In other words, for stainless steel pipes, in the range of the practical gap of the pipe joint, if the depth is more than 100 times the gap, corrosion is apt to occur suddenly. Experiments have shown that this does not occur.
Therefore, in the expansion pipe joint according to the present invention, for all pipe size joints, the depth length from the pipe end of the insertion side steel pipe to the liquid contact surface of the packing, the outer diameter of the insertion side steel pipe, and the receiving side steel pipe. The ratio of the dimensional ratio to the gap distance to the inner diameter of the stainless steel is maintained to be less than 100 times, which does not cause crevice corrosion peculiar to stainless steel. The present invention relates to a pipe joint for tightly connecting thin stainless steel pipes using a ring-shaped packing, and the pipe joint has performance equivalent to that of a drainage cast iron pipe or a ductile cast iron pipe for water supply.
An expansion joint for a stainless steel pipe according to the present invention has a large-diameter socket formed directly on one front end of the stainless steel pipe by plastic working. By forming the inclined flange portion at the pipe end of the receiving-side steel pipe, the inclined flange portion of the receiving steel pipe is tightened inward in the radial direction together with the wedge-shaped packing by the holding metal to maintain airtightness. It is preferable that an annular groove or a parallel annular ridge be provided near the inclined flange portion behind the packing position with respect to the inner peripheral surface of the receiving-side steel pipe to hold the snap ring of the stopper. Further, preferably, with respect to the insertion-side steel pipe on the side opposite to the receiving port side, by providing an annular projection for retaining the pipe in the vicinity of the pipe end, when the insertion-side steel pipe starts to be pulled out and retreats, the annular projection is used for sealing packing. Or stop by contacting the side of the fastener.
In another configuration of the present invention, the expansion joint for a stainless steel pipe may be provided with an annular groove or a parallel annular ridge on a rear inner peripheral surface of the receiving-side steel pipe to hold the packing. In this case, an annular convex portion for retaining is provided behind the packing position with respect to the insertion-side steel pipe on the opposite side to the receiving side, and a stopper engaging with this annular convex portion is attached to the pipe end of the receiving side steel pipe. In another configuration of the present invention, the expansion joint for a stainless steel pipe may be provided with a parallel annular ridge or an annular groove on the outer peripheral surface of the insertion-side steel pipe opposite to the receiving port side to hold the packing. In this case, a stopper which engages with the annular protrusion or the packing on the rear side of the insertion side steel pipe is attached to the pipe end of the reception side steel pipe.
Preferably, the stopper is a pair of loose flanges or semi-cylindrical halves when a flange is formed at the pipe end of the steel pipe on the receiving side. When an annular groove or a parallel annular ridge is provided at the pipe end of the receiving-side steel pipe, the snap ring may be held at this location. If an external thread is formed at the end of the tube, a lock nut can be used.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In the expansion joint 1 according to the present invention, the inclined flange portion 7 of the receiving steel pipe 2 can be formed simultaneously with directly forming the large-diameter receiving port 5 by plastic working. Although the inclination angle of the flange portion 7 is generally about 30 degrees as shown in FIG. 1, it can be increased or decreased from 30 degrees. In the expansion joint 1, the main component used is the packing 8, and the remaining components are only a pair of loose flanges 10 and 11 (FIGS. 1 to 3) and tightening bands 26 (FIG. 6) which are holding metal fittings. And overall cost is low and economical.
The packing used in the present invention is made of, for example, hard rubber, leather, felt, or plastic, and may be a metal packing such as copper, lead, or mild steel. The packing 8 having a rectangular cross section (FIG. 1) has a chamfer 9 corresponding to the inclined flange portion 7 and has a wedge shape due to the chamfer, and is tightened inward in the radial direction by the holding metal to maintain airtightness. be able to.
The packing used in the present invention may be a packing 58 (FIG. 7) having a triangular cut 60 on one side end surface. The packing 58 can be easily compressed in the vertical direction by the cuts 60 and can be sandwiched between the steel pipe 36 and the receiving port 69 as shown in FIG. In addition, the increase in the fluid pressure increases the force pressed against the sealing surface, and has the effect of increasing the sealing force. Since the packing 58 has the chamfer 62 on the other inner edge, the steel pipe 36 can be inserted.
In the expansion joint 1, an annular convex portion 18 (FIG. 2) is formed as a retaining portion. Instead of this annular projection, the annular ring 21 (FIG. 4) may be welded, or the front end 23 (FIG. 5) may be tapered. The annular convex portion 18 may be formed linearly, intermittently or partially in the circumferential direction. This annular convex portion may be relatively low as long as it comes into contact with the side surface of the packing 8 which is in close contact with the outer peripheral surface of the insertion-side steel pipe. On the other hand, if it is possible to make contact with the snap ring 42 (FIG. 3) or 66 (FIG. 7), it is necessary to make it relatively high in accordance with the inner diameter of the snap ring. If the stopper is a pair of loose flanges 75, 76 (FIG. 9) or a half body 94 (FIG. 10), the height of the annular convex portion can be set arbitrarily.
In the embodiment shown in FIG. 3, the snap ring 42 is fitted and fixed in the annular groove 40, but it is apparent that a parallel low annular ridge may be provided instead of the annular groove. The same applies to the packing 58 or the snap ring 66 shown in FIG. In the packing 90 shown in FIG. 9, an annular groove may be provided instead of the parallel annular protrusions 86 and 88.
In the case where a flange 74 is formed at the end of the steel pipe on the receiving side, the stopper is preferably a pair of loose flanges 75, 76 or a semi-cylindrical half body 94, or a donut. A plate (not shown) may be directly welded to the flange portion 74 or the receptacle 92 or bolted. If an annular groove 64 (FIG. 7) or a parallel annular ridge is provided at the pipe end of the receiving-side steel pipe, the snap ring 64 can be held at this location. Although not shown, a lock nut can also be used if an external thread is engraved at the end of the tube.
The expansion joint 1 is preferably used to connect a relatively large diameter stainless steel pipe used for drainage pipes of building equipment and food factories, piping of building equipment in general, and water distribution pipes for water supply. Since the expansion joint 1 is for thin-walled stainless steel pipes, a large-diameter socket can be directly formed by plastic working on one front end of the stainless steel pipe, and the time and effort for mounting a bushing or nipple to change the pipe diameter is omitted. it can.
[0019]
【Example】
Next, the present invention will be described based on examples, but the present invention is not limited to the examples. FIG. 1 shows an embodiment of the expansion joint 1 in cross section.
The pipe joint 1 normally connects thin stainless steel pipes 2 and 3 having the same diameter. On the front end of one stainless steel pipe 2, a larger diameter receiving port 5 is directly formed by plastic working. The stainless steel pipe 2 is provided with an inclined flange portion 7 at the pipe end of the receiving port 5, and the inclination angle of the flange is about 30 degrees.
In the pipe joint 1, for example, the stainless steel pipes 2 and 3 have a thickness of 2 mm and an outer diameter of 114 mm. If the outer diameter of the receiving port 5 is 123 mm, the gap distance D between the outer diameter of the insertion-side steel pipe 3 and the inner diameter of the receiving port 5 is 2.5 mm. On the other hand, if the depth H from the pipe end of the insertion-side steel pipe 3 to the liquid contact surface of the packing 8 is about 80 mm, this depth H is about 32 times the gap distance D, and is naturally 100 times. Maintain less than a relationship.
The ring-shaped seal packing 8 is made of hard rubber or plastic. The packing 8 has a rectangular cross section in which a front outer peripheral edge is chamfered, and the inclination angle of the chamfer 9 is about 30 degrees. The holding fitting is a pair of loose flanges 10 and 11. One loose flange 10 has an inner diameter slightly larger than the outer diameter of the receiving port 5 and chamfers a front inner peripheral edge at an inclination angle of about 30 degrees. The other loose flange 11 has an inner diameter slightly larger than the outer diameter of the steel pipe 3, and the outer diameter is equal to that of the flange 10.
In order to assemble the pipe joint 1, a loose flange 10 is previously provided in the receiving port 5 of the steel pipe 2. Next, after the packing 8 and the loose flange 11 are mounted on the steel pipe 3 on the insertion side, the steel pipe 3 is inserted into the receiving port 5, and the loose flanges 10 and 11 are fastened with a plurality of tightening bolts 12. As a result, the sealing packing 8 is tightened inward in the radial direction together with the inclined flange portion 7 by the loose flanges 10 and 11, and the sealing packing 8 is brought into close contact with the pipe end of the receiving port 5 to maintain watertightness.
In the pipe joint 1, since the dimensional ratio of the depth length H to the clearance distance D is about 32 times and less than 100 times, there is no occurrence of crevice corrosion peculiar to stainless steel. The pipe joint 1 can absorb the expansion and contraction of the pipe due to heat or an earthquake at the joint part because the insertion side steel pipe 3 can move back and forth. Since the pipe joint 1 is a loose type in which both the flanges 10 and 11 can rotate freely, the workability is better than a drainage cast iron pipe or a ductile cast iron pipe for water supply in which the stopper is integrally formed with the joint body. is there.
FIG. 2 shows a modification of the expansion joint, which avoids the possibility that the insertion-side steel pipe 3 in the expansion joint 1 of FIG. In the pipe joint 14, an annular convex portion 18 is formed near the front end face of the insertion-side steel pipe 16 as a retaining portion. The annular convex portion 18 is located forward of the packing 8 with respect to the steel pipe 16 at the time of insertion. The annular convex portion 18 may be formed to be shallow by plastic working from inside while rotating the steel pipe 16.
The pipe joint 14 is installed at a connection point where an internal pressure is not normally applied like a drain pipe of construction equipment, but a thrust load or the like acts on the connection point and the insertion side steel pipe 16 may come off. When the insertion-side steel pipe 16 starts to pull out and retreats, the annular convex portion 18 comes into contact with the side surface of the seal packing 8 and stops, thereby effectively preventing the steel pipe from slipping out.
In the pipe joint 34 shown in FIG. 3, a relatively high annular convex portion 37 is formed near the front end face of the insertion-side steel pipe 36, and the packing 8, that is, the inclined flange portion is formed on the inner peripheral surface of the receiving-side steel pipe 38. An annular groove 40 is provided behind and near the position 7, and a snap ring 42 capable of reducing the diameter is fitted and held in the annular groove. Regarding the receiving-side steel pipe 38, the annular groove 40 is located forward of the annular convex portion 37 of the insertion-side steel pipe 36 at the time of insertion.
The snap ring 42 is a ring-shaped spring plate, and can be reduced in diameter because it is not completely annular but partially cut away. Therefore, when the snap ring 42 is reduced in diameter and fitted into the annular groove 40, a slight gap is generated between the snap ring and the outer peripheral surface of the steel pipe 36.
In order to assemble the pipe joint 34, a loose flange 46 is previously provided in the receiving port 44 of the steel pipe 38. Next, the steel pipe 36 on the insertion side is provided with the snap ring 42, the packing 8 and the loose flange 48, and then inserted into the receiving port 44 to a predetermined depth, and the elastic snap ring 42 is reduced in diameter and fitted into the annular groove 40. . After the loose flanges 46 and 48 are aligned, they are fastened with a plurality of relatively long tightening bolts 50.
When a thrust load or the like is applied to the connection point, when the insertion-side steel pipe 36 starts to come off and retreats, the annular convex portion 37 comes into contact with the side surface of the snap ring 42 and stops. Prevent escape. Unlike the pipe joint 14 (FIG. 2), the pipe joint 38 is not prevented from coming off by a seal packing, but can be provided with a greater slippage prevention force by the snap ring 42.
The pipe joint 34 can be applied to pipes that require high elasticity and high escape prevention force as high earthquake resistance. The pipe joint 34 is suitable when the pressure of the internal fluid is high, such as in a water distribution pipe.
With reference to FIG. 2 or FIG. 3, a processing as shown in FIG. 4 or FIG. In FIG. 4, the annular ring 21 is welded along the outer peripheral surface of the steel pipe 20. In FIG. 5, the front end portion 23 of the steel pipe 22 is radially expanded outward in a tapered shape.
The holding member for the packing 8 may be tightened with a loose fastening band 26 as shown in FIG. 6 instead of the loose flange shown in FIGS. In FIG. 6, the ring-shaped packing 28 has a rectangular cross section in which the front and rear outer peripheral edges 29 and 30 are chamfered, and each of the double-sided chamfer angles is 45 degrees. The retainer 32 is formed of an annular plate having a cross section bent at 45 degrees, the inner peripheral surface of which contacts the outer peripheral surface of the packing 8, and the inclined inner peripheral surface of which contacts the outer peripheral edge 30 of the packing 28. The retainer 32 may be integrated when the packing 28 is formed, or may be separated from the packing 8.
The fastening band 26 is an annular plate having a substantially U-shaped cross section whose front and rear portions are inclined by 45 degrees so as to come into contact with the inclined outer peripheral surface of the retainer 32 and the outer peripheral surface of the inclined flange portion 7. The fastening band 26 can be fastened with one or two fastening bolts (not shown) arranged at right angles to the axis.
In the pipe joint 52 shown in FIG. 7, an annular groove 56 is provided on the inner peripheral surface of the steel pipe 54 on the rear side of the socket to hold the packing 58 for sealing. The packing 58 has a substantially rectangular cross section, is provided with a triangular cut 60 on one side end face to facilitate elastic compression in the radial direction, and forms a chamfer 62 on the other inner edge. An annular groove 64 is also provided at the pipe end of the receiving-side steel pipe 54, and a snap ring 66 capable of reducing the diameter is fitted and held in the annular groove.
On the other hand, with respect to the insertion side steel pipe 36, an annular convex portion 37 is provided as a retaining portion behind the packing position. When the annular convex portion 37 serving as a retaining portion engages with a snap ring 66 serving as a stopper, the steel tube 36 is prevented from coming off. In the pipe joint 52, it is preferable to carefully cut off burrs on the pipe end face of the steel pipe 36 and further perform a tapered chamfering 68 so as not to damage the packing 58 when the steel pipe 36 is inserted. Instead of the tapered chamfer 68, a process of slightly shrinking the pipe end may be performed.
In the pipe joint 52, for example, the stainless steel pipes 36 and 54 have a thickness of 2 mm and an outer diameter of 114 mm. If the outer diameter of the receiving port is 123 mm, the gap distance between the outer diameter of the insertion-side steel pipe 36 and the inner diameter of the receiving port becomes 2.5 mm. On the other hand, when the depth length from the pipe end of the insertion-side steel pipe 36 to the liquid contact surface of the packing 58 is about 50 mm, the depth length is about 20 times the gap distance. Has been maintained.
In order to assemble the pipe joint 52, a ring-shaped packing 58 is fitted in advance in the annular groove 56 behind the socket in the steel pipe 54. Next, in the steel pipe 36 on the insertion side, a snap ring 66 is provided behind the annular convex portion 37, and then inserted into the receiving port 69 to a predetermined depth, and the elastic snap ring 66 is reduced in diameter to be inserted into the annular groove 64. Fit it.
In the pipe joint 70 shown in FIG. 8, instead of the snap ring 66 and the annular groove 64 shown in FIG. 7, a flange 74 is formed at the pipe end of the steel pipe 54 on the receiving side, and a pair of loose flanges 75 are used as stoppers. , 76 are used. The inner diameter of the loose flange 75 is slightly larger than the outer diameter of the receiving port 72, and the inner diameter of the loose flange 76 is slightly larger than the outer diameter of the steel pipe 16, and both outer diameters are equal.
In order to assemble the pipe joint 70, a loose flange 75 is previously provided in the receiving port 72 of the steel pipe 54. Next, after inserting the loose flange 76 into the steel pipe 16 on the insertion side, the steel pipe 16 is inserted into the receiving port 72 to a predetermined depth, and the loose flanges 75 and 76 are fastened with a plurality of tightening bolts 78.
In the pipe joint 80 shown in FIG. 9, only the flange portion 74 is formed at the pipe end of the steel pipe 82 on the receiving side, and a pair of loose flanges 75 and 76 are used as fasteners. On the other hand, parallel annular convex portions 86 and 88 are provided on the outer peripheral surface of the insertion-side steel pipe 84, and the packing 90 is held between the two annular convex portions.
In order to assemble the pipe joint 80, a loose flange 75 is previously provided in the receiving port 92 of the steel pipe 82. Next, a packing 90 is attached between the annular projections 86 and 88 of the steel pipe 84 on the insertion side, a loose flange 76 is provided, and then a predetermined depth is inserted into the receptacle 92, and the loose flanges 75 and 76 are fastened with a plurality of tightening bolts. Fasten at 78.
In FIG. 10, instead of the loose flanges 75 and 76 used in FIGS. 8 and 9, semi-circular half bodies 94 and 94 are used as stoppers. The half body 94 has a U-shaped cross section, the inner diameter of the intermediate bottom wall is the outer diameter of the flange portion 74, the inner diameter of one end wall is the outer diameter of the receiving port 92, and the inner diameter of the other end wall is the outer diameter of the steel pipe 84. Is also slightly larger. The halves 94, 94 cover the flange 74 of the receptacle 92 and are tightened with bolts 96. Usually, two bolts 96 are arranged axially symmetrically.
[0044]
【The invention's effect】
In the expansion joint according to the present invention, the dimensional ratio between the gap and the depth is less than 100 times, so that crevice corrosion peculiar to stainless steel does not occur. On the other hand, in current drainage cast iron pipes and ductile cast iron pipes for tap water, problems such as corrosion of pipes and contamination of tap water have already become apparent, and in this field, the present invention also provides stainless steel having excellent corrosion resistance and high safety. This enables the use of steel pipes.
Since the expansion joint of the present invention is applied to a thin stainless steel pipe, a large-diameter socket can be directly formed on one of the stainless steel pipes by plastic working, and an inclined flange portion, an annular convex portion, and an annular groove can be formed. Also, it is easy to form a pipe end flange and the like. Therefore, pipe connection can be easily achieved at the work site, and an economical stainless steel piping system is provided.
The telescopic pipe joint of the present invention can absorb expansion and contraction of the pipe due to heat and earthquake at the joint part because the insertion side steel pipe can move back and forth. When a pair of loose flanges are applied to the expansion joint as a metal fitting for fastening or retaining the sealing gasket, these flanges can be freely rotated and positioned, so that the workability is extremely good.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an expansion joint according to the present invention.
FIG. 2 is a schematic sectional view showing a modification of the expansion joint.
FIG. 3 is a schematic sectional view showing a second modification of the expansion joint.
FIG. 4 is a partial cross-sectional view showing a modified example of a retaining portion provided near the pipe end with respect to the insertion-side steel pipe.
FIG. 5 is a partial sectional view showing another modification of the retaining portion.
FIG. 6 is a schematic cross-sectional view showing a modified example of the packing holding member.
FIG. 7 is a schematic sectional view showing a third modification of the expansion joint.
FIG. 8 is a schematic sectional view showing a fourth modification of the expansion joint.
FIG. 9 is a schematic sectional view showing a fifth modification of the expansion joint.
FIG. 10 is a schematic sectional view showing a modified example of a fitting for a steel pipe on the insertion side.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Expansion-pipe joint 2 Reception side steel pipe 3 Insertion side steel pipe 5 Reception port 7 Inclined flange part 8 Sealing seal 10, 11 Loose flange 12 Tightening bolt

Claims

A pipe joint for tightly connecting thin stainless steel pipes with a ring-shaped sealing gasket. A large-diameter socket is directly formed by plastic working on one front end of the stainless steel pipe, and the pipe end is formed on the pipe end of the steel pipe on the socket side. By forming the inclined flange, the holding flange clamps the inclined flange of the receiving steel pipe inward in the radial direction together with the wedge-shaped packing to maintain airtightness, and the depth from the pipe end of the insertion-side steel pipe to the liquid contact surface of the packing. A telescopic tube for stainless steel pipes in which the dimensional ratio between the length and the gap distance between the outer diameter of the insertion-side steel pipe and the inner diameter of the receiving-side steel pipe is less than 100 times that does not cause crevice corrosion peculiar to stainless steel. Fittings.

The expansion joint according to claim 1, wherein an annular groove or a parallel annular ridge is provided in the vicinity of the inclined flange portion rearward of the packing position with respect to the inner peripheral surface of the receiving-side steel pipe to hold the snap ring of the stopper.

With respect to the insertion-side steel pipe on the side opposite to the receiving port side, by providing an annular projection for retaining near the pipe end, when the insertion-side steel pipe starts to be pulled out and retreats, the annular projection becomes the side face of the seal packing or the stopper. The expansion joint according to claim 1, wherein the expansion joint is stopped by contacting the pipe.

A pipe joint for tightly connecting thin stainless steel pipes with a ring-shaped sealing gasket. A large-diameter socket is formed directly on one front end of the stainless steel pipe by plastic working, and the rear inner peripheral surface of the steel pipe on the socket side. An annular groove or a parallel annular ridge is provided on the inner side to hold the packing, and an annular convex portion for retaining is provided behind the packing position with respect to the insertion side steel pipe opposite to the receiving side, and the annular convex portion is engaged. Attach the fittings to the pipe end of the steel pipe on the receiving side, the depth length from the pipe end of the insertion side steel pipe to the liquid contact surface of the packing, and the clearance between the outer diameter of the insertion side steel pipe and the inner diameter of the receiving side steel pipe. An expansion joint for stainless steel pipes in which the dimensional ratio of the stainless steel pipe maintains a relationship of less than 100 times that does not cause crevice corrosion peculiar to stainless steel.

A pipe joint for tightly connecting thin-walled stainless steel pipes with a ring-shaped sealing gasket. A large-diameter socket is directly formed by plastic working on one front end of the stainless steel pipe, and the insertion side is opposite to the socket side. Along with a parallel annular ridge or annular groove provided on the outer peripheral surface of the steel pipe to hold the packing, and a stopper for engaging the rear annular convex part or the packing with respect to the insertion side steel pipe is attached to the pipe end of the receiving side steel pipe, The dimensional ratio of the depth length from the pipe end of the insertion-side steel pipe to the liquid contact surface of the packing and the gap distance between the outer diameter of the insertion-side steel pipe and the inner diameter of the receiving-side steel pipe does not cause crevice corrosion peculiar to stainless steel. An expansion joint for stainless steel pipes that maintains a less than double relationship.

A pair of loose flanges, semi-cylindrical halves, and an annular groove or a parallel annular ridge are provided at the pipe end of the receiving-side steel pipe when the stopper forms a flange at the pipe end of the receiving-side steel pipe. The telescopic joint according to claim 4 or 5, wherein the joint is a lock nut when a male screw thread is engraved.