JP4516695B2

JP4516695B2 - Replacement method for buried gas piping

Info

Publication number: JP4516695B2
Application number: JP2001001711A
Authority: JP
Inventors: 康弘豊田; 研二森; 幹夫中岡; 裕司岸本
Original assignee: Saibu Gas Co Ltd; Shinwa Sangyo Co Ltd; JFE Pipe Fitting Mfg Co Ltd
Current assignee: Saibu Gas Co Ltd; Shinwa Sangyo Co Ltd; JFE Pipe Fitting Mfg Co Ltd
Priority date: 2001-01-09
Filing date: 2001-01-09
Publication date: 2010-08-04
Anticipated expiration: 2021-01-09
Also published as: JP2002206667A

Description

【０００１】
【発明の属する技術分野】
本発明は、公道側から民地側にわたって埋設された鋳鉄管又は鋼管よりなる旧埋設ガス配管を樹脂製の新埋設ガス配管に入れ替える施工方法に関する。
【０００２】
【従来の技術】
既設の老朽した金属製の旧埋設ガス配管を樹脂製の新埋設ガス配管に入れ替える施工方法の一例を図９及び図１０を参照にして説明する。
図９は公道側から民地側にわたって旧埋設ガス配管が埋設されている入替え前の状態を、図１０は新埋設ガス配管に入れ替えた後の状態をそれぞれ示している。
【０００３】
図９に示すように、公道下の本管１、分岐サドル３２及び官民境界線Ｃまでの供給管２（以下、公道下の供給管２という。）を含む旧埋設ガス配管３はガス会社法人の資産であり、官民境界線Ｃからガスメーターへの供給管２（以下、民地下の供給管２という。）である旧埋設ガス配管３は消費者個人の資産である。したがって、ガス会社は、計画的に老朽した旧埋設ガス配管３の入替えを実施するにしても公道下の本管１及び官民境界線Ｃまでの供給管２の入替えと、民地下の供給管２の入替えとは、必ずしも同時に行うことができない場合がある。この場合は、ガス会社は、計画的に公道下の老朽管の入替えのみを先行し、後日に民地下の供給管２の入替えを行うという時差工事を採用せざるを得ない。
【０００４】
このように公道下の老朽管の入替えを先行して行うときは、民地を自由に掘削できないため、先ず、図１０に示すように、公道Ａの民地Ｂに達する手前の官民境界線Ｃ付近までの地面を掘削し、そして公道下の老朽した供給管２はその掘削により形成されたピット内に露出する箇所で切断して、公道下の本官１、分岐サドル３２及び供給管２のみを新設の樹脂製の本官４及び分岐サドル５、供給管３３と入れ替える。このとき、公道下の新設の供給管３３の端部と民地下の老朽した供給管２のピット内に臨む切断端部とはトランジション継手３４や中継管３５を用いて接続しておくことになる。そして、民地Ｂ下の供給管２を新設の樹脂製の供給管３６に入れ替える工事は後日に行われる。
【０００５】
【発明が解決しようとする課題】
しかるに、先行して公道下の新設の供給管３３への入れ替え工事と、その新設の供給管３３と地中に残された民地側の旧埋設ガス配管３との接続工事が公道側の官民境界線Ｃ付近で行われるという上記入替え施工法では、後日、民地下の供給管２の入替えを行うとき、再度、公道側の官民境界線Ｃ付近を掘り起こさなければならない。
【０００６】
本発明の目的は、このような問題を解消するためになされたもので、上記のような時差工事を採用する場合も、後日、民地下の埋設ガス配管の入替えを行うときは公道側を再度掘り起こす必要がなく、民地側の旧埋設ガス配管の入替え作業の能率化、工期の短縮化を図れる埋設ガス配管の入替え施工方法を提供することにある。また本発明の目的は、民地下の旧埋設ガス配管の入替えが活管状態で安全かつ容易に行い得る埋設ガス配管の入替え施工方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明の埋設ガス配管の入替え施工方法は、図１〜図８に例示するように、公道側の本管１から民地側のガスメーターにわたって老朽化した金属製の旧埋設ガス配管３が埋設されており、その旧埋設ガス配管３の公道側部分と民地側部分を時差工事で樹脂製の第１，２新埋設ガス配管１１，３０に入れ替える埋設ガス配管の入替え施工方法であって、公道下の旧埋設ガス配管３の一部を切断して、この旧埋設ガス配管３の切断部から本管１までを除去するとともに、前記旧埋設ガス配管３の切断部から民地側部分を地中に残す切断除去工程と、前記公道下の旧埋設ガス配管３の除去された部分に、旧埋設ガス配管３の内径より小さい外径を有する樹脂製の第１新埋設ガス配管１１を埋設するとともに、その第１新埋設ガス配管１１の先端部１１ａを、地中に残された前記旧埋設ガス配管３の切断端部から該旧埋設ガス配管３内に民地下に至る深さにまで挿入する入替え工程と、地中に残された前記旧埋設ガス配管３の切断端部と、前記第１新埋設ガス配管１１の外周との間の隙間を管継手６で気密状にシールする工程と、その後、民地側の旧埋設ガス配管３内に挿入されている前記第１新埋設ガス配管１１の先端位置の周辺の地面を掘削し、第１新埋設ガス配管１１の先端部１１ａからガスメーター側に所定間隔だけ離れた旧埋設ガス配管３の外周一部をガス漏洩防止状態下で穿孔する工程と、前記旧埋設ガス配管３の前記穿孔部から該旧埋設ガス配管内にバルーン２６を挿入してガス流通を遮断する工程と、前記旧埋設ガス配管３のバルーン２６よりガスメーター側寄り箇所を切断する工程と、前記旧埋設ガス配管３の第１新埋設ガス配管の先端部から公道側に所定間隔だけ離れた箇所を切断し、この旧埋設ガス配管３の切断部からガスメーター側部分をガスメーター側方向へ移動させて第１新埋設ガス配管１１の先端寄り側の一部を露出させ、この第１新埋設ガス配管１１の露出部を絞り封止する工程と、前記移動した旧埋設ガス配管３を第１新埋設ガス配管１１の先端方向へ引き抜く工程と、前記第１新埋設ガス配管１１の絞り封止部より下流の先端側端部に、ガスメーター側から布設され、第１新埋設ガス配管と同径・同材質の第２新埋設ガス配管３０の端部を接合する工程と、前記第１新埋設ガス配管１１の絞り封止状態を解除する工程と、を含むことに特徴を有するものである。
【０００８】
この場合において、上記民地側の入替え作業において、上記作業工程に代えて、次のような作業及び工程順で行うこともできる。
図６（ａ）〜（ｆ）に例示するように、民地側の旧埋設ガス配管３内に挿入されている前記第１新埋設ガス配管１１の先端位置の周辺の地面を掘削し、第１新埋設ガス配管１１の先端部１１ａから公道側に所定間隔だけ離れた旧埋設ガス配管３及び第１新埋設ガス配管１１の外周一部をガス漏洩防止状態下で穿孔する工程と、前記旧埋設ガス配管３及び第１新埋設ガス配管１１の前記穿孔部から第１新埋設ガス配管１１内にバルーン２６を挿入してガス流通を遮断する工程と、前記旧埋設ガス配管３及び第１新埋設ガス配管１１のバルーン２６よりガスメーター側寄り箇所を切断する工程と、前記旧埋設ガス配管３の第１新埋設ガス配管１１の先端部１１ａから公道側に所定間隔だけ離れた箇所を切断し、この旧埋設ガス配管３の切断部からガスメーター側部分をガスメーター側方向へ移動させて第１新埋設ガス配管１１の先端寄り側の一部を露出させ、この第１新埋設ガス配管１１の露出部を絞り封止する工程と、前記移動した旧埋設ガス配管３を第１新埋設ガス配管１１の先端方向へ引き抜く工程と、前記第１新埋設ガス配管１１の絞り封止部より下流の先端側端部に、ガスメーター側から布設され、第１新埋設ガス配管と同径・同材質の第２新埋設ガス配管３０の端部を接合する工程と、前記第１新埋設ガス配管１１の絞り封止状態を解除する工程と、から構成するというものである。
【０００９】
上記構成の埋設ガス配管の入替え施工方法によれば、先行して行う公道側の旧埋設ガス配管の入替え時に、第１新埋設ガス配管の先端部を、地中に残されている旧埋設ガス配管の切断端部から該旧埋設ガス配管内に民地下に至る深さにまで挿入するので、後日、民地側の旧埋設ガス配管を入れ替える時は民地を掘削するだけで足り、公道を再度掘り起こす必要が無くなる。
【００１０】
民地側の旧埋設ガス配管の入替え作業は、旧埋設ガス配管、又は旧埋設ガス配管及び第１新埋設ガス配管双方の一部をガス漏洩防止状態下で穿孔し、この穿孔部からバルーンを旧埋設ガス配管内又は第１新埋設ガス配管内に挿入したうえで、第１新埋設ガス配管の先端側の一部を絞り封止することにより活管状態でも安全かつ容易に行うことができる。
【００１１】
【発明の実施の形態】
本発明の実施例を図面に基づき説明する。図１は公道側の旧埋設ガス配管のみを新埋設ガス配管に入替えた状態の断面図、図２は公道側及び民地側双方の旧埋設ガス配管を新埋設ガス配管に入替えた状態の断面図、図３は図１における要部の拡大断面図、図４は図３の継手部分の拡大断面図、図５は民地側の入替え工程図、図６は他の実施例の民地側の入替え工程図、図７は他の実施例の新埋設ガス配管の先端部のシール部の断面図、図８は更に他の実施例の新埋設ガス配管の先端部のシール工程図、図９は公道側から民地側にわたって旧埋設ガス配管が埋設されている状態の断面図である。
【００１２】
本発明による埋設ガス配管の入替え施工方法を実施する前の段階では、図９に示すように、公道Ａの地中に鋳鉄管又は鋼管よりなる金属製の本管１、分岐サドル３２及び供給管２等の旧埋設ガス配管３が埋設され、民地Ｂの地中には前記旧埋設ガス配管３の供給管２が民地内のガスメーター（図示せず）の方向へ延長して埋設されている。図９中、Ｃは官民境界線、Ｄは側溝を示す。
【００１３】
本発明の方法により上記公道側の旧埋設ガス配管３である本管１、分岐サドル３２及び供給管２を先行して入れ替える作業は次の▲１▼〜▲９▼の順序で行われる。
【００１４】
▲１▼ 公道Ａの本管１、分岐サドル３２及び供給管２が埋設される周辺の地面を掘削する。このときの掘削量は、図１に符号Ｅで示すように、本管１、分岐サドル３２及び供給管２の周辺の地面を掘削するのみで足り、図１０に示すごとく官民境界線Ｃ付近にまで広く掘削しなくてもよい。
【００１５】
▲２▼ 掘削後、図１、図３に示すように、旧本管１及び旧分岐サドル３２を除去してポリエチレン等樹脂製の新本管４と入れ替え、また掘削により形成されたピット内で旧供給管２の中途部を切断して、旧供給管２の切断部２Ｂから上流側部分（本管側部分）は除去するとともに、その切断部２Ｂから下流側部分（民地方向側部分）は埋めたまま残す。
【００１６】
▲３▼ 新しく入れ替えた本管４には、図３に示すごとく新しいポリエチレン等樹脂製の分岐サドル５を電気融着等で取り付ける。
【００１７】
▲４▼ 次いで、地中に残された旧供給管２の切断部２Ｂの内面にごみ等が付着して汚れている場合はそれを清掃する。そのうえで、異径・異材質管どうしの接続を可能にする周知のメカニカル継手からなる管継手６の一端側の押輪７、抜止め部材８、リテーナ９、ガスケット１０の順にそれぞれを旧供給管２の切断部２Ｂ近傍の外周に装着する（図４参照）。
【００１８】
▲５▼ 次いで、新しいポリエチレン等樹脂製の第１新埋設ガス配管１１の先端部１１ａを、地中に残されている旧供給管２の切断部２Ｂから該旧供給管２内に挿入する（図１、図３参照）。このとき、第１新埋設ガス配管１１の先端部１１ａは旧供給管２内に民地Ｂ下に至る深さＦにまで挿入されるが、この挿入深さＦは、後日の民地Ｂ側の入れ替え時にこの入替え工事が行い易い場所に対応すべく設定される。
【００１９】
この第１新埋設ガス配管１１の挿入に際しては、予め、該第１新埋設ガス配管１１の先端部１１ａの外周の凹溝１２にゴム輪等のシールパッキン１３を装着するとともに、該シールパッキン１３を先端部１１ａの内面よりバックアップする鍔付き円筒状のスティフナー１４を先端部１１ａの内周に嵌合し、そのうえで、上述のように旧供給管２内に所定深さＦにまで挿入する。これにより第１新埋設ガス配管１１の先端部１１ａの外周と旧供給管２の内面との間の隙間が気密状にシールされてガス漏れを防ぐことができる。
【００２０】
その際、図７に示すように、第１新埋設ガス配管１１の挿入に先立って該管１１の先端部１１ａにスティフナー１４の内径よりも僅かに大きい外径の鋼球等の硬球１５を当てがっておく。かくして、第１新埋設ガス配管１１を旧供給管２内に挿入した後、硬球１５に先端部を繋いでいるワイヤー１６の後端側を上流側方向Ｇに引っ張って硬球１５をスティフナー１４及び第１新埋設ガス配管１１内に通して引き戻すことにより先端部１１ａを拡径することができ、この拡径によりシールパッキン１３を旧供給管２の内面に対し強く押し付けて密着させることができるため安定確実にシールすることができる。
【００２１】
また、第１新埋設ガス配管１１の先端部１１ａの外周と旧供給管２の内面との間の隙間をシールパッキン１３及びスティフナー１４を用いて気密状にシールする手段としては、次のような手段を採用することもできる。
スティフナー１４として、図８（ａ）に示すように、第１新埋設ガス配管１１の内径よりも僅かに大きい外径を有し、一端部１４ａの外径のみを第１新埋設ガス配管１１の内径と同じかそれよりも小さく形成し、他端部の外周に外向き鍔１４ｂを設けた段付き円筒状のスティフナー１４を用意する。
第１新埋設ガス配管１１の挿入に先立って、第１新埋設ガス配管１１の先端部１１ａの外周の凹溝１２にシールパッキン１３を嵌合し、かつ先端部１１ａの内周に前記スティフナー１４の一端部１４ａのみを嵌合するとともに、ワイヤー１６の先端部１６ａに繋がれた鋼球等の硬球１５をスティフナー１４の一端部１４ａの内部に嵌合し該一端部１４ａの開口端縁１４ｃを細口径に少し絞ることにより一端部１４ａ内に硬球１５を仮止め保持する。一方、第１新埋設ガス配管１１の基端部１１ｂの外周の雄ねじに押えカラー４０を螺合してセットし、この押えカラー４０の後端壁４０ａの雌ねじ４１に中空軸状のワイヤー引込みボルト４２に螺合挿通する。ワイヤー引きボルト４２の後端部にベアリング４３を介して配された筒状のワイヤー固定治具４４とワイヤー引きボルト４２にはワイヤー１６の後端部１６ｂを挿通させ、しかる後ワイヤー固定治具４４に付設された押えねじ４５を締め付けることにより該押えねじ４５の先端でワイヤー１６の後端部１６ｂをワイヤー固定治具４４内に固定する。
【００２２】
かくして、第１新埋設ガス配管１１を旧供給管２内に挿入した後、工具でワイヤー引きボルト４２を回転させて押えカラー４０から後退移動させることによりワイヤー１６を引っ張ると、図８（ｂ）に示すごとく、硬球１５を介してスティフナー１４が外向き鍔１４ｂを第１新埋設ガス配管１１の先端面１１ｃに当接させるまで第１新埋設ガス配管１１の先端部１１ａの内周に引き込まれる。このスティフナー１４の引込みにより第１新埋設ガス配管１１の先端部１１ａが拡径し、シールパッキン１３が旧埋設ガス配管２の内面に強く密着状に押し付けられる。更にワイヤー引きボルト４２を回転させてワイヤー１６を強く引っ張ると、図８（ｃ）に示すごとく硬球１５がスティフナー１４の一端部１４ａから引き離される。
これにおいても、第１新埋設ガス配管１１の先端部１１ａの外周と旧供給管２の内面との間の隙間がシールパッキン１３及びスティフナー１４により安定確実に気密状にシールすることができる。なお、このシール作業後、硬球１５及びワイヤー１６は押えカラー４０、ワイヤー固定治具４４ごと第１新埋設ガス配管１１の基端部１１ｂから取り外される。
【００２３】
▲６▼ 次いで、第１新埋設ガス配管１１の基端部１１ｂから管継手６の継手本体１７を該第１新埋設ガス配管１１上に挿通し、この継手本体１７の一端側の雄ねじ部１８を旧供給管２上の押輪７の雌ねじに螺合することにより継手本体１７を旧供給管２に仮止めする。
【００２４】
▲７▼ 次いで、第１新埋設ガス配管１１に、この基端部１１ｂから管継手６の他端側のガスケット１９、リテーナ２０、抜止め部材２１、押輪２２の順にそれぞれを挿通する（図４参照）。
【００２５】
▲８▼ 次いで、第１新埋設ガス配管１１の基端部１１ｂを前記分岐サドル５に、通電により発熱する電熱線２３ａを埋設してある電気融着継手２３等を用いて接続する（図３参照）。
【００２６】
▲９▼ 最後に、継手本体１７の一端側及び他端側をそれぞれ本締めすることにより、旧供給管２の切断部２Ｂと、第１新埋設ガス配管１１の外周との間の隙間が管継手６を介して気密状にシールされる。これにより第１新埋設ガス配管１１の外周と旧供給管２の切断部２Ｂの内面との間の隙間からのガス漏れを防ぐことができ、民地側の旧供給管２の入替え工事までの期間におけるガス使用に何等支障を来すことはない。以上の作業で公道側の旧埋設ガス配管３の入替え工事、つまり先行工事が終了する。
【００２７】
次に、上記先行工事を終え、所定期間経過後に実施される民地側の旧埋設ガス配管３である供給管２の入替え作業について図５（ａ）〜（ｆ）を参照にして説明する。この入替え作業は次の▲１▼〜▲７▼の順序で行われる。
【００２８】
▲１▼ 先ず、先行工事の情報に基き民地側の旧供給管２内に挿入されている樹脂製の第１新埋設ガス配管１１の先端部１１ａ位置の周辺の地面を掘削し、該先端部分を特定する。このときは、先行工事において、第１新埋設ガス配管１１の先端部１１ａを、旧供給管２内に民地Ｂ下に至る深さＦにまで挿入してあるので、民地Ｂ下の当該第１新埋設ガス配管１１の先端部１１ａの位置の周辺の地面を掘削するだけで足り、官民境界線Ｃ付近にまで幅広く掘削したり、また公道Ａを再度掘り起こす必要は無くなり、掘削量は少なくて済む。
【００２９】
▲２▼ 掘削後、図５（ａ）に示すごとく第１新埋設ガス配管１１の先端部１１ａから数十センチくらいガスメーター側の旧供給管２の穿孔予定箇所にサドル２４を取り付け、このサドル２４に既存の鋼管等穿孔用のホールソー３７を気密保持状態に装着し、このホールソー３７で旧供給管２の穿孔予定箇所を穿孔する。その穿孔部を符号２７で示す。この穿孔作業は、第１新埋設ガス配管１１がガス流通状態である（活管）の為ガス漏洩防止状態下で行うことが必要であり、このためにサドル２４にホールソー３７を気密保持状態に装着して穿孔する方法以外に、ホールソー３７全体をすっぽり覆うようガスバッグ（図示せず）をサドル２４に装着して穿孔することもできる。このような活管工事においてホールソーやガスバッグを用いて穿孔する方法それ自体は周知である。
【００３０】
▲３▼ 次いで、ホールソー３７を取り外し、代りに同図（ｂ）に示すごとくサドル２４にバルーン式管内閉塞装置２５をセットし、旧供給管２内にバルーン２６を収縮した状態で前記穿孔部２７から挿入し、加圧器（図示せず）により膨脹させて旧供給管２の内面に密接し、旧供給管２のガス流通を遮断する。バルーン式管内閉塞装置２５それ自体も周知のものである。
【００３１】
▲４▼ 次いで、同図（ｃ）に示すように、バルーン式管内閉塞装置２５、サドル２４を取り外し、旧供給管２のバルーン２６とサドル取付位置との間を切断する。その切断部は符号２Ｃで示す。
【００３２】
▲５▼ 次いで、同図（ｄ）に示すごとく第１新埋設ガス配管１１の先端部１１ａから数十センチくらい上流側の旧供給管２のみをロール式パイプカッターで切断し、この旧供給管２の切断部２Ｄより下流側部分２Ｅをバルーン２６ごと第１新埋設ガス配管１１からガスメーター側方向Ｘへ移動させて第１新埋設ガス配管１１の一部を露出させる。
【００３３】
▲６▼ 次いで、同図（ｅ）に示すごとく第１新埋設ガス配管１１の露出部をその弾性に抗してスクイズオフ装置の一対のロール部材２９ａ，２９ｂで挟むことにより絞り封止してガス流通を遮断し、旧供給管２の切断部２Ｄより下流側部分２Ｅを完全に引き抜き、第１新埋設ガス配管１１の先端部１１ａを切除する。
【００３４】
▲７▼ 最後に、同図（ｆ）に示すごとく第１新埋設ガス配管１１の絞り封止部より下流の切除端部１１ｃに、ガスメーター側から布設され、第１新埋設ガス配管１１と同径・同材質の第２新埋設ガス配管３０の端部を、通電により発熱する電熱線３１ａを埋設した電気融着継手等の継手３１で突き合わせ状に接合する。この接合後、絞り封止状態を解除することにより第１新埋設ガス配管１１は元の真っ直ぐな状態に弾性復帰して第２新埋設ガス配管３０とガス流通状態になる。以上の作業で民地側の旧埋設ガス配管３の入替え作業も終える。なお、旧供給管２の切断部２Ｄより下流側部分２Ｅは撤去されるが、その切断部２Ｄより上流側部分は埋め残される。
【００３５】
民地側の旧埋設ガス配管３（旧供給管２）の入替え作業は、バルーン２６を旧埋設ガス配管３内に挿入する上記作業に代えて、次のようにバルーン２６を第１新埋設ガス配管１１内に挿入する作業によっても行うことができる。
【００３６】
▲１▼ 先ず、上記▲１▼の場合と同様に、先行工事の情報に基き民地側の旧供給管２内に挿入されている樹脂製の第１新埋設ガス配管１１の先端位置の周辺を掘削し、該先端部分を特定する。
【００３７】
▲２▼ 掘削後、図６（ａ）に示すごとく第１新埋設ガス配管１１の先端部１１ａから数十センチくらい上流側の旧供給管２の外周の穿孔予定箇所にサドル２４を取り付け、このサドル２４に上記ホールソー３７と同じホールソー３７を同じように装着し、このホールソー３７で第１新埋設ガス配管１１及び旧供給管２の穿孔予定箇所を穿孔する。その穿孔部を符号２７で示す。
【００３８】
▲３▼ 次いで、ホールソー３７を取り外し、代りに同図（ｂ）に示すごとくサドル２４に上記バルーン式管内閉塞装置２５と同じものをセットし、第１新埋設ガス配管１１内にバルーン２６を収縮した状態で前記穿孔部２７から挿入して加圧器（図示せず）により膨らませて第１新埋設ガス配管１１内のガス流通を遮断する。
【００３９】
▲４▼ 次いで、同図（ｃ）に示すごとくバルーン式管内閉塞装置２５、サドル２４を取り外し、第１新埋設ガス配管１１及び旧供給管２のバルーン２６とサドル取付位置との間を切断する。その切断部は符号２Ｃ，１１ｃで示す。
【００４０】
▲５▼ 次いで、同図（ｄ）に示すごとく第１新埋設ガス配管１１の前記切断部１１ｃから数十センチくらい上流側の旧供給管２のみをロール式パイプカッターで切断し、この旧供給管２の切断部２Ｄから下流側部分２Ｅを第１新埋設ガス配管１１からガスメーター側方向Ｘへ移動させて第１新埋設ガス配管１１の一部を露出させる。
【００４１】
▲６▼ 次いで、同図（ｅ）に示すごとく第１新埋設ガス配管１１の露出部をスクイズオフ装置の一対のロール部材２９ａ，２９ｂで挟むことにより絞り封止してガス流通を遮断し、旧供給管２の切断部２Ｄから下流側部分２Ｅを完全に引き抜く。
【００４２】
▲７▼ 最後に、同図（ｆ）に示すごとく絞り封止状態下で、バルーン２６を抜き出し、第１新埋設ガス配管１１の絞り封止部より下流の先端部１１ｃに、ガスメーター側から布設され、第１新埋設ガス配管１１と同径・同材質の第２新埋設ガス配管３０の端部を電気融着継手等の継手３１で突き合わせ状に接合する。この接合後、絞り封止状態を解除することにより第１新埋設ガス配管１１は元の真っ直ぐな状態に弾性復帰して第２新埋設ガス配管３０とガス流通状態になる。
【００４３】
【発明の効果】
本発明によれば、先行して行う公道側の旧埋設ガス配管の入替え時に、第１新埋設ガス配管の先端部を、地中に残される旧埋設ガス配管の切断端部から該旧埋設ガス配管内に民地下に至る深さにまで挿入するので、後日、民地側の旧埋設ガス配管を入れ替える時は民地を掘削するだけで足り、公道側を再度掘り起こす必要が無くなり、民地側の旧埋設ガス配管の入替え作業を能率的に行うことができ、工期の短縮化を図れる。
また、民地側の旧埋設ガス配管の入替え作業は、バルーンを旧埋設ガス配管内又は第１新埋設ガス配管内に挿入し、第１新埋設ガス配管の先端側の一部を絞り封止することにより活管状態でも安全かつ容易に行えるという利点がある。
【図面の簡単な説明】
【図１】公道側の旧埋設ガス配管のみを新埋設ガス配管に入替えた後の状態の断面図である。
【図２】公道側及び民地側双方の旧埋設ガス配管を新埋設ガス配管に入替えた状態の断面図である。
【図３】図１における要部の拡大断面図である。
【図４】図３の継手部分の拡大断面図である。
【図５】（ａ）〜（ｆ）は民地側の入替え工程図である。
【図６】（ａ）〜（ｆ）は他の実施例の民地側の入替え工程図である。
【図７】他の実施例の新埋設ガス配管の先端部のシール部の断面図である。
【図８】（ａ）〜（ｃ）は更に他の実施例の新埋設ガス配管の先端部のシール工程図である。
【図９】公道側から民地側にわたって旧埋設ガス配管が埋設されている状態の断面図である。
【図１０】従来例の公道側及び民地側双方の旧埋設ガス配管を新埋設ガス配管に入替えた状態の断面図である。
【符号の説明】
１旧本管
３旧埋設ガス配管
６管継手
１１第１新埋設ガス配管
１１ａ第１新埋設ガス配管の先端部
２６バルーン
２７穿孔部
３０第２新埋設ガス配管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a construction method for replacing an old buried gas pipe made of a cast iron pipe or a steel pipe buried from a public road side to a private side with a resin-made new buried gas pipe.
[0002]
[Prior art]
An example of a construction method for replacing the existing old buried gas pipe made of metal with a new buried gas pipe made of resin will be described with reference to FIGS.
FIG. 9 shows the state before the replacement of the old buried gas pipe from the public road side to the private side, and FIG. 10 shows the state after the replacement with the new buried gas pipe.
[0003]
As shown in FIG. 9, the old buried gas pipe 3 including the main pipe 1 under the public road, the branch saddle 32 and the supply pipe 2 up to the public-private boundary line C (hereinafter referred to as the supply pipe 2 under the public road) is a gas company corporation. The old buried gas pipe 3 which is a supply pipe 2 from the public-private boundary line C to the gas meter (hereinafter referred to as a private underground supply pipe 2) is an asset of the consumer. Therefore, the gas company replaces the main pipe 1 under the public road and the supply pipe 2 up to the public-private boundary line C, and the private underground supply pipe 2 even if the old buried gas pipe 3 is replaced systematically. In some cases, it is not always possible to perform the replacement. In this case, the gas company is forced to adopt a time difference construction in which only the replacement of the old pipe under the public road is planned in advance, and the supply pipe 2 in the private underground is replaced later.
[0004]
When exchanging old pipes under public roads in advance, the private land cannot be excavated freely. First, as shown in FIG. The ground up to the vicinity is excavated, and the old supply pipe 2 under the public road is cut at a portion exposed in the pit formed by the excavation, and only the headquarters 1, the branch saddle 32 and the supply pipe 2 under the public road are cut. Are replaced with the newly-prepared resin headquarter 4, branch saddle 5, and supply pipe 33. At this time, the end of the new supply pipe 33 under the public road and the cut end facing the pit of the aged supply pipe 2 in the private basement are connected using the transition joint 34 and the relay pipe 35. . And the construction which replaces supply pipe 2 under private land B with new resin supply pipe 36 is performed at a later date.
[0005]
[Problems to be solved by the invention]
However, the replacement work to the new supply pipe 33 under the public road and the connection work between the new supply pipe 33 and the old buried gas pipe 3 on the private side left underground are public and private sectors. In the above replacement method, which is performed near the boundary line C, when the supply pipe 2 in the private basement is replaced at a later date, the public road side public-private boundary line C must be dug up again.
[0006]
The purpose of the present invention is to solve such problems, and even when adopting the above-mentioned time difference construction, the public road side should be reconnected when replacing the underground gas pipes in the private basement at a later date. It is an object of the present invention to provide a method for exchanging buried gas pipes, which eliminates the need to dig up and improves the efficiency of exchanging old buried gas pipes on the private side and shortening the construction period. It is another object of the present invention to provide a method for replacing buried gas pipes in which replacement of old buried gas pipes in a private basement can be performed safely and easily in a live pipe state.
[0007]
[Means for Solving the Problems]
As shown in FIGS. 1 to 8, the buried gas pipe replacement method according to the present invention includes a metal old buried gas pipe 3 that is aged from a main road 1 on a public road to a gas meter on a private side. A method for replacing the buried gas pipe, in which the public road side portion and the private side portion of the old buried gas pipe 3 are replaced with the first and second new buried gas pipes 11 and 30 made of resin by time difference construction, A part of the old buried gas pipe 3 below is cut to remove the main pipe 1 from the cut portion of the old buried gas pipe 3, and the private side portion is grounded from the cut portion of the old buried gas pipe 3. The first new buried gas pipe 11 made of resin having an outer diameter smaller than the inner diameter of the old buried gas pipe 3 is buried in the removed portion of the old buried gas pipe 3 under the public road. In addition, the front end 1 of the first new buried gas pipe 11 a replacing step of inserting a from the cut end portion of the old buried gas pipe 3 left in the ground to a depth reaching the private basement in the old buried gas pipe 3, and the old left in the ground A step of sealing the gap between the cut end of the buried gas pipe 3 and the outer periphery of the first new buried gas pipe 11 in an airtight manner with the pipe joint 6, and then in the old buried gas pipe 3 on the private side The excavation of the ground around the tip position of the first new buried gas pipe 11 inserted into the first buried gas pipe 11 and the old buried gas pipe 3 separated from the tip portion 11a of the first new buried gas pipe 11 by a predetermined distance to the gas meter side. A step of perforating a part of the outer periphery in a gas leakage prevention state, a step of inserting a balloon 26 from the perforated portion of the old buried gas pipe 3 into the old buried gas pipe and shutting off gas flow, and the old buried Cut the gas meter side of the gas pipe 3 from the balloon 26 Cutting the portion of the old buried gas pipe 3 away from the tip of the first newly buried gas pipe by a predetermined distance from the front end to the public road side, and the gas meter side portion from the cut portion of the old buried gas pipe 3 to the gas meter side. Moving the direction of the first newly buried gas pipe 11 to expose a portion of the first newly buried gas pipe 11 on the side closer to the tip, the exposed portion of the first newly buried gas pipe 11 is squeezed and sealed, and the moved old buried gas pipe 3 Is drawn from the gas meter side at the end of the first new buried gas pipe 11 at the distal end side downstream from the throttle sealing portion of the first new buried gas pipe 11. And a step of joining the end of the second newly embedded gas pipe 30 having the same diameter and the same material as the above, and a step of releasing the throttle sealing state of the first newly embedded gas pipe 11 It is.
[0008]
In this case, the replacement work on the private side can be performed in the following work and process order in place of the work process.
As illustrated in FIGS. 6A to 6F, the ground around the tip position of the first new buried gas pipe 11 inserted in the old buried gas pipe 3 on the private side is excavated, and the first A step of perforating a part of the outer periphery of the old buried gas pipe 3 and the first newly buried gas pipe 11 which are separated from the front end portion 11a of the new buried gas pipe 11 by a predetermined distance to the public road side in a gas leakage preventing state, A step of inserting a balloon 26 from the perforated portion of the buried gas pipe 3 and the first new buried gas pipe 11 into the first new buried gas pipe 11 to block gas flow, and the old buried gas pipe 3 and the first new buried gas pipe 11 Cutting the portion closer to the gas meter than the balloon 26 of the buried gas pipe 11, and cutting a place away from the distal end portion 11 a of the first new buried gas pipe 11 of the old buried gas pipe 3 by a predetermined distance toward the public road; From the cutting part of this old buried gas pipe 3 Moving the meter side portion in the gas meter side direction to expose a portion of the first newly embedded gas pipe 11 on the side closer to the tip, and narrowing and sealing the exposed portion of the first newly embedded gas pipe 11; A process of pulling out the moved old buried gas pipe 3 toward the distal end of the first new buried gas pipe 11 and a distal end side downstream from the throttle sealing portion of the first new buried gas pipe 11 are installed from the gas meter side. A step of joining the end of the second new buried gas pipe 30 having the same diameter and the same material as the first new buried gas pipe, and a step of releasing the throttle sealing state of the first new buried gas pipe 11 It is to compose.
[0009]
According to the replacement method of the buried gas pipe having the above configuration, the old buried gas in which the tip of the first newly buried gas pipe is left in the ground when the old buried gas pipe on the public road side is replaced in advance. Since it is inserted from the cut end of the pipe to the depth to the private underground in the old buried gas pipe, when exchanging the old buried gas pipe on the private side at a later date, it is only necessary to excavate the private road. There is no need to dig up again.
[0010]
Replacing the old buried gas pipe on the private side is to drill a part of the old buried gas pipe or both the old buried gas pipe and the first new buried gas pipe in a gas leakage prevention state, After inserting into the old buried gas pipe or the first new buried gas pipe, a part of the front end side of the first newly buried gas pipe is squeezed and sealed, so that it can be performed safely and easily even in a live pipe state. .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view of a state where only the old buried gas pipe on the public road side is replaced with a new buried gas pipe. Fig. 2 is a cross section of a state where the old buried gas pipe on both the public road side and the private side is replaced with the new buried gas pipe. 3 is an enlarged cross-sectional view of the main part in FIG. 1, FIG. 4 is an enlarged cross-sectional view of the joint part of FIG. 3, FIG. 5 is a replacement process diagram of the private side, and FIG. FIG. 7 is a sectional view of the seal portion at the tip of the new buried gas pipe according to another embodiment, FIG. 8 is a flowchart of the seal process at the tip of the newly buried gas pipe according to another embodiment, and FIG. FIG. 3 is a cross-sectional view of a state where an old buried gas pipe is buried from the public road side to the private side.
[0012]
In the stage before the buried gas pipe replacement method according to the present invention is implemented, as shown in FIG. 9, the main pipe 1 made of cast iron pipe or steel pipe, the branch saddle 32, and the supply pipe in the ground of the public road A An old buried gas pipe 3 such as 2 is buried, and a supply pipe 2 of the old buried gas pipe 3 is extended in the ground of the private area B in the direction of a gas meter (not shown) in the private area. . In FIG. 9, C indicates a public-private boundary line, and D indicates a lateral groove.
[0013]
The operation of exchanging the main pipe 1, the branch saddle 32 and the supply pipe 2 which are the old buried gas pipes 3 on the public road side by the method of the present invention is performed in the following order (1) to (9).
[0014]
(1) Excavate the surrounding ground where the main pipe 1, the branch saddle 32 and the supply pipe 2 of the public road A are buried. The amount of excavation at this time is sufficient to excavate the ground around the main pipe 1, the branch saddle 32 and the supply pipe 2 as shown by the symbol E in FIG. It is not necessary to drill widely.
[0015]
(2) After excavation, as shown in FIGS. 1 and 3, the old main pipe 1 and the old branch saddle 32 are removed and replaced with a new main pipe 4 made of resin such as polyethylene, and in the pit formed by excavation. The middle part of the old supply pipe 2 is cut, and the upstream part (main pipe side part) is removed from the cut part 2B of the old supply pipe 2, and the downstream part (private direction side part) from the cut part 2B. Leave buried.
[0016]
(3) A new branched saddle 5 made of a resin such as polyethylene is attached to the newly replaced main pipe 4 by electrofusion or the like as shown in FIG.
[0017]
(4) Next, if dirt or the like adheres to the inner surface of the cutting portion 2B of the old supply pipe 2 left in the ground, it is cleaned. In addition, a push ring 7, a retaining member 8, a retainer 9, and a gasket 10 on one end side of a pipe joint 6 made of a well-known mechanical joint that enables connection of pipes of different diameters and different materials are respectively connected to the old supply pipe 2 in this order. It is mounted on the outer periphery in the vicinity of the cutting part 2B (see FIG. 4).
[0018]
(5) Next, the tip 11a of the first new buried gas pipe 11 made of a new resin such as polyethylene is inserted into the old supply pipe 2 from the cut portion 2B of the old supply pipe 2 remaining in the ground ( (See FIGS. 1 and 3). At this time, the distal end portion 11a of the first new buried gas pipe 11 is inserted into the old supply pipe 2 up to a depth F reaching the bottom of the private land B. This insertion depth F is the private land B side at a later date. It is set to correspond to a place where this replacement work is easy to be performed at the time of replacement.
[0019]
When inserting the first new buried gas pipe 11, a seal packing 13 such as a rubber ring is attached to the concave groove 12 on the outer periphery of the front end portion 11 a of the first new buried gas pipe 11. Is fitted to the inner periphery of the tip end portion 11a and then inserted into the old supply pipe 2 to a predetermined depth F as described above. Thereby, the clearance gap between the outer periphery of the front-end | tip part 11a of the 1st newly embedded gas piping 11 and the inner surface of the old supply pipe | tube 2 is sealed airtightly, and a gas leak can be prevented.
[0020]
At that time, as shown in FIG. 7, prior to the insertion of the first new buried gas pipe 11, a hard ball 15 such as a steel ball having an outer diameter slightly larger than the inner diameter of the stiffener 14 is applied to the tip 11a of the pipe 11. Keep it. Thus, after the first new buried gas pipe 11 is inserted into the old supply pipe 2, the rear end side of the wire 16 that connects the distal end portion to the hard ball 15 is pulled in the upstream direction G, thereby pulling the hard ball 15 into the stiffener 14 and the second stiffener 14. 1 The tip portion 11a can be expanded in diameter by being pulled back through the new buried gas pipe 11, and the seal packing 13 can be strongly pressed against the inner surface of the old supply pipe 2 by this expansion, so that it is stable. It can be surely sealed.
[0021]
Further, as a means for sealing the gap between the outer periphery of the front end portion 11a of the first new buried gas pipe 11 and the inner surface of the old supply pipe 2 in an airtight manner using the seal packing 13 and the stiffener 14, the following is possible. Means can also be employed.
As shown in FIG. 8A, the stiffener 14 has an outer diameter slightly larger than the inner diameter of the first new embedded gas pipe 11, and only the outer diameter of the one end portion 14 a is the first newly embedded gas pipe 11. A stepped cylindrical stiffener 14 is prepared which is formed to be equal to or smaller than the inner diameter and is provided with an outward flange 14b on the outer periphery of the other end.
Prior to the insertion of the first new buried gas pipe 11, the seal packing 13 is fitted into the concave groove 12 on the outer periphery of the front end portion 11a of the first new buried gas pipe 11, and the stiffener 14 is fitted on the inner circumference of the front end portion 11a. Only one end portion 14a of the wire 16 and a hard ball 15 such as a steel ball connected to the tip end portion 16a of the wire 16 is fitted inside the one end portion 14a of the stiffener 14, and the opening edge 14c of the one end portion 14a is formed. The hard ball 15 is temporarily fixed and held in the one end portion 14a by narrowing down to a small diameter. On the other hand, a presser collar 40 is screwed and set to a male screw on the outer periphery of the base end portion 11b of the first new buried gas pipe 11, and a hollow shaft-shaped wire lead-in bolt is fitted to a female screw 41 on the rear end wall 40a of the presser collar 40. 42 is screwed through. The rear end portion 16b of the wire 16 is inserted into the tubular wire fixing jig 44 and the wire pulling bolt 42 arranged at the rear end portion of the wire pulling bolt 42 via the bearing 43, and then the wire fixing jig 44 is inserted. By tightening the press screw 45 attached to the wire 16, the rear end portion 16 b of the wire 16 is fixed in the wire fixing jig 44 at the tip of the press screw 45.
[0022]
Thus, after the first new buried gas pipe 11 is inserted into the old supply pipe 2, when the wire 16 is pulled by rotating the wire pulling bolt 42 with a tool and moving it backward from the presser collar 40, FIG. 8 (b). As shown, the stiffener 14 is drawn through the hard ball 15 into the inner periphery of the distal end portion 11a of the first newly embedded gas pipe 11 until the outward flange 14b is brought into contact with the distal end surface 11c of the first newly embedded gas pipe 11. . By pulling in the stiffener 14, the tip end portion 11 a of the first new embedded gas pipe 11 is expanded, and the seal packing 13 is strongly pressed against the inner surface of the old embedded gas pipe 2. When the wire pulling bolt 42 is further rotated to pull the wire 16 strongly, the hard ball 15 is pulled away from the one end portion 14a of the stiffener 14 as shown in FIG.
In this case as well, the gap between the outer periphery of the front end portion 11a of the first new buried gas pipe 11 and the inner surface of the old supply pipe 2 can be stably and surely sealed by the seal packing 13 and the stiffener 14. After the sealing operation, the hard ball 15 and the wire 16 are removed from the base end portion 11 b of the first newly embedded gas pipe 11 together with the presser collar 40 and the wire fixing jig 44.
[0023]
(6) Next, the joint body 17 of the pipe joint 6 is inserted into the first new buried gas pipe 11 from the base end portion 11 b of the first new buried gas pipe 11, and the male threaded portion 18 on one end side of the joint body 17. Is screwed into the female thread of the push ring 7 on the old supply pipe 2 to temporarily fix the joint body 17 to the old supply pipe 2.
[0024]
(7) Next, the gasket 19 on the other end side of the pipe joint 6, the retainer 20, the retaining member 21, and the push ring 22 are inserted through the first new buried gas pipe 11 in this order (FIG. 4). reference).
[0025]
(8) Next, the base end portion 11b of the first new buried gas pipe 11 is connected to the branch saddle 5 by using an electric fusion joint 23 or the like in which a heating wire 23a that generates heat when energized is buried (FIG. 3). reference).
[0026]
(9) Finally, one end side and the other end side of the joint body 17 are finally tightened, so that a gap between the cutting portion 2B of the old supply pipe 2 and the outer periphery of the first new buried gas pipe 11 becomes a pipe. It is sealed airtight through the joint 6. This can prevent gas leakage from the gap between the outer periphery of the first new buried gas pipe 11 and the inner surface of the cut portion 2B of the old supply pipe 2, and the replacement of the old supply pipe 2 on the private side is possible. There will be no hindrance to gas use during the period. With the above operation, the replacement work of the old buried gas pipe 3 on the public road side, that is, the preceding work is completed.
[0027]
Next, the replacement work of the supply pipe 2 which is the old buried gas pipe 3 on the private side, which is carried out after a lapse of a predetermined period after finishing the preceding construction, will be described with reference to FIGS. This replacement work is performed in the following order (1) to (7).
[0028]
(1) First, the ground around the position of the front end portion 11a of the first resin-made first buried gas pipe 11 inserted in the old supply pipe 2 on the private side is excavated based on the information of the preceding construction, and the front end Identify the part. At this time, since the leading end 11a of the first new buried gas pipe 11 has been inserted into the old supply pipe 2 to a depth F reaching the bottom of the private area B in the preceding construction, It is only necessary to excavate the ground around the position of the front end portion 11a of the first newly buried gas pipe 11, and it is not necessary to excavate widely to the vicinity of the public-private boundary line C, and it is not necessary to excavate the public road A again. I'll do it.
[0029]
(2) After the excavation, as shown in FIG. 5 (a), a saddle 24 is attached to a planned drilling portion of the old supply pipe 2 on the gas meter side from the front end portion 11a of the first newly buried gas pipe 11 by several tens of centimeters. A hole saw 37 for drilling an existing steel pipe or the like is mounted in an airtight state, and a hole to be drilled in the old supply pipe 2 is drilled with the hole saw 37. The perforated portion is denoted by reference numeral 27. This drilling operation needs to be performed in a gas leakage prevention state because the first newly buried gas pipe 11 is in a gas flow state (live pipe). For this purpose, the hole saw 37 is kept in an airtight state in the saddle 24. In addition to the method of mounting and drilling, a gas bag (not shown) may be mounted on the saddle 24 so as to completely cover the entire hole saw 37. The perforation method using a hole saw or a gas bag in such live pipe construction is well known.
[0030]
(3) Next, the hole saw 37 is removed, and instead the balloon-type intravascular occlusion device 25 is set in the saddle 24 as shown in FIG. And is inflated by a pressurizer (not shown) so as to be in close contact with the inner surface of the old supply pipe 2 and shut off the gas flow in the old supply pipe 2. The balloon type intravascular occlusion device 25 itself is also well known.
[0031]
(4) Next, as shown in FIG. 4C, the balloon-type in-tube occlusion device 25 and the saddle 24 are removed, and the space between the balloon 26 of the old supply pipe 2 and the saddle mounting position is cut. The cut portion is denoted by reference numeral 2C.
[0032]
(5) Next, as shown in FIG. 6 (d), only the old supply pipe 2 upstream from the front end portion 11a of the first new buried gas pipe 11 by several tens of centimeters is cut with a roll-type pipe cutter. The downstream portion 2E from the second cutting portion 2D is moved together with the balloon 26 in the gas meter side direction X from the first newly embedded gas pipe 11 to expose a part of the first newly embedded gas pipe 11.
[0033]
(6) Next, as shown in FIG. 6 (e), the exposed portion of the first newly buried gas pipe 11 is squeezed and sealed by being sandwiched between a pair of roll members 29a and 29b of the squeeze-off device against its elasticity. The gas flow is shut off, the downstream portion 2E is completely withdrawn from the cutting portion 2D of the old supply pipe 2, and the front end portion 11a of the first newly buried gas pipe 11 is cut off.
[0034]
(7) Finally, as shown in FIG. 5 (f), the cut end 11c downstream of the throttle seal portion of the first new buried gas pipe 11 is laid from the gas meter side, and the same as the first new buried gas pipe 11. The ends of the second newly embedded gas pipe 30 having the same diameter and the same material are joined in a butted manner by a joint 31 such as an electric fusion joint in which a heating wire 31a that generates heat by energization is embedded. After the joining, by releasing the throttle sealing state, the first newly buried gas pipe 11 is elastically restored to the original straight state and becomes in a gas flow state with the second newly buried gas pipe 30. With the above operation, the replacement work of the old buried gas pipe 3 on the private side is also completed. In addition, although the downstream part 2E is removed from the cutting part 2D of the old supply pipe 2, the upstream part is left unfilled from the cutting part 2D.
[0035]
The replacement work of the old buried gas pipe 3 (old supply pipe 2) on the private side is replaced with the above work of inserting the balloon 26 into the old buried gas pipe 3, and the balloon 26 is replaced with the first new buried gas as follows. It can also be performed by inserting the pipe 11 into the pipe 11.
[0036]
(1) First, as in the case of (1) above, the vicinity of the tip position of the first newly buried gas pipe 11 made of resin inserted in the old supply pipe 2 on the private side based on the information of the preceding construction And the tip portion is specified.
[0037]
(2) After the excavation, as shown in FIG. 6 (a), a saddle 24 is attached to the perforated scheduled location on the outer periphery of the old supply pipe 2 on the upstream side of the front end portion 11a of the first new buried gas pipe 11 by several tens of centimeters. The same hole saw 37 as the hole saw 37 is mounted on the saddle 24 in the same manner, and the first newly buried gas pipe 11 and the old supply pipe 2 are to be drilled with the hole saw 37. The perforated portion is denoted by reference numeral 27.
[0038]
(3) Next, the hole saw 37 is removed and, instead, the same one as the balloon-type tube closure device 25 is set in the saddle 24 as shown in FIG. In this state, the gas is inserted from the perforated part 27 and inflated by a pressurizer (not shown) to block the gas flow in the first newly embedded gas pipe 11.
[0039]
(4) Next, as shown in FIG. 4C, the balloon-type in-tube occlusion device 25 and the saddle 24 are removed, and the first newly embedded gas pipe 11 and the old supply pipe 2 are cut between the balloon 26 and the saddle mounting position. . The cut portion is denoted by reference numerals 2C and 11c.
[0040]
(5) Next, as shown in FIG. 4 (d), only the old supply pipe 2 upstream from the cutting part 11c of the first newly buried gas pipe 11 by several tens of centimeters is cut with a roll-type pipe cutter. The downstream portion 2E from the cutting portion 2D of the pipe 2 is moved in the gas meter side direction X from the first newly buried gas pipe 11 to expose a part of the first newly buried gas pipe 11.
[0041]
(6) Next, as shown in FIG. 5 (e), the exposed portion of the first newly-embedded gas pipe 11 is sandwiched between a pair of roll members 29a and 29b of the squeeze-off device to shut off the gas flow, The downstream portion 2E is completely pulled out from the cutting portion 2D of the old supply pipe 2.
[0042]
(7) Finally, as shown in FIG. 5 (f), the balloon 26 is pulled out under the throttle-sealed state, and laid from the gas meter side to the distal end portion 11c downstream from the throttle-sealed portion of the first newly embedded gas pipe 11. Then, the end of the second new buried gas pipe 30 having the same diameter and the same material as the first new buried gas pipe 11 is joined in a butted manner by a joint 31 such as an electric fusion joint. After the joining, by releasing the throttle sealing state, the first newly buried gas pipe 11 is elastically restored to the original straight state and becomes in a gas flow state with the second newly buried gas pipe 30.
[0043]
【The invention's effect】
According to the present invention, at the time of replacing the old buried gas pipe on the public road side, the old buried gas pipe is moved from the cutting end of the old buried gas pipe remaining in the ground. Since it will be inserted into the pipe to a depth that reaches the private basement, it will be sufficient to excavate the private land at a later date to replace the old buried gas pipe on the private side. The replacement work of the old buried gas piping can be efficiently performed, and the construction period can be shortened.
In addition, the replacement of the old buried gas pipe on the private side is performed by inserting a balloon into the old buried gas pipe or the first new buried gas pipe and squeezing and sealing a part of the tip side of the first newly buried gas pipe. By doing so, there is an advantage that it can be performed safely and easily even in a live tube state.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a state after replacing only an old buried gas pipe on a public road side with a new buried gas pipe.
FIG. 2 is a cross-sectional view showing a state in which the old buried gas pipe on both the public road side and the private side is replaced with a new buried gas pipe.
FIG. 3 is an enlarged cross-sectional view of a main part in FIG.
4 is an enlarged cross-sectional view of the joint portion of FIG.
FIGS. 5A to 5F are replacement process diagrams on the private land side.
FIGS. 6A to 6F are replacement process diagrams on a private land side according to another embodiment.
FIG. 7 is a cross-sectional view of a seal portion at the tip of a new buried gas pipe according to another embodiment.
FIGS. 8A to 8C are sealing process diagrams of a tip portion of a new buried gas pipe of still another embodiment.
FIG. 9 is a cross-sectional view of a state in which an old buried gas pipe is buried from the public road side to the private side.
FIG. 10 is a cross-sectional view showing a state in which the old buried gas pipe on both the public road side and the private side in the conventional example is replaced with a new buried gas pipe.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Old main pipe 3 Old buried gas piping 6 Pipe joint 11 1st new buried gas piping 11a The front-end | tip part 26 of 1st newly buried gas piping Balloon 27 Punching part 30 2nd new buried gas piping

Claims

An old metal gas pipe that is aged from the main road on the public road side to the gas meter on the private side is buried, and the public road side part and the private side part of the old buried gas pipe are made of resin by the time difference construction. 1, 2, a method for replacing buried gas pipes to be replaced with new buried gas pipes,
Cut a part of the old buried gas pipe under the public road to remove the old buried gas pipe from the cut part to the main pipe, and leave the private side part in the ground from the old buried gas pipe cut part. Cutting and removing process;
A resin-made first new buried gas pipe having an outer diameter smaller than the inner diameter of the old buried gas pipe is buried in the removed portion of the old buried gas pipe under the public road, and the tip of the first new buried gas pipe A replacement step of inserting a part from a cut end of the old buried gas pipe left in the ground to a depth reaching the private underground in the old buried gas pipe;
Sealing the gap between the cut end portion of the old buried gas pipe left in the ground and the outer periphery of the first new buried gas pipe with a pipe joint in an airtight manner;
After that, the ground around the tip position of the first new buried gas pipe inserted in the old buried gas pipe on the private side is excavated, and only a predetermined interval from the tip of the first new buried gas pipe to the gas meter side. Perforating a part of the outer circumference of the old buried gas pipe away from the gas leakage prevention state,
Inserting a balloon from the perforated portion of the old buried gas pipe into the old buried gas pipe to shut off the gas flow;
Cutting the gas meter side location from the balloon of the old buried gas pipe;
A portion of the old buried gas pipe that is separated from the front end of the first new buried gas pipe by a predetermined distance is cut, and the gas meter side portion is moved in the gas meter side direction from the cut portion of the old buried gas pipe. A step of exposing a part of the new buried gas pipe closer to the tip, and squeezing and sealing the exposed portion of the first new buried gas pipe;
Withdrawing the moved old buried gas pipe toward the tip of the first new buried gas pipe;
The end of the second newly buried gas pipe having the same diameter and the same material as that of the first newly buried gas pipe is laid from the gas meter side at the end of the first downstream side of the first newly buried gas pipe downstream from the throttle sealing portion. Joining, and
Releasing the throttle-sealed state of the first new buried gas pipe;
A method for exchanging buried gas pipes, characterized by comprising:

An old metal gas pipe that is aged from the main road on the public road side to the gas meter on the private side is buried, and the public road side part and the private side part of the old buried gas pipe are made of resin by the time difference construction. 1, 2, a method for replacing buried gas pipes to be replaced with new buried gas pipes,
Cut a part of the old buried gas pipe under the public road to remove the old buried gas pipe from the cut part to the main pipe, and leave the private side part in the ground from the old buried gas pipe cut part. Cutting and removing process;
A resin-made first new buried gas pipe having an outer diameter smaller than the inner diameter of the old buried gas pipe is buried in the removed portion of the old buried gas pipe under the public road, and the tip of the first new buried gas pipe A replacement step of inserting a part from a cut end of the old buried gas pipe left in the ground to a depth reaching the private underground in the old buried gas pipe;
Sealing the gap between the cut end portion of the old buried gas pipe remaining in the ground and the outer periphery of the first new buried gas pipe with a pipe joint in an airtight manner;
After that, the ground around the tip position of the first new buried gas pipe inserted in the old buried gas pipe on the private side is excavated, and only a predetermined distance from the tip of the first new buried gas pipe to the public road side. Perforating a part of the outer periphery of the old buried gas pipe and the first newly buried gas pipe away from each other under a gas leakage prevention state;
Inserting a balloon from the perforated portion of the old buried gas pipe and the first new buried gas pipe into the first newly buried gas pipe to shut off the gas flow;
Cutting the gas meter side portion from the balloon of the old buried gas pipe and the first new buried gas pipe;
A portion of the old buried gas pipe that is separated from the front end of the first new buried gas pipe by a predetermined distance is cut, and the gas meter side portion is moved in the gas meter side direction from the cut portion of the old buried gas pipe. A step of exposing a part of the new buried gas pipe closer to the tip, and squeezing and sealing the exposed portion of the first new buried gas pipe;
Withdrawing the moved old buried gas pipe toward the tip of the first new buried gas pipe;
The end of the second newly buried gas pipe having the same diameter and the same material as that of the first newly buried gas pipe is laid from the gas meter side at the end of the first downstream side of the first newly buried gas pipe downstream from the throttle sealing portion. Joining, and
Releasing the throttle-sealed state of the first new buried gas pipe;
A method for exchanging buried gas pipes, characterized by comprising: