The ztj-a stage collar is the device for discontinuous cementing operation in two times. It mainly consists of two-stage coupling (built-in hollow plug), first-stage plug, shut-off baffle, free-fall opening plug and closing plug. 1 drilling free stage tool use the standalone action model, that is every action, just is the related part to do, other parts will not be affected, prevent the operation mistake, for example, advance opening and advance closing. 2 there have the two plugsdesign for first-stage cementing. That is after first-stage plug downwards to stage tool, and compounded with hollow plug which in the stage tool, use the peculiarity of good isolation impression of hollow plug, solve the question that remain slurry in the inside wall of casing. 3 second-stage cementing use the design of easy open, easy close, slide smoothly. Free-fall plug use the heavy design, closing plug use the design of two element composite, it will realize drilling free cementing operation in the real sense. 4 all accessories, made from premium quality rubber or aluminum material, have very good anti-rotating mechanism that makes drillout easy.  specification(in) 51/2â inï¼?ð¤139.7mmï¼? First-stageâ plugâ openingâ pressureï¼?mpa 2 Free-fallâ plugâ openingâ pressureï¼?mpa 6â±1 Closingâ plugâ cosingâ pressureï¼?mpa 6â±1 Sealingâ capacityï¼?mpa 25 Ratedâ loadï¼?t 120 Connectionâ thread Apiâ 51/2inâ ltcâ (btc) Max. odï¼?mm Ф174 Drill-outâ idï¼?mm Ф118 Lengthâ ofâ first-stageâ plugï¼?mm 363 Lengthâ ofâ free-fallâ plugï¼?mm 240 Lengthâ ofâ closingâ plugï¼?mm 295 Lengthâ ofâ shut-offâ baffle, â mm 320 Overallâ lengthï¼?mm 1090
