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Figure 5-17.Correct and incorrect methods of installing flared fittings.
Inspection

Fluid Power - Intro to Hydraulics, Pneumatics, and how it all works
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FLARELESS-TUBE  CONNECTORS This  type  of  connector  eliminates  all  tube flaring, yet provides a safe, strong, and depend- able   tube   connection.   This   connector   consists of  a  fitting,  a  sleeve  or  ferrule,  and  a  nut. (See  fig.  5-18.) NOTE Although  the  use  of  flareless  tube connectors is widespread, NAVSEA policy is  to  reduce  or  eliminate  use  of  flareless fittings  in  newly  designed  ships;  the  extent to which flareless fittings are approved for use  in  a  particular  ship  is  reflected  in applicable  ship  drawings. Flareless-tube fittings are available in many of  the  same  shapes  and  thread  combinations  as flared-tube  fittings.  (See  fig.  5-16.)  The  fitting  has a counterbore shoulder for the end of the tubing to  rest  against.  The  angle  of  the  counterbore causes the cutting edge of the sleeve or ferrule to cut into the outside surface of the tube when the two  are  assembled. The nut presses on the bevel of the sleeve and causes it to clamp tightly to the tube. Resistance to  vibration  is  concentrated  at  this  point  rather than at the sleeve cut. When fully tightened, the sleeve or ferrule is bowed slightly at the midsection and  acts  as  a  spring.  This  spring  action  of  the sleeve  or  ferrule  maintains  a  constant  tension between the body and the nut and thus prevents the  nut  from  loosening. Prior  to  the  installation  of  a  new  flareless-tube connector, the end of the tubing must be square, Figure 5-18.—Flareless-tube  connector. concentric, and free of burrs. For the connection to be effective, the cutting edge of the sleeve or ferrule  must  bite  into  the  periphery  of  the  tube (fig. 5-19). This is ensured by presetting the sleeve or  ferrule  on  the  tube. Presetting Presetting consists of deforming the ferrule to bite  into  the  tube  OD  and  deforming  the  end  of the  tube  to  form  a  shallow  conical  ring  seating surface. The tube and ferrule assembly should be preset in a presetting tool that has an end section identical  to  a  fitting  body  but  which  is  made  of specially  hardened  steel.  This  tool  hardness  is needed to ensure that all deformation at the tube end  seat  goes  into  the  tube. Presetting is done with a hydraulic presetting tool or a manual presetting tool, either in the shop or  aboard  ship.  The  tool  vendor’s  instructions must  be  followed  for  the  hydraulic  presetting  tool. If  a  presetting  tool  is  not  available,  the  fitting body intended for installation is used in the same manner  as  the  manual  presetting  tool.  (If  an aluminum fitting is used, it should not be reused in the system.) The manual tool is used as follows: WARNING Failure  to  follow  these  instructions  may result  in  improperly  preset  ferrules  with insufficient bite into the tube. Improperly preset ferrules have resulted in joints that passed  hydrostatic  testing  and  operated  for weeks  or  years,  then  failed  catastrophically under shock, vibration, or normal operat- ing  loads.  Flareless  fitting  failures  have Figure 5-19.—Unused  ferrules. 5-15







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