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Hot tapping into water lines using a LPHT Hot Tapping Machine

Posted by Alan Hillier on Mar 16, 2018 6:36:00 AM


    

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The Mirage LPHT is a low pressure hot tapping machine, making it ideal for use on utility pipelines, such as water and gas lines requiring where holes from 3” up to 12”. This compact and portable machine is available with a choice of pneumatic and hydraulic drive motors used to rotate the cutter. The feed on this machine is advanced manually using a hand wheel up to a maximum stroke capacity of 30”.

How is the LPHT hot tapping machine installed on-site?

The LPHT Low Pressure Hot Tapping Machine is mounted onto a live pipeline via a pre-installed ‘Gate Valve’. It is secured by a series of high tensile 1” studs & nuts to the cutter housing or ‘Flange Adaptor’. The Flange Adaptor is then secured to the Gate Valve by a similar series of bolts or studs.

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Hot tapping projects can vary enormously, but to give you an overview, one example procedure is described below:

  • Before making any attempt to secure the LPHT312 to a ‘Gate Valve’, measurements should be taken to predict how far the cutter should be fed until it has completely cut through one side of the pipe wall. The image of a typical ‘Hot Tapping Data Sheet’ below shows the key measurements to determine.

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  • Before offering the machine to the pipe the cutter is retracted into the cutter housing to prevent it clashing with any of the pipeline assembly.
  • Next, a new sealing element is fitted between the ‘Cutter Housing’ and the ‘Gate Valve’.
  • The low pressure hot tapping machine can now be lifted and manoeuvred until the cutter housing is roughly aligned with the ‘Gate Valve’.
  • Ensure that before securing the LPHT to the pipeline, it is orientated so that any controls will be easily accessible when the machine is in place.
  • Next the corresponding holes between the cutter housing’ and gate valve are aligned.
  • Insert appropriate studs and nuts and tighten equally using a calibrated torque wrench to the correct torque figure.
  • Check the cutter has not been trapped by rotating the manual feed handwheel to see if the cutter can move freely up and down in the cutter housing.
  • The LPHT is now properly installed & the Motor hoses can now be connected.

Operating the low pressure hot tapping machine

  • Before cutting can commence, the cutter & pilot drill assembly needs to be positioned ready to cut. This is done with the motor turned off and the gate valve open. The position is adjusted by turning the manual feed handwheel until the pilot drill stops as it hits the pipe.
  • Then the cutter and pilot is retracted slightly by turning the feed handwheel in the opposite direction (approximately five turns). This is to allow a suitable gap between the pilot drill & pipe.
  • Next, rotation of the cutter can be started by engaging the hydraulic motor.
  • Refer to the pre-cut data that was previously calculated. The design of the machine will accept a depth stop if required.
  • To start feeding the cutter towards the pipe, the manual feed handwheel is rotated until and continued until it has made a complete cut through one side of the pipe.
  • When the cut is complete, stop rotating the manual feed handwheel and turn the hydraulic motor off.
  • The cutter is retracted by turning the manual feed handwheel in the opposite direction.
  • The pipeline ‘coupon’ will be retained by the pilot drill and can be recovered later when the machine is removed from the pipeline.

The table below is a summary of specifications of the LPHT Low Pressure Hot Tapping Machine

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Related resources

 

Download the Mirage Machines Hot Tapping and Line Stopping Buyers Guide

 

Topics: hot tapping

   

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