Hot Tapping under pressure and temperature –
impressively simple!

The Hot Tapping Method under Pressure and Temperature


Hot tapping under pressure and temperature is part of a process that was developed
to connect new consumers to existing piping systems during ongoing operation
and thus reliably avoid interrupting the supply to existing consumers.

The previous conventional method is significantly more time-consuming and cost-intensive.
The pipeline has to be taken out of operation and drained.
A section of the existing pipe is then cut out and replaced with a T-piece.
Finally, the pipeline must be refilled with the medium and vented.

With the hot tapping Method pipe extensions due to small connections, but also larger outlets on pipelines in operation
can be carried out more economically and without restricting the supply to consumers connected to the network.
This is why the hot tapping method is becoming increasingly important for network consolidation and expansion.

In the following, we explain the hot tapping process step by step.

You can also find more information on our hot tapping page.

Applications:

  • can be used in heating and cooling systems - all other systems after testing
  • suitable for operating temperatures from -30°C to 200°C
  • maximum permissible operating pressure: 25 bar
  • for nominal diameters from DN 20 to DN 200

Certifications:

  • regular testing and certification by recognized experts in accordance with AGFW guidelines (Worksheet FW432 of the AGFW, Energy Efficiency Association for Heating, Cooling and KWK e.V.)
  • Hot tapping tool with TÜV component marking

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The hot tapping method in detail



1. Preparation of the hot tapping site

  • First of all, the type of medium in the pipeline to be drilled, its pressure and temperature, the nominal diameter and material of the existing pipeline as well as the nominal diameter of the outlet to be produced must be clarified.
  • In addition, it must be determined whether there is sufficient space at the construction site for the work and where the nearest pipe shut-off points are.
  • The fire alarm systems at the construction site must be switched off for the duration of the welding process.

2. Preparation of the hot tapping valve

  • The next step is to prepare the hot tapping ball valve. The welding end contour of the hot tapping valve (on the side facing away from the thread) must be formed according to the radius of curvature of the main pipe.
  • The hot tapping valve can be welded to the main pipe at any radial angle between 0 and 360 degrees. The angle to the pipe centerline must be exactly 90 degrees.
  • The hot tapping must not be carried out on the weld seam of a welded main pipe. The weld must meet the necessary strength requirements. If necessary, the connection must be reinforced with a collar ring.
  • No weld metal may enter the inside of the hot tapping valve in order to prevent the hole saw from seizing up and causing damage.
  • Finally, carry out an actuation test on the cooled hot tapping valve and ensure that the hot tapping ball valve is fully open for the hot tapping operation.

3. Preparation of the hot tapping tool

  • The adapter, hole saw and twist drill with expansion spring corresponding to the nominal diameter (DN) of the hot tapping ball valve must be selected in accordance with the adjacent adjustment table.
  • The drilling machine is set to clockwise rotation and drilling. Set the speed according to the adjustment table (last line).
  • Then screw the nominal diameter adapter firmly onto the hot tapping tool. Ensure that an undamaged O-ring is inserted into the ring groove of the adapter. Then mount the hole saw with the twist drill on the drill bit holder and fix this unit on the drill spindle.
  • The center drill must be inserted into the drill bit holder until the required 20 mm (dimension B) protrusion to the hole saw is present. It is advisable to use a ring magnet around the drill bit to catch more drill chips.
  • The drill spindle must be lubricated in the sealing area (grease/cutting oil) and inserted into the hot tapping tool up to the limit stop with the ball lock housing retracted to prevent it from jamming when the tool is mounted on the hot tapping ball valve.
  • The preassembled hot tapping tool is screwed onto the thread of the fully opened hot tapping ball valve until the sealing O-ring is seated on the outer welding end. Then, with the ball valve housing retracted, the spindle is carefully guided through the ball valve to the pipe with slight rotary movements.
  • The flushing valve must be opened and the hose laid in such a way that the flushing medium with the drilling swarf is drained away safely.
  • inally, the correctly adjusted drilling machine with angular gear is mounted on the square of the drilling spindle.

4. Leak test

  • It is essential to carry out a leak test with water or air through the flushing valve before each hot tapping. All components used for the hot tapping (weld seam between the existing pipe and the hot tapping ball valve, the weld seams on the hot tapping ball valve and all areas of the hot tapping tool) are checked for leaks.

5. Execution of the drilling

  • First, the centering hole is drilled by slowly and evenly advancing the feed unit until the pipe is drilled through (medium exits through the flushing hose). Once the centering bore has been completed, the flushing valve is closed.
  • For the main bore, the speed of the drilling machine is reduced to the value corresponding to the nominal diameter in accordance with the adjustment table.
  • With the drilling machine running, the spindle is then turned towards the main pipe until the hole saw is seated. The main hole is then drilled by turning the feed unit slowly and evenly. During the drilling process, the flushing tap is open to remove the drilling chips.
  • Once the main drilling is complete, the flushing valve is closed again and the drill spindle is carefully moved back to the limit stop with the ball lock housing retracted. The hot tapping ball valve is now free from the drilling unit and is closed. It is secured against unintentional operation by screwing on the cover screw.
  • Opening the flushing valve ensures that the hot tapping valve closes tightly and the hot tapping tool can be removed safely. The hot tapping tool is now removed and the circular cut-out is removed from the hole saw. The main drilling is complete.

6. Tapping protocol

  • In accordance with AGFW worksheet FW432, a drilling log must always be kept of the entire drilling operation.

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