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Testing & Commissioning of Heat Exchangers

Preparation & Pre Testing & Commissioning Work

Before start of testing & commissioning the completeness of the system shall be ensured by physical inspections and interpreting the previously submitted and approved work inspection reports/records.

All tools/equipment/instruments required are calibrated and having valid certificate.

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Safe access to work areas shall be provided and shall be approved by the safety person prior to commencement of works.

Temporary electricity supply to be arranged where required.

Testing & Commissioning Sequence

Commissioning and pre-checks

Commissioning may only be done by staff which has been trained specially for the job or by suppliers commissioning engineers.

Control, maintenance and repair of the installation may only be done by authorized, trained and properly instructed staff.

Maintenance and cleaning may only be done with a shutdown heat exchanger.

Check if all connections are fitted correctly.

Filtration:

The media flowing through the heat exchanger should not contain particles larger than 0,5 mm diameter. If necessary filters should be fitted.

Check the pressures and temperatures of the media and make sure that these are not more than the values specified on the identification plate.

It is essential that the heat exchanger is not subjected to thermal or mechanical shock as this could lead to premature gasket failure

 Operation

Start cold circuit first, than the hot circuit.

– Fully vent the system;

– Close isolation valves between pump and exchanger;

– Fully open valve fitted into return line from the exchanger;

– Start the circulation pump;

– Gradually open closed valve fitted to inlet line of exchanger;

– Vent system again if necessary.

Repeat the above for the secondary circuit.

When using steam as one of the media:

Use slow acting control valves and mechanisms only!

Before start up:

– Ensure that the steam control valve is fully closed

– Ensure that the heat exchanger is fully drained of condensate

– Start cold circuit first, then the steam side

– Open steam control valve slowly – this prevents water hammer of any

condensate in the steam line and reduces the pressure / thermal shock to

the exchanger

– Ensure that the steam trap is correctly sized to allow full condensate

discharge – this prevents water clogging inside the exchanger

Check for proper operation:

  • Check for pressure pulses in the system caused by the pumps or control valves. If found, stop operation and rectify. Continuous pressure pulses will result in fatigue failure of the plates.
  • Visually check the unit for leakages.
  • Check that all vents are closed to prevent air being sucked into the system

Heat Exchangers

When in operation, the conditions should not be changed. The maximum conditions specified on the identification name plate should not be exceeded.

Shut-down for a short period

If the plate type heat exchanger has to be shut down for a short period, please

follow the following procedure:

– Slowly close the control valve in the hot circuit whilst maintaining the

full flow in the cold circuit;

– Switch off the hot circuit pump;

– Cool down the heat exchanger to the level of the cold medium;

– Slowly close the control valve in the cold circuit;

– Switch off the cold circuit pump;

– Close all remaining isolating valves.

Shut-down for a long period

If the unit is to be taken off line for an extended period of time then the

following procedure can be followed:

– Allow unit to cool down;

– Drain all circuits;

– Lubricate tie bolts;

– Loosen tie bolts until the plate pack is “relaxed” (max. “a” size + 10%).

– The tie bolts should not be removed or loosened to such an extent that dirt is allowed to enter in-between the plates. We recommend that a warning notice is attached to the exchanger to remind personnel that the tie bolts need adjustment before the unit can be put back into service.

– Cover the plate pack with black plastic to exclude any sun light.

Opening the heat exchanger

When opening and assembling the heat exchanger observe the following:

– Measure and note the actual “a” size;

– Use the correct tools and lubricant;

– Shut down the heat exchanger

– Make sure the heat exchanger cools down (<40 ºC); with EPDM < 20 ºC

– Ensure there is no pressure on any part of the unit;

– Clean the clamping bolts and grease them;

– Loosen the clamping bolts equally in the correct order (fig. 10) i.e. that the follower shall have a parallel opening motion.

– Pull the follower back towards the column.;

– Remove the plates without damaging the gaskets.

Checklists

Testing & commissioning checklist for Heat Exchanger should be used when performing the T&C of the systems


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