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					IMPERVIOUS GRAPHITE
   COMPACT BLOCK
  HEAT EXCHANGERS


                 INSTALLATION
                  OPERATION
                     AND
                MAINTENANCE
                INSTRUCTIONS




RALPH COIDAN LIMITED
DURHAM LANE INDUSTRIAL PARK
EAGLESCLIFFE, STOCKTON-ON-TEES
UNITED KINGDOM, TS16 0PN
TEL: +44 1642 790100
FAX: +44 1642 790488
E-mail: sales@coidan.co.uk
Web Site: www.coidan.co.uk
                                         CONTENTS
1.    Standard design of HYKARB block heat exchangers ............................... 4

2.    Inspection ................................................................................................. 4

3.    Testing ...................................................................................................... 4

4.    Installation................................................................................................. 5

5.    Change in application ............................................................................... 5

6.    Start-up and operation .............................................................................. 5

7.    General maintenance ............................................................................... 6

8.    Cleaning ................................................................................................... 6

9.    Repair of cubic bock heat exchangers ...................................................... 6

10. Plugging leaking holes ............................................................................. 6

11. Mixing and curing instructions for “CN” cement ....................................... 7




                                                         2
Part No.   Description
   1       Hykarb core block
   2       Process plate inlet
   3       Process plate outlet
   4       Service plate in/outlet
   5       Service plate return
   6       Process side pressure pad
   7       Service side gasket in/outlet
   8       Service side gasket return
   9       Tie bolts
  10       Process side stud bolts
  11       Service side stud bolts




      3
1.      Standard design of HYKARB block heat exchangers
The HYKARB compact block heat exchangers comprise of a solid impervious graphite block
drilled with the process side holes perpendicular to the service holes. The block is fitted with
multi-pass steel covers on the service side.

2.      Inspection
All HYKARB heat exchangers are subjected to rigid tests and inspection prior to shipment
from our Works. For your protection, inspect and test your new HYKARB heat exchanger as
soon as it is received so that any in-transit damage can be identified. Do not give the carrier a
clear receipt or put the equipment into storage before testing. If possible this inspection
should be carried out before the exchanger is removed from the carrier vehicle.
It is very difficult for the manufacturer to assume responsibility for any damage, which may be
found at a later date. Any damage should be reported immediately to the carrier and the
manufacturer should also be informed. Inspect all stub pipes, flanges, supports and exposed
HYKARB parts, then test the exchanger as follows:

3.      Testing
Support the heat exchanger on wooden blocks with the process side holes vertical as shown
below:




Remove all packaging material and connect the lower service branch to the water supply and
a valve and pressure gauge to the upper service connection.

Fill the service side with water through the lower service side branch allowing the displaced
air to be vented through the upper service side branch.

Pressurise the unit on service side to the test pressure on the nameplate of the exchanger.

A fall in pressure together with water leaking from process holes indicates breakage.
Breakage or gasket leakage should be reported to Ralph Coidan Limited immediately.

After testing, the exchanger should be completely drained of water to prevent damage caused
by freezing at a later date.



                                               4
4.      Installation
HYKARB compact block heat exchangers are usually installed as condensers in a vertical
position as shown below:




Brackets on the service headers should be used to support the heat exchanger. The service
fluid should be connected with the inlet as the lower connection and the outlet as the upper
connection. The process fluid is normally connected as shown above, however if the unit is to
be used as a “Knock-back” condenser with both the vapour inlet and condensate outlet at the
bottom, the manufacturer should be connected to check for suitability.

Wherever possible all pipe-work should be arranged in such a way as to allow complete
draining by gravity to eliminate the risk of damage by freezing during process shutdown.

5.      Change in application
HYKARB heat exchangers are designed for a specific duty, taking into account type of fluid,
pressures and temperatures involved. Before any changes are made, Ralph Coidan Limited
should be consulted. This is especially important if the proposed changes involve:
            a. Increased operating pressure
            b. Increased fluid temperature
            c. Increased flow rate
            d. Concentration
            e. Type of fluid handled

6.      Start-up and operation
Start the service side liquid flowing through the exchanger and ensure that any trapped air
has been vented.

Gradually introduce the process fluids and adjust both flow-rates o the specified values.

If the vapour is not being fully condensed check that the flow-rates and temperatures of both
process and service fluids are in accordance with the design specification. The flow-rate of
the service fluid should not be increased as this will have little effect and may damage the
exchanger. Instead the service fluid inlet temperature should be reduced. If the heat



                                               5
exchanger has been installed for some time check on the extent of scaling should also be
made.

Ensure that the process pipe-work is clear and valves are open to prevent build up of
condensate in the heat exchanger.

7.       General maintenance
Routine inspection, normal for process equipment, should be carried out for HYKARB
compact block heat exchangers. Gasket joints should be checked for leaks and discovered
should be rectified immediately to avoid damage to other equipment by corrosion. Corroded
bolts should be replaced promptly. Gaskets should always be replaced by items of identical
material since the original material was chosen to suit the particular duty handled by the
exchanger. If the performance of the heat exchanger is found to be gradually deteriorating,
the unit should be removed from service and examined for reasons of poor performance, for
example scale build-up or hole blockage. The unit should be cleaned as described in the
following section or returned Ralph Coidan Limited if refurbishment is required.

8.       Cleaning
To maintain the heat exchanger performance a regular cleaning programme is recommended.
Chemical cleaning methods are preferred, but depending on the type and composition of the
scale, mechanical methods may be used.

  a. After removing the four headers, inspect the holes for evidence of any scaling.
  b. Where scaling has occurred, so long as the holes are not completely blocked, they can
     be cleaned with a stiff close-fitting bristle or nylon brush, combined with frequent
     washings with hot or cold water. A low-pressure steam jet can also be used to clean the
     block. Under no circumstances should rods or drills be used to remove heavy scale
     deposits. If the scale has become a solid plug in the hole, it is best to leave the hole
     blocked rather than risk breaking through the graphite wall.
  c. If the above methods have not removed the scale deposit the unit should be re-
     assembled and a suitable solvent (not an oxidising agent) should be circulated through
     the unit, low-pressure steam could be passed through the service side to warm the
     solvent.
  d. Should the above methods fail to remove the scale, return the unit to Ralph Coidan Ltd.
     for inspection and repair, giving details of failure or reason for return.


9.       Repair of compact bock heat exchangers
HYKARB blocks are relatively easy to repair, providing they have not been cracked or the
gasket faces extensively damaged.

To determine the extent of damage to a block it can be tested as shown previously. Any
leaking holes should be marked, dried and plugged as described in the following section.

Important aspects of repair work are careful planning and cleanliness. All tools should be
cleaned after the repair is completed and care must be taken to protect personnel and tools
from residual corrosive process fluids. Where possible, the cause of the damage should be
identified and action taken to prevent recurrence.

Cement joints should be as thin as possible (less than 0.6mm) but large contact areas should
be provided.

10.      Plugging leaking holes
      I. Carefully clean the hole using a drill of the same diameter as the hole.




                                                6
      II. Check that the plug fits into the hole. If it is too large reduce the diameter using emery
          paper until the plug is about 1mm smaller than the hole.




                      5mm




                                Cement Dam
   III. Saw the plug in half.

   IV. Ensure that all the surfaces of the plug are clean and dry.

      V. Mix the cement in accordance with the instructions given on the following page.

   VI. Apply cement from to the inside of the hole and to the surface of the second plug and
       push the plug well into the hole.

  VII. Apply more cement to the inside of the hole and to the surface of the second plug and
       push the plug into the block as shown.

  VIII. Remove excess cement from the block face ensuring that all gasket faces are clean.
        The remaining traces of cement can be removed using a cloth soaked in acetone or
        MEK.

   IX. Repeat steps 7 and 8 for the other end of the hole.

      X. Cure the cement as described in the following section.

11.       Mixing and curing instructions for “CN” cement
„CN' cement is the cement most commonly used for HYKARB heat exchangers. It is a two-
component cement comprising a powder and a phenolic resin syrup, supplied in two separate
containers. The cured cement gives good adhesion, high strength and substantially non-
porous joints.

Storage
The powder must be stored under dry conditions and the resin kept in a cool place away from
sunlight or heat. In these conditions in sealed containers, the shelf life of the components is
about six months. During storage a small amount of water may separate and float on the
surface of the resin. This must be poured off before use, and never mixed into the resin.

Precautions to be taken in handling
People with sensitive skin may experience skin irritation when handling `CN' cement. It is,
therefore, advisable to wear barrier creams and rubber gloves, keeping the hands clean. If the
cement does come into contact with the skin it should be wiped off immediately and the
affected area washed well with soap and abrasive such as fine sand. Solvents should never
be used. Contact with eyes must be avoided.
Where possible avoid working in confined spaces. If this is necessary, ensure that adequate
ventilation is provided and goggles worn to avoid irritation to eyes. The cement should be
mixed in a well-ventilated, airy environment.



                                                  7
Mixing Proportions
The correct mixing proportions are:
     4 parts by weight `CN' powder.
     3 parts by weight 'CN' resin.

Mixing
This is best carried out in a clean container, using a clean trowel or suitable spatula. Half the
quantity of powder is placed in the container, 'CN' resin is added and mixed to a thin paste.
The remainder of the powder is added and mixed thoroughly taking care that any small lumps
of powder are broken down. The size of the batch mixed should not exceed the amount,
which can be used within the Pot Life of two to three hours at 10°C. Once the cement has
started to stiffen, it should be thrown away. More resin should never be added in an attempt
to make it workable.

„CN‟ cement should never be mixed or used in freezing conditions. The cement must not be
applied in wet, damp or dirty conditions.

Curing
The rate of setting and hardening is markedly influenced by the prevailing temperature. At
normal temperatures of about 20°C the mixed cement begins to set in about six hours and is
hard after twenty-four hours. Under cold conditions (10°C) hardening takes about seventy-two
hours and it is advisable to speed this up by mild dry heat (electric radiators, hot air blowers,
etc.). The setting period can be considerably accelerated by means of mild dry heat to raise
the temperature to approximately 80°C when initial cementing should be sufficiently hardened
off for further cementing work after about two hours. Curing is completed after six to eight
hours at 80°C.




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