Installation - Mounting - Maintenance - Cleaning - Failures - Fault finding
        
It is recommended that the heatexchanger´s shellside contains the process fluid with cooling fluid on the tubeside. The heatexchangers should be mounted as shown.
It is important that air is kept out of the system, particularly on the cooling water side. Aerated  water can cause erosion on the tubes.
         For better performance, heatexchangers should always be piped for counter flow, that is with the process fluid flowing in the opposite direction to that of  the cooling water. The cooling water inlet should be the lower and the outlet the upper connection. These ports must de diametrically opposite. Always circulate the recommended seawater and freshwater flows. Excessive flow can cause corrosion/  erosion, reduced flow can also damage and destroy the tubes!
         If a temperature control valve is fitted in the cooling water circuit, it should be on the inlet side to the heat exchanger. This will avoid  unnecessary pressurizing of the unit with cooling water.
         When cooling hydraulic oil, the heatexchanger should be fitted in the return to the tank line; this allows all the hot oil to pass through it. If this is not possible and if the pressure side of the pump is outside the working pressure of the heatexchanger, then it should be piped in its own circuit.
         In case of heatexchangers on board ship it  is essential that bronze endcovers are used, when using seawater for cooling.

Mounting scheme


Maintenance
Generally, heatexchangers require little attention in service. However, it is advisable to check the following points when carrying out routine maintenance to ensure good working order of  the heatexchangers and equipment to which they are fitted.

1.) Check that any temperature control valves in the cooling water circuit are functioning correctly, and that they are on the inletside of the cooler. Keep all valves open unless isolation of the heatexchanger is required. Any partially closed valves, especially on the shell side, will reduce cooling performance.

2.) If the cooling water contains slit or scale, a strainer or filter is probably fitted. Make sure this is clean and working properly.

3.) Regular checks on cooling water pH should be made and this should be maintained between 7,2 and 7,8. If this value falls below 7 the water becomes acidic and will cause corrosion/ erosion of the tubes.

4.) Always study any information given by water treatment specialists to ensure that all chemicals used in the control of cooling water conditions are compatible with the materials of the heatexchanger.

5.) Excessive water flows are wasteful and can cause erosion. Therefore, only circulate the amount recommended which is particularly important with seawater. Bear in mind, that a reduced flowrate can also destroy the heatexchanger!

6.) When draining the heatexchanger in cold weather, ensure that the waterside is completely empty. Partially filled units can be subject to corrosion and can possibly be damaged by frost!

It is important that the heatexchanger is kept clean on both, the shell and tube side, as a choked cooler will perform poorly.


Cleaning
Removal of the crews around the periphery each end will allow the endcovers and the seals to be removed. Following this operation the tubestack can be withdrawn from either end of  the body.
The method of cleaning should be in accordance with the degreasing solvent manufacturers´ instructions, generally we recommend immersing the dismantled heatexchanger into a tank and allowing to soak. This will loosen any  foreign matter in the form of grease or sludge and also any small contaminates within the tubes.
After general soaking the units should be removed from the tank and thoroughly washed down with clean fresh water, a 3 mm diameter rod pushed through the tubes (opposite to the flow direction) will remove any other obstructions.
It is recommended that the medium, which is more impure, should be connected to the tubeside.  The use of chemical detergents can be problematic as precautions have to be taken in view of chemical clear away of the material. Ask APTE replacement, just in case !

Having successfully finished cleaning  the heatexchanger should be reassembled in reverse order. In principle new O-seals have be fitted, were necessary.

Tube failures
Heatexchangers, unlike mechanical devices, rarely fail, but if misused they can fail like any other product. There is seldom any visible warning trouble, unlike a machine which runs incorrectly and shows obvious signs.

Generally speaking, the majority of problems facing a heatexchanger are those injuring the protective layer (patina). During normal operation this layer is being replaced automatically. There are basically four types of problems:

This is only a brief description of problems. The subject is complex and the purpose on these notes is to outline in very general terms what may occur under extreme conditions.

Fault finding
There are four conditions which can give an indication of possible problems with heatexchangers. These have been listed below with the cause and the remedy required.

Symptoms

A) Temperature increase on the shell and/ or tubeside.
B) Increase of pressure loss on the shell and/ or tubeside, compared to the initial.
C) Process fluid leaking into the cooling water circuit, or cooling water leaking into the process fluid.
D) Upon cleaning of oilcoolers, water is detected in the endchambers on the shellside
     (scar over on the bottom of the shellside)