Have you all seen it? The head of the heat exchanger is welded
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Have you ever seen it? The end caps of heat exchangers are welded. There are three heat exchangers in my unit, and all of their end caps are welded. What happens if such a heat exchanger develops an internal leak? Do we have to stop the operation for maintenance? And what is the frequency of such maintenance? Would it work if it is changed to a flange connection?:
There’s nothing wrong with using welded end caps, as long as the tests are successful. It’s not clear where the flange connections need to be modified; the head can be changed to a flat cover head.
Generally, in heat exchangers with a relatively large diameter, the tube box is welded to the tube sheet due to sealing issues; however, an access hole must be provided on the tube box stub for maintenance purposes. It is quite rare for the end cap to be welded directly to the tube sheet; in my opinion, this design is not very reasonable, as the poster mentioned, it makes maintenance difficult.
Maintenance should be taken into consideration during design.
For large-diameter equipment, the end caps are welded directly to the tube sheet. A nitrogen heat exchanger with a diameter of 2600 was manufactured in this way: the end caps were welded directly to the tube sheet, with flanges used at one end only, rather than having welding on both ends. A manhole was added at the welded end (otherwise it would have become a reactor: lol). It’s a design provided by foreigners, using stainless steel equipment. The main reason for this is to save money; a device flange costs over 200,000. :funk:
It should be possible. For the equipment in the fertilizer factory that our company used to manufacture, those with a diameter of over one meter were all welded together, and the tube boxes had manholes. When the pressure of the water in the shell side is applied, the inspector goes inside the tube sheet to check whether there is any leakage at the welds between the heat exchange tubes and the tube sheet
If the corrosion condition is clear, this approach is also feasible.
The main purpose is to reduce costs； Large-diameter versions come with manholes, while small-diameter versions are generally used in environments with favorable operating conditions (in such cases, the pipe leak is repaired by cutting open the end cap and then welding it back together)
There’s nothing wrong with using welded end caps, as long as the tests are successful. When we manufactured oil coolers, the American designs called for direct welding of the head to the tube sheet, with the head diameter being only 325 mm. However, a section of cylinder was added to the edge of the head so that it could be cut off during maintenance, repaired, and then welded back in place. Later, I changed the design to use flanges for connecting to the tube sheet, which made maintenance easier; moreover, the tube flanges required were not expensive at all.