Issues with heat exchanger tube bundle replacement
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In pressure vessel regulations, the heat exchanger tube bundle is considered a major pressure-bearing component of the pressure vessel; does its replacement constitute a major maintenance or modification task? Replacing tube bundles is a common practice in the petroleum refining industry. Is it necessary to carry out supervision and inspection for such maintenance and renovation work? Could someone with relevant experience give some guidance?
According to Article 5.2.1 of TSG21-2016, replacing the heat exchange tube bundle constitutes a major repair. The work must be carried out by a construction unit with the appropriate qualifications, and notification of commencement must be given prior to starting the work. Additionally, in accordance with Article 5.2.5 of TSG21-2016, it is necessary to determine whether there has been a change in the welding method, in order to decide whether a pressure test is required for this repair, as well as whether heat treatment is needed. Then, in accordance with Article 6.1.2.2 of TSG21-2016, determine whether supervision inspection is required.
It is required, including supervision and inspection for tube bundle manufacturing, as well as supervision and inspection for on-site replacement and installation.
Replacing the heat exchange tube bundle constitutes a major repair, and it must be carried out by a unit with the appropriate qualifications for manufacturing pressure vessels.
May I ask if a hydrostatic test is required when replacing the tube bundle of a U-tube heat exchanger?
Of course, a hydrostatic test is required.
According to Article 5.2.5 of TSG21-2016, replacing the tube bundle of a BEU U-tube heat exchanger does not fall under the category of replacing major pressure-bearing components using welding (adhesive bonding) methods, and a pressure test is not a mandatory requirement. I’m not sure if this understanding is correct. :)
The U-tube and the tube sheet are mostly welded together (strength expansion joining is also used); how could it not be a welded connection? Do you mean that the restraint and the shell-side cylinder are not welded together? Even if the tube bundle is not welded to the shell, after the tube bundle is installed in the shell, with at least two gaskets and bolts used for fastening, can it be put into use with confidence without conducting a hydrostatic test?
Brother upstairs, replacing the tube bundle itself doesn’t involve welding or bonding; however, before installation, the tube bundle must undergo strength testing and pass it. In practice, after the tube bundle is installed, a seal test should be conducted on the seal between the tube bundle and the cylinder, as well as a pressure resistance test on the cylinder itself. During the equipment manufacturing process, the tube bundle is usually installed inside the cylinder before undergoing pressure tests or airtightness tests.