Reading Notes – Updated Content of TEMA 2019 Version (Part 2)

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CB-4.4.2.1 Longitudinal baffle: 2007:2019: Interpretation: The thickness of the longitudinal baffle is differentiated based on carbon steel and stainless steel; the thickness for carbon steel remains at 6.4, while for alloy steel it can be 3.2. CB-4.4.2.3 Height of the weld leg of the longitudinal baffle: 2007:2019: Interpretation: No changes, broken chain references removed. Version 2007: C cites B, and B cites A. Version 2019: C cites A directly. RCB-4.4.3 – Vibration solutions for special operating conditions. Added in 2019: Interpretation: Regarding the scenarios 1–4 outlined in RCB-4.4.3, as for how to address the vibration of baffle plates, support plates, and tube bundles, TEMA provides 4 recommendations: 1. Reduce the spacing between baffle plates within the allowable pressure drop range. 2. On the baffle, additional tube banks are installed in the inlet and outlet spaces. 3. Provide additional support plates between the baffle plates, such that the support does not hinder fluid flow within the tube bundle. 4. Modify the baffle type (for example, change tube bundle vibration to NTIW with no tubes in the windows). RCB-4.5 Instructions on the spacing of baffle supports – New content added in 2019: Explanation: Section 4.5 deals with general baffles, as well as the specified minimum and maximum spacings between support plates, and the span without supports. The actual baffle spacing should be determined through heat transfer or hydraulic calculations, taking into account operating conditions, heat load, and the elimination of fluid-induced vibrations. RCB-4.6.1 Placement of impact barriers 2007: 2019: Explanation: The 2019 version places the explanations for the units of speed and density at the beginning, thereby avoiding the need to repeat those explanations wherever speed and density are used later on. Added detailed explanations for single-phase fluids ； It was added that other gases and Vapors contain steam. Another solution for when the speed is too high is provided, which involves adding an inlet distribution section. The installation of anti-erosion baffles remains basically the same as before; for more details, refer to the original article: Is it necessary to install anti-erosion baffles for non-abrasive gas-liquid mixtures? New addition RCB-4.6.2.5/6 2019: Explanation: Anti-erosion baffles can be replaced by anti-erosion rods or inlet distribution sections. RCB-4.6.3 Protection against backflow in the pipe side: 2007:2019: Explanation: This protection mechanism is required when either of the following conditions is met: two-phase flow, an axial inlet fitting, or a ρv2 value that meets certain criteria. Compared to GB151, it refers to the liquid ρv2 value + axial inlet nozzle. As mentioned above, two-phase fluids carry more energy than single-phase fluids, resulting in more severe erosion; therefore, it is unreasonable to refer to them simply as liquids, and a revision is recommended. RCB-4.8 Bypass Sealing 2007:2009: Interpretation: New requirements for anti-short circuit structures such as bypass baffles and pipe guards have been added. Compared to the previous brief mention, the 2019 version provides much more detail. It can be used for comparison with API660. RCB-4.9 Kettle Reboiler 2007:2019: Interpretation: Adds requirements for slides and stop plates for the U-tube bundles of kettle reboilers. In addition to the angle steel limits from 2007, a new limiting structure as shown in the figure above has been added. Delete R-6.33, CB-6.33 2007: 2019: Delete requirement interpretation: The flatness requirement in CB-6.33 of the 2007 version is incorrect; it should refer to RCB-1.3, which pertains to hydrostatic testing. In 2019, the requirements regarding the flatness of the sealing surfaces in contact with gaskets at the split diaphragm were removed for R-6.33 and CB-6.33; since this is a manufacturing tolerance requirement, it was moved to Chapter F-5 in the 2019 version. Compared to the 2007 requirements, this means that the requirements for CB are now the same as those for R. RCB-6.4 Minimum width of the split diaphragm groove: 2007: 2019: Interpretation: A revision to the specification regarding the minimum width of the split diaphragm groove. The 2007 version for