How to install series-connected equipment; issues regarding supervision and inspection
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One drum (pressure vessel) and two heat exchangers (pressure vessels) are connected by 168-sized piping. How should these three pieces of equipment in the manufacturing plant be pressurized? The connecting pipes should be considered pressure pipelines, right? ； Without taking over the individual drawings, how can supervision, inspection, and equipment installation be carried out?
This is a quite interesting question. First, we need to clarify two things: 1. A pressure vessel is a piece of equipment, not the entire system. 2. According to the poster’s description, the three components were not manufactured in a skid-mounted format; in other words, the piping section was not designed and drawn by a pressure vessel manufacturer. Well, then a problem arises. Normal pressure vessel drawings show only the first flange sealing surface; other pipes are generally not depicted on the drawings, as this is standard practice. So, how should these pipelines be handled properly? The auxiliary pipelines can be designed, manufactured, and inspected by the pressure vessel manufacturer as attachments, before being supplied to the user. In this way, the issue of installation supervision is easily resolved. Otherwise, the inspector will only follow the drawings; if there are no pipes shown in the drawings, they won’t sign off, and you won’t be able to operate it. Of course, if you’re good at “communicating”, maybe someone will give you the green light. Also, the steam drum should be connected to the boiler. Generally, manufacturers follow the procedures for boiler accessories in this regard. In contrast, heat exchangers are usually manufactured by pressure vessel factories; these are two different things. It is recommended that you determine the ownership first. To avoid wasting effort.
The pipes connecting the steam drum and the heat exchanger are welded directly to the equipment casing, without any flanges
This post was last edited by In short_myP89 on 2021-2-2 at 13:56. So, how should it be handled for maintenance and replacement thereafter? Is there no valve connection between the steam drum and the heat exchanger? No bypass device, no filter valve, no stop valve? The heat exchanger interface isn’t a flange either? In other words, the pipeline is essentially an “exit branch” of the drum, welded on-site and then connected to the heat exchanger? In the case of field welding, non-destructive testing becomes an issue; this involves weld grading, pressure, and the medium involved. If neither the drum nor the heat exchanger has flanges, that’s quite unusual; the container department generally wouldn’t allow such a practice, as it poses many safety risks. Are there any diagrams or photos?
Welded joints are used to prevent leaks. However, the method of connection is another topic. The conditions required by the specifications must not be changed due to the method of linking. For reference.
Not all are directly connected via pipes; there are 8 pipes that serve as connections
Clause 1.6 in GB150 defines the scope of containers; when two or three heat exchangers are shown on the same drawing, supervision and inspection should be carried out in accordance with the definition of containers specified in the standard.
Clause 1.6 in GB150 defines the scope of containers; when two or three heat exchangers are shown on the same drawing, supervision and inspection should be carried out in accordance with the definition of containers specified in the standard.
The upper and lower devices are connected via flanges; in this case, the pipes are directly welded
From what you describe, it sounds like a skid-mounted unit
But if we go with skid-mounted units, they can’t be installed on-site; consequently, they can’t be transported at all