Newbie asks: Does the instrument panel box have to be mounted on a pipe rack? (Posted in the wrong section; posting again)
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I looked at the drawings that were released a couple of days ago; after examining the floor plans for the pipe racks and instrument enclosures, I found that on the same floor of the same building, the floor plan for the pipe racks and the floor plan for the instrument enclosures cannot overlap. In some areas, there are instrument enclosures present, but no pipe racks are shown in the pipe rack diagram. 1. Logically, shouldn’t the tray be placed on the pipe rack? 2. Also, I heard the managers discussing that after the electrical junction boxes are in place, the instrument junction boxes should be hung below them? Is this okay too? Or did I misunderstand? ?
This post was last edited by fpiliuwei on 2019-5-5 16:28. 1. The design of instrument cable trays should take into account any leaks from piping systems, in order to prevent cable damage caused by corrosion and to avoid errors in signal transmission due to electrical interference. Based on this principle, designers should strive to choose cable trays for the instrumentation system at the top of the pipe tray. 2. It can be hung under the conduit in the electrical junction box, but compared to installation on the conduit, using brackets makes the work much more complicated, and it is also less convenient to lay the cable junction boxes; therefore, it is not the preferred option. Plan the location of the instrument cable trays at the earliest possible stage, reserving the corresponding tray positions during the overall design and foundation design phases. Otherwise, it will be extremely difficult to find a location and design the path of the trough boxes during the detailed design phase. Design engineers need to have a certain degree of foresight, and of course this foresight requires the accumulation of experience.
1. Logically, shouldn’t the tray be placed on the pipe rack? Answer: Generally, cable trays are placed on the top layer of the pipe tray system. Therefore, in some cases there is no overlap; this might be because the electrical or instrumentation team prepares the cable tray layout first, while the structural or piping team prepares their drawings later, which is why an overlap cannot be achieved. We can make fine adjustments on site; that’s the Chinese style of design. 2. Also, I heard the managers discussing that after the electrical junction boxes are in place, the instrument junction boxes should be hung below them? Is this okay too? Or did I misunderstand? ? Answer: You’re not misunderstanding; it is permissible to lay the electrical cable trays and the instrumentation cable trays parallel to each other (there is a issue regarding the minimum spacing required; for specific details, refer to national standards, which are not relevant to this question). It is also acceptable to place the instrumentation cable trays beneath the electrical cable trays. Your leader is in the electrical field, right? When I design cable trays, I usually place the instruments on top and the electrical components below……
Got it, thanks to the experts up above for their replies.
The guy on the 2nd floor explained it quite well. 1. For new project design, the instrument enclosures are definitely designed to be mounted on pipe racks. Otherwise, such a situation would arise only if the division of labor among various specialties and the cross-design processes were chaotic. During the basic design phase or the early stage of the detailed design phase (when there is no basic design), the conditions related to the trough boxes should be estimated in advance and submitted to the piping and structural engineering teams. For the exact location of the trough box, refer to the relevant specifications. 2. Similarly, if most of the paths in a new project are designed according to your supervisor’s instructions, the result will be extremely ugly; such a design may not even meet the regulatory requirements.
My design here is even worse – the electrical and instrumentation cables run in the same conduit. Does that have any impact? Gurus?
There will naturally be interference when power cables and instrument signal cables are placed in the same tray; generally, per regulations, they should not be used in the same cable tray.