Fire road issues

1. Column spacing of the pipe gallery. The column spacing in the pipe gallery should meet the requirements of most pipes, ideally ranging from 6 m to 9 m, with 6 m being the common value. Why is a span of 6m commonly used for pipe tunnels? As can be seen from the pipe span table, for pipes with a diameter of DN80, whether they are insulated or not, and whether they are used for gas or liquid transport, using a support every 6 meters is sufficient to meet the maximum span requirements. For small pipes smaller than DN80, large pipes can be used for support on the pipe tray, or additional secondary beams can be added. 2. Width of the duct corridor. To determine the width of the pipe tray, it is first necessary to establish the following: (1) the number of pipes in the upper pipe tray, their diameters, and the required spacing between them (specific regulations must be set for this spacing; as a general rule, the clear distance between pipes should be ≮50 mm, the clear distance from the outer edge of the flanges to adjacent pipes should be ≮25 mm, and the clear distance from the pipes to the columns of the pipe tray should be ≮100 mm). (2) The required width of the tray for overhead instrument cables and electrical cables. (3) The width required for the reserved pipeline. Generally, for newly constructed utility tunnels, a width margin of 30% is allocated as reserved space for future pipeline installations. (4) When installing air coolers on the pipe gallery, the dimensions of the support pillars for the air cooler framework also need to be considered. (5) When installing pumps under the pipe gallery, it is also necessary to consider the size of the pump base as well as the width of the passages required for operating and maintaining the pumps. By carefully considering the above five factors, the width of the pipe gallery can be calculated, after which rounding can be applied. 3. Height of the duct tunnel. (1) When air coolers are installed above the pipe gallery and pumps, heat exchangers, or other small devices are installed below it, the layout of the pipe gallery and these devices shall comply with the relevant provisions of the \"Code for Design of Layout of Petrochemical Process Units\" SH3011 or the \"Regulations for Design of Equipment Layout in Chemical Plants\" HG/T 20546 ； (2) When used as a fire escape under the pipe gallery, the minimum clear height from the pipe gallery to the ground should not be less than 4.5 m ； (3) When the pipe gallery is arranged in a single layer or multiple layers, the clear height of the lowest layer shall be determined based on the height of the equipment located beneath the gallery, the height of the pipes connecting the equipment, and the height requirements for operation and maintenance access ； (4) When there is a truss in the pipe gallery, the clear height of the gallery shall be calculated based on the height of the truss bottom ； (5) The layer spacing of multi-layer pipe galleries should be determined based on the pipe diameter and the pipe rack structure. The spacing between the upper and lower layers should be 1.2~2.4m ； For large installations, the spacing between the upper and lower layers can be 2.5~3m, while for larger devices it can be 1.25~1.5m. In actual calculations, the height between the upper and lower layers of the utility tunnel is determined by taking 6D and then rounding it off. D is the maximum pipe diameter of all pipes in the ductwork, and shall be not less than 150 mm. That is, if all the pipes in the pipe tray are DN150, the minimum spacing between the upper and lower layers is 0.9m. (6) When the pipe gallery changes direction or two pipe galleries intersect at right angles, they should be arranged on different floors, with the height difference between these floors being 0.6~1.2m ； In actual calculations, when there is an intersection in the east-west or north-south direction, the height of the pipe gallery is determined by taking H+3D or H-3D and then rounding it off. Similarly, here D is the maximum pipe diameter among all pipes in the utility tunnels, and it must be no less than 150 mm. How did 3D come about? Here, when the direction of a pipe needs to be changed, the most common approach is to use two long-radius elbows; the length of a long-radius elbow is 1.5D, so naturally, two such elbows result in a total length of 3D. For particularly large pipes, two 45-degree long-radius elbows can also be used. When it comes to the staggered layout of pipe galleries, it should be emphasized here that when the direction of the pipe racks changes, their elevation must also change (this is because when the pipes change direction, the order of the pipes may need to change as well, and therefore the elevation of the pipe racks needs to be adjusted to accommodate this) ； The pipe supports in the tunnel should be arranged so that they get higher at each step; if this cannot be achieved, it is still necessary to ensure that the pipe support in the middle is the highest while those on the sides are lower. It is absolutely unacceptable for the middle part to be lower than the sides, as such an arrangement will cause the pipes in the tunnel to form bulges.

According to the Urban Fire Protection Regulations, fire roads are roads established to facilitate the entry and exit of fire trucks and personnel to the scene of a fire. Installing utility tunnels above fire roads may impede the passage of fire trucks and the conduct of firefighting operations; therefore, under normal circumstances, it is not permitted to construct utility tunnels above fire roads. To ensure fire safety, it is necessary to comply with the requirements of relevant laws and regulations. In case there are special circumstances that require the installation of pipe corridors, approval from the relevant fire department must be obtained, and the relevant regulations must be strictly followed. .

The utility tunnel is usually located on one side of the road; although the area beneath it may be a hard surface, it is not part of the road. When the tunnel intersects with a road, an adequate clearance height is provided based on the characteristics of the vehicles that pass by. Therefore, on the pipe racks located above major production pathways such as the equipment area and tank farm, the bottom elevation of the pipe racks is indicated to alert passing vehicles. These roads also serve as primary routes for fire trucks. Therefore, it is possible to cross the pipe gallery above the fire escape, but a clear height must be reserved based on the characteristics of the fire trucks.