When is seismic support installation required? These scenarios demand special attention.

As building safety standards continue to evolve, the installation of seismic support brackets is no longer an “optional feature” but a “mandatory requirement” for certain structures. However, many project owners and contractors remain unclear about which scenarios require seismic support installation and which can be exempted. Today, we clarify the scope of seismic support installation based on national standards and practical engineering scenarios to avoid omissions or over-installation.

First, establish the core premise: According to General Principle 1.0.2 of the General Specification for Seismic Design of Buildings and Municipal Engineering, all new, expanded, or renovated buildings and municipal projects in areas with seismic fortification intensity of 6 or higher must implement seismic fortification. This means the mechanical and electrical systems in such buildings must install seismic support brackets. In areas with seismic fortification intensity below 6, selective installation may be considered based on the building’s importance (e.g., hospitals, schools, shopping malls, and other densely populated venues).

Based on GB50981-2014 “Code for Seismic Design of Building Mechanical and Electrical Engineering” and practical engineering experience, seismic supports must be installed in the following scenarios without exception:

I. MEP Piping Scenarios (Core Installation Scenarios)

1. Water Supply and Drainage Piping: Indoor water supply, hot water, and fire protection pipes with horizontal diameters ≥ DN65 must undergo seismic design and install seismic supports; Vertical pipes with a bottom elevation exceeding 0.15m above ground level also require seismic supports; when pipes traverse building settlement joints, account for differential settlement effects and install seismic supports.

2. HVAC Piping: Ductwork for ventilation and air conditioning systems, especially ducts with diameters exceeding 1200mm, as well as chilled water pipes, require seismic support installation. Lateral seismic supports/hangers must be installed within 0.6m of horizontal ductwork bends.

3. Electrical Piping: Cable ladders, cable trays, cable ducts, and electrical conduit with widths exceeding 600mm must be installed with seismic supports. When the distance (width) between suspension rods and cable trays is ≤160mm and the slenderness ratio verification fails to meet requirements, reinforcement measures must be implemented.

4. Gas and Heat Pipelines: Flammable, explosive, or high-temperature pipelines such as gas and heat lines pose significant hazards in case of leakage. Regardless of diameter, seismic supports must be installed in areas with seismic fortification intensity of 6 or higher to prevent rupture and leakage during earthquakes.

II. Building Function Scenarios (Critical Protection Scenarios)

1. High-Occupancy Facilities: Hospitals, schools, kindergartens, shopping malls, stations, airports, stadiums, etc. These locations concentrate large numbers of people. Failure of mechanical and electrical systems during an earthquake could cause severe casualties. Therefore, all qualifying mechanical and electrical pipelines must be fully equipped with seismic supports, strictly adhering to code requirements with no exemptions permitted.

2. Critical Public Buildings: Government offices, libraries, museums, financial institutions, broadcasting centers, etc. These structures support essential public services and must resume operations swiftly post-earthquake. Their mechanical and electrical systems require robust seismic protection, with seismic support installations meeting the highest standards.

3. Special Industrial Buildings: Chemical plants, nuclear power stations, pharmaceutical factories, etc. Pipelines in these facilities transport flammable, explosive, toxic, or hazardous substances. Pipeline ruptures during earthquakes can trigger secondary disasters. Seismic support installation must incorporate structural designs tailored to the specific properties of these media for enhanced stability.

III. Special Pipeline Layout Scenarios

1. Long-Distance Horizontal Piping: Each section of horizontal straight piping should have lateral seismic supports installed at both ends. When the distance between two lateral seismic supports exceeds the maximum design spacing, additional supports must be added in between. Each section of horizontal straight piping must have at least one longitudinal seismic support; if spacing exceeds standards, additional supports must be added sequentially.

2. Pipe bends and size transitions: Install lateral seismic supports within 0.6m of horizontal pipe bends. For pipe tees, size transitions, valves, and other fittings weighing over 25kg, install both lateral and longitudinal seismic supports.

3. Vertical pipe scenarios: When a vertical pipe exceeds 1.8m in length, four-way seismic supports must be installed at its top and bottom. When exceeding 7.6m, additional seismic supports must be added mid-length. When a vertical pipe passes through a structural floor via a sleeve, the sleeve may serve as a horizontal four-way seismic support.

Additionally, two special scenarios require attention: First, exemption scenarios—where equipment or piping gravitational forces do not exceed 8 kN, or suspension rod lengths do not exceed 300 mm, seismic supports may be omitted per code, except for “lifeline systems” such as fire protection, oxygen supply, and emergency communications; Second, retrofitting existing buildings. For structures originally without seismic supports located in seismic zones of intensity 6 or higher, where mechanical and electrical systems remain in operation, seismic retrofitting must be performed to install seismic supports.