How to keep seismic disturbances at check by using seismic mounts?


With the more stringent life-safety related building codes all across the globe, it has become commonplace for historically non-seismic regions or the country to require seismic restraint of MEP (Mechanical, Electrical and Plumbing) equipment. The concept of seismic or base isolation as a means of earthquake protection seems to be more than 100 years old. However, until the 1980s, few structures were built using this principle. Today the concept has matured into a practical reality and is taking its place as a viable alternative to conventional (fixed base) seismic-resistant construction. Seismic Applications are basically the same as non-Seismic but complicated by the need to keep equipment in place. All mountings, hanger-cables or snubbers are designed to resist the seismic force in any zone or specification and Seismic Mounts are among the best. Seismic mounts should be used in locations where earthquakes or seismic disturbances are considered to be a potential hazard. Holding down the equipment can be achieved in two ways, a mechanical snubbing device can be placed in conjunction with standard spring isolators or spring isolators with built-in snubbing devices can be used. These are what can be referred to as seismic isolators. Typical supports for piping, trays, and other equipment are designed for the gravity, or vertical, loads but do not take into account the horizontal loading caused by earthquakes. The main purpose of seismic bracing is safety – to minimize the loss of life due to an earthquake.

The function of Seismic Vibration Isolators

  • All seismic restraints are designed to withstand seismic forces of approximately 2G even at maximum rated load.
  • All seismic vibration Isolators are suitable & safe for most critical applications (including Zone 4 areas).
  • The function of Seismic Vibration Isolators is to absorb the vibration of rotating machines & restraints Seismic forces from all direction during earthquakes

Integrated seismic mounts for mechanical equipment are designed to combine spring mount vibration isolation with multi-directional flexible restraint to limit equipment movement under seismic disturbance. These are spring mounting systems able to withstand earthquakes, and are manufactured with mechanical anchoring systems which ensure integrity in static applications while offering multi-directional flexible restraint to limit movement during a seismic disturbance. Seismic Mounts are used where equipment requires the use of a spring type mounting for a high degree of isolation under normal operating conditions, over a range of interfering frequencies. The seismic spring mounts can also incorporate microcellular polyurethane which is effective in isolating vibration at mid to higher frequencies. Seismic mounts and restraints are designed to provide the strength and isolation necessary to maximize the chances of these systems remaining attached to the building structure.

Seismic vibration isolators are used for absorbing vibration & restraints seismic forces for air handling units, centrifugal fans, pumps & chillers, etc. when these units are installed near seismic zones. The anti-vibration mounts with the seismic structure are suggested to isolate indoor/outdoor chillers, HVAC roof-top equipment, cooling towers, condensers, fans, diesel engines, generators, pumps and air-handling units (AHU). The key characteristics include: –

  • Rugged fabricated steel construction
  • Heavy duty stable steel spring
  • Acoustic isolation pad
  • Single fully adjustable central vertical restraint bolt
  • Anti-skid elastomeric acoustical pad is standard with all seismic restraints
  • Fully weatherproofed

There is wide range of seismic spring mounts available in the market for full range of applications, as well as a rubber seismic mount and independent seismic restraints. All seismic isolators are manufactured using modern robotic welders. The standard finish on the housings and springs is powder coating and all hardware within the mounting is zinc electroplated. The housings can also be ordered as hot dipped galvanized for superior corrosion resistance. Also, available are cable restraints, which are used in conjunction with spring or rubber hangers for the seismic restraint of suspended piping and equipment. Proper sizing and placement of seismic isolators and accurate calculation of anchor bolt forces are imperative in adequately restraining equipment against seismic effects.

There are manufacturers out there offering a variety of seismic mounts. Select a company who is specialized in the same and opt for mounts that best fits the applicational requirement. Consult with the specialist to help you with the selection of the seismic mounts. The expert will consult with engineers and architects to determine the best possible seismic solutions for your projects.

Seismic isolation devices for the safety of industrial machines

Seismic Isolation devices are equipment’s used for preventing the transmission of vibration to the structure caused due to the earthquake. This is a method adopted to separate the building/ machine from the ground by installing seismic isolation devices to prevent the transmission of the vibration and to maintain the safety of the building. So, by installing seismic isolators one can dampen the vibration of the seismic force, thus protecting the structure/ building from any impact. The foundation of the seismic isolation device is placed at the base of the structure/building all to protect them from seismic vibration.

The primary purpose of installing these Seismic Isolation devices on to an equipment machine or structure is to separate them from the floor of the building in order to reduce the transmitted severe seismic movement. It basically acts as an ideal countermeasure for protecting the equipment/instrument/structure from any damage.  In a seismic application where vibration isolation of the mechanical equipment is required, these kinds of equipment’s are still required for proper isolation. However, in these installations, the lateral & vertical movement of the equipment should be minimized to ensure the equipment remains in place during a seismic event.

When Seismic forces are exerted on a building/structure during an earthquake, the forces act horizontally upon the structure and the adjoining equipment’s like the piping, cable trays, duct work, and other building systems within the structure. Holding down the equipment during this phase can only be achieved by either attaching a mechanical snubbing device in conjunction with “standard” spring isolators or use spring isolators with in-built snubbing devices. Typical for piping, trays, and other suspended equipment are designed for the gravity, or vertical, loads but it does not take into account the horizontal loading caused by earthquakes. For this seismic restraint is used to resist the horizontal forces and to keep the systems in place and secure. The main purpose of seismic bracing is to minimize the damage and loss of life caused due to the earthquake.

To understand more about seismic isolation devices, we have listed down various benefits of seismic isolators and they are as follows.

Improved Safety- If you install a seismic isolator, you will be assured of least or no damage to the interior equipment as well as the building. Further this will ensure prevention of disasters like loss of workers life in that building. 

Stability in functionality:

Even after a severe earthquake, the functionality of the building will not be disrupted and will have a stabile functionality.

Security of Property:

With seismic Isolation device you need not worry of repair or rebuilding or replacing of damaged structure or equipment’s. the property shall be well secured with installation of seismic mounts and seismic spring isolators.

Cost effective- Seismic Isolation will reduce the cost of damage and cost incurred due to the short life span of the machine due to the earthquake. So, there would be practically no damage or rather minimum cost incurred for repairs in such scenarios.

 

How to minimize the impact of vibration on buildings & machines caused by a seismic force?

Seismic force is an outcome of the energy caused due to the tectonic movement of the earth’s crust. The outburst of the energy and its corresponding effects have tremendous impact on the structural stability of buildings in the vicinity, causing threat to human lives. However, to minimize the impact and reduce the transmission of the energy to the structure and its internal parts, scientific techniques are adopted to provide structural safety and to control the internal forces and displacement within limits. One of the most common method adopted for protecting the structures from the effects of earthquakes is using a seismic isolation device to damp the seismic energy.

Seismic isolators are equipment’s that provide adequate resistance to the vibrations caused by the seismic force. This ensure effective isolation of vibration and protection to the structure exposed to such destructions. Installing seismic base isolators will help dissipate the energy and restrict the transfer of vibrations from source to structures. Seismic isolation is a technique used to reduce the impact of earthquake on structure and their components. The device protects the structure from any sort of damage caused due to the critical event.

By installing seismic base isolator, they effectively help decouple the supporting structure from mounting structure and protect the base of the building and ensures stability and sturdiness. Offering a significant structural protection, seismic isolators are considered as a much better protection device as it isolates the vibrating source and dissipates the energy internally. The seismic isolators and energy dissipating devices are seen as an effective solution. They dampen the undesired seismic energy under the ground of the structure and reduce the effects of lateral loads on the above surface.  Not just that, Isolators as we all know amend the dynamic characteristics of the structural system by distributing the mass within structure.  Currently, the isolation industry offers two types of seismic isolators namely the seismic spring isolators and seismic mounts. Both the seismic isolators are installed in a structure to offer stability and desired strength.

Depending on the location, seismic isolators are generally categorised under either externally mounted seismic isolators and internally mounted seismic isolators. While the external type seismic mounts are installed outside the structural location and provide isolation externally through foundation of structure, the internal type of seismic mounts is an energy dissipating mechanism that facilitates internal stability through effective isolation. We all know that preventing a natural disaster like earthquake is not in our hands. However, eliminating the potential damage by taking precautionary measures by installing equipment’s like seismic isolators will sure help reduce or limit the impact of such disaster. Consult a specialist or seismic isolator manufacturers in your area and accordingly install seismic devices that best fit your requirement.

 

Seismic isolators for protecting industrial machines from the effects of earthquake

Seismic energy wave is the outburst of energy created during tectonic movement of earth crust and large man-made explosions which generate low-frequency acoustic energy. Seismic energy and its corresponding effects strongly impact the structural stability of a structure and possess severe threat to human life. Specific scientific techniques are adopted to provide structural safety and comfort by controlling the internal forces and displacement within the particular limits. One of the most common method for protecting structures against destructive effects of earthquakes is to damp the seismic energy by the structural elements like seismic mounts. These isolators provide adequate resistance to the undesired vibrations. This method offers certain level of protection however; there is a probability of structure being damages when exposed to critical situations. To overcome this scenario another method for protection of the structures against the seismic energy is to isolate the structure by installing seismic isolators whose function is to dissipate the energy and restrict transfer of vibrations from source to structures.

seismic isolation

seismic isolation

Seismic isolation is a technique used to reduce the effects of earthquake on structure, their components and protect them from damaging. It effectively decouples a supporting structure from mounting structure grouted on a shaking ground thus protecting a building or a structure’s integrity, stability and strength. Seismic isolators offer much better protection as it isolates the vibrating source and dissipates the energy internally, thus providing significant structural protection. The seismic isolators and energy dissipating devices are seen to be an effective solution. They are installed in the structure to damp the seismic energy or placed between the foundation and vertical structural systems to provide the desired result.

Seismic isolator dampens the undesired seismic energy under the ground of the structure, thus decreasing the effects of lateral loads on the above surface. As defined in physics that when external seismic forces are exerted on any structure mounted on floor, its stability is governed by its mass, stiffness and energy damping characteristics. Response or stability of structure can be controlled by changing stiffness of structure. Higher the damping effect of building lesser is the reaction towards undue acceleration and displacements. Today there are two types of seismic isolators available which include seismic spring isolators and seismic mounts that are installed in a structure to offer stability and desired strength.

Isolators amend the dynamic characteristics of the structural system by changing total mass and the distribution of mass within structure.  They act as energy dissipating mechanism and are classified in two major categories depending on their location and operating principles. When we focus on location wise seismic isolators they are generally categorised under the head of externally mounted seismic isolators and internally mounted seismic isolators. As the name suggests, external type seismic mounts are installed outside the structural location and cater to provide isolation externally through foundation of structure. Whereas, internal type seismic mounts act as an energy dissipating mechanism that provides internal stability through effective isolation. Natural disaster like earthquake cannot be prevented and is beyond human control but eliminating the potential damage by taking the precautions against the natural calamity is possible through equipment’s like seismic isolators.