Engineering, Stress Analysis, Vibration Isolation, Design for Seismic and Impact Loads

High Viscosity Dampers

vd-426

CKTI-Vibroseism possesses an unique technology of high viscosity dampers (VD) to protect structures, systems, components, equipment and pipings from operational vibration, seismic, impulse, shock, explosive loads and special dynamic impacts.
During last 25 years more than 1600 VD damper units have been installed at many nuclear and conventional power plants, as well as chemical plants.
VD damper working principle is based on hydrodynamic resistance forces originating due to relative movement of piston, inner elements and casing. A damper works at any oscillation frequency, but most effectively within 0-40 Hz range.
HV damper design is covered by RF patent No. 1689693 of 10.01.1994. General information and dampers operational requirements as well as their overall dimensions are presented in specification TU 4192-001-20503039-01.

Advantages of High Viscosity dampers application

  • Effective damping of any kind of dynamic impacts (vibration, shocks, seismic, explosions etc.) for all 6 spatial degrees of freedom;
  • Long (at least 60 years) service life without maintenance and repairs;
  • Resistance against explosion, radiation, aggressive media and heat (from -10°С to +150°С), high fire safety, no toxic substances;
  • Negligible reaction force due to thermal expansions;
  • No delay in response to dynamic load, no gaps and friction.
  • Cost-effective solution: low manufacturing cost without operational and maintenance expenses at unbeaten dynamic characteristics.

High viscosity damper design

A High Viscous Damper (HVD) consists of housing, piston and special high viscous grease inside. A HVD bears all kind of dynamic loads and does not bear static load.

The damper is mounted vertically. Any relative housing-piston dynamic displacement in any degree of freedom creates dampening force in the grease.

Usually the housing flange is fixed to the base, and the piston flange to the component or the piping to be protected from dynamic/vibration loads. However it is possible to make opposite fixing: the damper’s housing to the component, and the piston to the base. It is also possible to connect two vibrated objects by HVD’s flanges. The housing and the piston both have uniform rectangular flanges convenient to fix them at any object even in operational condition.

HV dampers are divided into 7 principal sizes: VD-108, VD-159, VD-219, VD-325, VD-426, VD-630, and VD-850 that differ from each other by diameter and overall dimensions, dynamic stiffness, maximal allowable displacements and nominal load. HV dampers are used for the damping of different systems from small bore tubing and light systems (VD-108) up to pipelines of 60 inches (1500 mm) diameter and powerful components and equipment (VD-630 and VD-850). HVD are also used for vibration and seismic isolation systems of huge structures, e.g. Nuclear Power Plant Reactor Building (VD-850). High viscous grease is not toxic, fire and radiation proof, biologically inert, non-corrosive and can be used in a wide range of ambient temperatures.

High viscosity damper characteristics

  • Damping range (Dynamic Stiffness): from 10 to 105 kN/m (5.6x106 lbf/in);
  • Nominal dynamic load: up to 350 kN (78 750 lbf);
  • Maximum thermal expansion limit: up to +/- 254 mm (+/- 10 in );
  • Range of Environmental Temperature: from -50C to +250C (-60F to 500F);
  • Maximal Radiation Doze: up to 20 Mrad (200 kJ/kg);
  • Service life: at least 60 years+ (more than operational life of a conventional engineering system).