ISO 20154:2017 pdf download

ISO 20154:2017 pdf download.Ships and marine technology — Guidelines on vibration isolation design methods for shipboard auxiliary machinery
1 Scope
The purpose of this document is to provide general guidelines on the design of ship vibration isolation based on the basic methodology of vibration isolation for shipboard machinery, for example, auxiliary engine, compressor, fan, pump, etc. A well-designed vibration isolation system can significantly reduce the vibration transmission from shipboard machinery to ship structures lowering the noise level onboard the ship or the underwater noise radiated from the ship.
2 Normative reference
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 20283-3, Mechanical vibration — Measurement of vibration on ships — Part 3: Pre-installation vibration measurement of shipboard equipment
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1 single-stage vibration isolation
vibration isolation where a single machinery or assembly is mounted on the ship foundation through a stage of elastic connection by a group of isolators
3.2 double-stage vibration isolation
vibration isolation where a single machinery or assembly is flexibly installed on an intermediate frame through a first stage isolator group, and an intermediate frame is mounted on the ship foundation through a second stage isolator group
3.3 displacement limiter
rigid element which is used in combination with the vibration isolator to avoid excessive displacement and consequent damages of the vibration isolation system
3.4 coast down test
test to determine the resonant frequencies of the machine isolation system for the machinery from a certain speed while it is shut down, simultaneously recording the vibration level until the machine stops
Note 1 to entry: Annex A gives information on the determination of the resonant frequencies of machine isolation system.
4 Basic requirements of vibration isolation system design
4.1 Vibration isolation performance
The design of vibration isolation should meet the requirements of vibration isolation performance and avoid resonance according to the structural dynamic characteristics of the ship structure including machinery foundation. The choice of vibration isolation type depends on the vibration levels difference between shipboard machinery and ship structure, as well as the limit of weight and space onboard the ship. The design requirements on the limit of the ship structure vibration response in ISO 20283-5 and relevant ship specifications can be referred to. In general, the effect of vibration reduction can reach more than 15 dB when the single-stage vibration isolation is adopted and reach 25 dB to 30 dB when the double-stage vibration isolation is adopted. Especially for the double-stage vibration isolation, transmissibility of the isolation system varies with different intermediate mass values. The heavier the intermediate mass block is, the better the vibration reduction effect is. Design of the weight of the intermediate mass block depends on the weight restriction and vibration reduction requirement. Meanwhile, the advantage of introducing the intermediate mass block is more obvious in the high-frequency range.