ISO 20154:2017

INTERNATIONAL ISO
STANDARD 20154
First edition
2017-10
Ships and marine technology —
Guidelines on vibration isolation
design methods for shipboard
auxiliary machinery
Navires et technologie maritime — Lignes directrices pour la
conception de l'isolation antivibratoire des machines auxiliaires de bord
Reference number
ISO 20154:2017(E)
©
ISO 2017

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ISO 20154:2017(E)

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© ISO 2017, Published in Switzerland
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ISO 20154:2017(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Basic requirements of vibration isolation system design . 2
4.1 Vibration isolation performance . 2
4.2 Vibration severity of machinery . 2
4.3 Stability of machinery . 2
4.4 Environmental adaptability . 2
4.5 Ease of installation and maintenance. 2
5 Design procedure of single-stage vibration isolation . 2
5.1 General . 2
5.2 Spectral analysis of disturbance . 3
5.3 Natural frequency . 3
5.4 Select type of vibration isolator . 4
5.5 Layout of vibration isolators . 4
5.6 Design of foundation . 5
5.7 Single-stage vibration isolation system calculation . 5
6 Design procedure of double-stage vibration isolation . 5
6.1 General . 5
6.2 Vibration character analysis of machinery . 5
6.3 Design of intermediate mass and foundation . 6
6.4 Selection of upper and lower isolators . 6
6.5 Arrangement of isolators . 6
6.6 Machinery items isolation . 6
6.7 Calculation of double-stage vibration isolation system. 6
Annex A (informative) Determination of the resonant frequencies of machine isolation system .9
Bibliography .10
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ISO 20154:2017(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 8, Ship design.
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ISO 20154:2017(E)

Introduction
This document has been developed in response to the demand, noted by the International Maritime
Organization (IMO) and its Marine Environment Protection Committee (MEPC), for an International
Standard on reduction of vibration and noise from machinery onboard ships, considering the negative
effects of ship vibration and noise on the health of seafarers and the negative effects of underwater
noise radiated from ships on marine life.
The reduction of ship vibration and noise may necessitate machinery vibration isolation measures.
Although marine machinery vibration isolation design can be done by professional groups, such as
consultant companies, with the development of modern shipbuilding technology, the integration of
various technical fields for ship design is becoming a necessity.
The ship designers themselves should also understand the procedures, requirements and basic
methodology of vibration isolation for shipboard machinery. The purpose of developing a basic
methodology in this document is not limited to better vibration isolation measures, but to help ship
designers take into account the need of machinery vibration isolation, planning for the space and
weight for machinery vibration isolation in advance at the design stage and to consequently promote
the application of vibration isolation design technology onboard.
Vibration isolation concerns the use of comparatively resilient elements called vibration isolators.
Practical vibration isolators usually consist of springs, of elastomeric elements with damping or of a
combination of these. The primary purpose of isolators is to attenuate the transmission of vibrations,
whereas the main purpose of dampers is the dissipation of mechanical energy. Simple models based
on systems with a single degree of freedom are useful for establishing some fundamental relations,
such as single-stage isolation. Extensions of these models can account for the non-rigidity of supports
and isolated items, as well as for reaction effects on vibration sources. More complex models apply
to two-stage isolation that can provide greater attenuation than single-stage isolation systems. As
common measures onboard a ship, single-stage and double-stage vibration isolation design methods
are suggested in this document.
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INTERNATIONAL STANDARD ISO 20154:2017(E)
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.
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ISO 20154:2017(E)

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.
4.2 Vibration severity of machinery
The vibration response of mechanical machinery will be enhanced after elastic installation. When the
value of the machinery vibration severity is large, it is easier to cause fatigue damage of machinery and
to reduce the reliability of machinery operation. Therefore, machinery that is installed resiliently should
meet the requirements of the vibration limits of machinery according to the product specification or
ISO 10816.
4.3 Stability of machinery
Machinery installed resiliently should be ensured to work normally under conditions of machinery
rocking by ship motion, such as yawing, rolling and pitching. Limiters can be mounted in combination
with the vibration isolators to prevent the maximum displacement of any flexible joints isolating the
system from exceeding the permissible value.
4.4 Environmental adaptability
Vibration isolation elements shall meet the requirements of marine products and be approved by the
related administrator after inspection.
4.5 Ease of installation and maintenance
The vibration isolation system of shipboard machinery shall meet the requirements of space and weight
for maintenance and machinery reinstallation of isolation elements. The specifications of vibration
isolation elements should be universal for the convenience of maintenance.
5 Design procedure of single-stage vibration isolation
5.1 General
The design of single-stage vibration isolation depends on vibrat
...