SIST EN ISO 21487:2023

SLOVENSKI STANDARD
oSIST prEN ISO 21487:2021
01-julij-2021
Mala plovila - Trajno vgrajeni rezervoarji za bencinsko in dizelsko gorivo (ISO/DIS
21487:2021)
Small craft - Permanently installed petrol and diesel fuel tanks (ISO/DIS 21487:2021)
Kleine Wasserfahrzeuge - Fest eingebaute Ottokraftstoff- und Dieselkraftstofftanks
(ISO/DIS 21487:2021)
Petits navires - Réservoirs à carburant à essence et diesel installés à demeure (ISO/DIS
21487:2021)
Ta slovenski standard je istoveten z: prEN ISO 21487
ICS:
47.020.20 Ladijski motorji Marine engines and
propulsion systems
47.080 Čolni Small craft
oSIST prEN ISO 21487:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 21487:2021

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oSIST prEN ISO 21487:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 21487.2
ISO/TC 188 Secretariat: SIS
Voting begins on: Voting terminates on:
2021-06-03 2021-07-29
Small craft — Permanently installed petrol and diesel fuel
tanks
Petits navires — Réservoirs à carburant à essence et diesel installés à demeure
ICS: 47.080
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 21487.2:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2021

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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General properties . 2
4.1 Resistance to liquids in contact . 2
4.2 Copper-based alloys . 2
4.3 Provisions to tanks . 2
4.4 Installation of tanks . 3
4.4.1 Non-integral tank mechanical fixing . . 3
4.4.2 Other installation requirements . 3
5 Petrol fuel tanks: design, and type tests . 3
5.1 Design . 3
5.2 Tests to be performed . 4
6 Diesel fuel tanks: design, and type tests . 4
6.1 Design . 4
6.2 Tests to be performed . 4
7 Type tests . 5
7.1 General . 5
7.2 Hydraulic pressure tests . 5
7.2.1 Leakage test . . 5
7.2.2 Hydraulic pressure/strength type test . 6
7.3 Pressure-impulse type test for petrol fuel tanks . 7
7.4 General fire-resistance test for non-metallic fuel tanks . 7
7.5 Fire-resistance test for non-metallic fuel tanks as installed .10
8 Marking .11
Annex A (informative) Permeation testing of non-metallic fuel tanks .12
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2013/53/EU aimed to be covered .16
Bibliography .17
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement. Forecast
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 188, Small craft, in collaboration with
the European Committee for Standardization (CEN) Technical Committee CEN/TC 464, Small craft, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 21487:2012) and its Amendments
(ISO 21487:2012/Amd 1:2014 and ISO 21487:2012/Amd 2:2015), which have been technically revised.
The main changes compared to the previous amended edition are as follows:
— added Annex A, specifying a permeation test to determine the evaporative emissions from non-
metallic tanks.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

Introduction
This document specifies the requirements for the design, materials, installation and testing of
permanently installed fuel tanks for small craft.
Some countries have environmental controls for evaporative emissions from petrol fuel systems and
this document includes an informative Annex A describing limits and test procedures for the control of
evaporative emissions from permanently installed petrol fuel tanks. The details in Annex A allow for
future standardization and application of evaporative emissions on small craft.
As the international community further restricts fuel system emissions, it is anticipated that Annex A
will have increased global acceptance.
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oSIST prEN ISO 21487:2021

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oSIST prEN ISO 21487:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 21487.2:2021(E)
Small craft — Permanently installed petrol and diesel fuel
tanks
1 Scope
This document specifies requirements for the design,, installation and testing of petrol and diesel fuel
tanks for internal combustion engines, that are intended to be permanently installed in small craft.
2 Normative references
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 10088:2013, Small craft — Permanently installed fuel systems
ISO 12215-5:2019, Small craft — Hull construction and scantlings — Part 5: Design pressures for monohulls,
design stresses, scantlings determination
ISO 12215-6:2008, Small craft — Hull construction and scantlings — Part 6: Structural arrangements and
details
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:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
petrol
hydrocarbon fuel, or blend of hydrocarbon fuel and denatured ethanol, that is liquid at atmospheric
pressure and is used in spark ignition engines (3.3)
3.2
diesel
hydrocarbon fuel, biofuel, or blend of these, that is liquid at atmospheric pressure and is used in
compression ignition engines (3.4)
3.3
spark ignition engine
engine in which an electrical spark is produced to ignite the fuel/air mixture
3.4
compression ignition engine
engine in which ignition is obtained by means of compressing the fuel/air mixture
3.5
permanently installed
securely fastened by bolts, brackets, screws, paint, adhesive, welding, or other means so that it cannot
be unattached without the use of tools or chemicals, or if intended at all
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

3.6
integral tank
tank that forms part of the outer hull envelope, so that at least one boundary of the tank is formed by
the hull
Note 1 to entry: Structural components, such as bulkheads, are not part of the hull.
3.7
tank range
fuel tanks that are characterized by the following attributes: general geometric shape, material, and
wall thickness
3.8
craft
small craft
recreational boat, and other watercraft using similar equipment, of up to 24 m length of hull (L )
H
Note 1 to entry: The measurement methodology for length of hull is defined in ISO 8666.
[SOURCE: ISO 8666:2020, 3.15, modified – Note 1 to entry has been added]
3.9
non-integral tank
fuel tank that is a component that does not rely on any portion of the craft to retain fuel
4 General properties
4.1 Resistance to liquids in contact
4.1.1 All seals such as gaskets, O-rings and joint-rings shall be of non-wicking, i.e. non-fuel absorbent,
material.
4.1.2 All materials used shall be resistant to deterioration by the fuel for which the system is designed
and to other liquids or compounds with which the material can come in contact as installed under normal
operating conditions, e.g. grease, lubricating oil, bilge solvents and sea water.
4.2 Copper-based alloys
Copper-based alloy fittings are not permitted on aluminium alloy fuel tanks unless a galvanic barrier is
arranged between the fitting and the tank.
4.3 Provisions to tanks
4.3.1 There shall be provisions to determine the fuel level or quantity in the tank, considering the
requirements in 5.1.2 for petrol fuel tanks and in 6.1.5 for diesel fuel tanks.
4.3.2 Metal tanks shall be designed and installed so that no exterior surface traps water.
4.3.3 All rigid tubes and pipes which extend near the tank bottom shall have sufficient clearance to
prevent contact between the tube and the bottom of the tank during normal operation of the craft.
4.3.4 On metallic tanks, all metallic non-integral tank supports, chocks or hangers shall either be
separated from the surface of the tank by a non-metallic, non-hygroscopic, non-abrasive material, or
welded to the tank.
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

4.3.5 If baffles are provided, the total open area provided in the baffles shall be not greater than 30 %
of the tank cross-section in the plane of the baffle.
4.3.6 Baffle openings shall be designed so that they do not trap vapour across the top of the tank and
shall not prevent the fuel flow across the bottom of the tank.
4.3.7 The fuel fill pipe on the tank shall have a minimum inside diameter of 28,5 mm.
2
4.3.8 Each ventilation pipe on the tank shall have a minimum inside diameter of 11 mm (95 mm ) or
a ventilation opening designed to prevent the tank pressure from exceeding 80 % of the maximum test
pressure marked on the tank label when tested in accordance with ISO 10088:20132021.
4.3.9 Tanks shall be constructed using suitable metallic materials and shall meet the minimum material
thicknesses required for corrosion resistance as listed in Table 1.
NOTE Other materials are permitted if the tank manufacturer can demonstrate equivalent fuel and
corrosion resistance.
Table 1 — Metallic tank materials
Minimum nominal
sheet thickness for
Material Fuel
corrosion resistance
mm
Copper, internally tin-coated 1,5 Petrol only
Aluminium alloys containing no more than 0,1 % copper 2,0 Diesel and petrol
Stainless steel, with all welding deposits removed 1 Diesel and petrol
Mild steel 2 Diesel only
Mild steel externally hot-dip zinc-coated after fabrication 1,5 Diesel only
Mild steel externally and internally hot-dip zinc-coated after
1,5 Petrol only
fabrication
Aluminized steel 1,2 Diesel and petrol
4.4 Installation of tanks
4.4.1 Non-integral tank mechanical fixing
Non-integral tanks shall be installed so that the loads due to the mass of the tank when filled to its
maximum capacity are safely distributed into the structure, with due consideration given to upward
and downward acceleration due to the craft's movements at maximum speed.
Note: Continuous flexible supports spreading loads are preferable to rigid ones. Metal or textile hold-
down straps are considered as a good practice provided that chafe and corrosion are kept to a minimum.
4.4.2 Other installation requirements
All other installation requirements (e.g. filling, vent lines, fuel circuit,) shall be in accordance with
ISO 10088:2013.
5 Petrol fuel tanks: design, and type tests
5.1 Design
5.1.1 Petrol fuel tanks shall not be integral with the hull.
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

5.1.2 Petrol fuel tanks shall have all fittings and openings on top, except non-metallic integrally
moulded or welded metallic fill and ventilation pipes, which may be connected to the sides or ends of
petrol fuel tanks, provided that they are welded to the tank and reach above the top of the tank.
5.1.3 Tank drains shall not be fitted on petrol fuel tanks.
5.2 Tests to be performed
5.2.1 Petrol fuel tanks shall be leakage tested in accordance with Table 2.
5.2.2 Petrol fuel tanks shall be pressure-impulse tested in accordance with Table 2.
5.2.3 Non-metallic petrol fuel tanks shall be fire tested according to Table 2.
6 Diesel fuel tanks: design, and type tests
6.1 Design
6.1.1 Diesel fuel tanks may be a non-integral tank, or integral with the structure of the craft. If an
integral tank is installed in a cored hull construction, the core shall not deteriorate from exposure to
diesel fuel, and to commonly used additives, and shall not permit fuel to migrate.
6.1.2 Diesel fuel integral tanks shall be built in accordance with ISO 12215-5:2019.
NOTE National standards and classification rules can be applied to prove structural integrity and welding
quality.
6.1.3 If fittings in the bottom, sides or ends are installed, each connection shall have a shut-off valve
directly connected to the tank. The valve shall be protected or located to prevent physical damage, or be
of at least 25 mm nominal diameter.
6.1.4 Diesel fuel tank drains, where fitted, shall have a shut-off valve with a plug fitted in the outlet that
is permanently installed, or the handle of the drain shut-off valve shall be removable with the valve in its
closed position.
6.1.5 Sight gauges, if used, shall be fitted with valves at the top and bottom connections to the tank.
The bottom valve shall be a manually operated self-closing valve that can only be in the open position
while attended.
6.1.6 Diesel fuel tanks shall be equipped with inspection hatch(es) having a suitable diameter of at
least 120 mm at suitable position(s) for cleaning and for the inspection of the lowest part(s) of the tank.
The hatch shall remain accessible without the removal of permanent structures when the tank has been
installed in the craft. The hatch(es) may be located on the top or side of the tank.
6.2 Tests to be performed
6.2.1 Diesel fuel tanks shall be leakage tested in accordance with Table 2.
6.2.2 Diesel fuel tanks shall be pressure tested in accordance with Table 2.
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

6.2.3 Non-metallic non integral diesel fuel tanks installed in an engine compartment shall pass the fire
tests:
a) in accordance with 7.4 where the actual installation conditions are not known; or
b) in accordance with 7.5 in craft specific installations using a specific tank design.
7 Type tests
7.1 General
Fuel tanks shall be subjected to the tests described Table 2 The tank to be tested shall be a complete
assembly (excluding sight gauges that are protected by a self-closing valve) and include the fuel pick-up
tube, fuel fill pipe, and fuel gauge/sender specified for the fuel tank.
Table 2 — Tank tests to be performed
Tank Type Leakage test Hydraulic Pres- Impulse test Fire Test
sure/ strength test
Petrol tanks
Petrol metal 7.2.1 7.2.2.1 for 5 min 7.3 NA
or
7.2.2.2 for 5 min
Petrol fibre-rein- 7.2.1 7.2.2.1 for 5 min 7.3 7.4 or 7.5
forced
Petrol thermoplastic 7.2.1 7.2.2.3 for 5 h 7.3 7.4 or 7.5
low density
Petrol thermoplastic 7.2.1 7.2.2.3 for 60 min 7.3 7.4 or 7.5
high density
Diesel tanks
Diesel metal 7.2.1 7.2.2.1 for 5 min NA NA
Diesel thermoplastic 7.2.1 7.2.2.3 for 5 h NA 6.2.3
low density
Diesel thermoplastic 7.2.1 7.2.2.3 for 60 min NA 6.2.3
high density
Diesel fibre-rein- 7.2.1 7.2.2.1 for 5 min NA 6.2.3
forced
Non-Integral
Diesel fibre-rein- 7.2.1 7.2.2.1 for 5 min NA NA
forced Integral
NOTE  NA is not applicable.
7.2 Hydraulic pressure tests
WARNING — Take care not to exceed the maximum static test pressure.
7.2.1 Leakage test
Each fuel tank shall be internally tested with a hydraulic pressure. The test pressure shall be the greater
of:
a) 20 kPa; or
b) 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up height above tank top); or
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

c) 1- to 1/2 times the maximum hydrostatic head at the designed tank fill level plus the system relief
pressure if the tank is to be used in a sealed fuel system.
The static test pressure shall be applied for 5 minutes without pressure drop or rise. After the test, the
test fuel tank shall not show any leakage, when using a leak detection method other than the pressure-
drop method.
NOTE Soapy water or a similar solution, both of which should be non-corrosive and non-toxic, can be used as
well as total immersion of the tank in water. Most small leaks do not produce an immediately detectable drop on
the face of the pressure gauge, but soap solutions or immersion can reveal very small leaks by bubbling. Do not
use solutions containing ammonia which is present in some soaps and detergents. This creates a condition that
attacks brass fittings like those used in fuel systems. Damage may be undetectable at first, and these fittings may
develop cracks in a matter of months creating a very hazardous situation.
7.2.2 Hydraulic pressure/strength type test
After the leakage test (7.2.1) the fuel tank, with all its accessories, shall be pressurized again according
to Table 2 to confirm strength requirements.
7.2.2.1 Metal and fibre-reinforced plastic (FRP) tanks
The pressure shall be gradually increased to the greater of
a) 20 kPa; or
b) 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up or overflow height above tank top); or
c) 1,5 times the maximum hydrostatic head at the designed tank fill level plus the system relief
pressure if the tank is to be used in a sealed fuel system.
This pressure shall be maintained for 5 min.
During this time, the tank shall not crack or leak, however, it may be permanently deformed.
7.2.2.2 Alternate pressure test for metal petrol fuel tanks
Metal tanks meeting the following criteria, can be pressure tested to this clause:
a) plating thicknesses, section modules and web shear areas of stiffeners meet the requirements in
ISO 12215-5 for integral tanks; and
b) follows the recommendations in ISO 12215-6 regarding structural details of metal construction;
and
c) welding quality meeting recognized industry accepted standards.
NOTE Requirements for the welding quality are found in ISO 5817.
The pressure shall be gradually increased to the greater of:
— 30 kPa; or
— 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up height above tank top) plus 10 kPa.
This pressure shall be maintained for 5 min.
During this time, the tank shall not crack or leak, however, it may be permanently deformed.
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

7.2.2.3 Thermoplastic tank
Prior to the hydraulic pressure test, thermoplastic tanks shall filled and stored for at least 28 days at an
ambient temperature of not less than 21 °C. with one of the following fuels. The hydraulic pressure test
shall be performed immediately after emptying the test liquid out of the tank.
7.2.2.3.1 The fuel for which the tank is fabricated, or
7.2.2.3.2 Liquid C test fuel blended to 10,0 ± 1,0 % ethanol by volume, or
7.2.2.3.3 CE10 fuel which is a mixture of 90 % by volume of liquid C and 10 % by volume of fuel ethanol.
NOTE Lliquid C specifications can be found in ISO 1817.
The pressure shall be gradually increased to the greater of:
— 20 kPa; or
— 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up height above tank top); or
— 1,5 times the maximum hydrostatic head at the designed tank fill level plus the system relief
pressure if the tank is to be used in a sealed fuel system.
This pressure shall be maintained according to Table 1.
During this time, the tank shall not crack or leak, however, it may be permanently deformed.
7.3 Pressure-impulse type test for petrol fuel tanks
7.3.1 A test fuel tank, representative of the tank range, shall not exhibit any leakage or other signs of
failure after 25 000 cycles of pressure impulses.
7.3.2 The pressure-impulse test of thermoplastic tanks shall be conducted on a tank prepared in
accordance with 7.2.5.
7.3.3 The tank to be tested, fully filled with water, shall be mounted using the support, chocks or
brackets, either furnished with the tank or as intended to be used in a craft installation.
7.3.4 The tank to be tested shall be attached to a regulated source of pressure of either air, nitrogen
or water. The control mechanism of the pressure source shall then be set to cause pressure in the tank
under test, measured at its top-most surface, to vary from 0 kPa to 20 kPa to 0 kPa at a rate of not more
than 15 cycles per minute.
7.3.5 Before and after the pressure-impulse test, the tank shall meet the leakage test specified in 7.2.1.
7.4 General fire-resistance test for non-metallic fuel tanks
7.4.1 This test shall be conducted to qualify fuel tanks where the actual installation conditions are not
known.
7.4.1.1 A representative sample from the tank range can be selected for fire test.
The following criteria shall be met for a tank to be considered to be of the same range:
a) fabricated from the same material using the same methods;
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oSIST prEN ISO 21487:2021
ISO/DIS 21487.2:2021(E)

b) same wall thickness;
c) similar shape and must have the same number of surfaces, see Figure 1;
d) configuration, i.e. arrangement and geometric form of stiffeners, cones, recesses and fittings are
very similar;
e) if baffles are to be fitted, a maximal volume to
...

SLOVENSKI STANDARD
oSIST prEN ISO 21487:2020
01-december-2020
Mala plovila - Trajno vgrajeni rezervoarji za bencinsko in dizelsko gorivo (ISO/DIS
21487:2020)
Small craft - Permanently installed petrol and diesel fuel tanks (ISO/DIS 21487:2020)
Kleine Wasserfahrzeuge - Fest eingebaute Ottokraftstoff- und Dieselkraftstofftanks
(ISO/DIS 21487:2020)
Petits navires - Réservoirs à carburant à essence et diesel installés à demeure (ISO/DIS
21487:2020)
Ta slovenski standard je istoveten z: prEN ISO 21487
ICS:
47.020.20 Ladijski motorji Marine engines and
propulsion systems
47.080 Čolni Small craft
oSIST prEN ISO 21487:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 21487:2020

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oSIST prEN ISO 21487:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 21487
ISO/TC 188 Secretariat: SIS
Voting begins on: Voting terminates on:
2020-10-05 2020-12-28
Small craft — Permanently installed petrol and diesel
fuel tanks
Petits navires — Réservoirs à carburant à essence et diesel installés à demeure
ICS: 47.080
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 21487:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020

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oSIST prEN ISO 21487:2020
ISO/DIS 21487:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

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oSIST prEN ISO 21487:2020
ISO/DIS 21487:2020(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General properties . 2
4.1 Resistance to liquids in contact . 2
4.2 Copper-based alloys . 2
4.3 Provisions to tanks . 2
4.4 Installation of non-integral tanks . 3
4.4.1 Tank mechanical fixing . 3
4.4.2 Other installation requirements . 4
5 Petrol fuel tanks: design, construction and tests . 4
5.1 Design . 4
5.2 Tests to be performed . 4
5.3 Evaporative emissions from non-metalic tanks . 4
6 Diesel fuel tanks: design, construction and tests . 5
6.1 Design . 5
6.2 Tests to be performed . 5
7 Tests . 5
7.1 General . 5
7.2 Hydraulic pressure test . 6
7.2.1 Leakage test . . 6
7.2.2 Hydraulic pressure/strength type test . 6
7.2.3 Metal and fibre-reinforced plastic (FRP) tanks . 7
7.2.4 Thermoplastic tanks . 7
3 7
7.2.5 Thermoplastic of density ≥ 935 kg/m .
3 7
7.2.6 Thermoplastic of density < 935 kg/m .
7.3 Pressure-impulse type test for petrol fuel tanks . 7
7.4 General fire-resistance test of non-metallic fuel tanks. 8
7.5 As-installed fire-resistance test of non-metallic fuel tanks . 9
8 Marking .10
Annex A (normative) Permeation testing of non-metallic fuel tanks .11
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2013/53/EU aimed to be covered .15
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oSIST prEN ISO 21487:2020
ISO/DIS 21487:2020(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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 188, Small craft.
This fourth edition cancels and replaces the third edition (ISO 21487:2012), which has been technically
revised.
The main changes compared to the previous edition are as follows:
Added informative Annex A defining how non-metalic fuel tanks are tested to determin evaporite
emissions.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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oSIST prEN ISO 21487:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 21487:2020(E)
Small craft — Permanently installed petrol and diesel
fuel tanks
1 Scope
This document establishes requirements for design, construction, installation and test of petrol and
diesel fuel tanks, for internal combustion engines, that are intended to be permanently installed in
small craft.
For installation requirements, ISO 10088:2013 applies.
2 Normative references
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 1817:2015, Rubber, vulcanized or thermoplastic — Determination of the effect of liquids
ISO 5817:2014, Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding
excluded) — Quality levels for imperfections
ISO 10088:2013, Small craft — Permanently installed fuel systems
ISO 11192:2005, Small craft — Graphical symbols
ISO 12215-5:2019, Small craft — Hull construction and scantlings — Part 5: Design pressures for monohulls,
design stresses, scantlings determination
ISO 12215-6:2008, Small craft — Hull construction and scantlings — Part 6: Structural arrangements
and details
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:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
petrol
hydrocarbon fuel or blend of hydrocarbon fuel and denatured ethanol which is liquid at atmospheric
pressure and is used in spark ignition engines
3.2
diesel
hydrocarbon fuel, biofuel or blend of these which is liquid at atmospheric pressure and is used in
compression ignition engines
3.3
spark ignition engine
engine in which an electrical spark is produced to ignite the fuel/air mixture
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oSIST prEN ISO 21487:2020
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3.4
compression ignition engine
engine in which ignition is obtained by means of compressing the fuel/air mixture
3.5
permanently installed
securely fastened so that tools need to be used for removal
3.6
integral tank
tank which forms part of the outer hull envelope
Note 1 to entry: An integral tank is one where at least one boundary of the tank is formed by the hull. Other
structural components such as bulkheads are not part of the hull.
3.7
tank family
fuel tanks that are characterized by the following attributes: General geometric shape, material, and
wall thickness.
3.8
craft
small craft
recreational boat, and other watercraft using similar equipment, of up to 24 metres length of hull (LH)
Note 1 to entry: the measurement methodology for length of hull is defined in ISO 8666.
[SOURCE: ISO 8666:2016, 2.13, modified – Note 1 to entry has been added.]
4 General properties
4.1 Resistance to liquids in contact
4.1.1 All seals such as gaskets, o-rings and joint-rings shall be of non-wicking, i.e., non-fuel absorbent,
material.
4.1.2 All materials used shall be resistant to deterioration by the fuel for which the system is designed
and to other liquids or compounds with which the material can come in contact as installed under normal
operating conditions, e.g., grease, lubricating oil, bilge solvents and sea water.
4.2 Copper-based alloys
Copper-based alloy fittings are not permitted on aluminium fuel tanks unless a galvanic barrier is
arranged between fitting and tank.
4.3 Provisions to tanks
4.3.1 There shall be provisions to determine the fuel level or quantity in the tank considering the
requirements in 5.1.2 for petrol fuel tanks and 6.1.3 for diesel fuel tanks.
4.3.2 Metal tanks shall be designed and installed so that no exterior surface will trap water.
4.3.3 All rigid tubes and pipes which extend near the tank bottom shall have sufficient clearance to
prevent contact between the tube and the bottom of the tank during normal operation of the craft.
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4.3.4 On metallic tanks, all metallic non-integral tank supports, chocks or hangers shall either be
separated from the surface of the tank by a non-metallic, non-hygroscopic, non-abrasive material or
welded to the tank.
4.3.5 If baffles are provided, the total open area provided in the baffles shall be not greater than 30 %
of the tank cross section in the plane of the baffle.
4.3.6 Baffle openings shall be designed so that they do not prevent the fuel flow across the bottom or
trap vapour across the top of the tank.
4.3.7 The fuel fill pipe on the tank shall have a minimum inside diameter of 28,5 mm.
2
4.3.8 Each ventilation pipe on the tank shall have a minimum inside diameter of 11 mm (95 mm ) or
a ventilation opening designed to prevent the tank pressure from exceeding 80 % of the maximum test
pressure marked on the tank label when tested in accordance with ISO 10088:2013.
4.3.9 Tanks shall be constructed using suitable metallic materials and minimum recommended
material thicknesses required for corrosion resistance as listed in Table 1.
Note Other materials may be used if the tank manufacturer can demonstrate equivalent fuel and corrosion
resistance.
4.3.10 Diesel tanks shall be equipped with inspection hatch(es) having a suitable diameter of at least
120 mm at suitable position(s) for cleaning and inspection of the lowest part(s) of the tank. The hatch
shall remain accessible without removal of permanent structure when the tank has been installed in the
craft. The hatch(es) may be located on the top or side of the tank.
Table 1 — Metallic tank materials
Minimum nominal
sheet thickness for
Material Fuel
corrosion resistance
mm
Copper, internally tin-coated 1,5 Petrol only
Aluminium alloys containing no more than 0,1 % copper 2,0 Diesel and petrol
Stainless steel, with all welding deposits removed 1 Diesel and petrol
Mild steel 2 Diesel only
Mild steel externally hot-dip zinc-coated after fabrication 1,5 Diesel only
Mild steel externally and internally hot-dip zinc-coated after
1,5 Petrol only
fabrication
Aluminized steel 1,2 Diesel and petrol
4.4 Installation of non-integral tanks
4.4.1 Tank mechanical fixing
Non-integral tanks shall be installed so that the loads due to the mass of the tank when filled to
maximum capacity are safely distributed into the structure, with due consideration given to upward
and downward acceleration due to the craft's movements at maximum speed in the sea.
Note Continuous flexible supports spreading loads are preferable to rigid ones. Metal or textile hold-down
straps are considered as a good practice provided that chafe and corrosion are kept to a minimum.
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4.4.2 Other installation requirements
For other installation requirements (filling, vent lines, fuel circuit, etc.), ISO 10088: 2013 applies.
5 Petrol fuel tanks: design, construction and tests
5.1 Design
5.1.1 Petrol fuel tanks shall not be integral with the hull.
5.1.2 Petrol fuel tanks shall have all fittings and openings on top, except metallic fill and ventilation
pipes, which may be connected to the sides or ends of metal petrol fuel tanks, provided that they are
welded to the tank and reach above the top of the tank.
5.1.3 Tank drains shall not be fitted on petrol fuel tanks.
5.2 Tests to be performed
5.2.1 Petrol fuel tanks shall be leakage tested in accordance with 7.2.1
5.2.2 Petrol fuel tanks shall be pressure-impulse tested in accordance with 7.3.
5.2.3 Metallic tanks may as an alternative method be pressure tested in accordance with 7.2.2, using a
pressure which is the higher of the following:
— 30 kPa, or
— 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up height above tank top) plus 10 kPa.
During this test, the tank shall not crack or leak, however, it may be permanently deformed.
The following alternative test method for metal tanks may only be used if:
— plating thicknesses, section modules and web shear areas of stiffeners meet the requirements in
ISO 12215-5 for integral tanks, and
— construction follows the recommendations in ISO 12215-6 regarding structural details of metal
construction, and
— welding quality meets at least class B in accordance with ISO 5817 or other equivalent national
welding standards.
5.2.4 Non-metallic petrol fuel tanks shall meet the fire test in accordance with 7.4 or 7.5.
5.3 Evaporative emissions from non-metalic tanks
5.3.1 Non-metalic fuel tanks shall be constructed such that evaporative emissions from the tank do not
2
exceed 1,5 g/m /day when measured according to the procedures in Annex A.
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6 Diesel fuel tanks: design, construction and tests
6.1 Design
6.1.1 Diesel fuel tanks may be constructed independent of or integral with the structure of the craft. If
an integral tank is installed in a cored hull construction, the core shall not deteriorate from exposure to
diesel fuel, and commonly used additives, and shall not permit fuel to migrate.
6.1.2 Diesel fuel integral tanks shall be built in accordance with ISO 12215-5:2019.
Note alternatively, other acknowledged national standards and/classification rules may be applied to proof
structural integrity and welding quality.
6.1.3 If fittings in the bottom, sides or ends are installed each connection shall have a shut-off valve
directly coupled to the tank. The valve shall be protected or located to prevent physical damage or be of
at least 25 mm nominal diameter.
6.1.4 Diesel fuel tank drains, where fitted, shall have a shut-off valve with a plug fitted in the outlet that
is permanently installed, or the handle of the drain shut-off valve shall be removable with the valve in its
closed position.
6.1.5 Sight gauges, if used, shall be fitted with a self-closing valve at the bottom that can only be
manually operated to the open position while attended. The top valve is not required to be self-closing.
6.2 Tests to be performed
6.2.1 Diesel tanks shall be leakage tested in accordance with 7.2.1.
6.2.2 Diesel tanks shall be pressure tested in accordance with 7.2.2.
6.2.3 Non-metallic, non-integral tanks, if installed in an engine compartment, shall be fire tested in
accordance with 7.4 or 7.5.
7 Tests
7.1 General
Representative samples of the fuel tanks shall be subjected to the tests described herein. The tank to be
tested shall be a complete assembly [excluding sight gauges which are protected by a self closing valve]
and include the fuel pick-up tube, fuel fill pipe, and fuel gauge/sender specified for the fuel tank.
A single fuel tank from a tank family shall be tested as a representative of the tank family. It shall be the
largest volume in the tank family and shall be of the same general geometric shape, material, and wall
thickness. If the tank is a plastic tank the number of internal cones shall be the same to be considered
in the same family. See table 1.
NOTE Fuel type, capacity, length, width, height, cross-section, surface area, # of joints/joint type, # of
inserts, and fill location, can all vary within a family.
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oSIST prEN ISO 21487:2020
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Figure 1 — Primary Fuel Tank Shapes
7.2 Hydraulic pressure test
WARNING — Take care not to exceed the maximum static test pressure. Do not use solutions
containing ammonia for testing.
7.2.1 Leakage test
Each fuel tank shall be internally tested with a hydraulic pressure. The test pressure shall be the
greater of
— 20 kPa; or
— 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up height above tank top).
— or 1-1/2 times the maximum hydrostatic head at the designed tank fill level plus the system relief
pressure if the tank is to be used in a sealed fuel system.
The static test pressure shall be applied for 5 minutes without pressure drop or rise. After the test, the
test fuel tank shall not show any leakage. when using a leak detection method other than the pressure-
drop method.
Note Soapy water or a similar solution, both of which should be non-corrosive and non-toxic, can be used as
well as total immersion of the tank in water. Most small leaks do not produce an immediately detectable drop on
the face of the pressure gauge, but soap solutions or immersion will reveal very small leaks by bubbling
7.2.2 Hydraulic pressure/strength type test
After the leakage test (7.2.1) the tank, with all its accessories, shall be pressurized again as given in
7.2.3 to 7.2.6.
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7.2.3 Metal and fibre-reinforced plastic (FRP) tanks
The pressure shall be gradually increased to the greater of
— 20 kPa; or
— 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up or overflow height above tank top); or
— 1-1/2 times the maximum hydrostatic head at the designed tank fill level plus the system relief
pressure if the tank is to be used in a sealed fuel system.
This pressure shall be maintained for 1 minutes
During this time, the tank shall not crack or leak, however, it may be permanently deformed.
7.2.4 Thermoplastic tanks
Prior to the hydraulic pressure test, thermoplastic tanks shall be stored filled with test liquid C in
accordance with ISO 1817:2015 or the fuel for which the tank is fabricated for at least 28 days at an
ambient temperature of not less than 21 °C. The hydraulic pressure test shall be performed immediately
after emptying the test liquid out of the tank.
3
7.2.5 Thermoplastic of density ≥ 935 kg/m
The pressure shall be gradually increased to the greater of
— 20 kPa; or
— 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up height above tank top), or
— 1-1/2 times the maximum hydrostatic head at the designed tank fill level plus the system relief
pressure if the tank is to be used in a sealed fuel system.
This pressure shall be maintained for 60 minutes.
During this time, the tank shell shall not crack or leak, however, it may be permanently deformed.
3
7.2.6 Thermoplastic of density < 935 kg/m
The pressure shall be gradually increased to the greater of
— 20 kPa; or
— 1,5 times the highest hydrostatic pressure to which the tank may be subjected in service (maximum
fill-up height above tank top), or
— 1-1/2 times the maximum hydrostatic head at the designed tank fill level plus the system relief
pressure if the tank is to be used in a sealed fuel system.
This pressure shall be maintained for 5 h.
During this time, the tank shell shall not crack or leak, however, it may be permanently deformed.
7.3 Pressure-impulse type test for petrol fuel tanks
7.3.1 A test fuel tank, representative of the tank series type, shall not exhibit any leakage or other signs
of failure after 25 000 cycles of pressure impulses.
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oSIST prEN ISO 21487:2020
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7.3.2 The pressure-impulse test of thermoplastic tanks shall be conducted on a tank prepared in
accordance with 7.2.4.
7.3.3 The tank to be tested fully filled with water shall be mounted using support, chocks or brackets,
either furnished with the tank or as intended to be used in a craft installation.
7.3.4 The tank to be tested shall be attached to a regulated source of pressure of either air, nitrogen
or water. The control mechanism of the pressure source shall then be set to cause pressure in the tank
under test, measured at its top-most surface, to vary from 0 kPa to 20 kPa to 0 kPa at a rate of not more
than 15 cycles per minute.
7.3.5 Before and after the pressure-impulse test, the tank shall meet the leakage test defined in 7.2.1
7.4 General fire-resistance test of non-metallic fuel tanks
7.4.1 This test shall be conducted to assess tanks if the actual installation conditions are not known.
7.4.2 Prior to the fire test, the tank shall be tested and meet the requirements of 7.2 After this test, the
test liquid shall be removed.
7.4.3 The tank to be tested shall be supported at its ends and at each baffle in a test enclosure. The
enclosure shall be a fire-resistant box closed on its top, bottom and ends, and only open on one of its
sides (see Figure 1). The clearance between the tank to be tested and the test enclosure shall be at least
50 mm on the sides, 150 mm on the ends and between 175 mm and 850 mm on the top.
7.4.4 The lowest point of the tank to be tested shall be vertically 75 mm above the liquid surface of
the reservoir containing heptane. The sides of the reservoir shall extend 50 mm beyond the vertical
sides and 150 mm beyond the ends of the tank to be tested. The reservoir shall be made leakproof and
accommodate enough heptane to burn continuously for 2,5 minutes See Figure 1.
7.4.5 The area in which the test is to be conducted shall be free from draughts but shall allow a free
inflow of air during the test.
7.4.6 Fill the tank to be tested to 25 % of its maximum capacity with the intended fuel.
All openings in the tank to be tested shall be capped or plugged, except fuel-tank vent lines which shall
be extended outside the fire-test area. Components fitted on the tank or in the test rig that are not
intended to be tested shall be sufficiently heat protected.
7.4.7 The heptane in the reservoir shall be ignited and permitted to burn fo
...