ISO/TR 13086-2:2017
(Main)Gas cylinders — Guidance for design of composite cylinders — Part 2: Bonfire test issues
Gas cylinders — Guidance for design of composite cylinders — Part 2: Bonfire test issues
ISO/TR 13086-2:2017 addresses the topic of safety and performance of composite cylinders in a fire situation. A statement of safety addresses the topics which should be understood in order to operate cylinders safely in service. The remainder of this document provides a basic level of understanding of these topics.
Bouteilles à gaz — Recommandations pour la conception des bouteilles en matière composite — Partie 2: Aspects concernant les essais à la flamme vive
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Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 13086-2
First edition
2017-12
Gas cylinders — Guidance for design
of composite cylinders —
Part 2:
Bonfire test issues
Bouteilles à gaz — Recommandations pour la conception des
bouteilles en matière composite —
Partie 2: Aspects concernant les essais à la flamme vive
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Background . 1
5 Statement of safety . 2
6 Components of fire testing . 2
6.1 Composite materials . 2
6.2 Fire . . 3
6.2.1 General. 3
6.2.2 Fire tests in standards . 5
6.2.3 Standardized fire test . 7
6.2.4 Considerations for future standardized fire tests . 8
6.3 Pressure relief devices. 9
6.4 Venting .11
6.5 Interaction.12
6.6 Availability of reports .16
6.7 Optimized test method using thermally activated pressure relief devices .17
6.7.1 Explanation of optimized test method .17
6.7.2 Procedures for optimized test method .20
7 Summary .23
Annex A (informative) Comparison of fire tests in standards and reports .24
Annex B (informative) Standardized test requirements using thermally active pressure
relief devices .28
Bibliography .33
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
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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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 3,
Cylinder design.
iv © ISO 2017 – All rights reserved
Introduction
Composite reinforced cylinders have been used in commercial service for about 40 years. Common
fibres used in composite cylinders include glass, aramid, and carbon. Resin matrix materials are
commonly epoxy or vinyl ester.
Composite cylinders are known to be exposed to the action of fire, ranging from radiant heating to
full engulfment in the fire. Cylinder performance during exposure to fire might depend on the cylinder
materials of construction, size of the fire, dimensions of the cylinder, its orientation, its contents, and
the use of temperature or pressure activated relief devices.
Fire exposure tests are often included in composite cylinder standards, sometimes as a mandatory
test and sometimes as an optional test. This document addresses issues related to composite cylinders
exposed to fire, summarizes test requirements, and offers a new approach to qualifying cylinders with
relief devices.
TECHNICAL REPORT ISO/TR 13086-2:2017(E)
Gas cylinders — Guidance for design of composite
cylinders —
Part 2:
Bonfire test issues
1 Scope
This document addresses the topic of safety and performance of composite cylinders in a fire situation.
A statement of safety addresses the topics which should be understood in order to operate cylinders
safely in service. The remainder of this document provides a basic level of understanding of these topics.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
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 https://www.iso.org/obp
4 Background
Composite cylinders began service in the 1950s, initially as rocket motor cases with glass fibre
reinforcement. This led shortly to glass fibre pressure vessels with rubber liners, and then to glass fibre
pressure vessels with metal liners. Metal liners were typically either aluminium or steel. Eventually,
new structural fibres, such as aramid and carbon, came into use for reinforcing pressure vessels. Today,
typical reinforcements are glass and carbon, either individually or together as a hybrid. Typical liner
materials are steel, aluminium, or polymers, often high density polyethylene (HDPE) or a polyamide (PA).
Composite cylinders offer certain advantages, particularly light weight and corrosion resistance.
However, there are some performance requirements that tax the abilities of composite cylinders. One
of these is the ability to withstand exposure to fire conditions without rupture. Fire conditions might
include both direct exposure to fire, and to the elevated temperatures resulting from a fire. Direct
exposure might include localized flames, or an engulfing fire.
Sources for a fire could include discharge of flammable gases from nearby cylinders, spilled liquid fuel
from motor vehicles, car fires, house or building fires, and grass or forest fires, to name a few. There is
significant variation in the fire conditions that arise from each of these causes, and there are issues on
reproducibility of any of these types of fires.
Composite cylinders might be able to withstand a certain level of fire exposure on their own. However,
it is more common in certain applications to use a system approach that could include isolation from
fire, insulation, pressure activated relief valves or devices, and/or thermally activated relief devices.
However, there might be conditions where the risk of rupture is less than the risk and consequence of
leakage, and a pressure relief device (PRD) or similar device would not be used. Individual cylinders
might be tested without any type of protection, but it is also common for the cylinder to be tested as part
of a system that contains some means of protection. Regardless, the cylinder should be representative
of a production cylinder and the test should address hazards which might occur.
5 Statement of safety
Composite cylinders, and assemblies of composite cylinders, can be used safely in conditions where
there might be exposure to fire conditions if there is an:
— understanding of composite materials, including the liner;
— understanding of fires;
— understanding of PRDs, if used;
— understanding of insulation, if used;
— understanding of valves and their failure mechanisms;
— understanding of venting;
— understanding of single cylinder vs. multiple cylinder systems;
— understanding of interaction of the above elements;
— optimized test, which is developed, based on above understandings.
Clause 6 addresses the elements of the statement of safety, and provides some understanding for each
of the elements.
6 Components of fire testing
6.1 Composite materials
The reinforcement of a composite cylinder consists of reinforcing fibres in a resin matrix. There might
be resins or additives in the resin that affect structural or thermal performance. There might also be
external coatings that protect the composite, such as intumescents. When exposed to fire, intumescents
form a char layer which has low conductivity and protects the underlying material. There might also be
ablative layers, which could remove heat of the fire as they ablate.
Reinforcing fibres primarily include glass and carbon, and occasionally aramid. E-glass properties
[1]
on matweb.com show glass has a melting point of about 1 725 °C (3 137 °F), and therefore might
soften or melt in a bonfire test, where temperatures might reach 1 960 °C (3 500 °F) which is the flame
1)
® [2]
temperature of the combustion of natural gas in air. Kevlar properties on matweb.com show
aramid fibres begin to lose strength above 425 °C (797 °F), and might decompose and burn at 500 °C
(932 °F). Carbon fibre might oxidize in the fire and lose strength at temperatures of 600 °C (1 112 °F).
The onset of pyrolysis, affecting organic materials such as epoxy resin, can be as low as 300 °C (572 °F).
Resins are typically epoxy or vinyl ester. These materials might burn in a fire. The resins might contain
additives that are also attacked by fire, but some additives might be fire retardants.
A liner is generally used to prevent gas from leaking through the composite, and also ser
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