OS-C501

Offshore Standard DNV-OS-C501, November 2013
Sec.4 Materials - laminates – Page 64
6.8.2 Laminates made by filament winding, tape winding and similar processes may show a variation in fibre
tension, especially through the thickness. Laminate and ply properties should be established for a representative
combination of fibre tensions.
6.8.3 If fibre tensions vary, but the change in tension is known, the change in fibre tension may be added to
the loads acting on the ply in a stress analysis. If such an analysis can be carried out with sufficient accuracy a
re-qualification of the material properties is not required.
7 Properties under fire
7.1 Introduction
7.1.1 The performance of composites in a fire is a complex process, because the various constituent materials
respond differently to a fire.
7.1.2 The requirements under fire conditions can usually be found in the fire codes for a particular application.
7.1.3 Fire codes may implicitly assume that the structure is built of steel or metal. The relevance of a fire code
to composite materials shall be checked carefully.
7.1.4 Since most composites are flammable and temperature sensitive most applications use protective
measures to reduce the impact of fire. In this case the fire performance of the complete system, i.e. a composite
structure with fire protection shall be evaluated.
7.1.5 An advantage of composite laminates is their low thermal conductivity and the usually long times
required to reach burn through conditions.
7.1.6 Some aspects of fire performance can be modelled, but some experimental testing shall always be done
to demonstrate fire performance.
7.2 Fire reaction
7.2.1 Fire reaction describes the response of a composite to fire in terms of flammability, flame spread, smoke
development and emission of toxic gases. All these aspects shall be documented if relevant.
7.2.2 Special additives or fillers are often added to composites to improve fire reaction.
7.2.3 The influence of such additives or fillers on the basic mechanical properties shall be evaluated.
7.3 Fire resistance
7.3.1 Fire resistance describes the remaining strength of a composite structure under a fire.
7.3.2 As a first estimate of fire resistance the temperature dependent properties, as described in [5.2], can be
used.
7.3.3 The temperature within a composite laminate can be calculated by means of appropriate models.
7.3.4 If chemical reactions can occur within the laminate their influence on the temperature distribution shall
be considered.
7.3.5 Through thickness properties and matrix dominated properties shall be carefully evaluated, especially in
the region of joints. Matrix dominated properties tend to degrade rapidly in a fire.
Guidance note:
A panel with stiffeners may loose most of its stiffness if the stiffeners delaminate from the panel due to the fire.
7.4 Insulation
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7.4.1 The properties of the insulation with respect to fire reaction and fire resistance shall be evaluated.
7.4.2 Special consideration shall be given to the joints of the insulation and the method the insulation is
attached to the component. Attachment points and joints may create hot spots in the component.
7.4.3 All large scale testing shall be done with jointed insulation and the same attachments as used in the real
application.
7.5 Properties after the fire
7.5.1 A fire is usually seen as an accidental load case and properties after the fire shall be evaluated for each
individual case.
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