OS-C501

Offshore Standard DNV-OS-C501, November 2013
Sec.14 Calculation example: two pressure vessels – Page 183
SECTION 14 CALCULATION EXAMPLE: TWO PRESSURE VESSELS
1 Objective
1.1 General
1.1.1 This example shows the use of the standard for the body of two simple pressure vessels. The intention
of the example is to demonstrate the use of the standard, its flow and philosophy and to point out important
aspects to consider.
1.1.2 The example looks into many aspects of design, even though some aspects may not be critical for this
example. This is done to make the example more useful for a wide range of other applications.
1.1.3 The two pressure vessels described here are identical except for two aspects. The vessels are:
— a pressure vessel with liner for storage of gas (air)
— a pressure vessel without liner for storage of water.
1.1.4 The example will concentrate only on the body of the vessels to show the main approach.
1.1.5 Both vessels are designed for high safety class to demonstrate the difference of using a liner or not
without changing other parameters.
1.1.6 References to parts of the standard are given in some of the headings, if the respective section is related
to one section of the standard. In addition references are given to specific sections or paragraphs.
1.1.7 The interaction between liner and laminate is not considered in this example for reason of simplicity.
Effects of yielding of the liner (global or local), should be considered in a real design (Sec.7 [4]).
2 Design input
2.1 Overview
2.1.1 This part describes the input needed for the analysis of the structure.
2.1.2 The standard is organised in a way to ensure that the input is given in a systematic and complete way.
Checklists are provided to ensure that all aspects are considered.
2.1.3 An experienced designer may quickly show that many of the steps described here do not have to be
considered for this example. These steps are shown here as guidance for designing more complicated structures.
2.2 General function (ref. Sec.3 [2.1])
2.2.1 The components shall be two cylindrical pressure vessels, one for the storage of gas (air), the other for
the storage of liquid (water).
2.3 Product specifications (ref. Sec.3 [2])
2.3.1 A basic simple description is given in Table 14-1. Both pressure vessels are basically identical, except
that the gas vessel has a liner while the water vessel does not.
Table 14-1 Simple description of pressure vessels
Gas vessel with liner Water vessel without liner
Inner diameter: 250 mm 250 mm
Length of tank: 1800 mm 1800 mm
Thickness of laminate: 6 mm 6 mm
Max. Pressure: 46 bar* 14.8 bar*
Service Pressure: 46 bar* 14.8 bar*
Design temperature: Room temperature Room temperature
Design life: 25 years 25 years
Type of resin: Polyester Polyester
Type of liner: High density polyethylene None
Type of laminate: Filament winding Filament winding
Type of fibres: E-glass E-glass
* pressures have been chosen to demonstrate the maximum capability of the vessels, when both vessels have the same laminate layup
and the same thickness.
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