1. ISO 19901-7 Code check

1.1. Introduction

The ISO 19901-7 code-check is based on Petroleum and natural gas industries Specific requirements for offshore structures Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO 19901-7:2013).

1.2. Required results and output

To perform the code-check, the following input is needed as a minimum from the numerical model:

  • A single scalar with unit N
    The code-check will be performed for all scalar signals with unit N. The output from the code check is calculated safety factor and utilization for each input signal.

1.3. User input

The following user input is required

  • Type of mooring system (permanent or mobile)

  • Consequence class

  • Analysis type (intact, single or double failure)

  • Breaking strength

1.4. Code-check

1.4.1. Calculated safety factor

The calculated safety factor is calculated as

\[SF_{calc} = \frac{T_{MBL}}{T_{input}}\]

where TMBL is the breaking strength specified by the user and Tinput is the input signal.

1.4.2. Utilization

The utilization is calculated as

\[utilization = \frac{SF}{SF_{calc}}\]

where the safety factor SF is found from ISO 19901-7 based on the user’s choice of mooring system type, consequence class and analysis.