SINGLE POINT MOORINGS
Keep on top of your maintenance needs by these predictive wear analysis programmes from Oceantech
1. BASIS OF ANALYSIS
Both BERLIFE and SEALIFE programmes utilise data measured on the buoy to provide a presentation of the basic life dependent parameters in a form which allows the operator to compare with the manufacturer’s data.
Bearing life data is presented in the form of a histogram of rotational distance versus load level for a number of angular sectors, eg. 12 x 30 degree sectors with respect to buoy hull datum.
Seal life data is displayed as a histogram using working pressure as the abscica and seal distance moved as the ordinate, eg. seal radius multiplied by angular displacement in radians.
In addition, for BERLIFE, measurements of radial and axial bearing float can be made using LVDT sensors, thus correlating load with measurement bearing float. Where load angle is significant, this can also be measured using a potentiometric device, enabling bearing moment to be calculated and logged for more accurate assessment of load parameters.
Clearly, loads occurring with a high degree of regularity in the same angular sector will cause uneven bearing wear and thus, shorter bearing life.
A calculation of accumulated wear in the form of the sum of the product of load and distance travelled by the bearing for the entire 360 degrees or for each of the twelve sectors is available, together with radial and axial bearing float for the load prevailing.
Again, manufacturer’s data can be used to assign warning limits for lubrication or other forms of preventive maintenance, thus avoiding costly terminal down time.
Whilst there are a number of factors which affect seal life, eg. product type, temperature, and rotating seal surface finish, the fundamental wear parameters are load and seal wipe distance.
Sealife computes the sum of the products of working pressure and seal distance travelled, presenting the basic data in the form of a histogram.
The other parameters, eg. product type and temperature may also be stated for each loading/unloading operation so that these factors may be included in the analysis.
Again, the manufacturer’s recommendation and working experience may be used to set warning and upper limits to provide preventive maintenance prompts.