Mooring hardware shall include but not be limited to bollards, quick release hooks, other mooring fittings and base bolts. All mooring hardware shall be clearly marked with their safe working loads (or allowable working loads) [3.7]. The certificate issued by the manufacturer normally defines the safe working loads of this hardware.
SAFETY FACTORS FOR ROPES [3.7]
|Steel Wire Rope||1.82|
|Polyamide Tail for Wire Mooring Lines||2.50|
|Other Synthetic Tail for Wire Mooring Lines||2.28|
|Polyamide Tail for Synthetic Mooring Lines||2.75|
|Other Synthetic Tail for Synthetic Mooring Lines||2.50|
For new MOTs or berthing systems, a minimum of three quick-release hooks are required for each breasting line location for tankers greater than or equal to 50,000 DWT. At least two hooks at each location shall be provided for breasting lines for tankers less than 50,000 DWT. Remote release may be considered for emergency situations.
All hooks and supporting structures shall withstand the minimum breaking load (MBL) of the strongest line with a safety factor of 1.2 or greater. Only one mooring line shall be placed on each quick release hook (N/E).
For multiple quick release hooks, the minimum horizontal load for the design of the tie-down shall be:
|Fd||=||Minimum factored demand for assembly tie-down.|
|n||=||Number of hooks on the assembly.|
The capacity of the supporting structures must be larger than Fd (See Section 3107F.5.3).
Other fittings include cleats, bitts and bollards.
If the allowable working loads for existing fittings are not available, the values listed in Table 31F-3-13 may be used for typical sizes, bolt patterns and layout. The allowable working loads are defined for mooring line angles up to 60 degrees from the horizontal. The combination of vertical and horizontal loads must be considered.
ALLOWABLE WORKING LOADS
|TYPE OF FITTINGS||NO. OF BOLTS||BOLT SIZE (in)||WORKING LOAD (kips)|
|30 in. Cleat||4||11/8||20|
|42 in. Cleat||6||11/8||40|
|Low Bitt||10||15/8||60 per column|
|High Bitt||10||13/4||75 per column|
|441/2 in. Fit. Bollard||4||13/4||70|
|441/2 in. Fit. Bollard||8||21/4||200|
|48 in. Fit. Bollard||12||23/4||450|
Note: This table is modified from Table 6-11 of UFC 4-159-03 [3.10]
Base bolts are subjected to both shear and uplift. Forces on bolts shall be determined using the following factors:
- Height of load application on bitts or bollards.
- Actual vertical angles of mooring lines for the highest and lowest tide and vessel draft conditions, for all sizes of vessels at each particular berth.
- Actual horizontal angles from the mooring line configurations, for all vessel sizes and positions at each particular berth.
- Simultaneous loads from more than one vessel.
For existing MOTs, the deteriorated condition of the base bolts and supporting members shall be considered in determining the capacity of the fitting.