12.1.1 When links
within any length of chain cable are worn by 12% or greater (see
Vol 1, Pt 1, Ch 3, 5.3 Examination and testing – General 5.3.6 of the Rules
for Naval Ships) the length is to be renewed. For ships not built
in accordance with LR Rules where the fitted thickness is not available
in the ship’s documentation, plan approval advice should be
sought. The worn size of each condemned length is to be reported.
Chain cable worn to the renewal size should be removed from the chain
locker only if replacement cable is readily available, but if worn
cable is to be retained pending replacement, the worn lengths should
be fitted at the locker end of the cable.
12.1.2 Chain cable
worn so far below renewal size, that it is considered by the Surveyor
to be hazardous for it to be retained, should be removed whether or
not replacement cable is available. As a general guide, cable reduced
by greater than 15 per cent or more from its nominal diameter should
be removed.
12.1.3 When deciding
whether a worn length of cable should be removed, the general condition
of the links is of importance. If there are slack studs, deformed
links or links worn into a notch, it is expected that the cable would
break at a load far below the nominal breaking strength for the measured
diameter, whereas considerable wear which is not accompanied by the
above defects may be less significant, see
Figure 7.12.1 Anchor chain.
12.1.4 The practice
of ‘walking the cable’ by disconnecting the anchor length
and refitting it at the locker end should be encouraged in order to
promote uniform weardown of the cable, and this may be conveniently
effected when the cables are ranged for survey.
12.1.5 Particularly
close attention should be paid to the condition of the chain locker
at every opportunity, and a complete survey carried out at Special
Survey.
12.1.6 When inspecting
anchors and cables, the Surveyor should look for any signs of defective
links or shackles, attention being given to the fit of the shackle
pins. The Surveyor should prohibit the excessive use of oxy/acetylene
torches when opening up shackles of special quality steel. Excessive
heat produced by the torch has a detrimental effect on the properties
of the steel which can cause loss of strength and/or severe cracking.
Lugless shackles in particular are to be closely examined for any
evidence of cracking. The attention of those responsible for the subsequent
shackling up of the cable should be drawn to the importance of fitting
suitable locking pins to the shackle pins.
12.1.7 Crown pin
retaining bolts should be given special attention whenever anchors
and cables are ranged. On certain types of stockless anchors when
the fit of the crown pin becomes too slack in the head, allowing excessive
lateral movement, it is acceptable to fit sleeves in each end of the
head as a temporary repair measure for a short period of time to allow
a new crown pin to be prepared. Adequate clearance should, however,
be allowed to ensure normal free tripping of the anchor head.
12.1.8 In the case
of repair of anchors, the necessity for retesting would depend on
the nature of the repair.
Figure 7.12.1 Anchor chain