WIRE DAMAGE ON SHIP´S CRANES
In General Wire ropes are checked by the class society at the manufacturing plant according to their safeworking load (SWL) using a defined test load. During further operation, regular load tests with corresponding test loads (depending on the SWL) are performed in the presence of the class society. The “standards for wire rope operation” andespecially the “in-service-monitoring” are stated in the DIN 15 020, section 2. This norm specifies the safety regulations for the use and handling of wire ropes. The class societies have not made any regulations to this respect. Maintenance Wire ropes must be maintained regularly (e.g. every three months as stipulated by the crane manufacturer O&K) and must be greased at regular time intervals, whichare dependent on the condition and frequency of operation, whereby this application is to be performed especially in the range of the bending area. The lubricant used must be compatible with the existing lubricant on the wire rope, and it must be able to penetrate into the interior of the wire rope. By lubricating, potential corrosion can be reduced. Extremely fouled wire ropes should occasionallybe cleaned. It is highly recommended to rinse off wire ropes affected by sea water with fresh water before greasing, as salt binds moisture under the lubricant, which can then lead to corrosion. The date of the greasing is to be entered into the cargo gear book.
Wire Rope Check Wire ropes are to be checked regularly in order to recognize damage in good time. These checks are then to berecorded in the cargo gear book. The checks are to be performed according to the following criteria: a) wear and tear on the outer strands b) rust build-up c) twist loosening d) reduction in wire diameter e) wire- and strand fractures (the number of visible wire fractures are to be documented by means of sketches) f) location of the fractures g) chronological log of the wire fractures h) damage bypinches To this end, the areas to be checked are to be cleaned of grease and dirt.
Discarding Condition In order to ensure operational safety, the wire rope must be discarded when the following characteristics are present: a) wear and tear beyond 10% of the original diameter
b) significant build-up of corrosion
c) deformation similar to that of a corkscrew
d) the wire ropeis buckled
e) loosening of individual wires or strands
f) formation of knots
h) flattening by squeezing i) visible wire- and strand fractures corresponding to the register e.g. at a length of 6 x rope’s diameter; 15 visible wire fractures
at a length of 30 x rope’s diameter; 30 visible wire fractures
local concentration of wire fractures
Thereplacement of a wire rope is to be recorded in the cargo gear book. Unfortunately, there are no concrete rules or regulations regarding the timely discarding condition of wire ropes. Of course, some companies have published internal rules and regulations indicating when crane wires are to be discarded. Example: In regard to hoisting wires, a check of undersize and wire fractures is required to beperformed quarterly. If there is no exterior damage to the hoisting wires, or if there are no alterations to the required timely changing of hoisting wires, they are to be replaced according to the following timespans:
Wire diameter After the following Hours of Operation After the following Years of Use Ø 20 mm Ø 31 mm Ø 32 mm 1,500 2,200 2,500 or 3.5 or 3.5 or 4.0
We recommended thefollowing equipment:
Electro-Magnetic Testing Method The optical appraisal of wire ropes, particularly the determination of the number of fractions for discarding a wire rope (see pg. 3, discarding conditions, item “i”), is limited to only, as a rule, the external visible surface of the rope. The steel core, the interior wires of the outer strand, and the areas, in which the outer strands lie in the...