GB/T 5972-2023 Cranes - Wire ropes - Care and maintenance, inspection and discard
1 Scope
This document establishes general principles for the care and maintenance, and inspection and discard of steel wire ropes used on cranes and hoists.
In addition to guidance on storage, handling, installation and maintenance, this document provides discard criteria for those running ropes which are subjected to multi-layer spooling, where both field experience and testing demonstrate that deterioration is significantly greater at the crossover zones on the drum than at any other section of rope in the system.
It also provides more realistic discard criteria covering decreases in rope diameter and corrosion, and gives a method for assessing the combined effect of deterioration at any position in the rope.
This document is applicable to those ropes used on the following types of cranes:
a) cable and portal cable cranes;
b) cantilever cranes (pillar jib, wall or walking);
c) deck cranes;
d) derrick and guy derrick cranes;
e) derrick cranes with rigid bracing;
f) floating cranes;
g) mobile cranes;
h) overhead travelling cranes;
i) portal or semi-portal bridge cranes;
j) portal or semi-portal cranes;
k) railway cranes;
l) tower cranes;
m) offshore cranes, i.e. cranes mounted on a fixed structure supported by the sea bed or on a floating unit supported by buoyancy forces.
Note: For the definitions of cranes in a) to l) above, please refer to GB/T 6974.1.
This document applies to rope on cranes, winches and hoists used for hook, grabbing, magnet, ladle, excavator or stacking duties, whether operated manually, electrically or hydraulically.
It also applies to rope used on hoists and hoist blocks.
Note: In view of the fact that the exclusive use of synthetic sheaves or metal sheaves incorporating synthetic linings is not recommended when single-layer spooling at the drum, due to the inevitability of wire breaks occurring internally in large numbers before there is any visible evidence of any wire breaks or signs of substantial wear on the periphery of the rope, no discard criteria are given for this combination.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4301-1:1986 Cranes and lifting appliances - Classification - Part 1: General
ISO 17893 Steel wire ropes - Vocabulary, designation and classification
Note: GB/T 8706-2017, Steel wire ropes - Vocabulary, designation and classification (ISO 17893:2004, MOD)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 17893 and the following apply.
3.1
nominal diameter
d
diameter by which the rope is designated
3.2
measured diameter
actual diameter
dm
average of two measurements, taken at right angles to one another, of the diameter that circumscribes the rope cross-section
3.3
reference diameter
dref
measured diameter (3.2) of a section of rope that is not subject to bending, taken directly after running in the new rope
Note: This diameter is used as the baseline for uniform change in diameter.
3.4
cross-over zone
that portion of rope coincident with a crossing over of one wrap by another as the rope traverses the drum or rises from one layer to the next at the drum flange
3.5
wrap
one revolution of rope around a drum
3.6
reel
flanged spool on which rope is wound for shipment or storage
3.7
wire rope periodic inspection
in-depth visual inspection of the rope plus measurement of the rope and, if practicable, an assessment of its internal condition
Note: If required, this may include an MRT (3.11) performed by a person competent in the operation of MRT equipment and interpretation of trace data.
3.8
competent person
person having such knowledge and experience of wire ropes on cranes and hoists as is necessary for that person to assess the condition of the rope, make a judgement as to whether it may remain in service and stipulate the maximum time interval between inspections
Note: If an MRT (3.11) is required, it has to be performed by a competent person in that discipline.
3.9
valley wire break
wire break that occurs at the inter-strand contact point or valley area between two outer strands
Note: Outer wire breaks that also occur within the rope anywhere between one valley area and the next - see Figure 1 - including any strand-core breaks, may also be regarded as valley wire breaks The red lines indicate the contact points and the location of the valley breaks.
3.10
severity rating
amount of deterioration expressed as a percentage towards discard
Note: The rating may relate to either an individual mode of deterioration [e.g. broken wires, decrease in diameter or loss of metallic area as detected by MRT (3.11)] or the combined effect of more than one mode of deterioration, e.g. broken wires and decrease in diameter.
3.11
magnetic rope test; MRT
non-destructive testing (NDT) based on the measurement of the magnetic flux leakage of a magnetized rope
3.12
test head
device on that part of the MRT (3.11) instrument positioned around the rope during testing which generates the magnetizing field and contains the detecting or sensing elements
3.13
base trace
signals on the MRT (3.11) recording display as the rope travels through the test head on the first occasion that it is tested
Note: The trace is the datum against which future in-service deterioration effects are compared. The trace reflects the construction of the rope and changes in magnetic characteristics of the rope along its length, e.g. magnetic permeability differences.
3.14
local fault; LF
local flaw
short discontinuity in the wire rope.
Note: Such as a wire break, welded wire, corrosion pit or inter-strand nicking
3.15
loss of metallic area; LMA
change in metallic cross-sectional area expressed as percentage of nominal metallic cross-sectional area of the new rope
Note: Loss of metallic area is normally associated with damage such as uniform corrosion, wear, abrasion/mechanical damage or wire breaks.
4 Care and maintenance
4.1 General
In the absence of any instructions provided by the manufacturer of the crane in the operator’s manual and/or provided by the manufacturer or supplier of the rope, the general principles given in 4.2 to 4.7 shall be followed.
