• CHAPTER 5 ROPE AND CABLE TERMINATIONS Author: C. Robert Shaw ...


  •   
  • FileName: 05_rope_cable_terminations.PDF [read-online]
    • Abstract: Information section at the end of this handbook. a. Standard Wire Rope Thimbles -- This class of thimble is ... riggers familiar with conventional braid-on-braid splicing techniques. ...

Download the ebook

CHAPTER 5
ROPE AND CABLE TERMINATIONS
Author: C. Robert Shaw Reviewer: Tom Coughlin
1.0 INTRODUCTION 5-3
2.0 SELECTION CRITERION 5-4
2.1 Types and Sizes of Wire or Cable 5-4
2.2 Corrosion Potential 5-5
2.3 Loading and Cable Fatigue 5-5
2.4 Terminal Efficiency 5-5
2.5 Assembly Requirements and Cost 5-6
3.0 INSTALLATION PROCEDURES 5-7
3.1 Wire Rope Clips 5-9
3.2 Wire Rope Thimbles 5-11
3.3 Open Wedge Terminations 5-12
3.4 Poured on Spelter Sockets 5-13
3.5 Compressed Sleeves (Nicopress) 5-21
3.6 Swaged Terminations 5-22
3.7 Mechanical Terminations (Electroline 5-25
or Fiege)
4.0 ELECTRO-MECHANICAL TERMINATION 5-31
4.1 Electroline E-M Cable Terminations 5-32
4.2 Installation Procedures 5-32
4.3 Combination Mechanical/Epoxy Terminations 5-37
4.4 Helically Wound Terminations 5-42
5.0 KEVLAR APPLICATIONS 5-46
5.1 Working Ropes and Cables 5-46
5.2 Static Ropes 5-46
5.3 Winch Ropes 5-47
5.4 Dynamic Cycling Ropes 5-48
5.5 Electro-Mechanical Cables 5-48
5-2
6.0 JACKET MATERIALS FOR SYNTHETIC 5-49
ROPES
6.1 Braided 5-49
6.2 Extruded Polyethylene 5-49
6.3 Extruded Nylon 5-49
6.4 Extruded Polyurethane 5-49
6.5 Extruded Hytrel 5-49
6.6 Extruded Teflon - 5-51
7.0 TERMINATIONS FOR KEVLAR ROPES 5-51
7.1 Internal Plug or Wedge Termination 5-51
7.2 Internal Plug or Wedge Terminal 5-54
7.3 Chemical Potting 5-54
7.4 Eye Splicing 5-54
7.5 Swagged Ferrules 5-59
7.6 Line Pulling Grips 5-59
ACKNOWLEDGMENTS 5-63
5-3
1.0 INTRODUCTION
Selection of the proper type of wire or cable termination used in
oceanographic applications is a key factor in the safe and effective
utilization of the winch and wire system in the deep sea. The purpose of
this section will describe the seven basic types of wire rope
terminations, as well as those used with electromechanical cable. In
particular, the characteristics, advantages, limitations, and assembly
procedures for each type will be fully illustrated.
The selection of a wire or cable termination for a particular
application should be considered carefully, bearing in mind that there
are advantages and disadvantages to each termination type discussed in
this section. To select the correct type of terminal for a particular
application, the following factors should be carefully evaluated:
- Type and size of cable involved
- Corrosion potential
- Loading and cable fatigue
- Efficiency required
- Assembly requirements and cost
Primarily, seven basic types of wire rope terminations will be
discussed as follows:
a. Wire rope clips - A U-bolt and saddle combination or a “fist-
grip” nut and bolt arrangement used to fasten a loop of wire rope that is
formed around a thimble.
b. Open-wedge terminations -- Also called “wedge sockets”; the
cable is looped around a wedge, which is inserted into a socket or
“basket” and held secure by tension on the line.
c. Poured-socket termination - - Also known as Spelter sockets;
molten zinc or an epoxy compound is poured into the socket to bond the
wire rope inside the fitting.
d. Compressed sleeves -- Also known as Nicopress terminations;
sleeves are crimped or compressed around the cable, usually by use of
hand tools.
5-4
e. Swaged terminations - - Attached by cold forming under high
pressure so that the metal of the fitting flows around and between
strands and wires of the rope.
f. Mechanical terminations - - Also known as Electroline fittings;
these devices utilize wedge or plugs of various sizes and configurations
to hold the cable inside a threaded lock sleeve.
g. Helical terminations - - Also known as Preformed Dyna-grip
terminations. This device utilizes helical gripping wires, which wrap
around the cable and are finished in a thimble or epoxy filled fitting.
2.0 SELECTION CRITERION
As mentioned in the introduction, a series of five criteria should be
considered in the selection of a wire or cable termination. The
following discussion of these criteria will provide insight into the
problems, which can be encountered in the selection process.
2.1 Type and Size .of Wire or Cable
The terminations selected must be compatible with the type of
cable being used and must result in the maximum effective holding
strength. For example, swaged terminations, compressed sleeves and
wire rope clips are not efficient terminals for hemp-core wire rope,
armored electrical cables or synthetic cables. Application of such
terminations requires squeezing them onto the cable, and “soft-core”
cable material will give way under the pressure, thereby weakening the
effectiveness of the termination. Mechanical, poured-socket and open-
wedge terminations can be use effectively with these types of cables
since they achieve their efficiency from bonding or compressing only
the steel of the wire or cable.
Cable size is a major consideration because of the standard
capacities of termination devices that are generally available.
Compressed sleeves can be used on cables up to 5/8-inch diameter.
Wire rope clips, open wedges and mechanical fittings are standard for
cables up to 1-1/2 inches in diameter. Swaged terminals can be obtained
as large as 2-1/2 inches and poured sockets up to 4 inches.
5-5
2.2 Corrosion Potential
The corrosion problems experienced in an oceanographic
application, when wires and terminations are subjected to alternate
immersion and drying cycles, is well known. Given this as an existing
condition, it is important to consider the standard materials in which the
various termination devices are available. In the main, poured sockets,
helical terminations, wire rope clips, and open-wedge sockets are
stocked only in stell, although zinc plating on these terminations is
available. Compressed sleeves (Nicopress), swaged terminations, and
mechanical fittings (Electroline), are available in a wide variety of
materials ranging from steel to stainless steel. Compressed sleeves and
the mechanical fittings are also produces, in certain sizes, in both
bronze and aluminum for special applications. The variety of materials
available in termination constructoin, make the matching of a specific
fitting to a particular application a fairly simple process.
2.3 Loading and Cable Fatigue
All seven basic types of terminations are suitable for static and
moderately cyclic loads such as those imposed by cranes, hoists, guy
wires, tie downs, slings, etc. Only the mechanical and helical
terminations, however, are designed to accommodate the shock and
vibration loads imposed by winches, buoys and towed bodies in the
marine environment.
The mechanical fittings have a “transition zone” in the nose where
the cable enters the termination. In this “semi- loose” transition zone,
the tension, compression and bending stresses in the rope strands are
dissipated. Because of the ways in which other types of terminations are
affixed to the cable, they have a hard transition from the cable to the
terminal which can contribute to shorter cable fatigue life The helical
type termination provides a long cable life by dissipating the shock and
vibration loads in the spring action of the helical gripping wires.
2.4 Terminal Efficiency
The more efficient the terminal, the smaller and lower cost the
cable may be. This also can affect the cost of winches and other
handling equipment.
5-6
The swaged and helical terminals are rated for 100% of the cable’s
rated breaking strength. Poured sockets, compressed sleeves and
mechanical fittings are rated at 95% to 100%, while wire rope clips and
open-wedge terminations are rated at 75% to 85%. Wire rope clips tend
to lose their holding strength with use and must be retightened from
time-to-time. At the other end of the scale are the mechanical and open-
wedge terminals in which the wedging action actually increases
efficiency with loadings (Table I).
2.5 Assembly Requirements and Cost
Wire rope clips are both the least expensive and easiest ter-
mination that can be applied in the field. They require only attention to
clip spacing, placement, and tightening torque to perform efficiently.
The open-wedge termination is only slightly more expensive, but is just
as simple to install, requiring only hand tools for the application.
Although the simplest, they are also the least efficient of the six
terminations discussed. The compressed sleeve (Nicopress) fitting
represents another low cost, but highly efficient means of terminating a
wire rope. Special tooling, which is available from the manufacturers, is
available to ensure proper compression of the sleeve and the installer
needs only to match the required number of compression to the sleeve
size selected for use. Used in the proper situation, the compressed
sleeve can be rapidly and efficiently reapplied in the field with no
special training.
The swaged and poured socket (Spelter) terminations represent a
moderately priced fitting with a high efficiency rating. Swaged
terminations require large hydraulic presses for proper installation and
do not readily lend themselves to reapplication in the field under most
circumstances. The poured socket represents a highly efficient fitting,
which can be reapplied in the field using either molten zinc or an epoxy
resin to achieve wire bonding. This approach, however, requires careful
attention to detail and the use of an aid to clean the wire ends prior to
fitting installation.
The mechanical termination represents a more expensive fitting
type discussed in this section due to the number of components
involved in each assembly. Although it appears to be a complicated
termination, it can be easily installed without special equipment and
with only the training received from the manufacturers’ literature.
Attention to assembly detail and adequate proof loading are all that is
required to produce a highly efficient termination using this fitting.
5-7
The helical terminal is the most expensive. Assembly can be
accomplished easily in the field with no special training or equipment.
However there is a 24-hour cure for the epoxy filling.
Inspection is another important assembly consideration. The
swaged and compressed sleeve terminals can be inspected for effective
assembly by measuring the final diameters. Wire rope clips can be
inspected with a torque wrench. The poured socket cannot be inspected
to determine if the assembly is proper. The mechanical terminal has an
inspection hole built in to facilitate visual checking. The helical
termination can be inspected to assure that no wires are crossing
themselves and that the body is filled with epoxy.
Perhaps the single most important thing to remember in the
selection of a termination for either wire rope or cable is that the fitting
should be chosen at the same time as the cable is specified. A second
major consideration is physical size of the termination relative to the
instrument or device it will be attached to. This is especially important
when the fitting is required to pass through an instrument as in the case
of a piston-coring device or over a sheave. In these cases physical size
and configuration of a fining will influence the type selected. Since the
wire or cable termination is vital to the safe and efficient use of the wire
or cable, it should be viewed as an integral part of the system and gives
careful consideration then purchased.
In order to select the proper terminations for an application, the
factors discussed here should be carefully considered as well as those
presented in Table I.
3.0 INSTALLATION PROCEDURES
In order to ensure the highest possible reliability in applying the
particular termination selected for use, the following procedures have
been detailed, along with information, which affects long-term
performance. For any type of termination there are “tricks of the trade”
which assure the integrity of the fitting once applied, and which should
not be deviated from if full reliability is to be achieved. The following
procedures, if carefully followed, will assure the reliability required in
an oceanographic application.
5-8
5-9
3.1 Wire Rope Clips
Wire rope clips (Figure 5-1) are sized and marked on the body of
the clip with the wire diameter that they are to be used. It is important
that the clip be matched to the diameter wire that is in use, as
mismatches will result in a drastic reduction in termination holding
power and efficiency. Placement of the wire rope clip is of prime
importance to achieve maximum holding power. It should be noted that
most available wire rope clip data sheets specify only a minimum
number of clips needed for ordinary loads. Where heavy loading is
anticipated, it is strongly recommended that two additional clips be
added to each installation.
The recommended procedure for applying wire rope clips to
achieve the maximum termination holding power is as follows:
-- Turn back the amount of wire required based on Table 2. This
distance is measured from the thimble to the bitter end of the wire.
5-10
-- The U-Bolt portion of the clip must be placed over the bitter end of
the wire while the saddle of the clip is placed on the standing part
of the wire. Any reversal of this procedure or a staggering of the
clips will result in reduced efficiency of the termination.
TABLE 2
Wire Rope Clip Assembly Data **
** Table based on Crosby Group Data
-- The first clip should be installed within one saddle width of the
end of the turned back wire and the nuts evenly tightened. The
second clip should be installed as near the thimble or loop as is
possible with nuts firmly installed, but not tightened.
-- Space additional required clips evenly between the two clips
already on the wire. Light tension should be applied between the
terminal loop and the standing part of the cable
before tightening all clips to their recommended torque. This
5-11
process will eliminate stack occurring in the bitter end of the cable
and produce a more uniform application.
-- An initial load should be applied to the termination and all nuts
retightened to their recommended torque prior to use of the
termination. Once applied in accordance with the above
procedures, the resulting termination will have an efficiency rating
of 75-85% of the breaking strength of new wire.
-- When a wire rope clip type of termination is used, it is advisable
to periodically tighten the nuts to their recommended torque since
wire vibration can result in a loosening of the U-bolt nuts.
3.2 Wire Rope Thimbles
The use of a thimble is highly recommended with this type of
termination and some discussion of thimble styles is necessary at this
point. Essentially, thimbles fall into three broad categories: I) Standard
Wire Rope Thimbles, 2) Extra Heavy Thimbles, and 3) Solid Thimbles.
Specific data relating to each style discussed will be found in the Useful
Information section at the end of this handbook.
a. Standard Wire Rope Thimbles -- This class of thimble is
designed primarily for use in light duty situations where loading is
minimal. Their use in heavy-duty situations will result in a complete
deformation of the thimble and the placing of excessive stress on the
wire at the head of the loop. Under this situation, a failure of the wire
can be expected, which will occur below the rated strength of both the
termination and the wire.
b. Extra Heavy Wire Rope Thimble -- This style of thimble has
been designed for heavy-duty service where high loading conditions are
expected to Occur. They are far more resistant to deformation due to
loading and work to maintain an even wire loading condition in the
loop of the termination. As in all thimbles under load, the size of the pin
used to attach the toad to the cable is critical. Its diameter should be
closely matched to the internal diameter of the thimble in order to
reduce point loading.
c. Solid Thimble - This thimble is designed as the ultimate in
crush-proof thimbles due to its solid steel construction. Primarily a unit
for very heavy load conditions, it has a single disadvantage in that the
hole-sizes available are more limited than those found in
5-12
the extra-heavy thimble. Where heavy loading situations are
anticipated on a regular basis, it is recommended that a solid thimble
be considered.
3.3 Open-Wedge Termination
Although this type of termination is typically found on crane
cables, it has occasionally been used for limited trawl wire operations.
Because of its diverse usage in the field, it is felt prudent to provide
proper assembly instructions for this type of fitting.
The open wedge termination (Figure 5-2), although a simple style
of fitting to install, should be approached with a certain amount of
caution during installation of the wire. Improper placement of the wire
can result in excessive wire stress at the termination resulting in a
reduction of wire loading potential.
a. Installation Procedure - The simplicity and rapid installa-
tion potential of the open-wedge can be further enhanced by attention to
a few details calculated to produce the maximum efficiency from this
style of termination. The proper installation procedure is as follows:
5-13
-- An inspection of both the socket and wedge should be made to
identify any rough or burred surfaces on the wire path, which
could damage the wire under load. If irregularities are discovered,
they should be removed, if possible, or the socket or wedge
replaced.
-- The bitter end of the wire should be clean cut and served in order
to prevent unlaying. It is important that the bitter end be clean cut
rather than fused due to cutting with a torch in order to allow the
individual wire strands to adjust around the sharp bend of the
wedge. If the wire end is fused on installation, the movement of
individual wire strands will be translated to the standing part of the
wire causing irregularities in shape and unequal loading.
-- To install the wire in the socket, the socket must be in an upright
position (ears downward). The wire is then brought into the socket
to form a large, easily handled loop. Care should be taken to
ensure that the standing part of the wire is in line with the sockets
ear (Figure 5-2).
-- The bitter end of the wire should extend above the socket for a
distance equal to nine (9) times the diameter of the wire used. At
this point the wedge is placed in the socket and a wire rope clip
placed around the bitter end of the wire by clamping it around a
short length of wire, which has been attached to the bitter end to
provide the mass required for the wire clips seating. The U-bolt of
the wire clip should bear on the bitter end and the saddle on the
added short piece of wire.
-- By securing the fitting to a convenient pad eye or bit, a load
should be placed on the standing part of the wire. This load is
steadily applied until the wedge and wire are pulled into position
with enough strain to hold them in place when the load is released.
During the seating of the wedge, sudden surge or shock loading
should be avoided.
3.4 Poured or Spelter Sockets
The spelter socket (Figure 5-3) represents a highly reliable
termination with 100% efficiency, when properly applied. The key
factor in achieving the 100% efficiency of this termination is careful
cleaning of the wire ends with a solvent solution and the position-
5-14
ing of the socket on the wire prior to the pouring of either the zinc or
resin used to hold it in place. The cleaning of the wire ends allows for
the maximum bonding action of the filler chosen while exact
positioning of the socket on the wire ensures an even loading of the
wire strands in the field.
A certain amount of caution should be used when dealing with this
style of termination. The rigidity, which is caused by the bonding action
of the zinc or resin on the end of the wire, causes a sudden dampening
of wire vibration at the point where the wire enters the fitting. This
dampening of vibration can lead to fatiguing of the wires at this point
and frequent, careful inspection of the area for broken wire should be
made. The detection of any broken wires should dictate the immediate
replacement of the fitting.
a. Zinc Socketing Procedures (Figure 5-4) - The
procedures for applying zinc-pouted sockets is as follows:
-- Measure the rope ends for socketing and apply serving at
the base of the socket. As indicated in Figure 5-4a, the length of
the rope end should be such that the ends of the wires when un-laid
from the strands will be at the top of the socket basket. Apply a
tight wire-serve band for a length of two, rope diameters begin-
fling at the base of the socket and extending away from it.
5-15
-- Broom out strands and wires in the strands (Figures 5-4b and 5.4c).
Un-lay and straighten the individual strands of the rope and spread
them evenly so they form an included angle of approximately 60°. If
the rope has a fiber core, cut out and remove the core as close to the
serving band as possible. Un-lay the wires from each individual
strand for the full length of the rope end, being careful not to disturb
or change the lay of the wires and strands under the serving band. If
the rope has an independent wire rope core (IWRC), un-lay the wires
of the IWRC in the same manner.
-- Clean the broomed-out ends (Figure 5-4d). A suggested solvent for
cleaning is SC-5 Methyl Chloroform. This solvent is also known
under the names of Chlorothane VG or 1,1,1-trichloroethane.
CAUTION: Breathing the vapor of chlorinated solvents is harmful;
use only with adequate ventilation. Follow the solvent
manufacturer’s instructions; observe the label instructions.
When using a solvent, swish the broomed-out rope end in the solvent
and vigorously brush away all grease and dirt making sure to clean
all the wires of the broomed-out portion to a point close to the
Serving band. A solution of hydrochloric (muriatic acid) may be
used for additional cleaning. However, if acid is used, the broomed-
out ends of the rope should be subsequently rinsed in a solution of
bicarbonate of soda to neutralize any acid that may remain on the
rope. Care should also be exercised that acid does not enter the core,
particularly if the rope has a fiber core. Ultrasonic cleaning is a
preferred method for cleaning rope ends for socketing.
After cleaning, put the broomed-out ends upright in a vise until it is
certain that all the solvent has evaporated and the wires are dry.
- Dip the broomed-out rope ends in flux (Figures 5-4e). Make a hot
solution of zinc-ammonium chloride flux such as Zalcon K. Use a
concentration of one pound of zinc-ammonium chloride in one gallon
of water and maintain the solution at a temperature of 180° to 200°F.
Swish the broomed-out end in the flux solution, put the open end
upright in the vise, and permit all wires to dry thoroughly.
5-16
5-17
-- Close rope ends and install the socket (Figures 5-4f and 5-4g). Use
clean wire to compress the broomed-out rope end into a tight bundle
so that the socket can be slipped over the wires. A socket should
always be cleaned and heated before placing it in the rope. The
heating is necessary to dispel any moisture and to prevent premature
cooling of the zinc.
CAUTION: Never heat a socket after it has been placed on the rope
because of the hazard of heat damage to the wire rope.
When the socket has been put on the rope end, the wires should be
evenly distributed in the socket basket so that zinc can surround
every wire. Use utmost care to align the socket with the centerline of
the rope and to ensure that there is a vertical, straight length of rope
exiting the socket that is equal to a minimum of 30 rope diameters.
Seal the base of the socket with fire clay or putty, but be sure this
material is not inserted into the base of the socket; if this were done,
it would prevent the zinc from penetrating the full length of the
socket basket and would, create a void, which would collect moisture
when the socket is placed into service.
-- Pour the zinc (Figure 5-4h). Use zinc that meets the requirements in
ANSI/ASTM B6-70, Specification for Zinc Metal (Slab Zinc), for
“high grade” or Federal Specification QQ-Z351-a Amendment I, and
Interim Amendment 2. Pour the zinc at a temperature of
approximately 95O~F to 975°F making allowances for cooling if the
zinc pot is more than 25 feet from the socket.
CAUTION: Do not heat zinc above 1100°F or its bonding properties
will be lost.
The temperature of the zinc may be measured with a portable
pyrometer or a Templistik. Remove all dross before pouring. Pour
the zinc in one continuous pour to the top of the socket basket so that
all the wire ends are covered; there should be no “capping” of the
socket.
-- Remove the serving band (Figure 5-4i). Remove the serving band
from the base’ of the socket and check to see that zinc has penetrated
to the base of the socket.
5-18
-- Lubricate the rope. Apply a wire rope lubricant to the rope at the
base of the socket and on any section of the rope from which the
original lubricant has been removed.
b. Procedure for Thermoset Resin of Wire Rope
-- General -- Before proceeding with thermoset resin socketing, the
manufacturers instructions for using this product should be
carefully read. Particular attention should be given to sockets that
have been designed specifically for resin socketing.
-- Seizing and Cutting the Rope - - The rope manufacturer’s
directions for a particular size or construction of rope should
be followed with regard to the number, position length of seizing,
and the seizing wire size to be used. The seizing which will be
located at the base of the installed fitting, must be positioned so
that the ends of the wires to be embedded will be slightly below the
level of the top of the fitting’s basket. Cutting the rope can best be
accomplished by using an abrasive wheel.
-- Opening and Brooming the Rope End - - Prior to opening the rope
end, place a short temporary seizing directly above the seizing that
represents the base of the broom. The temporary seizing is used to
prevent brooming the wires the full length of the basket and also to
prevent the loss of lay in the strands and rope outside the socket.
Then move all seizings between the end of the rope and the
temporary seizing. Un-lay each of the strands that make-up the
construction of the rope. Open each strand of the rope and broom
or un-lay the individual wires.
When the brooming is completed, the wire should be distributed
evenly within a cone so that they form an included angle of
approximately 60°. Some types of sockets require a different
brooming procedure and the manufacturers instructions should be
followed.
-- Cleaning the Wires and Fittings - Different types of resin with
different characteristics require varying degrees of cleanliness. For
some, the use of soluble oil for cleaning wires has been found to be
effective. For one type of polyester resin on which over 700 tensile
tests on ropes in sizes 1/4 to 3-1/2 inches in diameter were made
without experiencing any
5-19
failure in the resin socket attachment, the cleaning procedure is as
follows:
Thorough cleaning of the wires is required to obtain resin adhesion.
Ultrasonic cleaning in recommended solvents such as
trichloroethylene or I-I-I trichloroethane or other nonflammable
grease-cutting solvents is the preferred method of cleaning the wires
in accordance with OSHA Standards. Where ultrasonic cleaning is
not available, brush or dip cleaning in trichloroethane may be used;
but fresh solvent should be used for each rope and fitting and
discarded after use. After cleaning, the broom should be dried with
clean compressed air or in some other suitable fashion before pro-
ceeding to the next step. The use of acid to etch the wires before
resin socketing is unnecessary and not recommended. Since there is
a variation in the properties of different resins, the manufacturer’s
instructions should be carefully followed.
-- Placement of the Fitting - Place the rope in a vertical position with
the broom up. Close and compact the broom to permit insertion of
the broomed rope end into the base of the fitting. Slip on the fitting,
remove any temporary banding or seizing as required. Make sure the
broomed wires are uniformly spaced in the basket with the wire ends
slightly below the top edge of the basket; make sure that the axis of
the rope and the fittings are aligned. Seal the annular space between
the base of the fitting and the existing rope to prevent leakage of the
resin from the basket. A non-hardening butyl rubber-base sealant
gives satisfactory performance. Make sure that the sealant does not
enter the base of the socket so that the resin may fill the complete
depth of the socket basket.
-- Pouring the Resin - Controlled heat curing (but without open flame)
at a temperature range of 250° to 300°F is recommended -- and is
essential if ambient temperatures are less than 60°F. When
controlled heat curing is not available and ambient temperatures are
not less than 60°F, the attachment should not be disturbed and
tension should not be applied to the socketed assembly for at least 24
hours.
-- Lubrication of Wire Rope after Socket Attachment - After the resin
has cured, re-lubricate the wire rope at the base of the socket to
replace the lubricant that was removed during the cleaning operation.
5-20
c. Description of the Resin
-- General - Resins vary considerably according to the manufacturer;
it is important to refer to the manufacturer’s instructions before
using resins as no general rules about them can be established.
Properly formulated thermoset resins are acceptable for socketing.
These resin formulations, when mixed, form a pourable material
that hardens at ambient temperatures or upon the application of
moderate heat. No open-flame or molten-metal hazards exist with
resin socketing since heat-curing, when necessary, can only be
carried out at a relatively low temperature (250° to 300°F) that can
be supplied by electric-resistance heating.
Tests have shown satisfactory wire rope socketing performance by
resins having the properties of a liquid thermoset material that
hardens after mixing with the correct proportion of catalyst or
curing agents.
-- Properties of Liquid (Uncured) Material - Resin and catalyst are
normally supplied in two separate containers, the complete contents
of which, after thorough mixing, can be poured into the socket
basket. Liquid resins and catalyst should have the following
properties:
1) Viscosity of Resin-Catalyst Mixture - - The viscosity of the
resin-catalyst mixture should be 30,000 to 40,000 CPS at 75°F
immediately after mixing. Viscosity will increase at lower ambient
temperatures and resin may need warming prior to mixing in the
catalyst if ambient temperatures drop below 40°F.
2) Flash Point - Both resin and catalyst should have a minimum
flash point of 100°F.
3) Shelf Life – Resin and catalyst should have a minimum of one-
year shelf life at 70° F.
4) Pot Life and Cure Time - After mixing, the resin-catalyst blend
should be pourable for a minimum of eight minutes at 60°F and should
harden in 15 minutes. Heating of the resin in the socket to a maximum
temperature of 250°F is permissible to obtain full cure.
5-21
-- Properties of Cured Resin
1) Socket Performance - Resin should exhibit sufficient bonding
to solvent-washed wire in typical wire rope end fittings to develop the
nominal strength of all types and grades of rope. No slippage of wire is
permissible when testing resin-filled rope socket assemblies in tension;
however, after testing, some “seating” of the resin cone may be
apparent and is acceptable. Resin adhesion to wires shall also be
capable of withstanding tensile shock loading.
2) Compressive Strength - The minimum compressive strength
for fully cured resin should be 12,000 lb/in2.
3) Shrinkage - - Fully cured resin may shrink a maximum of
2%. The use of an inert-filler in the resin is permissible to control
shrinkage, if the viscosity provisions specified for the liquid resin are
met.
4) Hardness - A desired hardness of the resin is in the range of
Barcol 40-55.
-- Resin Socketing Compositions - Manufacturers directions should be
followed in handling, mixing, and pouring the resin composition.
-- Performance of Cured Resin Sockets - - Poured resin sockets may be
moved when the resin is hardened. After the ambient or elevated
temperature cure recommended by the manufacturer, resin sockets
should develop the nominal strength of the rope, and should also
withstand shock loading sufficient to break the rope without cracking
or breakage. Resin socketing materials that have not been tested to
these criteria by the manufacturer should not be used.
3.5 Compressed Sleeves (Nicopress)
The compressed or Nicopress sleeve (Figure 5-5) represents a
style of wire and cable termination which has been available for the
past thirty years. Its high efficiency, 95% - 100% of the breaking
strength of the wire, and its simplicity of installation have made it an
ideal type of termination for general field use. The success of the
compressed sleeve is dependent upon the selection of the proper sleeve
to match the wire to be terminated and matching the compression
requirements of the sleeve. Specialized tooling is produced which will
5-22
ensure proper compression to achieve the maximum holding power of
the fitting.
When terminating a rope or cable, both the sleeve and tool should
match the requirements of the cable size. Table 3 provides a guide to
this selection as well as the recommended compressions needed for
maximum efficiency.
It should be noted that in Table 3 the number of sleeves, required
per installation, to achieve the maximum holding power is the same for
all wire sizes. The manufacturer recommends a single sleeve per
termination and the addition of more sleeves in no way increases the
ultimate holding power of this type of termination. One factor, which
can affect the efficiency of the compressed sleeve, is excessive
compression. The recommended compressions shown in the table and
in Figure 5-5, allow for ultimate holding while providing an adequate
stress relief at both ends of the sleeve. This factor can become
extremely important when Stainless steel sleeves are used in the
termination of a wire.
As with other types of terminations, which require the wire to be
looped at the termination point, it is necessary to use a properly sized
thimble to protect the wire. The discussion found in Chapter 6, Section
3.2, also applies to the use of compressed sleeves.
3.6 Swaged Terminations
The swaged style of wire termination, possesses a 100% efficiency
rating when compared to the breaking strength of the wire being
5-23
5-24
terminated. Its high efficiency is achieved through the use of large
hydraulic presses, which exert a uniform compressive force on the
fitting (Figure 5-6).
When swaged sockets are used with 3 x 19 wire rope, it is
necessary to insert filler pieces into the spaces between the strands,
inside the socket, prior to compression of the fitting. The soft wire
fillers serve to increase the effective surface area of the 3 x 19 rope and
allow a more uniform compression and holding power to be achieved
(Figure 5-7).
The specialized nature of the swaged termination does not lend itself
easily to field applications due to operate the equipment. The frequent
re-termination of both trawl and hydrographic wires that is required at
sea also precludes the use of this particular type of fitting for working
cable applications. In addition, the corrosion potential within the
swaged socket occurs in an area, which is impossible to inspect.
Corrosion of the filler wire can occur over time and eventually result in
a failure of the termination without prior warning or evidence of
weakening.
5-25
3.7 Mechanical Terminations (Electroline or Fiege)
Perhaps the most common fitting used to terminate the deep-sea
trawl wire is the Electroline eye socket assembly or “Fiege fitting” as it
is frequently called. The Electroline termination (Figure 5-8), is a three
component device consisting of a threaded sleeve, socket assembly and
a plug which, when properly assembled, will result in a termination
strength equal to 95%-100% of the ropes’ breaking strength. The high
level of fitting efficiency is achieved through the use of the plug as a
wedge and by carefully following the assembly instructions.
5-26
Although this type of fitting can be used with all styles of wire
rope construction, only three-strand, torque balanced wire rope will be
discussed here. Changes in wire construction will require changing the
style and possi


Use: 0.0385