HNSA Crest with photos of visitors at the ships.
SECTION 9-3

INSTALLING CABLE STRAPS AND HANGERS
 

1. UTILIZATION OF SPARES.

When the electronic installation worker needs to run a cable for a new installation, he should find out if there are spare cables in existing wireways, and spare stuffing tubes in bulkheads. If no spares are available in wireways, it will be necessary to make up additional straps and hangers.

2. METHOD OF MAKING STRAPS.

The material used in making straps is strap steel, 3/4 inches x 3/32 inches for overhead spans up to 6 inches wide. For all vertical runs, horizontal runs and overhead spans over 6 inches wide, use 3/4 inches x 1/8 inches steel.

Straps must fit the cables snugly to avoid chafing and vibration that would eventually damage the cables, so the straps must be accurately formed. This cannot be done easily on the job; it requires the use of shop equipment designed for convenience in forming straps to any desired shape. This equipment consists of a set of short, steel rods, in sizes corresponding to the diameters of all commonly used cables, and a clamping mechanism for holding any desired grouping of these rods.

The strap is clamped, at one end, to the rods and is formed to the shape of the rods by use of a hammer and drive bar. (See Figure 9-11).

Holes are then punched or drilled to clear a 5/16 inch -18 machine screw at appropriate locations. It is important to file all sharp edges from the straps and to remove any burrs from the drilled or punched holes.

  Prior to mounting the cable straps, a protective coating, such as zinc plating, to give a good metal to metal contact between armor and cable strap, should be given the straps in order to comply with radio noise interference reduction requirements.

3. MOUNTING CABLE STRAPS.

Cable straps are supported by means of pads, studs, and hangers. Pads are round pieces of steel, usually 9/16 inch in diameter by 3/8 inch thick, drilled and tapped for ANS, right hand, 5/16 inch- 18 threads with class 2 fit. They are welded to the ship's structure so that the cable straps can be screwed in place. Installing pads is easiest when they are drilled and tapped and secured to the cable strap. Spot weld or tack the pads and then remove the cable strap before welding the pad entirely to prevent damage to the strap.

Pads or studs may be used on bulkheads not subject to condensation or moisture. Hangers are used where condensation occurs or where the bulkhead is insulated. Where aluminum bulkheads or overheads are encountered, drilling and riveting or bolting may be necessary to secure the hangers or straps.

No attempt will be made here to outline all the procedures to be followed for all the various conditions one encounters. These are found in BuShips 9-S-3980-L Alt. 27. Some of the more commonly encountered conditions are shown in Figure 9-2 to Figure 9-7.

Studs, attached to the ship by the stud welding process (Fig. 9-8) may be used to support cable straps. Studs are a type of headless machine bolt welded to steel bulkhead or overhead.

 
9-20

Single cable support for steel decks or W.T. Bulkhead
Single cable support for steel or aluminum N.W.T. bulkheads
Single cable support for steel or aluminum decks or W.T. bulkheads
Single cable support for steel or aluminum N.W.T. bulkheads
Single cable support for stel decks or bulkheads or damp locations 3/8 inch minimum from deck to back strap.

FIGURE 9-2
METHODS OF SUPPORTING SINGLE CABLES

 
9-21
 

Single row of cables support on steel decks, topside installations and W.T. Bulkheads where excessive moisture or drip is present.

Method of supporting a single row of cables on steel or aluminum N.W.T. Bulkheads.

Methods of supporting a single row of cables on steel decks and bulkheads having insulation.

FIGURE 3
METHODS OF SUPPORTING CABLES

 
9-22
 

9 inch max.

FIGURE 9-4
METHOD OF SUPPORTING A SINGLE ROW OF CABLES
ON STEEL DECKS AND W.T. BULKHEADS

1/2 inch min clearance
hanger steel

FIGURE 9-5
METHOD OF SUPPORTING MULTIPLE ROWS OF
CABLES ON STEEL DECKS

 
9-23
 

1-1/4 inch x 1/4 inch hanger support-steel
3/4 inch x 1/8 cable strap -steel
1/2 inch min clearance between top of largest cable and bulkhead or bottom of hanger flange.
3/8 inch - 16 hex head bolt and nut
Spacer washer to be used when hangers are butted as shown.

FIGURE 9-6
METHOD OF SUPPORTING TWO ROWS
OF CABLES ON STEEL BULKHEADS

 
9-24
 

1/4 inch x 5/16 hanger support - steel
1/4 x 1/4 hanger support - steel
3/8 inch - 16 hex head bolt and nut -steel

FIGURE 9-7
METHOD OF SUPPORTING TWO ROWS OF CABLES ON STEEL
BULKHEADS HAVING INSULATION

 
9-25
 

Steel hanger plate 7/4 x 3/32 for overhead spans up to and including 6 inch 3/4 x 1/8 for overhead spans over 6 inch and up to 9 inch and all horizontal and vertical runs.
Studs and 2 nuts - steel 5/16-18 for single cable support.
5/16 inch-18 for single row of cables up ot 6 inch span (Largest cable 150,000 CM)
3/8 inch-16 for single row of cables, over 6 inch and up to 9 maximum span.

Figure 9-8
STUD SECURED BY THE WELDING PROCESS

 
9-26
 
They are available in sizes 1/4 inch, 5/16 inch and 3/8 inch. Hexagonal nuts and lock washers are used with them.

Another type of stud known as the collar stud has a shoulder, which allows the securing nut to be turned down to the shoulder thus giving a spacing between the cable and the bulkhead or overhead.

Before mounting cable straps, make a thorough inspection of all spaces the cable will go through. Avoid obstructions, hot objects, and unventilated spaces if practicable. Locate places where watertight bulkheads must be drilled and mark the location for drillers, allowing space for the welder to work all around stuffing tubes. Inspect both sides of a bulkhead before drilling to check clearance and avoid damage.

Mark the location of hangers, pads, or

  studs used in the cable run for welder. If the surface over which the cable is to run is insulated, cut away the insulation where the hangers or studs are to be welded, allowing just enough space for the welder to work. If studs are used, it is necessary to grind the steel surfaces to a bright finish before welding. Hanger spacing should not exceed 16 inches center to center. After all the hangers and clamps are in place, the cable is run as described in "Installation in Wireways". When running cables across beams, and in order to avoid obstructions and preserve alignment of the cable run, make use of cable supports (Figure 9-9) and extended cable hangers . When going through decks, a kickpipe (Figure 9-10) will usually be necessary to protect the cable from damage.
 
9-27

Channel running accross frames.

FIGURE 9-9
METHOD OF SUPPORTING CABLE USING CHANNEL

 
9-28
 

Cable secured to bulkhead in any approved manner as applicable and shown on this drawing.
Space around cable to be filled with insulation plastic sealer.
A 3/32 inch steel brace shall be used to insure a rigid support, when distance from deck to top of stuffing tube body exceeds 12 inches.
Vertical or angle to suit.

FIGURE 9-10
TYPICAL KICKPIPE ASSEMBLY
CABLE SUPPORTS

 
9-29
 

Strap forming jig with short pieces of cable in varius sizes in place.

FIGURE 9-11
CABLE STRAP FORMATION

 
9-30
 

SECTION 9-4

INSTALLATION IN WIREWAYS
 

1. INTRODUCTION.

Because cable runs should be as direct as possible, wireways should be planned before the development of deck wiring plans. While this is mainly a function of the design section, some considerations in planning are presented to acquaint the installation worker with some of the problems involved. The plan for wireways should provide for:

a. Protection from battle damage

b. Circuit trunking

c. Protection from excessive heat

d. Protection from excessive moisture

e. Protection in hazardous locations

f. Minimum interference with machinery removal

g. Spare wireway area for future expansion

h. Cables to guns and directors

i. Cables away from the magnetic compasses

The greater part of cable installation in wireways is usually done while a ship is still on the ways, with no equipment aboard. This work is handled by the electrical group. However, an understanding of installation methods and practices will benefit the electronic installation men when equipment is added or short runs must be made.

Tools and material necessary for the average cable run are as follows:

Wrench (adjustable, open-end, for stuffing-tube gland nuts)

Black 1 inch friction tape, packing material (see section on stuffing tubes)

 
Plastic sealer, hacksaw, knife, diagonal cutters, screw driver, side cutters, armor strippers, lacing cord and shuttle.

A spin-tite wrench and box wrench are very useful in tightening down the 5/16 inch - 18 hex machine screw used with pads. Round head machine screws may also be used.

2. HANDLING CABLE.

a. BENDING. - In handling cable, both before and during installation, care should be taken to avoid abrasion and crushing, or sharp bends made without the aid of a mandrel. Such bends are most likely to occur when a cable is taken off a reel or unwound from a coil. Sharp "kinks", if pulled on, can ruin that section of cable by causing internal damage to insulation. All bends should be made with a radius no less than the minimum given in the table.

Where cables spread out to enter bulkhead stuffing tubes, the bends should be given a generous sweep to allow for flexibility at this point. Sufficient flexibility should exist to allow for deflection of the bulkhead without subjecting the cables to destructive tension or shearing. Run enough excess cable to permit repairs to be made at cable ends and to avoid cable renewals.

b. LOW TEMPERATURES. - Cables become stiff at temperatures below 35°F and must be handled extra carefully to avoid cracking or rupturing the sheath or the insulation.

Any compartment in which cables are being installed should be heated and the cables should be handled only when their temperature is above freezing.

 
9-31
 
If cable must be installed in a compartment at 35°F. or below, stow the cable first in a compartment heated to at least 50°F. but not over 120°F. , and leave it there until it is warm enough so that installation in the cold compartment can be completed before the cable cools down.

Cable installations can be made successfully, at or slightly below 35°F. by handling the cable very carefully. While pulling the cable into the wireways, the radius of bend should be no shorter than absolutely necessary.

The part of the cable where a bend is to be made in putting it into its final position should be heated with a portable, warm-air blower. The bend should not have a radius less than the minimum given in the cable bend data tables.

3. GROUPING CABLES.

When grouping cables in wire-ways, arrange those types and sizes of cable that can be bent on the shortest radius on the inner side of the cable group, allowing the cables that cannot be bent as sharply to be placed on the outside of the group (Figure 9-12). Avoid grouping together cables which will result in building up of electrical disturbances or interfere with the proper functioning of the electrical circuits involved. All shipboard circuits may be classified as either low level, medium high level, or high level for the purposes of grouping.

Low level circuits are those circuits which normally carry small levels of useful signal (1000 microvolts or less), such as transducer lead-ins.

Medium high level circuits are those which normally carry useful signals in the order of several volts or less such as audio amplifiers.

  High level circuits are those which normally carry high levels of power such as ships service power supply.

All low level circuits should be physically removed as far as practicable from high level circuits.

EXAMPLE: Radar pulse cables are causing serious interference trouble on low level cables, such as sonar cables to the transducer. Separation of these circuits is essential to the proper operation of the sonar system.

4. LAYING CABLE IN WIREWAYS.

From the reels, cables should be "walked in" cable runs. Only the manual efforts of the installation crew are used to pull cables. Under no circumstances should block and tackle, chain falls, or other mechanical devices be used to pull cables taut.

The sag between hangers should be the same for large and small cables and should be maintained uniform between all hangers in the run. Such sag should not exceed one inch.

Temporary cable straps, made oversize without cable outline, are useful in arranging cables neatly as work along a wireway proceeds. They are installed at positions ahead of those being worked upon and support the cables loosely. Soft baling wire may be used to support cables in hangers temporarily, especially at bends. Permanent straps are installed after the cables are properly arranged with regard to break-offs and separation into two or more wireways. After the cables are located in the wireway, tighten the straps so that they hold the cable but are not so tight as to cause deformation of cables or to prevent lengthwise movement of the cables.

 
9-32
 

Cable having largest minimum bend radius.
Cable having smallest minimum bend radius.

FIGURE 9-12
ARRANGING CABLES IN WIREWAYS

 
9-33
 
5. PASSING THROUGH BULKHEADS.

a. NWT BULKHEADS. - Where cables pass through non-watertight bulkheads or beams that are 1/4 inch thick or over, no stuffing tubes are used, but the clearance holes should be drilled slightly larger than the cable and the edges of the holes rounded off to prevent chafing of the leads. Where non-watertight beams or bulkheads are under 1/4 inch in thickness, standard or special bushings as shown in Figure 9-13A, 13B, and 13C should be used. On all non-watertight bulkheads, where sharp bends occur in the cables immediately after passing through such holes, standard or special bushings are used.

b. WT BULKHEADS. - When cables pass through W T bulkheads they will feed through W T stuffing tubes. The usual practice is to stuff and pack the tubes as they are encountered along the cable run. Avoid using a screw driver for packing as this may damage threads and insulation. A tool similar to the

  packing stick described in section on tools is recommended. Proper packing methods are described in the section on stuffing tubes.

6. APPLIANCE ENTRANCES.

Where cables enter into vertically installed NWT appliances, avoid entering the appliance from the top. Water should not accumulate in NWT appliances, but condensation can run down a cable entering at the top and cause a failure. If possible enter at the bottom or side. When an entrance at the bottom is made, take care that the cable end is taped and sealed to prevent the entrance of moisture into the interior of the cable (Figure 9-14).

Commercial cable clamps (Figure 9-15) (Greenfield Connectors) are widely used where cables enter NWT appliances. These are discussed in the chapter on stuffing tubes.

 
19-34

Method of running cables through N.W.T. steel or aluminum bulkheads and beems under 1/4 inch thickness using threaded bushing.
Method of running cables through think steel bulkheads where air and fume tightness is required.

FIGURE 9-13A
METHODS CF RUNNNG CABLES
THROUGH N.W.T. BULKHEADS

 
9-35
 

Flared bushing tubing steel size to fit cable, length to suit.
Method of running single cables through N.W.T. steel or aluminum bulkheads and beams using flared bushing.

Round edges sufficiently to prevent abrasion of cable.
Method of running cable through steel beams under 1/4 thickness where drilling of holes for bushing is not permissible.

FIGURE 9-13B
METHODS OF RUNNING CABLES
THROUGH N.W.T. BULHEADS

 
9-36
 

A 1/16 inch steel liner welded in place may be used for additional support of cables as may be deemed advisable by the supervisor.
Round edges sufficiently to prevent abrasion of cable.
Method of running single cables through N.W.T. bulheads and beams 1/4 inch thickness and over.

1 inch x 1/8 inch liner-steel round inside edges.
Method of running cables through lightening holes or cable wasy in structural members or N.W.T. bulkheads (non light tight)

FIGURE 9-131C
METHODS OF RUNNING CABLES
THROUGH N.W.T. BULKHEADS

 
9-37
 

Fill area between conductor with plastic sealer.
Cable extends through tube at least 1/8 inch

FIGURE 9-14
METHODS OF MAKING UP CABLE ENDS
CABLE ENTERING BOTTOM OF ENCLOSURE

 
9-38
 

Cable clamp with one machine screw.
Cable clamps with tow machien screws

FIGURE 9-15
CABLE CLAMPS-COMMERCIAL TYPE
FORMED SHEET STEEL

 
9-39
 
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