quality manual excerpt cable support systems

7/26/2019 Quality Manual Excerpt Cable Support Systems

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General design

Quality manual



2. Cable support systems

In this chapter the principals of the cable supporting systems are described.

2.1 Planning

The cable routing throughout the vessel to be determined in an early stage of the engineeringprocess. Such cable routing describes the location, position and sizes of the through cable routingconsisting of cable trays, ducting and penetrations.

The local cable supports (secondary iron-work) to be determined on board based on theengineered and planned installation of apparatuses, piping and ducting.

The following criteria to be observed during the cable routing design;

o Cable tray to be applied within the range of 100mm and 600mm. Widths exceeding 600mmto be assembled from two smaller cable trays.

o Cable trays with a width up to 1000mm may be applied if equivalent strength is guaranteedas for the assembled trays. Yard’s opinion and decision on acceptance is binding.

o The supports, including the welds, to have sufficient strength to carry the expected cable load.

o Bends in cable trays to be curved. The radius depends on the type of cables providedon these cable trays. Generally no straight angle bends (90 degrees) are allowed

o Separation of HV cables from other cables. Minimum distance from other cabling approx.250mm

o Separation of cabling to achieve the EMC requirements based on a EMC-plan

o Cable routing to be away from excessive heat areas or surfaces (boilers or exhaust gas lines) o Cable routing to be free from service, transport or hoisting areas

o Suitable protection against mechanical damages to be provided o No through cable routing through high fire risk areas

o Duplicated routes for essential and duplicated services

o Expansion points in through cable routes, if so provided in the hull structure design

o Where required for any additional protection (electromagnetic or mechanic) cables to beinstalled in pipes or ducts. Also cables under floor plates in all engine rooms and on outside

areas will be led in a pipe.

o Network cables will be led in a pipe.

o Cables to be installed on/in dedicated devices like, trays, strips, bars, pipes or ducts. It is notallowed to support cables on other ship’s structures like pipe supports, ceiling hangers orany system piping.

o

Generally the cable tray supports to be attached to the ship’s structure and not directlyto decks or bulkheads.

o Size and location of penetrations to be checked with the ship’s structure design parameters o Digital and analog instrumentation signals will not be combined in one cable.



2.2 Material

Cable trays and strips to be of steel (St.Grade A / St37) and provided with ship primer beforeinstalling on board. Cable trays inside the vessel will be hot dipped galvanized finished with paint.

Cable pipes to be of galvanized solid drawn steel. Special primer (zinc spray) to be appliedafter machining, treating or adding supports or others.

If stainless steel for exposed areas is specified the grade to be AISI 316L.

All cables will be of a Halogen free and approved marine type. The maximum cable coretemperature is 85°C.

2.3 Cable supports

A cable tray is a standard metal construction provided on board to support generally more than 6cables.

o The following main cable trays are generally used (See also Figure 2): o Cable tray with flat rungs (≤ 300mm) o Cable tray with V-profiled rungs (≥400mm up till 600mm)

o Cable tray with Z-profiled rungs (subject cables are laid on the top only. Only atlocations with limited space, and after formal agreement, cables may be fittedunderneath these rungs)

On locations where due to lack of space the above type cable tracks cannot be adoptedthe trays with Z-profiled rungs may be applied.

o A cable tray is consisting of:

o Cable support: The connection between the cable tray and the ship’s construction o Cable rungs: The part of the cable tray to which the cables are fitted.

Flat iron

V-profiled

Z-Profiled

≤ 300mm ≥ 400mm up till 600mm

Figure 2: Generally used main cable trays

Cable trays which are crossing or at a T-crossing should not end on the same height. Crossingof cable trays on the same height is not allowed.



Bends in cable trays to be curves as in Figure 3. Generally no straight angle bends (90 degrees)are allowed.

Not to be applied

Figure 3: Generally used cable tray bends

The intermediate distance between each rung to be max. 300mm. In exposed or wet areas therungs to be fully welded to prevent corrosion as in Figure 4. In all other cases spot welding isacceptable, subject that the rung can carry the full cable weight.

Not accepted welding method for exposed and wet areas

Figure 4: Example of corrosion on exposed and wet areas

2.3.1 Fitting instructions

Generally strips, angle bars and other supports for cable trays, strips and pipes to be welded tothe structure (i.e. beams, girders, frames) and not to the plating.

Supports fitted to “Holland” profiles to be welded as shown on following principal detail s.

In cases of doubts or exceptions specials instructions will be given by the Yard’s structuralengineers. In Figure 5, Figure 6 and Figure 7 several examples are illustrated.



Girder

Angle bar of

strip support

Theoretical Example 1 Theoretical Example 2

Figure 5: Theoretical welding methods of support to Bulb/Holland frames

Practical Example 1 Practical Example 2

Supports welded to the long side of girder Supports welded to the top of the girder

Figure 6: Practical examples of supports welded on frames



Frame or Support bracket

40x40x5mm

girder

Flat bar

30x4mm

Approx.

1500mm

Bulkhead

Approx.300mm

MCT only: Approx.50mm

MCT with additional MCT coaming coaming Approx.200mm

Typical for vertical cable tray support in non-exposed

Figure 7: Typical for vertical cable tray support in non-exposed areas

Where this is not feasible or practicable such supports to be welded to deck or bulkhead plating.In such cases a double plate for each support to be added to avoid “hard” stress poin ts. Double plates may be either in a square or round execution.Figure 8 is a typical of double plates.



*

* *

*

* *

Dimension double plate *+50

Double plate

Full welded

Figure 8: Typical if cable tray supports are welded to plating

Angle bars for supporting the cable trays to the ship’s structure to be applied for all cable

trays exceeding a width of 200mm. The end of each angle bars to be rounded or canted.

Steel strips may be applied for cable trays with width < 200mm. Dimensions of angle bars and steelstrips depends on the length of it. See Table 1 for the dimensions of the cable supports. Figure 8 andFigure 9 are a typical for the cable supports and an example of a smoothed/canted angle bar.

Distance from ship’s structure Angle bar Steel strips

≤200mm 40x40x5mm 30x8mm

≥200mm till ≤500mm 40x40x5mm -

≥500mm till ≤1000mm 50x50x5mm -

≥1000mm 60x60x6mm -

Table 1: Dimensions of cable supports



Cable support welded to ship’s structure

Angle bar Strip

40x40x5mm approx. 30x8mm

Cable rung

To be smoothed

or canted

Full welded in exposed

Angle bar support and wet areas Flat bar support

Figure 8: Typical details for cable supports

To be smoothed or canted

Figure 9: Typical of smoothed/canted angle bar

The intermediate distance of any cable tray support to be maximum 1600mm.The free space above a cable tray to be at least 200mm. Locally (i.e. crossing piping, ducting or beams or girders) this distance may be reduced to 120mm.



At any penetration the last cable tray support to be fitted at a maximum distance ofapprox.300mm from the coaming or penetration.

MCT for fire or Coaming if required for Girder or deckbeam

wate rintegrity stress compension Alt. bu lkhead or tween deck

*

* *

*= Approx.300mm

Edges to be smoothed

Cable tray in way of a w.t./fire penetration Cable tray in way of a coaming or protected

Figure 10: Typical for the cable tray supports close to penetrations

2.3.2 Cable strips

Cable strips can be applied to install a limited number of branch cables. See Table 2 for the amountof cables for several cable strip dimensions. Only one side of the cable strip to be used. Currentcarrying cables may not be fully covered regarding the heat dissipation. The maximum width of acable strip to be 50mm. The intermediate distance of the supporting pieces is 500 ~ 700mm. A typicalof the cable strips is shown in Figure 11.

Generally the supports to be welded to the ship’s structure and not directly to decks or bulkheads.

In weld areas and on open decks full welds to be applied. Otherwise one side tag welding andother side full welding to be applied.

In the case where such supports are positioned to decks or bulkheads a double plate to be addedand fully welded.

Dimensions of cable strip

Maximum amount of cables

30x5mm 1 x 5

40x5mm 1 x 7

50x5mm 1 x 9

Table 2: Amount of cables for cable strips

Flat strip

Cables

Figure 11: Typical of cable strip



2.3.3 Cable pipes, conduits or trunking (IEC 60092-352)

Where cables should be mechanically protected or where cables to be laid in pipes to avoidelectromagnetic interference metal cable pipes to be applied. See Figure 12, Figure 13 and Figure14 for some typicals regarding cables installed in pipes.

Drain holes

Max.150mm

Closed pipe protection

Open pipe protection

Figure 12: Typical of closed and open pipe protection

Where cable pipes are required to avoid mechanical damaging of cables no “open” pipe system tobe applied. If an “open” pipe system is applied the maximum spacing between two pipe pieces ismaximum 150mm.

The size of the cable pipes to be carefully selected based on the general rule requirement.

A filling rate of max. 40% to be taken into account. This is subject the rule requirements as applicable.Where only signal cables are led in pipes a filling rate of max. 65% to be taken into account.

The following details to be taken into consideration;

1. Drain holes to be provided where condensation or water cannot escape2. Pipe ends to be smoothened

3. To support the cables, strips to be welded at both pipe ends or a fixed strip to be providedclose to the pipe ends. (alternatively synthetic caps or rings can be applied to support or protectthe cables)

4. Pipe-extensions for cable fixation to be executed with a slim part in the middle to prevent the tie-rap from sliding off.

5. Steel cable pipes to be galvanized for non-exposed areas. Special primer (zinc spray) tobe applied after machining, treating or adding supports or others. Cable pipes on deck and

wet/exposed area’s must be stainless steel (AIS316L).

6. Double pipe pieces to be applied when a cable pipe passes a weather or water tight deck.Doubling length approx 100mm with approx. 50mm above deck.

7. Cable pipes can be fitted with special pipe clamps or directly welded. Mounting brackets must bewelded before cable pipe is galvanized.

8. Cable pipes used for weather or water tight penetrations to be provided with a cable gland atone side.



Cable pipe *

Double pipe * Gland

Welded

Approx.50mm

Deck

Welded

Double pipe * Pipe piece *

Figure 13: Typical of single cable penetrations through exposed deck

Note: * Alternatively a heavy duty pipe can be applied

Fully welded (Only wet areas and exposed decks)

Cables

Max.1000mm

Fully welded (Only wet areas and exposed decks)

Cable pipe

Pipe clamp

Cables

Figure 14: Typical for cable installation in pipe



Cable pipe fitted by clamping Cable pipe fitted by welding

Figure 15: Typical of cable pipe fitted with clamps or welded to ship's structure

2.3.4 Weld finishing

All welds for the described details to be cleaned and free from weld slag and other dirt.

quality manual excerpt cable support systems

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