Access To and Within Tanks and Double Hull Spaces of Oil Tankers

  Access from weather deck

  6 Tanks, and subdivision of tanks, having lengths of 35 m and above, should be fitted with at least two access hatchways and ladders, as far apart as practicable longitudinally. Where the tanks are of confined construction, two separate means of access from the weather deck are recommended, one each at either end of the tank space.

  7 Access to cofferdams, vertical wing and double bottom space of ballast tanks, cargo tanks and other spaces in the cargo area should be direct from the open deck and such as to ensure their complete inspection. Access to double bottom spaces, particularly with regard to double hull tankers, may be interpreted to include a ladder/platform arrangement that leads from the open deck to the double bottom space through the double hull space. Access to double bottom spaces may be through a cargo pump-room, pump-room, deep cofferdam, pipe tunnel or similar compartments, subject to consideration of ventilation aspects.

  Accessibility for personnel safety and inspection

  8 The dimensions of any access hatchway should to allow a person wearing a self-contained breathing apparatus to ascend or descend the ladder without obstruction and also to provide a clear opening to facilitate the removal of an injured person from the space. Alternatively, one of the deck access hatches can be enlarged and fitted with a hinged top ladder and with clear vertical straight access down to the tank bottom.

  9 For access through horizontal openings, hatches and manholes, the minimum clear opening should be not less than 600 mm by 600 mm. Openings of 600 mm by 600 mm minimum clearance, or larger, should be provided in each horizontal girder in vertical alignment within the vertical wing space. The term minimum clear opening of not less than 600 mm by 600 mm means that such openings may have corner radii up to 100 mm maximum, due regard being given to stress concentration.

  10 Any opening or open hatchway larger than 200 mm diameter on bulkhead stringers and horizontal girders should be fitted with gratings or safety guide rails of adequate design and construction. The free edge of walkways, bulkhead stringers and horizontal girders should be fitted with two-tier guide rails and vertical plate at least 50 mm high around edge of platform except in way of ladder. Guide rails or fencing should be free from sharp edges and should consist of an upper rail at a height of 900 mm and an intermediate rail at a height of 500 mm. The rails may, where necessary, consist of taut wire or taut chain. Step rungs and grip rails should be provided on inclined or curved surfaces to assist footing.

  11 For access through openings, or manholes providing passage through the length and breadth of the space, the minimum clear opening should be not less than 600 mm by 800 mm, at a height of not more than 600 mm from the bottom shell plating or stringer unless gratings or other footholds are provided. Such openings should be provided with grab bars. The term minimum clear opening of not less than 600 mm by 800 mm also includes an opening with corner radii 300 mm. For inspection purposes, an adequate number of vertical access openings should be provided.

  12 Smaller dimensions may be approved by the Administration in accordance with SOLAS regulation II-1/12-2.5.

  Access methods for inspection of tank structures

  13 The access methods for the inspection of tank structures may include:

• .1 Permanent access arrangement such as:

  • .1 the fitting of permanent staging;

  • .2 the fitting of bulkhead stringers as walkways;

  • .3 the fitting of horizontal girders as walkways;

  • .4 the fitting of independent horizontal walkways;

  • .5 the use of enlarged longitudinal girders as walkways;

  • .6 the fitting of step rungs on face plates of longitudinal girders;

  • .7 the fitting of vertical climbing rails on face plates of longitudinal girders;

  • .8 the fitting of vertical or inclined ladders on face plates of longitudinal girders;

  • .9 the fitting of vertical and inclined ladders on transverse bulkheads^footnote;

  • .10 the fitting of step rungs and grip rails on inclined or curved surfaces; and

  • .11 the fitting of permanent lugs, clips and pad eyes for temporary staging or portable staging support.

• .2 Temporary staging

• .3 Portable staging/mobile platform/mechanical arms

• .4 Temporary/portable ladder

• .5 Rafting

• .6 Remotely operated vehicles

• .7 Use of divers

• .8 Remotely-operated video system.

  Inspection in cargo tanks

  14 Rafting and climbing are possible in open type cargo tanks. However, it is recommended that the following should also be provided:

• .1 Permanent staging and/or walkway at strategic locations below the deckhead to monitor possible structural fractures and corrosion.

• .2 Permanent walkways along the longitudinal and transverse bulkheads.

• .3 Large access openings in swash bulkheads and centreline and side girders for raft passage, where feasible. Alternatively, large deck access hatches should be provided on both sides of the swash bulkhead.

  Inspection in vertical wing spaces

  15 Rafting in the double hull vertical wing space is not considered practical and is deemed unsafe. Permanent access arrangements, therefore, should be provided.

  16 Permanent horizontal walkways with clear width of 600 mm or greater, positioned at intervals harmonised with the design of ship's structures, should give an adequate coverage for inspection purposes. These may be formed by horizontal girders or enlarged longitudinal girders, as opposed to purpose-built walkways. Such permanent walkways could be incorporated in the design of the ship's structures during the design stage.

  17 Step rungs, grab bars and vertical ladders should be considered only as secondary means to assist in reaching those vertical areas which cannot readily be visually inspected from the walkways. These should also be limited to 3 to 4 metre extent.