Section 9 Bulkheads and deep tanks
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 1 Ship Structures - Part 6 Hull Construction in Steel - Chapter 3 Scantling Determination - Section 9 Bulkheads and deep tanks

Section 9 Bulkheads and deep tanks

Parent topic: Chapter 3 Scantling Determination

9.1 General

9.1.1 The requirements of this Section, unless specified otherwise, are applicable to all ship types, NS1, NS2 and NS3.

9.1.2 The requirements of this Section apply to a vertical system of stiffening on bulkheads. They may also be applied to a horizontal system of stiffening provided that equivalent end support and alignment are provided.

9.1.3 The basic structural scantlings of NS1 ships are to be determined in accordance with Vol 1, Pt 6, Ch 3, 3 NS1 scantling determination The basic structural scantlings of NS2 and NS3 ships are to be determined in accordance with Vol 1, Pt 6, Ch 3, 4 NS2 and NS3 scantling determination The minimum requirements in Vol 1, Pt 6, Ch 3, 2 Minimum structural requirements are also to be complied with. Arrangements are to be in accordance with Vol 1, Pt 3, Ch 2, 3 Main hull structure and Vol 1, Pt 6, Ch 2, 3 Buckling.

9.1.4 The buckling requirements of Vol 1, Pt 6, Ch 2, 3 Buckling are also to be satisfied.

9.1.5 The scantlings of bulkheads are to be suitably increased where bulkhead stiffeners support deck girders, transverses or pillars over, see Vol 1, Pt 6, Ch 3, 12 Pillars and pillar bulkheads.

9.1.6 For bulkheads in way of partially filled holds or tanks, sloshing forces may be required to be taken into account. Where such forces are likely to be significant, the scantlings will be required to be verified by additional calculations.

9.1.7 For RAS tanks or other tanks subjected to increased loads such loads are to be indicated on the plans submitted.

9.1.8  For ships with an internal blast notation certain bulkheads will require to be strengthened in accordance with Vol 1, Pt 4, Ch 2 Military Load Specification

9.1.9 Where a watertight bulkhead includes a shaft seal, the maximum deflection is to be limited to the lesser of:
  1. the seal manufacturer’s stated tolerances in the axial and radial directions and;
  2. the criteria as defined in Vol 1, Pt 6, Ch 3, 3 NS1 scantling determination or Vol 1, Pt 6, Ch 3, 4 NS2 and NS3 scantling determination (NS2 and NS3 ships).

9.2 Deep tank stiffening

9.2.1 Deep tank bulkhead stiffeners are to be bracketed at both ends. The thickness of the brackets is to be not less than the web thickness of the stiffener, see Vol 1, Pt 6, Ch 6, 6 Construction details

9.3 Gastight bulkheads

9.3.1 Where gastight bulkheads are fitted, in accordance with the requirements of Vol 1, Pt 3, Ch 2, 4 Bulkhead arrangements the general scantling equations for bulkheads, see Vol 1, Pt 6, Ch 3, 3.12 Deck structures for NS1 ships and Vol 1, Pt 6, Ch 3, 4.6 Watertight bulkheads and deep tanks for NS2 and NS3 ships, are to be complied with using a design pressure of 2 times the test pressure.

9.3.2 In addition the requirements for pillar bulkheads and minimum thickness requirements of Vol 1, Pt 6, Ch 3, 2 Minimum structural requirements are to be complied with where appropriate.

9.4 Non-watertight or partial bulkheads

9.4.1 Where a bulkhead is structural but non-watertight, the scantlings are in general to be as for watertight bulkheads or equivalent in strength to web frames/primary stiffeners in the same position.

9.4.2 Partial bulkheads which are neither watertight nor structural are to have scantlings and arrangements which are suitable for the intended purpose, such bulkheads are outwith the scope of classification.

9.5 Corrugated bulkheads

9.5.1 The plating thickness and section modulus for symmetrical corrugated bulkheads are to be in accordance with watertight bulkheads or deep tank bulkheads as appropriate. The spacing, s, is to be taken as b, as defined in Figure 2.2.2 Corrugated section in Vol 1, Pt 6, Ch 2 Design Tools

9.5.2 In addition, the section geometric properties of Vol 1, Pt 6, Ch 2, 2.9 Proportions of stiffener sections are to be complied with.

9.5.3 The actual section modulus may be derived in accordance with Vol 1, Pt 6, Ch 2, 2.3 Section properties 2.3.1

9.6 Wash plates

9.6.1 Stiffeners are to be fitted at every frame and efficiently bracketed at top and bottom.

9.6.2 The plate thickness is to be not less than the structural element from which the wash bulkhead is formed.

9.6.3 The general stiffener requirements are to be in accordance with Vol 1, Pt 6, Ch 3, 3.11 Watertight bulkheads and deep tanks for NS1 ships and 4.6 for NS2 and NS3 ships. However, the section modulus may be 50 per cent of that required if the end connections are bracketed.

9.6.4 The area of perforation is to be not less than 5 per cent and not more than 10 per cent of the total area of the bulkhead.

9.7 Cofferdams

9.7.1 The scantlings of cofferdams are to comply with the requirements of deep tank bulkheads or non-watertight bulkheads as appropriate.

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