5.1 Piping scantlings
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Statutory Documents - IMO Publications and Documents - International Codes - IBC Code - International Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in BulkAmended by Resolution MEPC.225(64) - Chapter 5 Cargo transfer - 5.1 Piping scantlings

5.1 Piping scantlings

  5.1.1 Subject to the conditions stated in 5.1.4 the wall thickness (t) of pipes shall not be less than:

where:
t0 = theoretical thickness
=
= with
P = design pressure (MPa) referred to in 5.1.2
D = outside diameter (mm)
K = allowable stress (N/mm2) referred to in 5.1.5
e = efficiency factor equal to 1.0 for seamless pipes and for longitudinally or spirally welded pipes, delivered by approved manufacturers of welded pipes, which are considered equivalent to seamless pipes when non-destructive testing on welds is carried out in accordance with recognized standards. In other cases, an efficiency factor of less than 1.0, in accordance with recognized standards, may be required depending on the manufacturing process.
b = allowance for bending (mm). The value of b shall be chosen so that the calculated stress in the bend, due to internal pressure only, does not exceed the allowable stress. Where such justification is not given, b shall be not less than:
=
= with
r = mean radius of the bend (mm).
c = corrosion allowance (mm). If corrosion or erosion is expected, the wall thickness of piping shall be increased over that required by the other design requirements.
a = negative manufacturing tolerance for thickness (%).

  5.1.2 The design pressure P in the formula for to in 5.1.1 is the maximum gauge pressure to which the system may be subjected in service, taking into account the highest set pressure on any relief valve on the system.

  5.1.3 Piping and piping-system components which are not protected by a relief valve, or which may be isolated from their relief valve, shall be designed for at least the greatest of:

  1. .1 for piping systems or components, which may contain some liquid, the saturated vapour pressure at 45°C;

  2. .2 the pressure setting of the associated pump discharge relief valve;

  3. .3 the maximum possible total pressure head at the outlet of the associated pumps when a pump discharge relief valve is not installed.

  5.1.4 The design pressure shall not be less than 1 MPa gauge except for open-ended lines, where it shall be not less than 0.5 MPa gauge.

  5.1.5 For pipes, the allowable stress K to be considered in the formula for to in 5.1.1 is the lower of the following values:

where:
Rm = specified minimum tensile strength at ambient temperature (N/mm2)
Re = specified minimum yield stress at ambient temperature (N/mm2). If the stress-strain curve does not show a defined yield stress, the 0.2% proof stress applies.
= A and B shall have values of at least A = 2.7 and B = 1.8.

  5.1.6.1 The minimum wall thickness shall be in accordance with recognized standards.

  5.1.6.2 Where necessary for mechanical strength to prevent damage, collapse, excessive sag or buckling of pipes due to weight of pipes and content and to superimposed loads from supports, ship deflection or other causes, the wall thickness shall be increased over that required by 5.1.1 or, if this is impracticable or would cause excessive local stresses, these loads shall be reduced, protected against or eliminated by other design methods.

  5.1.6.3 Flanges, valves and other fittings shall be in accordance with recognized standards, taking into account the design pressure defined under 5.1.2.

  5.1.6.4 For flanges not complying with a standard, the dimensions for flanges and associated bolts shall be to the satisfaction of the Administration.

Parent topic: Chapter 5 Cargo transfer
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