Cargo Transfer
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Construction and Classification of Ships for the Carriage of Liquid Chemicals in Bulk, July 2022 - The Rules and Regulations for the Construction and Classification of Liquid Chemicals in Bulk - Cargo Transfer

Cargo Transfer

Parent topic: The Rules and Regulations for the Construction and Classification of Liquid Chemicals in Bulk

5.1 Piping scantlings

5.1.1 Subject to the conditions stated in Ch 1, 5.1 Piping scantlings the wall thickness (t) of pipes shall not be less than:

where:
t0 = theoretical thickness
=
  • with
P = design pressure (MPa) referred to in Ch 1, 5.1 Piping scantlings
D = outside diameter (mm)
K = allowable stress (N/mm2) referred to in Ch 1, 5.1 Piping scantlings
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 Ch 1, 5.1 Piping scantlings 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. for piping systems or components, which may contain some liquid, the saturated vapour pressure at 45°C;

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

  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 Ch 1, 5.1 Piping scantlings 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.

LR 5.1(a) The nominal thickness of steel pipes is to be not less than shown in Table 12.2.4 Minimum thickness for steel pipes in Pt 5, Ch 12 of the Rules for Ships.

LR 5.1(b) Stainless steel pipes will receive special consideration.

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 Ch 1, 5.1 Piping scantlings 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 Ch 1, 5.1 Piping scantlings.

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.

5.2 Piping fabrication and joining details

5.2.1 The requirements of this section apply to piping inside and outside the cargo tanks. However, relaxations from these requirements may be accepted in accordance with recognized standards for open-ended piping and for piping inside cargo tanks except for cargo piping serving other cargo tanks.

5.2.2 Cargo piping shall be joined by welding except:

  1. for approved connections to shutoff valves and expansion joints; and

  2. for other exceptional cases specifically approved by the Administration.

5.2.3 The following direct connections of pipe lengths without flanges may be considered:

  1. Butt-welded joints with complete penetration at the root may be used in all applications.

  2. Slip-on welded joints with sleeves and related welding having dimensions in accordance with recognized standards shall only be used for pipes with an external diameter of 50 mm or less. This type of joint shall not be used when crevice corrosion is expected to occur.

  3. Screwed connections, in accordance with recognized standards, shall only be used for accessory lines and instrumentation lines with external diameters of 25 mm or less.

5.2.4 Expansion of piping shall normally be allowed for by the provision of expansion loops or bends in the piping system.

  1. Bellows, in accordance with recognized standards, may be specially considered.

  2. Slip joints shall not be used.

5.2.5 Welding, post-weld heat treatment and non-destructive testing shall be performed in accordance with recognized standards.

LR 5.2(a) Welding, post heat treatment and non-destructive examination is also to be in accordance with the requirements of Ch 13 Requirements for Welded Construction of the Rules for Materials.

5.3 Flange connections

5.3.1 Flanges shall be of the welded-neck, slip-on or socket-welded type. However, socket-welded-type flanges shall not be used in nominal size above 50 mm.

5.3.2 Flanges shall comply with recognized standards as to their type, manufacture and test.

5.4 Test requirements for piping

5.4.1 The test requirements of this section apply to piping inside and outside cargo tanks. However, relaxations from these requirements may be accepted in accordance with recognized standards for piping inside tanks and open-ended piping.

5.4.2 After assembly, each cargo piping system shall be subject to a hydrostatic test to at least 1.5 times the design pressure. When piping systems or parts of systems are completely manufactured and equipped with all fittings, the hydrostatic test may be conducted prior to installation aboard the ship. Joints welded on board shall be hydrostatically tested to at least 1.5 times the design pressure.

5.4.3 After assembly on board, each cargo piping system shall be tested for leaks to a pressure depending on the method applied.

5.5 Piping arrangements

5.5.1 Cargo piping shall not be installed under deck between the out-board side of the cargo-containment spaces and the skin of the ship unless clearances required for damage protection (see Ch 1, 2.6 Location of cargo tanks) are maintained; but such distances may be reduced where damage to the pipe would not cause release of cargo provided that the clearance required for inspection purposes is maintained.

5.5.2 Cargo piping located below the main deck may run from the tank it serves and penetrate tank bulkheads or boundaries common to longitudinally or transversally adjacent cargo tanks, ballast tanks, empty tanks, pump-rooms or cargo pump-rooms provided that inside the tank it serves it is fitted with a stop-valve operable from the weather deck and provided cargo compatibility is assured in the event of piping failure. As an exception, where a cargo tank is adjacent to a cargo pump-room, the stop valve operable from the weather deck may be situated on the tank bulkhead on the cargo pump-room side, provided an additional valve is fitted between the bulkhead valve and the cargo pump. A totally enclosed hydraulically operated valve located outside the cargo tank may, however, be accepted, provided that the valve is:

  1. designed to preclude the risk of leakage;

  2. fitted on the bulkhead of the cargo tank which it serves;

  3. suitably protected against mechanical damage;

  4. fitted at a distance from the shell as required for damage protection; and

  5. operable from the weather deck.

5.5.3 In any cargo pump-room where a pump serves more than one tank, a stop valve shall be fitted in the line to each tank.

5.5.4 Cargo piping installed in pipe tunnels shall also comply with the requirements of Ch 1, 5.5 Piping arrangements 5.5.1 and Ch 1, 5.5 Piping arrangements 5.5.2. Pipe tunnels shall satisfy all tank requirements for construction, location and ventilation and electrical hazard requirements. Cargo compatibility shall be assured in the event of a piping failure. The tunnel shall not have any other openings except to the weather deck and cargo pump-room or pump-room.

5.5.5 Cargo piping passing through bulkheads shall be so arranged as to preclude excessive stresses at the bulkhead and shall not utilize flanges bolted through the bulkhead.

5.6 Cargo transfer control systems

5.6.1 For the purpose of adequately controlling the cargo, cargo-transfer systems shall be provided with:

  1. one stop-valve capable of being manually operated on each tank filling and discharge line, located near the tank penetration; if an individual deepwell pump is used to discharge the contents of a cargo tank, a stop-valve is not required on the discharge line of that tank;

  2. one stop valve at each cargo-hose connection;

  3. remote shutdown devices for all cargo pumps and similar equipment.

LR 5.6(a) Standby means for pumping out each cargo tank are to be provided. See Pt 5, Ch 15, 3.1 General 3.1.2 of the Rules for Ships.

5.6.2 The controls necessary during transfer or transport of cargoes covered by the Code other than in cargo pump-rooms which have been dealt with elsewhere in the Code shall not be located below the weather deck.

5.6.3 For certain products, additional cargo-transfer control requirements are shown in column o in the table of chapter 17.

5.7 Ship's cargo hoses

5.7.1 Liquid and vapour hoses used for cargo transfer shall be compatible with the cargo and suitable for the cargo temperature.

LR 5.7(a) Details of such hoses are to be submitted together with a type test certificate issued by a recognized Authority.

5.7.2 Hoses subject to tank pressure or the discharge pressure of pumps shall be designed for a bursting pressure not less than 5 times the maximum pressure the hose will be subjected to during cargo transfer.

5.7.3 For cargo hoses installed on board ships on or after 1 July 2002, each new type of cargo hose, complete with end-fittings, shall be prototype-tested at a normal ambient temperature with 200 pressure cycles from zero to at least twice the specified maximum working pressure. After this cycle pressure test has been carried out, the prototype test shall demonstrate a bursting pressure of at least 5 times its specified maximum working pressure at the extreme service temperature. Hoses used for prototype testing shall not be used for cargo service. Thereafter, before being placed in service, each new length of cargo hose produced shall be hydrostatically tested at ambient temperature to a pressure not less than 1.5 times its specified maximum working pressure but not more than two-fifths of its bursting pressure. The hose shall be stencilled or otherwise marked with the date of testing, its specified maximum working pressure and, if used in services other than the ambient temperature services, its maximum and minimum service temperature, as applicable. The specified maximum working pressure shall not be less than 1 MPa gauge.

LR 5.7(b) The term 'extreme' in the eighth line of the above refers to the highest and/or lowest service temperature for which the hose is intended.

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