Section 4 Materials for equipment and components at low temperatures enhanced – Winterisation MEn

4.1 Application

4.1.1 For Winterisation MEn(t) , the requirements in Ch 1, 5 Equipment and systems – Winterisation C are to be complied with and, in addition, a risk assessment, or equivalent method acceptable to LR, of additional equipment and systems for the ship, which are not included in Table 1.3.1 List of equipment and components, is to be carried out with the subsequent material requirements identified to be complied with.

4.1.2 The additional equipment and systems to be included in the risk assessment are to be agreed between the Owner, Shipbuilder and LR.

4.1.3 The risk assessment is to follow the approach outlined in Ch 1, 4.2 Risk assessment and be carried out with representative specialists from the Owner, Shipbuilder and LR.

4.1.4 A summary of the risk assessment is to be documented and submitted to LR.

4.2 Risk assessment

4.2.1 For any component, an assessment is made of the likelihood of failure and associated consequence:

Likelihood of failure:
This is the likelihood of failure during service and includes the frequency and size of loads, stress level (due to static/dynamic/fatigue loading), e.g. low stress and rarely used, low continuous cyclic stress or subject to high impact loads. This may also include the welded condition, exposure/corrosion, geometry, and the equipment location. This aspect may additionally consider any relevant service experience, inspection and maintenance regimes, and engineering judgement, as appropriate.
Consequence of failure:
This considers the importance of the component, i.e. what effect the failure of the component will have on the operation of the ship. This is to include the impact on personnel safety, the environment and ship safety.

4.2.2 The likelihood of failure may be graded between 1 and 3:

Likelihood of failure:
1	Low	failure may occur during a ship’s life.
2	Medium	failure may occur during the mid life of a ship’s operation.
3	High	failure may occur during any year of a ship’s operation.
The consequence of failure may be graded between A and C:
Consequence of failure:
C	Low	local failure with minor effect to operation with some impact on the item’s intended function.
B	Medium	possible loss on equipment/machinery/system, without any impact on personnel safety, the environment or ship safety.
A	High	component fails and results in an impact on personnel safety, the environment or ship safety.

4.2.3 The risk matrix is a tool comprising the likelihood of failure and the consequence of failure. By locating the component in the risk matrix, the class and certification requirement may be determined. See Table 1.4.1 Risk matrix.

Table 1.4.1 Risk matrix

Risk matrix		Likelihood of failure
Risk matrix		1 Low	2 Medium	3 High
Consequence of failure	A High	1/A	2/A	3/A
	B Medium	1/B	2/B	3/B
	C Low	1/C	2/C	3/C

4.2.4 The classes may then be determined from the following bands:
Class I 1/C, 1/B or 2/C
Class II 1/A, 2/B or 3/C
Class III 2/A, 3/B or 3/A.

4.2.5 Once the material class is determined, the thickness and external design air temperature may be used to determine the corresponding material grade or testing temperature of the component, using Ch 1, 3.4 Plating, Ch 1, 3.5 Piping, valves and fittings and Ch 1, 3.6 Forging and castings as appropriate.