ISSN 2086-5953 method has not been prepared yet.
1.2 Problem Description
The four MDM are proposed to determine the reliability of ship oil system with RGEC
method, they are: a.
Pertamina [7] has stated, if there is a non conformities
maintenance scheduling
that influences the reliability impact by hazard and
without reviewing significant or not failures, so the reliability is equal with value before hazard.
b. Pertamina [7] used harmonisation terminology
or maintenance
scheduling combination.
Bieman [1] has stated that if failure repaired onto many system which have almost the same
maintenance schedul with other system, that can join their repairing.
c. Rasmussen [8] had stated with Effective
Maintenance Strategies model. He stated that
the component replacement with high effectivity one could implied a cost saving. This strategies
call Effective Maintenance Program. d.
Innovation is divided into therminology and procedure. This therminology is enclosed at
Technology Atlas Project Form of Tokyo Programme on Technology for Development,
Kibrio [5]. Innovation is consist of human ware, techno ware, organ ware, and info ware.
System Reliability
is evaluated
with compliance of the five actions, they are:
1. Harmonisation to the duration of the component
maintenance and the subsystem are different. Harmonisation is implemented to the some of
them and then system reliability is calculated based on configuration.
2. If the 3-MDM happened, they are : hazard
handling, innovation, and using non standard effectivity component; it is necessary to
evaluate the system reliability after re- harmonisation.
3. Component and subsystem reliability is
determined with the judgement of how the effectiveness of the replacer component in
system and how long percentage of component and subsystem duration to duration of the
system.
4. Reliability reduction of the certain component
or subsystem is not valid when there is delay time or repairing so that causes system stops
running. 5.
If there is not significant component or subsystem and based on the design it is reliable
until the end of life time of the system, so its reliability is perfectly and never goes down.
This paper presents the result of a study case was using ship oil system RGEC based on TTF
data and MDM proposes was used to estimate the reliability of ship oil system and to understand the
phenomenon in speed down reliability reduction of maintenance system. Reliability determination is
the part of other reliability determination review based on non technical case. Temporary using,
paralel circuit as stand by, impulsive system, real caused by routine maintenance, are examples of
non technic reliability problem. Focussing on evaluation with compliance on five actions of
MDM are observed.
2 METHOD AND VALIDATION
2.1 Methods Of RGEC
The kernel of RGEC
In the beginning of the twentieth century various empirical equation was emerged, for
examples equation from Duane and Crow. The story of maintenance system is the developing of
the four methodologies : Planned Maintenance System
PMS, Total Productive Maintenance TPM,
Optimum Maintenance
Management OMM, and Reliability Centered Maintenance
RCM. Evaluate of the system reliability contibutes to RCM.
The function which declared success or one minus failure number
to the time for domain limit of the maintenance duration named Reliability
Function , its notation is `Rt. The assumption of
the reliability function uses Weibull distribution with maintenance duration from TTF data, David
and Mary [4]. Reliability Growth Function also uses ‗Rt‟. Domain reliablity growth fuction is the
running time start from null kilometre until system permanently damage. Reliability growth function
assumption follows
mathematics formula
matematik of an expert, Crow [3]. The first differential of Rt to the time is
notified by Reliability Growth Gradient or `ft=dRtdt. For the first time Mean time
between failure or MTBF was introduced by
Duane. Its
notification is
‗1 t‘ or
‗MTBF=Rtft‘. An ideal condition of reliability growth results MTBF constantly during the
equipment system running. Reliability growth decreases to the raise of the running time of system,
For example for t
1
where ft
1
0, if MDM is implemented using reliability growth parameter at
t
2
= t
1
, so ft
2
0. Although reliability decreases but ft
2
ft
1
. This condition is named Reliability Growth
. The failure of reliability was happened to
ISSN 2086-5953 the component. It consists of five types, they are :
caused by inherent defect, component blocking, component which causing locking system, total
damage fraction as C-type which could be overcame, and total damage fraction as P-type
which could not be overcame, Bieman and Malaiya [1]. The failure of reliability growth happened on
the subsystem and system with the 3-types, A, Bc, and Bd.
An RGEC form of some empirical equation can be written as follow
The reliability of component replacement without reviewing failure follows empirical
equation from Duane and Weibull . Cummulative MTBF and instantaneous MTBF of Duane is
notified with the equation below :
C – MTBF = m
c
= b t
1
I – MTBF = m
i
= 1 -
-1
b t
2
2
2 1
a a
3 b
t b
MTBF C
a ln
ln ln
ln
1 1
1
4 b
t b
MTBF C
a ln
ln ln
ln
2 2
2
5 Weibul declared that the scale parameter, notation
‗ ‘ and the shape parameter, notation ‗‘ to the
MTBF formula becomes : MTBF = t
i
– t
i-1
R
t
e
-t
= 1 –
t
-1
6 = 10 -
log
7 Reliability growth equation, notation ‗R
t
‘ in the duration
t
i
, is notified below : Crow [3]
1 1
t t
t i
i t
t
e t
t R
R
8 Reliability growth equation-8 is valid for the 3-
types of fail ure with value ‗
and ‗ as follows: Crow [2] for Bc-type and Army Material System
Analysis Activity AMSAA method with equation:
n i
n i
i Nq
i
t t
n
1 1
ln ln
9
n i
tn n
1
10
Nq
T n
11
n i
i i
i i
i i
T t
t t
t t
t
1 1
1 1
ln ln
ln
n and
are the constanta resulted from iteration and T is a life time until system could not be used
anymore. Failure intensity model
Nelson [ 6
] for Bd- type and component effectivity, notation ‗d‘ with
equation:
m i
i
T d
t d
n T
n
1
1
13
n i
i
t T
m
1
ln
14
m i
i
d m
d
1
1
15 Crow, L.H.[3] for A-type with the parameter
equation ‗ and ‘ as follows :
N i
i i
t t
kN
1 1
ln
16
N i
i q
q
t N
N
1
17 ‗k‘ is a total amount of failure kind based on the
types, ‗N
q
‗ is the amount of failure component for certain types, and ‗t
i
‗ is a time running of the component.
The RGEC equation for case study is proposed to change become as follows:
1 1
dt t
dt R
d R
R
t t
t
18
N i
t d t
i i
t
e t
t dt
R d
1 1
1 1
19
Figure 1.
Influent of MDM to reliability using RGEC equation
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2.2 Application of RGEC model
Kategori