introduction to reliability engineering...outline | expectations introduction to reliability...

Introduction to 

System Reliability 

Engineering

Course Instructor

Name: Oseghale Lucas Okohue BEng. Msc. CIPMP 

Position: Manager | Business Development  | Snr. Consultant  

Email: oseghaleokohue@chesssubseaengineering.com

Summary : Project Management, RAMS of Production Systems  (Onshore | Offshore  | Subsea), Drilling Engineering

Education :PhD. RAMS of Production System  (Onshore  | Offshore) ‐ Inview

Msc. Subsea Engineering

BEngr . Petroleum Engineering

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Aim | Objectives

Appreciation of System Reliability Engineering

Reliability Engineering

‐ Design

Outline | Expectations

Introduction to Reliability Engineering 

load Strength Relationship  ‐ No Overlaps

load Strength Relationship  ‐ Overlaps

Objectives of Reliability Engineering 

System Load | Strength Relationship

Importance of Reliability Engineering 

Summary

Introduction to Reliability

Reliability is associated with unexpected failures of products or

services and understanding why these failures occur is key to

improving reliability.

The main reasons why failures occur includes:

The product is not fit for purpose or more specifically the

design is inherently incapable.

The item may be overstressed in some way.

Introduction to Reliability

Items are designed for a specific operating environment

and if they are then used outside this environment then

failure can occur.

Note : There are many reasons for failure in system the

list above is a generic list.

System Load | Strength Relationship

The load and strength of an item may be generally known,

however there will always be an element of uncertainty.

The strength values of any system components will varies.

Some components will be relatively strong while others will

be relatively weak.

Although most will be of nearly average strength.

System Load | Strength Relationship

Similarly there will be some loads greater than others but

mostly they will be average.

load Strength Relationship  ‐ No OverlapsMaximum Load Maximum Strength

Note: The load strength relationship with no overlap shows

the maximum load and strength that can be withstand.

load Strength Relationship  ‐ Overlaps

However if, there is an overlap of the two distributions then

failures will occur.

load Strength Relationship  ‐ Overlaps

Note:

Introduction of safety margin ensures that there is no overlap

of these distributions.

load Strength Relationship  ‐ Overlaps

Thus, to ensure good reliability the causes of failure need

to be identified and eliminated.

Objectives of Reliability Engineering 

Objectives of reliability engineering are as follows:

To apply engineering knowledge to prevent or reduce

the likelihood or frequency of failures;

To identify and correct the causes of failure that do occur;

To determine ways of coping with failures that do occur;

Objectives of Reliability Engineering 

To apply methods of estimating the likely reliability of

new designs, and for analyzing reliability data.

Importance of Reliability

Why is Reliability important?

Unreliability has a number of unfortunate consequences and

therefore for many products and services is a serious threat.

Importance of Reliability

For example poor reliability can have implications for:

Safety

Competitiveness

Profit margins

Cost of repair and maintenance

Delays further up supply chain

Reputation

Good will

Summary

Reliability is a measure of uncertainty and therefore

estimating reliability means using statistics and probability

theory.

Reliability is quality over time

Reliability must be designed into a product or service

Summary

Most important aspect of reliability is to identify cause of

failure and eliminate in design if possible otherwise identify

ways of accommodation

Reliability is defined as the ability of an item to perform a

required function without failure under stated conditions for

a stated period of time

The costs of unreliability can be damaging to a company

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