Failure Analysis Behind the Scene 1. Some thoughts on Failure - - PowerPoint PPT Presentation

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Failure Analysis – Behind the Scene

1. Some thoughts on Failure Analysis 2. Preparing the Quotation – look before you leap! 3. Lab Investigations – from Visual to Metallurgical examination 4. Preparing the Report a. Review of background information b. Analysis of lab investigation findings c. Evaluating the cause of failure d. Recommendations

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1. Incident occurred on 20 April 2004. 2. Think about it: if both the Prosecution and Main Con said they were right and the other party was wrong, who then was right?! 3. Can it be that both parties are right, or both wrong,

• r one right and one

wrong???

2

Source: Wikipedia

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• 1. The term “failure,” means the inability of a part or an

assembly to perform its intended function for any reason.

• 2. We usually think of failure in terms of fracture, wear,
• r corrosion.

(Ref: Understanding How Components Fail, D J Wulpi, ASM)

• 3. Think about it: the senior manager of a hotel stepped
• n a small piece of hard debris on the carpeted hotel

room and sent it for examination – in what ways can this be considered a “failure” ?

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Failure Analysis

1. In the study of any failure, the analyst must consider a broad spectrum

• f possibilities for the occurrence.

2. Often a large number of factors, frequently interrelated, must be understood to determine the cause of the original, or primary, failure. 3. Like a police detective attempting to solve a baffling case, the analyst must carefully examine and evaluate all evidence available, then prepare a hypothesis that can explain the “crime.”

(Ref: Understanding How Components Fail, D J Wulpi, ASM)

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5 (Ref: Incident Investigation and Accident Prevention in Process and Allied Industries, Ch 7, Dyadem Engineering Corp.)

Hypothesis . . .

At the beginning one does not know precisely and exactly what happened in the

• incident. Therefore any theories are hypothetical (i.e., they may be right, wrong or

partly correct). The objective is to create a single working hypothesis to be analyzed further to verify the true version of what has occurred. Hypotheses are basically unproven explanations. What is meant by the term hypothesis? A hypothesis is a proposed explanation for a phenomenon or observation. It is a tentative theory, explanation or supposition provisionally adopted to explain certain facts, and to guide in the investigation of

• thers; hence it is often called a working hypothesis. A hypothesis is a basis for

reasoning without having to assume it must be true.

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6 (Ref: Incident Investigation and Accident Prevention in Process and Allied Industries, Ch 7, Dyadem Engineering Corp.)

Hypothesis . . .

At the outset the focus will be on one or two dominant hypotheses. The remainder, less probable hypotheses, are canceled out by a process of elimination through reasoning.

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Case Study

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Case Study

(continued)

Remember:

• 1. Consider ALL possibilities and ALL evidence, and
• 2. NEVER be too quick to jump to conclusions.

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Accredited Test Labs

• 1. The importance of accreditation to commercial test laboratories
• 2. The importance of using accredited labs to customers

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STS’ Accreditations and Approvals

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Term Meaning

Accredit 1 : to give official authorization to or approval of: a : to provide with credentials; especially : to send (an envoy) with letters of authorization b : to recognize or vouch for as conforming with a standard. Certify 1 : to attest authoritatively: as a : CONFIRM b : to present in formal communication c : to attest as being true or as represented or as meeting a standard. 2 : to inform with certainty : ASSURE 4 : to recognize as having met special qualifications (as of a governmental agency or professional board) within a field <agencies that certify teachers> Conform 2 a : to be obedient or compliant —usually used with to <conform to another's wishes> b : to act in accordance with prevailing standards or customs <the pressure to conform> Comply 2 : to conform, submit, or adapt (as to a regulation or to another's wishes) as required or requested <comply with federal law> <the devices comply with industry standards> Qualify 3 a : to fit by training, skill, or ability for a special purpose b (1) : to declare competent or adequate : CERTIFY (2) : to invest with legal capacity : LICENSE intransitive verb 1 : to be or become fit (as for an office) : meet the required standard Verify 1 : to confirm or substantiate in law by oath 2 : to establish the truth, accuracy, or reality of <verify the claim>

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Term Meaning Technical standard 1. An established norm or requirement. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes and practices. 2. A technical standard can also be a controlled artifact or similar formal means used for

• calibration. Reference Standards and certified reference materials have an assigned value

by direct comparison with a reference base. A primary standard is usually under the jurisdiction of a national standards body. Secondary, tertiary, check standards and standard materials may be used for reference in a metrology system. A key requirement in this case is (metrological) traceability, an unbroken paper trail of calibrations back to the primary standard. 3. This article discusses formal technical standards. In contrast, a custom, convention, company product, corporate standard, etc which becomes generally accepted and dominant is often called a de facto standard. 4. A technical standard may be developed privately or unilaterally, for example by a corporation, regulatory body, military, etc. Standards can also be developed by groups such as trade unions, and trade associations. Standards organizations often have more diverse input and usually develop voluntary standards: these might become mandatory if adopted by a government, business contract, etc. 5. The standardization process may be by edict or may involve the formal consensus of technical experts.

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Term Meaning Types of standards The primary types of technical standards are: 1. A standard specification is an explicit set of requirements for an item, material, component, system or

• service. It is often used to formalize the technical aspects of a procurement agreement or contract. For

example, there may be a specification for a turbine blade for a jet engine which defines the exact material and performance requirements. 2. A standard test method describes a definitive procedure which produces a test result. It may involve making a careful personal observation or conducting a highly technical measurement. For example, a physical property of a material is often affected by the precise method of testing: any reference to the property should therefore reference the test method used. 3. A standard practice or procedure gives a set of instructions for performing operations or functions. For example, there are detailed standard operating procedures for operation of a nuclear power plant. 4. A standard guide is general information or options which do not require a specific course of action. 5. A standard definition is formally established terminology. 6. Standard units, in physics and applied mathematics, are commonly accepted measurements of physical quantities. Standard

• vs. Code

1. A Standard can be defined as a set of technical definitions and guidelines that function as instructions for designers, manufacturers, operators, or users of equipment. 2. A standard becomes a Code when it has been adopted by one or more governmental bodies and is enforceable by law, or when it has been incorporated into a business contract.

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Enquiry and Quotation Stage

• 1. Look before you leap!
• 2. View the failed item. (An item that’s lightweight to a

weight-lifter may be heavy to a sprinter.)

• 3. Obtain item description and brief background of the

failure.

• 4. Guiding keywords:
• a. 5Ws 1H – Who, What, When, Where, Why & How?
• b. 3Ms – Man, Material & Machine.
• 5. Establish scope of work and any requirement to out-

source (to factor in such cost, may be expensive).

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Typical Quotation for Failure Analysis of a Fractured Tube

Thank you for your interest in the services provided by STS. We are pleased to quote you a lump sum price of S$xxxx.00 for the following scope of work: 1. Visual inspection and photo documentation of the fractured tube. 2. Examination of the fracture surface with a stereo-microscope to identify macro- features as well as identify areas for further analysis. 3. Examination of the fracture surface using a scanning electron microscope (SEM) to establish the origin of failure, mode of failure, e.g. whether it was due to fatigue,

• verload, etc.

4. Energy dispersive x-ray (EDX) elemental analysis will be conducted on the fracture surface to establish the elemental constituents. 5. Quantitative chemical composition analysis. 6. Mechanical testing - tensile test, impact test, etc. 7. Metallurgical examination of the fracture surface to establish any microstructural factors that could have contributed to the failure. 8. Microindentation hardness test. 9. Interpretation of results, evaluation of the possible cause(s) of failure, and reporting.

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FAILURE ANALYSIS

(2) Visual/NDT/ Dimensional measurement (3) SEM/EDX Analysis (5) Metallographic Examination (4) Mechanical Testing (6) Chemical Analysis (7) Product Reliability Evaluation (8) Specialized Tests, e.g., H2 content . . . (1) Background information

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Coordinate Measuring Machine (CMM)

Fluorescent Particle Inspection

Radiographic Inspection

Some Preliminary Inspections

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Stereo-microscope (7.5 – 50X) How big

• r

how small?

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Fracture started here Fracture started here

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Which cutting machine/tool to use???

Horizontal Bandsaw Hacksaw