What Makes Us Do Failure What Makes Us Do Failure Analysis?Analysis?

ASM – AWS (NTX) Joint MeetingASM – AWS (NTX) Joint Meeting Michael S. Beaton, PE Michael S. Beaton, PE

16 October, 200716 October, 2007

CategoriesCategories

• OUT of ORDEROUT of ORDER• STRETCHING the NUMBERSSTRETCHING the NUMBERS• ““WHAT WADDLES LIKE A DUCK…”WHAT WADDLES LIKE A DUCK…”• COMEDY of ERRORSCOMEDY of ERRORS• WORKMANSHIPWORKMANSHIP• CHEAPNESSCHEAPNESS• NATURENATURE

OUT OF ORDEROUT OF ORDER

• Steam control valve stem Steam control valve stem • nitridednitrided• then threadedthen threaded..• Thread section was less strong / hard Thread section was less strong / hard

AND smaller sectionAND smaller section• Failure occurred in first full thread Failure occurred in first full thread viavia

FatigueFatigue

FATIGUEFATIGUE

• Repeated or fluctuating stressRepeated or fluctuating stress• Stress below tensile strength of the Stress below tensile strength of the

materialmaterial• Progressive fracture from initiation point(s)Progressive fracture from initiation point(s)

– Often created by aggressive environment or Often created by aggressive environment or sensitizing condition (corrosion, fretting, arc sensitizing condition (corrosion, fretting, arc strikes & weld spatter)strikes & weld spatter)

““WHAT WADDLES LIKE A DUCK…”WHAT WADDLES LIKE A DUCK…”

• Combustor can on Power Gas TurbineCombustor can on Power Gas Turbine• Four detail parts joined by weldingFour detail parts joined by welding• Two parts made of Two parts made of Austenitic Stainless Austenitic Stainless

SteelSteel• Alignment off-center -> parts rubbed, Alignment off-center -> parts rubbed,

cracked, machined away weld metalcracked, machined away weld metal• Weld repairs recrackedWeld repairs recracked

Off-Spec. conditionsOff-Spec. conditions

• Alloy selection was incorrect for two Alloy selection was incorrect for two componentscomponents

• Weld deposit was machined, REMOVED Weld deposit was machined, REMOVED 100% for 30 degrees of circumference.100% for 30 degrees of circumference.

• Clearances were not symmetricalClearances were not symmetrical

WORKMANSHIPWORKMANSHIP

• Reheat Pendant Tube SpliceReheat Pendant Tube Splice• Incomplete Penetration of Weld JointIncomplete Penetration of Weld Joint• Deep Geometric Notch at Weld RootDeep Geometric Notch at Weld Root• Tube Internal Pressure and Flow Vibration Tube Internal Pressure and Flow Vibration

Caused Notch to Grow, Joint FailedCaused Notch to Grow, Joint Failed

What Makes Us Do Failure What Makes Us Do Failure Analysis?Analysis?

• OUT of ORDEROUT of ORDER √• STRETCHING the NUMBERSSTRETCHING the NUMBERS• ““WHAT WADDLES LIKE A DUCK…”WHAT WADDLES LIKE A DUCK…” √• COMEDY of ERRORSCOMEDY of ERRORS• WORKMANSHIPWORKMANSHIP √• CHEAPNESSCHEAPNESS• NATURENATURE

Trinity Metals LaboratoryTrinity Metals LaboratoryQUALITY PHILOSOPHYQUALITY PHILOSOPHY

• QUALITY is a fundamental business strategy for QUALITY is a fundamental business strategy for Trinity Metals Laboratory.Trinity Metals Laboratory.

• Our GOAL is to be the best provider of testing Our GOAL is to be the best provider of testing services in our market in terms of accuracy, services in our market in terms of accuracy, dependability, and value to our customers.dependability, and value to our customers.

• We are committed to providing our customers We are committed to providing our customers with consistently high quality testing services, with consistently high quality testing services, – defect free defect free – on time on time – at competitive prices.at competitive prices.