Revalidating requirements rigging hardware case study
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Revalidating Requirements: Rigging Hardware Case Study. Anthony Underhill 321-730-6269 anthony.underhill@mantech.com capt_underhill@yahoo.com. “ We ’ ve always done it that way? ”. Is the requirement still relevant (effective) in today ’ s environment?.

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Revalidating Requirements: Rigging Hardware Case Study

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Revalidating Requirements:Rigging Hardware Case Study

Anthony Underhill

321-730-6269

anthony.underhill@mantech.com

capt_underhill@yahoo.com


“We’ve always done it that way?”

Is the requirement still relevant (effective) in today’s environment?

WHY DOES THE SAFETY REQUIREMENT EXIST?

How was the requirement validated?

What were the circumstances at the time?


FAST FORWARD TO TODAY

Facility Cost ⇒ $110K annual

User Mission Cost ⇒ $ 34K per mission

TOTAL COST ON Eastern Range = ~$1M per year


Cheap Insurance – Right?

BUT IS IT MORE SAFE?


Back to 1970

  • US NAVY – high number of accidents

    • Causes: Uncertainty in the load

      High corrosion environment

      No Consensus standard for design

    • Solution: Annual 2 x rated load test

  • OSHA in its infancy

  • US Air Force Range

    • Adopt 2 x RL in ESMC (1984)


Three Decades Later

WHAT DOES ASME SAY ABOUT 2 x RL TESTING?

Do not recommend exceeding 42% yield strength or

fatigue may occur (ASME B30.20 interpretation)


Is Range STD More Safe?

  • Does annual 2 x RL proof increase safety?

  • Are Magnetic Particle or Dye Penetrate inspections required to find critical flaws?


MYTH #1 – 2 x RL increase Safety

10 Fatigue Rated shackles failed in fatigue

when subject to 2 x RL

BUSTED


Myth 2 – Hair line crack

Failed @ 1.28 x RL

Failed @ 2.87 x RL

BUSTED

Failed @ 1.87 x RL

Failed @ 2.28 x RL


Additional Load Test Risk

  • Chance of improperly tested

  • Change of damage during installation

  • Change of damage during installation

Fact: 10,500 crane lift during EPF construction. No rigging gear failed. ASME B30 used.


CONCLUSION

  • REVISIT YOUR SAFETY REQUIREMENTS

  • REVALIDATE THEY ARE FULLFILLING THEIR INTENDED PURPOSE

    • YES – ENFORCE THEM

    • NO – CHANGE THEM


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