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Incident Study: Pipes

Group A
by

Michael Peters

on 11 October 2013

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Transcript of Incident Study: Pipes

Sections of pipe which allow fluid to be stagnant
Example: Steam connection to furnace
Example: Instrument support
Dead-Ends
Incident Study: Pipes
Pipes
Importance and ubiquity of pipe failure

Types of incidents:
Dead ends
Water hammer
Flange
Water injection
Poor support
Corrosion/Thermal stress
Notable incidents

Significance
Over half of leaks occur due to pipe failure
Ensure proper design specifications
Check to ensure proper construction and adherence to good engineering practice
Poor Support
Insufficient Support
Freedom to vibrate
Increase rapidness of failure:
Carrying heavy weight
Resonance of pipes
Impulses at own natural frequency

Ex. Control valve with different dimensions
Rigid Support
Not enough flexibility in the support
Pipes expand when heated

Ex. Pipe welded to steel support and bolted to concrete pier

Ex. Pipe located 5in from support beam
Water Injection
Miscellaneous Pipe Failures
Age of materials
Many failures have occurred because old pipes were reused
Grade of steel
Many failures have occurred because the wrong grade of steel was used for a pipeline.
For example:
the exit pipe from a high-pressure ammonia converter was constructed from carbon steel instead of 1.25.% Cr, 0.5% Mo alloy steel.
Hydrogen attack occurred, and a hole appeared at a bend.
The hydrogen leaked out, and the reaction forces pushed the converter over.
Steel can be analyzed easily with a spectrographic analyzer.
Corrosion occurred near the point shown
the oil leak caught fire
The rate of corrosion far exceeded the corrosion allowance of 0.05 in. per year
Poor arrangement
water injection pipe can be removed for inspection
However, if the injection pipe is installed as pointing upstream instead of downstream, this increases corrosion
equipment should be designed so that it is difficult or impossible to assemble it incorrectly
Better arrangement
Example 1
a hole of 6 in. long and 2 in. wide appeared on a 3-in. pipe carrying flammable gas under pressure.
The pipe had previously been used on a corrosive/erosive duty
a 4 1⁄2-in.-diameter pipe carrying a mixture of hydrogen and hydrocarbons at a gauge pressure of 3,600 psi and a temperature of 350 to 400 degrees C burst
a jet of flame longer than 30 m was produced
Investigation showed that the pipe had previously been used on another plant for 12 years at 500 ° C.
Therefore, it had used up a lot of its creep life.

Example 2
Thermal expansion/contraction
– Non-vented welds









Thermal Stress
& Corrosion
San Juanico: 500 dead, thousands injured
Flixborough: 28 dead, extensive damage
BP Oil spill: Irreparable environmental damage
Cubatao, Brazil: >508 dead, 700 tonnes gas spilled
–Mostly Children
Exxon Pipeline: 84,000 gallons crude oil
Notable incidents
Most ubiquitous incident for large accidents
Conclusion
References
Corrosion
– Source material contamination
– Internal deposits
Image from: Armstrong Plumbing
Image from: Armstrong Plumbing
Image from: "What went Wrong?" by Trevor Klets
Lessons learned:
Proper maintenance
Operational vigilance
Knowledgeable design
Water Hammer
Pressure or wave surge causing valve/pipe ruptures
Causes
Condensate allowed to accumulate in a Gas line
Flow of liquid in a pipeline is suddenly stopped/started
Condensate can accumulate in a valve if traps are improperly placed/misplaced, and when pipes have been unused for long periods of time.

This condensate can be set into motion by movement of the gas causing damage farther down the pipe
Flange Leaks
Small leaks in comparison to others

Primarily caused by technician error.
Water hammer caused by quickly opening a valve
Images from: "What went Wrong?" by Trevor Klets
Image from Wikipedia Commons
Image from: "What went Wrong?" by Trevor Klets
Image from: "What went Wrong?" by Trevor Klets
Image from: "What went Wrong?" by Trevor Klets
Image from: "What went Wrong?" by Trevor Klets
Both Images from: "What went Wrong?" by Trevor Klets
Image from Wikipedia Commons
Importance of observation and maintence
Continued Good Engineering
Practice
Questions?
Image taken from: BBC World News
Given our presentation, what do you think about the new oil pipeline through BC?
BBC World News. (2010). "China oil spill after pipe blast 'worse
than thought'"

Lees, F.P. (1996). "Loss Prevention in the Process Industries –
Hazard Identification, Assessment and Control, Volume 3, Appendix 4". Butterworth Heinemann, ISBN 0 7506 1547 8.

Marsh and McLennan. (1995). "Large Property Damage Losses in
the Hydrocarbon-Chemical Industries a thirty-year Review, 16th Edition" Marsh and McLennan Protection Consultants.

OEDC, Compedium, (1985).

Pietersen C. M. and Huerta S. C. (1984). "Analysis of the LPG
Incident in San Juan Ixhuatepec, Mexico City. 19 November 1984." The Hague: TNO

Trever, K. (2009). "What went wrong? Process Plant Disasters and
How They Could Have Been Avoided (5th Edition)". Oxford, England: Gulf Professional Publishing.

Group A: Michael Peters, Derek Fong, Andrew Madsen, Taylor Eshleman, Jo Lai
Taken from CHBE 479 Lecture Slides prepared by Dr. Christina Gyenge
Full transcript