Transcript Document

Ninety Nine Diseases of Pressure
Equipment
in the
Hydrocarbon Process Industry
National Pressure Equipment
Conference
Banff, Alberta
John Reynolds
10 February, 2005
Shell Global Solutions, US
Houston, Texas
What will I talk about this morning?
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What’s in the title (why the 99 Diseases)?
Who should know about the 99 Diseases?
How to use the 99 diseases to prepare RBI plans
Establishing Integrity Operating Windows (IOW’s) to avoid the 99
Diseases
Where to learn more about the 99 Diseases?
Then we’ll cover a few of the 99 Diseases
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What are the 99 Diseases?
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General types of degradation mechanisms that can cause failure of
pressure equipment, like:
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General and localized corrosion and erosion
Environmentally caused cracking
Metallurgical aging and degradation
High temperature degradation and brittle fracture
Mechanical cracking and damage
Welding and fabrication flaws
Anything that will cause materials of construction to degrade and
possibly cause failure of pressure equipment in service
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Who should know about the Diseases?
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Not just materials and corrosion specialists, but also:
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Inspectors
Operators
Process and technology engineers
RBI teams and PHA teams
Project and equipment engineers
Maintenance personnel
Everyone that has a stake or role in preventing pressure equipment failures
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What do “others” need to know?
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Enough to help them recognize degradation issues and to seek help
from materials and corrosion specialists, when necessary
Enough to help them understand the importance of operating within
the integrity operating windows (IOW’s)
Enough to help them understand and assess when changes to
equipment and/or process conditions might cause changes in types of
degradation or changes in rates of degradation
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Why Spread the Knowledge?
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Because in many cases of equipment failure, the materials and corrosion
engineer is the one person that “knew” what could happen and could
have helped to prevent the incident; but was not in a position to do
anything about it when it occurred
Because the people on the front lines or the people making changes
sometimes do not know about the types of degradation that might
happen and what their role is in preventing pressure equipment failures
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Why call them the 99 Diseases?
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There’s a good analogy with the medical profession
It’s much easier, much less expensive, and healthier (safer) to prevent diseases than
it is to cure them
We would all rather know and practice the necessary lifestyles that will prevent us
from having lung cancer or heart disease than it is to cure either after we contract
them
Same is true with the 99 diseases of pressure equipment
Preventing cracks, high corrosion rates, and metallurgical degradation is usually
easier, much less expensive, and safer than coping with the aftermath of
unexpected vessel and piping failures.
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Automobile Analogy
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With good care, automobiles can operate dependably for well over 200,000 miles
But it takes knowledge of what can go wrong and then doing the necessary preventive
maintenance (ie, taking good care of our automobiles)
Same is true for pressure vessels, heat exchangers, tanks, and piping
If we take care of them, understand what can make
them “break down” (ie, fail unexpectedly), and “drive
them” with care (ie, operate them within the properly
designated integrity operating window (IOW), they will
provide reliable, safe service throughout the life of our
process plants
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The 99 Diseases as input for RBI
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The 99 Diseases can be used as a checklist of possible causes of failure
from which we glean the probable causes of degradation and failure
Identifying all the possible degradation mechanisms is a critical success
factor for RBI
RBI team members each need to know a minimum amount about each
possible/probable degradation mechanism in order to contribute
effectively
But only one RBI team member needs to be a materials and corrosion
specialist
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Where can you learn more?
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Hundreds of materials and corrosion references that are available, but a new one really
stands out:
API RP 571, Damage Mechanisms Affecting Fixed
Equipment in the Refining Industry – it’s written for the nonmaterials/corrosion specialist
Or for other industries: WRC 488 - Damage Mechanisms
Affecting Fixed Equipment In Fossil Electric Power
Industry and WRC 489 - Damage Mechanisms
Affecting Fixed Equipment In The Pulp And Paper
Industry
Follow the whole series of the 99 Diseases in the Inspectioneering Journal, starting
with the Jan/Feb 2003 edition
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Organization of Each Section in API 571
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Description of each damage mechanism
Construction materials affected
Critical factors that cause the damage
Affected equipment and process units
Description of the appearance of the damage
Prevention and mitigation
Inspection and monitoring
Related damage mechanisms
Other references on each type of damage mechanism
Photos (macroscopic and microscopic)
Very concise – all this condensed into just ~2-4 pages for each damage mechanism
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Let’s Cover a Few of the 99 Diseases
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Caustic Cracking
Vibration Fatigue
885 Embrittlement
Short-Term Overheating (Stress Rupture)
Liquid Metal Cracking (LMC)
Repair Welds
External Chloride Stress Corrosion Cracking
Naphthenic Acid Corrosion (NAC)
Inadequate Overlay Weld Thickness/Chemistry
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Caustic Cracking
One of the most common and best understood types of environmental cracking –
often results in white crystalline external deposits near leaks
Cracks often wide-open, easy to see, but can be fine/tight
Typically in non-PWHT weldments and other areas of high residual stresses
Some common causes:
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steaming out and carry-over into non-PWHT equipment
Inadequately designed caustic injection nozzles
Inadequate PWHT and non-PWHT repair welds
Heat tracing in direct contact with caustic containing equipment
Operators and maintenance people that don’t understand the issue
Would your RBI team know about all the potential sources of caustic that might crack
your equipment in service?
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Vibration Fatigue
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Can lead to catastrophic consequences when vibrating nozzles fall off equipment or full
bore piping separation occurs
Often associated with SBP and screwed connections
Usually associated with proximity to rotating machinery, but can also be associated with
flow induced vibrations
Inspection is not typically useful for avoidance
Design modifications are key to corrective action
Don’t let vibration become the accepted norm at your plant!
Do your operators know enough about the consequences of vibration fatigue such that
they would report equipment vibration for possible mitigation?
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885 Embrittlement
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One of many types of embrittlement phenomena that can lead to brittle fracture of
equipment in service
Most commonly affects 400 series stainless steels in temperature range of 600-1000 F
(highest embrittlement occurs at 885 F)
Susceptible alloys suffer from toughness deterioration due to metallurgical changes in
service
Only detectable through some form of physical or mechanical testing (not NDE or
inspection)
Do you know about all the potential factors and conditions that might lead to
embrittlement of your equipment in service?
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Short Term Overheating
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Also known as “stress rupture” – not uncommon form of deterioration – sometimes
leads to catastrophic rupture
Involves localized exposure to higher than design temperature at design operating
pressures – sometimes just a few degrees can substantially shorten service life
Some susceptible equipment – furnace tubes – refractory lined equipment –
exothermic reactors
Canadian HPU furnace hot spot rupture resulted in explosion –> fire –> fatality
Preventable with IOW’s, hot spot monitoring, IR scanning, heat sensitive paint, burner
management, temperature monitoring, etc.
Do your operators have all the tools and knowledge to avoid short-term overheating
failures?
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Liquid Metal Cracking (LMC)
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A very insidious and very rapid cracking mechanism
Also known as Liquid Metal Embrittlement (LME)
Affects numerous alloys of Al, Cu, Ni, and Fe (SS)
Aluminum core exchangers have failed due to Mercury LMC – two incidents
with huge consequences
Galvanized coating (Zn) melts at 780F and drips on SS equipment causing
LMC
Cadmium plating on bolts melts at 480F --> LMC
Do you know if some of your equipment may be susceptible to LMC?
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Repair Welds
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Another potentially undetected flaw, sometimes with fairly insidious consequences
Repair welds are not infrequently the initiation site for cracking or corrosion failures
Often repair welds (both shop and field) don’t get reported or recorded and can have
inadequate QA/QC
Some construction codes don’t treat repair welds adequately in terms of specified QA/QC
Repair welds can produce metallurgical notches, stress raisers, high hardness, and
dissimilar weld issues
Do you require your fabricators and maintenance forces to record and report all repair
welds for your records?
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External Chloride Stress Corrosion Cracking
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ECSCC is an off-shoot of effective CUI programs and is difficult to avoid
and inspect for
Affects insulated solid SS equipment in CUI range from 140F (60C) to 300F
(150C), and higher temps
Even good CUI coatings break down after 10-15 years allowing moisture
and chlorides to contact the external surfaces under insulation
Chlorides come from insulation and the atmosphere
Fortunately SS toughness “usually” leads to LBB
Do you have insulated solid SS equipment that may be susceptible to
ECSCC?
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Naphthenic Acid Corrosion (NAC)
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An old problem that we are continuing to learn more about
Higher severity operations sometimes lead to more NAC in places where we did not find it
before
TAN, organic acids, sulfur content, temperature, and velocity all combine to determine
extent of NAC
Usually results in highly localized corrosion, but can be general thinning in lower alloys
Prevention includes upgrading to higher Moly containing alloys or blending crude diets
NAC susceptibility can be predicted with the CORAS model
Would your MOC program be able to predict accelerated NAC problems from changes in
crude diets?
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Weld Overlay Thickness/Chemistry
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Steel vessels, exchangers, flanges commonly weld overlaid with high alloy for
corrosion resistance
It’s vital that the top surface of the overlay be the right alloy content to resist
process corrosion, especially if there will be final grinding or machining
The proper thickness and chemistry QA/QC should be specified following
multiple layers of weld overlay
Don’t count on the machinist or grinder to know that he is defeating your
corrosion allowance!
Have you ever seen localized corrosion or rust stains bleeding through a weld
overlaid surface?
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Some More of the 99 Diseases
Graphitization - Temper Embrittlement – Strain Aging – Soil Corrosion – Atmospheric CorrosionCUI – Reheat Cracking – Dealloying – Condensate Corrosion – Oxidation – Sulfidation – MIC –
CO2 Corrosion – Cavitation – Thermal Shock – Carburization – Hydrogen Embrittlement – Sour
Water Corrosion – Ti Hydriding – HTHA – HCl Corrosion – Overhead Corrosion – Dew Point
Corrosion – Delayed Hydrogen Cracking – ECSCC – NAC – HIC – SOHIC – PASCC – Metal
Dusting – Fuel Ash Corrosion – Corrosion Fatigue – Chloride Cracking – Nitriding – Brittle
Fracture – Cavitation – Thermal Fatigue – Steam Blanketing – Erosion – Refractory Failure –
Cooling Water Corrosion – Graphitic Corrosion – DMW Cracking – Sigma Phase Embrittlement –
Mechanical Fatigue – Spheroidization – Erosion-Corrosion – Galvanic Corrosion – Carbonate
Cracking – Green Rot
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Questions to Ponder
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Do all the right people at your operating plant know enough about the
99 Diseases in order to do their part in preventing pressure equipment
failures?
Do you have integrity operating windows (IOW’s) established for all
the 99 Diseases to which you may be susceptible?
Do your RBI plans consider all the 99 Diseases when considering the
risk of failure at your plant?
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Ninety Nine Diseases of Pressure
Equipment in the Hydrocarbon Process
Industry
Time for Questions?
[email protected]
Houston, Texas