The document discusses the '99 diseases' of pressure equipment in the hydrocarbon process industry, highlighting various degradation mechanisms that can lead to equipment failure. It emphasizes the need for understanding these issues among personnel beyond just materials and corrosion specialists, including operators and engineers, to prevent failures through preventive measures and proper maintenance. The presentation also provides insights on using these diseases to inform risk-based inspection (RBI) plans and integrity operating windows (IOWs).

1. Ninety Nine Diseases of Pressure
Equipment
in the
Hydrocarbon Process Industry
National Pressure Equipment
Conference
Banff, Alberta
10 February, 2005
John Reynolds
Shell Global Solutions, US
Houston, Texas

2. 2
What will I talk about this
morning?
• 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

3. 3
What are the 99 Diseases?
• General types of degradation mechanisms that
can cause failure of pressure equipment, like:
- 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

4. 4
Who should know about the
Diseases?
• Not just materials and corrosion specialists,
but also:
- 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

5. 5
What do “others” need to know?
• 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

6. 6
Why Spread the Knowledge?
• 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

7. 7

8. 8
Why call them the 99 Diseases?
• 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.

9. 9
Automobile Analogy
• 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

10. 10
The 99 Diseases as input for RBI
• 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

11. 11
Where can you learn more?
• 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 non-materials/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

12. 12
Organization of Each Section in API 571
• 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

13. 13
Let’s Cover a Few of the 99
Diseases
• 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

14. 14
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:
- 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?

15. 15
Vibration Fatigue
• 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?

16. 16
885 Embrittlement
• 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?

17. 17
Short Term Overheating
• 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?

18. 18
Liquid Metal Cracking (LMC)
• 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?

19. 19
Repair Welds
• 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?

20. 20
External Chloride Stress Corrosion
Cracking
• 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?

21. 21
Naphthenic Acid Corrosion (NAC)
• 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?

22. 22
Weld Overlay
Thickness/Chemistry
• 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?

23. 23
Some More of the 99 Diseases
Graphitization - Temper Embrittlement – Strain Aging – Soil
Corrosion – Atmospheric Corrosion- CUI – 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

24. 24
Questions to Ponder
• 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?

25. 25

26. 26

27. 27

28. 28

29. Ninety Nine Diseases of Pressure
Equipment in the Hydrocarbon Process
Industry
Time for Questions?
John.reynolds@shell.com
Houston, Texas