Probability of Failure - Revision history

Richard House: /* Inspection Effectiveness Categories(Local Thinning) */

2014-07-17T18:38:38Z

Inspection Effectiveness Categories(Local Thinning)

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	===Inspection Effectiveness Categories(Local Thinning)===		===Inspection Effectiveness Categories (Local Thinning)===

	'''Inspection Effectiveness Categories (Local Thinning)'''		'''Inspection Effectiveness Categories (Local Thinning)'''

Richard House: /* Inspection Effectiveness Categories(General Thinning) */

2014-07-17T18:38:29Z

Inspection Effectiveness Categories(General Thinning)

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	Encompasses general and/or local thinning inside the equipment. All equipment and components are assumed to have or be capable of having damage caused by thinning.		Encompasses general and/or local thinning inside the equipment. All equipment and components are assumed to have or be capable of having damage caused by thinning.

	===Inspection Effectiveness Categories(General Thinning)===		===Inspection Effectiveness Categories (General Thinning)===
	'''Inspection Effectiveness Categories (General Thinning)'''		'''Inspection Effectiveness Categories (General Thinning)'''
	{\|border="1" align="center" style="border-collapse: collapse; width:800px;" cellpadding="5" cellspacing="5"		{\|border="1" align="center" style="border-collapse: collapse; width:800px;" cellpadding="5" cellspacing="5"

Richard House: /* Inspection Effectiveness Categories (Thinning/Buried Components) */

2014-07-17T18:36:58Z

Inspection Effectiveness Categories (Thinning/Buried Components)

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	\|Internal inspection via pigging and in-line inspection technologies (UT, MFL, internal rotary UT, etc.) of selected areas/sections, combined with statistical analysis or extreme value analysis (EVA). <br><br>External inspection of equipment that is only partially buried using an NDE crawler with circumferential inspection technology (MFL, lambwave UT) on selected areas/sections, combined with statistical analysis or extreme value analysis (EVA).		\|Internal inspection via pigging and in-line inspection technologies (UT, MFL, internal rotary UT, etc.) of selected areas/sections, combined with statistical analysis or extreme value analysis (EVA). <br><br>External inspection of equipment that is only partially buried using an NDE crawler with circumferential inspection technology (MFL, lambwave UT) on selected areas/sections, combined with statistical analysis or extreme value analysis (EVA).
	\|Excavation at "Selected" locations, 100% external visual, and 100% inspection with NDE technologies (UT thickness measurement such as handheld devices at close-interval grid locations, UT B-scan, automated ultrasonic scanning, guided-wave UT global search, crawler with circumferential inspection technology such as MFL or lambwave UT, digital radiography in more than one direction).		\|Excavation at "Selected" locations, 100% external visual, and 100% inspection with NDE technologies (UT thickness measurement such as handheld devices at close-interval grid locations, UT B-scan, automated ultrasonic scanning, guided-wave UT global search, crawler with circumferential inspection technology such as MFL or lambwave UT, digital radiography in more than one direction).
	\|a) CP System maintained and managed by NACE certified personnel and complying with NACE SP0169 [14] – includes Stray current surveys on a regular basis. <br>b) Close Interval Survey (at excavation sites) to assess the performance of the CP system locally. <br>c) Sample soil and water resistivity and chemistry~~. <br>d) Measurements~~ along entire structure. <br>e) DC Voltage Gradient (DCVG) to determine coating damage.		\|a) CP System maintained and managed by NACE certified personnel and complying with NACE SP0169 [14] – includes Stray current surveys on a regular basis. <br>b) Close Interval Survey (at excavation sites) to assess the performance of the CP system locally. <br>c) Sample soil and water resistivity and chemistry measurements along entire structure. <br>d) DC Voltage Gradient (DCVG) to determine coating damage.
	\|-		\|-
	\|'''Fairly Effective''' <span style="color:#FF0000"> (CAT. C)</span>		\|'''Fairly Effective''' <span style="color:#FF0000"> (CAT. C)</span>

Richard House: /* HTHA Damage Factor */

2014-07-17T18:28:45Z

HTHA Damage Factor

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	** Partial pressure of hydrogen		** Partial pressure of hydrogen
	** Temperature.		** Temperature.
	* HTHA is prevalent in carbon steels, C-0.5Mo, and Cr-Mo low alloy steels. Carbon steel that only contains ~~Fe3C~~ carbides has less resistance to HTHA than those that contain Cr-Mo carbides.		* HTHA is prevalent in carbon steels, C-0.5Mo, and Cr-Mo low alloy steels. Carbon steel that only contains Fe<sub>3</sub>C carbides has less resistance to HTHA than those that contain Cr-Mo carbides.
	* Mitigation is accomplished by increasing the alloy content of the steel and therefore increasing the stability of the carbides.		* Mitigation is accomplished by increasing the alloy content of the steel and therefore increasing the stability of the carbides.

Richard House: /* Inspection Effectiveness Categories- CUI CLSCC -Austenitic Component */

2014-07-17T18:28:07Z

Inspection Effectiveness Categories- CUI CLSCC -Austenitic Component

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	* Mitigation is accomplished by preventing chloride buildup on the SS surface under the insulation or with the use of coating or wrapping of the component in aluminum foil.		* Mitigation is accomplished by preventing chloride buildup on the SS surface under the insulation or with the use of coating or wrapping of the component in aluminum foil.

	===Inspection Effectiveness Categories- CUI CLSCC -Austenitic Component===		===Inspection Effectiveness Categories- CUI CLSCC - Austenitic Component===

	'''Inspection Effectiveness Categories – CUI CLSCC – Austenitic Component'''		'''Inspection Effectiveness Categories – CUI CLSCC – Austenitic Component'''

Richard House: /* CUI Damage Factor- Ferritic Component */

2014-07-17T18:27:39Z

CUI Damage Factor- Ferritic Component

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	* Plants located in areas with high annual rainfall, warmer climate or marine locations are more prone to external corrosion than those located in cooler, drier areas.		* Plants located in areas with high annual rainfall, warmer climate or marine locations are more prone to external corrosion than those located in cooler, drier areas.
	* Units located near cooling towers and steam vents or those whose operating temperatures cycle through the dew point on a regular basis are highly susceptible to external corrosion regardless of climate.		* Units located near cooling towers and steam vents or those whose operating temperatures cycle through the dew point on a regular basis are highly susceptible to external corrosion regardless of climate.
	* Proper painting/coating of the component surface is an accomplished method of mitigation for ~~external corrosion~~.		* CUI results from the collection of water in the annulus space between the insulation and the metal surface and causes wall loss by localized corrosion.
			* Proper painting/coating and insulation practices of the component surface is an accomplished method of mitigation for CUI. High quality immersion grade coating, such as those used in hot water tanks, is recommended.

	===Inspection Effectiveness Categories- CUI -Ferritic Component===		===Inspection Effectiveness Categories- CUI -Ferritic Component===
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	\|'''Poorly Effective'''<br><span style="color:#FF0000"> (CAT. D)</span>		\|'''Poorly Effective'''<br><span style="color:#FF0000"> (CAT. D)</span>
	\|>95% external visual inspection prior to removal of insulation<br>'''AND'''<br>remove >5% of total surface area of insulation including suspect areas<br>'''AND'''visual inspection of the exposed surface area with follow-up by UT, RT or pit gauge as required.		\|>95% external visual inspection prior to removal of insulation<br>'''AND'''<br>remove >5% of total surface area of insulation including suspect areas<br>'''AND'''<br>visual inspection of the exposed surface area with follow-up by UT, RT or pit gauge as required.
	\|For the total surface area:<br> >95% visual inspection<br>'''AND'''<br> > 5% inspection with highly effective NDE technique (such as profile or real-time radiography or guided wave UT) including suspect areas<br>'''AND'''<br>strip > 5% of areas where NDE technique is not effective (e.g., fittings)<br>'''AND'''<br>100% visual inspection of the exposed surface area with follow-up by UT, RT or pit gauge as required.		\|For the total surface area:<br> >95% visual inspection<br>'''AND'''<br> > 5% inspection with highly effective NDE technique (such as profile or real-time radiography or guided wave UT) including suspect areas<br>'''AND'''<br>strip > 5% of areas where NDE technique is not effective (e.g., fittings)<br>'''AND'''<br>100% visual inspection of the exposed surface area with follow-up by UT, RT or pit gauge as required.
	\|-		\|-

Richard House: /* External Corrosion Damage Factor- Ferritic Component */

2014-07-17T18:26:12Z

External Corrosion Damage Factor- Ferritic Component

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	==External Corrosion Damage Factor- Ferritic Component==		==External Corrosion Damage Factor- Ferritic Component==
	* Plants located in areas ~~where an accumulation of chloride can result from local conditions~~ or ~~units~~ located in ~~the mist~~ areas of cooling towers or steam vents ~~can be subject~~ to external ~~CLSCC~~.		* Plants located in areas with high annual rainfall, warmer climate, or marine locations are more prone to external corrosion than those located in cooler, drier areas.
	* ~~Cracking is predominantly intergranular and highly branched.~~		* Units located near cooling towers and steam vents or those whose operating temperatures cycle through the dew point on a regular basis are highly susceptible to external corrosion regardless of climate.
	* Two key parameters: chloride ion concentration and temperature.		* Proper painting/coating of the component surface is an accomplished method of mitigation for external corrosion.
	~~CLSCC~~ is ~~most prevalent in austenitic SS with~~ an 8% nickel content. Lower or higher nickel content SS shows greater resistance, with Duplex SS with a low nickel content or alloys with greater than 42% nickel content being generally immune to CLSCC.
	* Mitigation is accomplished ~~by preventing chloride buildup on the SS surface~~.

	===Inspection Effectiveness Categories- External -Ferritic Component===		===Inspection Effectiveness Categories- External -Ferritic Component===

Richard House: /* Stress Corrosion Cracking (SCC) Damage Factor- HIC/SOHIC-HF */

2014-07-17T18:24:46Z

Stress Corrosion Cracking (SCC) Damage Factor- HIC/SOHIC-HF

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	==Stress Corrosion Cracking (SCC) Damage Factor- HIC/SOHIC-HF==		==Stress Corrosion Cracking (SCC) Damage Factor- HIC/SOHIC-HF==

			* Components are subject to hydrogen-induced cracking and stress-oriented hydrogen induced cracking in HF services.
			* Source of hydrogen in the steel is the corrosion reaction with hydrofluoric acid.
			* Internal cracks can connect adjacent hydrogen blisters on different planes on the metal surface.
			* External applied stress does not always exist.
			* Driving force is high stresses at the circumference of the hydrogen blisters that are caused by buildup of internal pressure.
			* Buildup of blister pressure is related to the hydrogen permeation flux in the steel. Blistering does pose a danger to mechanical integrity when it approaches a weld which contains sufficient residual stresses.
	* Cleanliness of the steel is measured by the sulfur content. Reducing the sulfur content of the steel reduces the susceptibility to blistering. Additions of calcium or REMS (rare-earth elements) which control sulfide inclusion are generally beneficial.		* Cleanliness of the steel is measured by the sulfur content. Reducing the sulfur content of the steel reduces the susceptibility to blistering. Additions of calcium or REMS (rare-earth elements) which control sulfide inclusion are generally beneficial.
	* SOHIC is a stacked array of blisters joined by hydrogen-induced cracking aligned in the through-thickness direction of the steel as a result of high localized tensile stresses.		* SOHIC is a stacked array of blisters joined by hydrogen-induced cracking aligned in the through-thickness direction of the steel as a result of high localized tensile stresses.

Richard House: /* Stress Corrosion Cracking (SCC) Damage Factor- HSC-HF */

2014-07-17T18:21:39Z

Stress Corrosion Cracking (SCC) Damage Factor- HSC-HF

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	==Stress Corrosion Cracking (SCC) Damage Factor- HSC-HF==		==Stress Corrosion Cracking (SCC) Damage Factor- HSC-HF==
	* ~~Components are subject to hydrogen-induced cracking~~ and ~~stress-oriented hydrogen induced cracking~~ in ~~HF services.~~		* Combined action of tensile stress and corrosion in the presence of hydrogen from hydrofluoric acid (HF).
	* Source of hydrogen ~~in the steel is the corrosion reaction with~~ hydrofluoric acid.		* Two key parameters: metal hardness and presence of HF.
	* ~~Internal cracks can connect adjacent hydrogen blisters on different planes on the~~ metal ~~surface~~.		* HSC-HF is prevalent in high strength (hardness) steels or in hard heat-affected zones of lower strength steels.
	* ~~External applied stress does not always exist.~~		* The requirements of NACE RP 0472 should be followed to prevent HSC-HF. PWHT can lower the affect of HSC-HF; however, it is not preventative.
	* Driving force is high ~~stresses at the circumference~~ of ~~the hydrogen blisters that are caused by buildup of internal pressure~~.
	* ~~Buildup~~ of ~~blister pressure is related~~ to the ~~hydrogen permeation flux in the steel. Blistering does pose a danger to mechanical integrity when~~ it ~~approaches a weld which contains sufficient residual stresses~~.

	===Inspection Effectiveness Categories- SCC HSC-HF===		===Inspection Effectiveness Categories- SCC HSC-HF===

Richard House: /* Stress Corrosion Cracking (SCC) Damage Factor- CLSCC */

2014-07-17T18:20:05Z

Stress Corrosion Cracking (SCC) Damage Factor- CLSCC

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	* Occurs to austenitic stainless steel components in chloride containing aqueous environments.		* Occurs to austenitic stainless steel components in chloride containing aqueous environments.
	* Cracking is predominantly intergranular and highly branched.		* Cracking is predominantly intergranular and highly branched.
	* Three key parameters: pH of the process fluid~~, chloride~~ ion concentration ~~and temperature~~.		* Three key parameters:
			**pH of the process fluid
			**Chloride ion concentration
			**Temperature.
	* CLSCC is most prevalent in austenitic SS with an 8% nickel content. Lower or higher nickel content SS shows greater resistance, with Duplex SS with a low nickel content or alloys with greater than 42% nickel content being generally immune to CLSCC.		* CLSCC is most prevalent in austenitic SS with an 8% nickel content. Lower or higher nickel content SS shows greater resistance, with Duplex SS with a low nickel content or alloys with greater than 42% nickel content being generally immune to CLSCC.