aPI570 chap 5 Flashcards
Thickness measurement shall be obtained by whom?
inspector or the examiner at the director of the inspector
who is responsible that individuals conducting thickness measurement are trained and qualified?
owner/user
What is on stream thickness monitoring good tool for? (2)
- monitoring corrosion and
2. assessing potential damage due to process or operational changes
When is external visual used for? (9)
- condition of outside of the piping
- insulation system
- painting
- coating system
- hardware
- signs of misalignment
- vibration
- leakage
- pipe hangers and support
Types of screen techniques NDE? (2) and what data results it obtain? can be used to locate areas of interest for follow-up inspection using more quantitative NDE techniques
- guided wave testing/EMAT
- Lamb wave inspections
Qualitative
cons of screening techniques? (2)
- may miss significant localized corrosion
2. limited to the qualitative data results
Use screen technique with …
quantitative NDE techniques
what else should they be alert on during External visual? (4)
- bellows expansion joints
- presence of field modification or repairs
- presence of any components that may be unsuitable for long-term operation, such as improper flanges, temporary repairs, valve of improper specification
- weldment of attachments
Vibrating pipes and line movement surveillance at locations where vibrating piping system are restrained to resist dynamic pipe stresses - what should be done? (type of NDE -2)
periodic MT or PT should be considered to check for the onset of fatigue cracking
What is done on supplemental inspection? for fouling/plugging or leaks
- periodic use of RT or thermography to check for fouling or internal plugging.
- acoustic emission, and thermography can be used for remote leak detection
what type of NDE to be done with NPS > 12?
scanning of the areas with UT
of CML on higher CR or localized corrosion?
normally have more CMLs and monitored more frequently
How are thickness measurement made?
4 quadrants on pipe and fitting with special attention to the inside/outside radius of elbows and tees
When can CMLs be eliminated or the number reduce?
- when the expected damage mechanism will not result in a wall loss or other forms of deterioration - may need to consult with CS
Fewer CMLs can be selected for piping systems with any of the following three characteristics:
a) low potential for creating a safety or environmental emergency in the event of a leak;
b) relatively noncorrosive piping systems;
c) long, straight-run piping systems.
CMLs can be eliminated for piping systems with any of the following characteristics: (3)
a) extremely low potential for creating a safety or environmental emergency in the event of a leak;
b) noncorrosive systems, as demonstrated by history or similar service; and
c) systems not subject to changes that could cause corrosion as demonstrated by history and/or periodic reviews.
When is profile RT (PRT) used? (3)
- small bore piping (NPS 1 or less)
- may be used for measuring thicknesses, particularly in insulated systems
- where nonuniform or localized corrosion is suspected.
When ultrasonic measurements are taken above ____ F___instruments, couplants, and procedures should be used that will result in accurate measurements at the higher temperatures
150 F
When to use UT angle Beam examiners? (2)
a) detection of interior surface (ID) breaking flaws when inspecting from the external surface (OD); or
b) detection, characterization, and/or through-wall sizing of defects
Inspection for CUI shall be considered for externally-insulated carbon and low alloy piping operating between
10 °F
–12 °C) and 350 °F (175 °C
What NDE can help to determine if any scale is present behind the insulation without removal.
Non-intrusive techniques such as real time radiography
Mixing points? definition
locations in piping systems where two or more different streams meet.
the preferred methods of inspecting mixing points include; (2) - NDE
- radiography and
- ultrasonics (straight beam and/or angle beam) to determine the minimum measured thickness and/or the presence of other susceptible damage mechanisms
Mixing points may be treated as separate inspection circuits, and these areas may need to be inspected differently, using (3)
1 . special techniques,
- different scope,
- and at more frequent intervals when compared to the inspection plan for the parent/contributing piping stream(s).
Injection points are sometimes subject to ________ or _______ corrosion
accelerated or localized
When designing an injection point circuit for the purposes of inspection, the inspection (2) upstream/downstream
- upstream limit of the injection point circuit is a minimum of 12 in. (300 mm) or three pipe diameters upstream of the injection point,
- downstream limit of the injection point circuit is the second change in flow direction past the injection point, or 25 ft (7.6 m) beyond the first change in flow direction, whichever is less.
preferred methods of inspecting injection points (3) (NDE)
- radiography and/or
- UT scanning or
- closely spaced UT grid inspection
During periodic scheduled inspections, more extensive inspection should be applied where at the IP? upstream/downstream
to an area beginning 12 in. (300 mm) upstream of the injection nozzle and continuing for at least ten pipe diameters downstream of the injection
point.
The potential for localized corrosion can occur at the junction where the injection point enters_______ . The use of profile radiography at the junction and UT manual scanning of the primary pipe (surrounding and downstream of the junction) is recommended
into the primary pipe
________tests_____ are not normally conducted as part of a routine inspection
Pressure tests
pressure tests shall be performed in accordance with the requirements
ASME B31.3 , Additional considerations for pressure testing are provided in API 574, API 579-1/ ASME FFS-1, and ASME PCC-2 Article 5.1
When a pressure test is required, it shall be conducted after
any heat treatment.
Before applying a hydrostatic test, what should be done so that we know it is suitable for a hydrostatic load?
the supporting structures and foundation design should be reviewed by an engineer
The owner/user is cautioned to avoid exceeding 90 % of the specified ________for the material at test temperature and especially for equipment used in elevated temperature service.
minimum yield strength (SMYS)
Piping fabricated of or having components of austenitic stainless steel should be hydrotested with as solution made up of potable water (see note), de-ionized/de-mineralized water or steam condensate having a total chloride concentration (not free chlorine concentration) ___________________
of less than 50 ppm.
For sensitized austenitic stainless steel piping subject to polythionic stress corrosion cracking, consideration should be given to using an ______________for pressure test
alkaline-water solution for pressure testing (see NACE RP 0170).
The test fluid should be _______if not, another suitable nontoxic liquid may be used. If the liquid is flammable, its flash point shall be at least ______
water , 120 °F (49 °C) or greater
what needs to be considered when using a pneumatic pressure test?
potential risks to personnel and property of pneumatic testing shall be considered when carrying out such a test.
How to minimize brittle fracture during a pressure test? (3)
the metal temperature should be maintained at least
- 30 °F (17 °C) above the MDMT for piping that is more than 2 in. (5 cm) thick,
- and 10 °F (6 °C) above the MDMT for piping that have a thickness of 2 in. (5 cm) or less.
- The test temperature need not exceed 120 °F (50 °C)
what material is susceptible to brittle failure and at what temperatures?
at ambient temperatures AND carbon, low-alloy, and other steels, including high alloy steels
special attention shall be given to what materials because they are prone to temper embrittlement?
when testing low-alloy steels, especially 21 /4Cr-1Mo,
A number of failures have been attributed to brittle fracture of steels that were exposed to temperatures below their transition temperature and to pressures greater than 25 % of the _____(2).
- required hydrostatic test pressure
2. 8 ksi of stress, whichever is less
The potential for a brittle failure shall be evaluated by an______ prior to hydrostatic testing or especially prior to pneumatic testing because of the higher potential energy involved
engineer
During a pressure test, where the test pressure will exceed the set pressure of the pressure relieving device on a piping system, what should be done?(2)
- the pressure relieving device(s) should be removed or blanked for the duration of the test OR
- each valve disk shall be held down by a suitably designed test clamp.
what is prohibited during a pressure test for a PRD?
The application of an additional load to the valve spring by turning the adjusting screw is prohibited.
what to do with Other appurtenances that are incapable of withstanding the test pressure, such as gage glasses, pressure gages, expansion joints, and rupture disks, ?
should be removed or blanked.
Lines containing expansion joints that cannot be removed or isolated may be tested at a reduced pressure in accordance
ASME B31.3
who must approved to alternatives NDE to pressure test ?
only after the engineer and inspector have approved the substitution.
NDEs used for alternative pressure test?
- UT –> owner/user shall specify industry-qualified UT angle beam examiners
- ASME B31 Code Case 179 may be used in lieu of RT for B31.1 piping welds
- alternative UT acceptance criteria provided in B31 Code Case 181 may be used in lieu of those described in para.
which APi code for Material verification?
API578
Inspection plans for sulfidation corrosion should be in accordance with
API 939-C.
In lines in older process units operating above 500 °F (260 °C) and subject to sulfidation corrosion, carbon steel piping containing less than 0.1 wt % silicon can corrode at _________ silicon carbon steels (modern “silicon-killed” process).
significantly higher rates than
what is 344.6.2 of ASME B31.3 use for?
for closure welds that have not been pressure tested and for welding repairs identified by the engineer or inspector
What kind of inspection should be considered on older low silicon carbon steels?
consideration should be given to conducting inspection of each piping segment in order to identify the worst case corrosion rate / limiting component
What kind of inspections are performed on valves?
visually examine when valves are dismantle for unusual corrosion patterns and thinning.
Bodies of valves that are exposed to significant temperature cycling should be examined ______.
periodically for thermal fatigue cracking.
If gate valves are known to be or are suspected of being exposed to severe or unusual corrosion-erosion….what to be done and where on the valve
thickness readings should be conducted on the body between the seats, since this is an area of high turbulence and high stress.
Control valves or other throttling valves, particularly in high-pressure drop and slurry services, can be susceptible to___________. If such metal loss is suspected, what should be done?____ (2).
- localized corrosion/erosion of the body downstream of the orifice.
- he valve should be removed from the line for internal inspection.
- The inside of the downstream mating flange and piping also should be inspected for local metal loss.
When valve body and/or closure pressure tests are performed after servicing, they should be conducted in accordance
with API 598
Critical check valves shall be
adequately inspected or tested to provide greater assurance that they will prevent flow reversals
inspection for check valves? (3)
a) Checking to insure that the flapper is free to move,
b) The flapper stop should not have wear beyond tolerance.
c. The flapper nut should be secured to the flapper bolt to avoid backing off in service.
Why use an NDE method that is different from the one employed during original fabrication?
good practice to do what?
may reveal pre-existing flaws that were not caused by in-service exposure ,
For this reason, it is often a good practice to specify the types of NDE during original fabrication that the owner/user plans to apply during in-service inspections
What to do when radiographic profile examinations of welds that have been in-service may reveal a flaw in the weld. (2)
- further inspection with weld quality radiography and/or UT should be used to assess the magnitude of the imperfection.
- inspector should try to determine whether the crack-like imperfections are from original weld fabrication or may be from an environmental cracking mechanism.
Crack-like flaws and environmental cracking shall be assessed by an engineer in accordance
with API 579-1/ASME FFS-1 and/or corrosion specialist. Preferential weld corrosion shall be assessed by the inspector.
For in-service piping weldments, it may not be appropriate to use the original construction code radiography acceptance criteria for weld quality in __(code book)__. Why?
ASME B31.3.
B/C….
The B31.3 acceptance criteria are intended to apply to new construction on a sampling of welds, Some welds may exist that will not meet these criteria but will still perform satisfactorily inservice after being hydrostatically tested. This is especially true on small branch connections that are normally not examined during new construction
The owner/user shall specify industry-qualified UT angle beam examiners when the owner/user requires either of the following items (2)
a) Detection of interior surface (ID) breaking planar flaws when inspecting from the external surface (OD).
b) Where detection, characterization, and/or through-wall sizing is required of planar defects.
welds are often inspected for corrosion as part of a (2) NDE
- radiographic profile inspection
2. or as part of internal inspection.
Flanged joints should be examined for evidence of
leakage, such as stains, deposits, or drips.
flange faces should be examined for (2)
for distortion and to determine the condition of gasket-seating surfaces.
If flanges are significantly bent or distorted, what should be done
- their markings and thicknesses should be checked against engineering requirements before taking corrective action.
Flange fasteners should be examined visually for (2)
corrosion and thread engagement.
Additional guidance on the inspection of flanged joints can be found in
ASME PCC-1.
Any fastener is considered acceptably engaged if the lack of complete engagement is not
more than one thread.
