1. Fion Zhang/ Charlie Chong API RP 574 In-house training
Inspection Practices for Piping System Components My Self Study
Notes
2. Fion Zhang/ Charlie Chong -
3. Fion Zhang/ Charlie Chong
4. Fion Zhang/ Charlie Chong Foreword API RP 574 (RP) API 570
API, ; , 5 API , , 2 . 6. -RP, .
5. Fion Zhang/ Charlie Chong Contents 1 Scope 2 Normative
References 3 Terms, Definitions, Acronyms, and Abbreviations 4
Piping Components 5 Pipe-joining Methods 6 Reasons for Inspection 7
Inspection Plans 8 Frequency and Extent of Inspection 9 Safety
Precautions and Preparatory Work 10 Inspection Procedures and
Practices 11 Determination of Minimum Required Thickness 12 Records
Annex A (informative) External Inspection Checklist for Process
Piping
6. Fion Zhang/ Charlie Chong 1 Scope RP API 570 . RP, .
574-1
7. Fion Zhang/ Charlie Chong 2.Normative References 574-2
8. Fion Zhang/ Charlie Chong 3. Terms, Definitions, Acronyms,
and Abbreviations ,, 574-3 Please refer to text
12. Fion Zhang/ Charlie Chong 4.1 Piping NPS48 574-4
13. Fion Zhang/ Charlie Chong 574-4 Pipe wall thicknesses are
designated as: (1) pipe schedules in NPS up to 36 in. (2) The
traditional thickness designations: Standard weight, (ST) Extra
strong, and (XS) Double extra strong (XXS) differ from schedules
and are used for NPS up to 48 in.
14. Fion Zhang/ Charlie Chong 574-4
15. Fion Zhang/ Charlie Chong 574-4
16. Fion Zhang/ Charlie Chong 574-4
17. Fion Zhang/ Charlie Chong 4.1.1.2 Pipe wall thicknesses are
designated as pipe schedules in NPSs up to 36 in. (914 mm). The
traditional thickness designations- standard weight, extra strong,
and double extra strongdiffer from schedules and are used for NPSs
up to 48 in. (1219 mm). NPS1/8 ~ NPS36 pipe schedules . NPS1/8 ~
NPS48 / / 574-4
18. Fion Zhang/ Charlie Chong 574-4 NPS14 OD=NPS NPS12
ODNPS
29. Fion Zhang/ Charlie Chong 574-4 ERW / Ej = 0.85
30. Fion Zhang/ Charlie Chong 574-4 Ej = 1
31. Fion Zhang/ Charlie Chong 574-4
32. Fion Zhang/ Charlie Chong SSAW Welded Pipe 574-4 Ej =
0.80~1.0 () Ej = 0.85~1.0 ()
33. Fion Zhang/ Charlie Chong 574-4
34. Fion Zhang/ Charlie Chong SAW Welded Pipe () 574-4 Ej = 0.8
~ 1.0 () / 0.85 ~1.0 ()
35. Fion Zhang/ Charlie Chong // 574-4
36. Fion Zhang/ Charlie Chong NPS 13 574-4
37. Fion Zhang/ Charlie Chong 4.1.1.3 Allowable tolerances in
pipe diameter differ from one piping material to another. Table 3
lists the acceptable tolerances for diameter and thickness of most
ASTM ferritic pipe standards 574-4
38. Fion Zhang/ Charlie Chong 574-4 4.1.1.3 Allowable
tolerances in pipe diameter differ from one piping material to
another. Table 3 lists the acceptable tolerances for diameter and
thickness of most ASTM ferritic pipe standards. The actual
thickness of seamless piping can vary from its nominal thickness by
a manufacturing tolerance of as much as 12.5 %. The under tolerance
for welded piping is 0.01 in. (0.25 mm). Cast piping has a
thickness tolerance of +1/16 in. (1.6 mm) and 0 in. (0 mm), as
specified in ASTM A530 12.5 % 0.01 (0.25mm) ASTM A530: 1 /16(1.6)
-0(0)
39. Fion Zhang/ Charlie Chong 4.1.1.4 Cast iron piping is
generally used for nonhazardous service, such as water; it is
generally not recommended for pressurized hydrocarbon service. The
standards and sizes for cast iron piping differ from those for
welded and seamless piping. , . 574-4
44. 4.1.2.8 Standardized FRP piping systems commonly called
commodity piping are manufactured for a variety of services and are
sold as products with a predetermined design, resin, corrosion
barrier and structure FRP . Fion Zhang/ Charlie Chong
46. Clad pipe has a metallic liner that is an integral part of
the plate material (1) rolled or explosion bonded before
fabrication of the pipe Fion Zhang/ Charlie Chong
47. They may instead be separate strips of metal fastened to
the pipe by welding referred to (2) strip lining Fion Zhang/
Charlie Chong
48. Corrosion-resistant metal can also be applied to the pipe
surfaces by various (3) weld overlay processes. Fion Zhang/ Charlie
Chong
49. Some common nonmetallic lining materials for piping are
concrete, castable refractory, plastic, and thin-film coatings , ,
Fion Zhang/ Charlie Chong
50. Fion Zhang/ Charlie Chong
51. Fion Zhang/ Charlie Chong 574-4 4.2 Tubing
52. . ODNPS Fion Zhang/ Charlie Chong
53. 4.3 Valves Fion Zhang/ Charlie Chong
54. Fion Zhang/ Charlie Chong
55. 4.3 Valves 4.3.1 General The basic types of valves are
gate, globe, plug, ball, diaphragm, butterfly, check, and slide
valves. : , , ,., , , . ,: ASME B16.34 or API 599, API 600, API
602, API 603, API 608, or API 609, as applicable. Fion Zhang/
Charlie Chong
56. 4.3.2 Gate Valves (), . 2 full-ported valve. reducing port
valve , Fion Zhang/ Charlie Chong
57. Gate Valves ,. Full-ported valve. Reducing port valve ,
Fion Zhang/ Charlie Chong
58. Fion Zhang/ Charlie Chong Reducing Port Valve 574-4
Reducing port valve ,
94. Fion Zhang/ Charlie Chong 574-4 Welding Neck Flange
95. Fion Zhang/ Charlie Chong Lap-Joint Flange 574-4
96. Fion Zhang/ Charlie Chong Socket Welded Flange 574-4
97. Fion Zhang/ Charlie Chong Slip-on Flange 574-4
98. Fion Zhang/ Charlie Chong Blind Flange 574-4
99. Fion Zhang/ Charlie Chong Thread Flange 574-4
100. Fion Zhang/ Charlie Chong 4.6 Expansion Joints 574-4
101. Fion Zhang/ Charlie Chong 574-4 Expansion joints are
devices used to absorb dimensional changes in piping systems, such
as those caused by thermal expansion, to prevent excessive
stresses/strains being transmitted to other piping components, and
connections to pressure vessels and rotating equipment. While there
are several designs, those commonly found in a plant are metallic
bellows and fabric joint designs. Metallic bellows can be single
wall or multilayered, containing convolutions to provide
flexibility. Often, these joints will have other design features,
such as guides, to limit the motion of the joint or type of loading
applied to the joint. Metallic bellows are often found in
high-temperature services and are designed for the pressure and
temperature of the piping system. Fabric joints are often used in
flue gas services at low pressure and where temperatures do not
exceed the rating of the fabric material. (1) (2) . . .
102. Fion Zhang/ Charlie Chong 574-4
103. Fion Zhang/ Charlie Chong 574-4
104. Fion Zhang/ Charlie Chong 574-4
105. Fion Zhang/ Charlie Chong 574-4
106. Fion Zhang/ Charlie Chong 574-4
107. Fion Zhang/ Charlie Chong 574-4
108. Fion Zhang/ Charlie Chong 574-4
109. Fion Zhang/ Charlie Chong 5 Pipe-joining Methods 574-4 5
Pipe-joining Methods 5.1 General 5.2 Threaded Joints 5.3 Welded
Joints 5.4 Flanged Joints 5.5 Cast Iron Pipe Joints 5.6 Tubing
Joints 5.7 Special Joints 5.8 Nonmetallic Piping Joints.
110. Fion Zhang/ Charlie Chong 5.1 General 574-4
111. Fion Zhang/ Charlie Chong 5.1 General 5.2 Threaded Joints
NPS2 24(610)(ASME B1.20.1) 574-4
112. Fion Zhang/ Charlie Chong Threaded Joint Fittings
574-4
113. Fion Zhang/ Charlie Chong 574-4 5.3 Welded Joints
119. Fion Zhang/ Charlie Chong 5.5 Cast Iron Pipe Joints
574-4
120. Fion Zhang/ Charlie Chong 5.5 Cast Iron Pipe Joints :
flanged, packed, sleeve, hub-and-spigot-end or hub-and-plain-end,
or bell-and spigot-end or bell-and-plain-end type. Push-on joints
with rubber or synthetic ring gaskets are available. Clamped joints
are also used. Threaded joints are seldom used for cast iron.
574-4
121. Fion Zhang/ Charlie Chong 574-4
122. Fion Zhang/ Charlie Chong bell-and spigot-end 574-4
127. Fion Zhang/ Charlie Chong 5.7 Special Joints : : ,
574-4
128. Fion Zhang/ Charlie Chong 5.8 Nonmetallic Piping Joints
574-5
129. Fion Zhang/ Charlie Chong 5.8 Nonmetallic Piping Joints
5.8.1 General API570 / 574 : FRB/GRP Some common joint designs in
FRP pipe systems include a bell-and-spigot, butt-and-wrap,
taper-taper and flange-flange. : , bell-and-spigot , butt-and-wrap
, taper-taper . flange-flange 574-5
130. Fion Zhang/ Charlie Chong 574-5
131. Fion Zhang/ Charlie Chong 5.8.2 Bell and
Spigot/Taper-taper 574-5
132. Fion Zhang/ Charlie Chong 574-5 5.8.2 Bell and Spigot
/Taper-taper
133. Fion Zhang/ Charlie Chong 574-5 Bell and Spigot
134. Fion Zhang/ Charlie Chong 5.8.3 Butt and Wrap 574-5
135. Fion Zhang/ Charlie Chong Butt and Wrap 574-5
136. Fion Zhang/ Charlie Chong 5.8.4 Flange-flange 574-5
137. Fion Zhang/ Charlie Chong 6 Reasons for Inspection 574-6 6
Reasons for Inspection 6.1 General 6.2 Safety 6.3 Reliability and
Efficient Operation 6.4 Regulatory Requirements
138. Fion Zhang/ Charlie Chong 6.1 General 574-6
139. Fion Zhang/ Charlie Chong 6.1 General The primary purposes
of inspection are to identify active deterioration mechanisms and
to specify repair, replacement, or future inspections for affected
piping. These actions should result in increased operating safety,
reduced maintenance costs, and more reliable and efficient
operations. API 570 provides the basic requirements for such an
inspection program. () : (1), (2) (3) 574-6
140. Fion Zhang/ Charlie Chong 6.2 Safety 574-6
141. Fion Zhang/ Charlie Chong 6.2 Safety Adequate inspection
is a prerequisite for maintaining this type of piping in a safe,
operable condition. In addition, federal regulations such as OSHA
29 CFR 1910.119 has mandated that equipment, including piping,
which carries significant quantities of hazardous chemicals be
inspected according to accepted codes and standards which includes
API 570. OSHA 29 CFR 1910.119 , (API 570). 574-6
142. Fion Zhang/ Charlie Chong 574-6
143. Fion Zhang/ Charlie Chong 6.3 Reliability and Efficient
Operation 574-6
144. Fion Zhang/ Charlie Chong 6.3 Reliability and Efficient
Operation Thorough inspection and analysis and the use of detailed
historical records of piping systems are essential to the
attainment of acceptable reliability, efficient operation, and
optimum on-stream service. Piping replacement schedules can be
developed to coincide with planned maintenance turnaround schedules
through methodical forecasting of piping service life. (1) , (2)
574-6 , , ,.
145. Fion Zhang/ Charlie Chong 6.4 Regulatory Requirements
574-6
146. Fion Zhang/ Charlie Chong 6.4 Regulatory Requirements API
570 was developed to provide an industry standard for the
inspection of in-service process piping. It has been adopted by a
number of regulatory and jurisdictional authorities. In addition,
in some areas other requirements have been specified for the
inspection of piping. Each plant should be familiar with the local
requirements for process piping inspection. API570. 574-6
147. Fion Zhang/ Charlie Chong : Reasons for Inspection (//) +
574-6
148. Fion Zhang/ Charlie Chong 7 Inspection Plans 574-7 7
Inspection Plans 7.1 General 7.2 Developing an Inspection Plan 7.3
Monitoring Process Piping 7.4 Inspection for Specific Damage
Mechanisms 7.5 Integrity Operating Envelopes
149. Fion Zhang/ Charlie Chong 7.1 General 574-7
150. Fion Zhang/ Charlie Chong 7.1 General API570 574-7 An
inspection plan should contain the inspection tasks, scope of
inspection, and schedule required to monitor damage mechanisms and
assure the mechanical integrity of the piping components in the
system. (1) (2) (3) -
151. Fion Zhang/ Charlie Chong : a) (,, CUI) b) c) ; d) ; e) f)
. 574-7
153. Fion Zhang/ Charlie Chong 7.2 Developing an Inspection
Plan 574-7
154. Fion Zhang/ Charlie Chong 7.2 Developing an Inspection
Plan (1) , (2) (3) (4) : Operating temperature ranges, operating
pressure ranges, process fluid corrosive contaminant levels, piping
material of construction, piping system configuration, process
stream mixing and inspection/maintenance history./ 574-7 .
155. Fion Zhang/ Charlie Chong . , API NACE . , 574-7
156. Fion Zhang/ Charlie Chong (1): ;CML (CUI); 574-7
157. Fion Zhang/ Charlie Chong (2): (Dead Legs) (PMI);
574-7
160. Fion Zhang/ Charlie Chong Inspection plans based upon an
assessment of the likelihood of failure and the consequence of
failure of a piping system or circuit is RBI. RBI may be used to
determine inspection intervals and the type and extent of future
inspection/examinations. API 580 details the systematic evaluation
of both the likelihood of failure and consequence of failure for
establishing RBI plans. API 581 details an RBI methodology that has
all of the key elements defined in API 580. API 580/581 RBI -
(1)(2) RBI (1) (2) (3) 574-7
161. Fion Zhang/ Charlie Chong 7.2.1.2 . API571 . 574-7
162. Fion Zhang/ Charlie Chong 7.2.1.3 (1) (), (2) , (3) , (4)
(5) 7.2.1.4 API 580. 574-7
164. Fion Zhang/ Charlie Chong 7.2.2 Interval-based Inspection
Plans 574-7
165. Fion Zhang/ Charlie Chong 574-7 Inspection plans which are
based upon the specific inspection intervals for the various types
of piping inspection and of specific types of damage are considered
interval based. The types of inspection where maximum intervals are
defined in API 570 include: external visual, CUI, thickness
measurement, injection point, S/A interface, SBP, auxiliary piping
and threaded connections. The interval for inspections is based
upon a number of factors, including the corrosion rate and
remaining life calculations, piping service classification,
applicable jurisdictional requirements and the judgment of the
inspector, the piping engineer, or a corrosion specialist. The
governing factor in the inspection plan for many piping circuits is
the piping service classification. (API570 )
166. Fion Zhang/ Charlie Chong 574-7 API570
167. Fion Zhang/ Charlie Chong API570- CUI Inspection -API570
574-7
168. Fion Zhang/ Charlie Chong 7.2.3 Classifying Piping Service
API 570, . 1 ~ 3 Factors to consider when classifying piping are:
Toxicity, Volatility Combustibility location of the piping w.r.t to
personnel / equipment experience and history 574-7
169. Fion Zhang/ Charlie Chong 574-7
170. Fion Zhang/ Charlie Chong 574-7 Class?
171. Fion Zhang/ Charlie Chong 574-7 Class?
172. Fion Zhang/ Charlie Chong 574-7 Class?
173. Fion Zhang/ Charlie Chong 574-7 API 570- Classification of
piping for inspection
174. Fion Zhang/ Charlie Chong 574-7 API 570- 6.3.4.2 Class 1
Services with the highest potential of resulting in an immediate
emergency if a leak were to occur are in Class 1. Such an emergency
may be safety or environmental in nature. Examples of Class 1
piping include, but are not necessarily limited to those containing
the following. Flammable services that can auto-refrigerate and
lead to brittle fracture. Pressurized services that can rapidly
vaporize during release, creating vapors that can collect and form
an explosive mixture, such as C2, C3, and C4 streams. Fluids that
can rapidly vaporize are those with atmospheric boiling
temperatures below 50 F (10 C) or where the atmospheric boiling
point is below the operating temperature (typically a concern with
high-temperature services). Hydrogen sulfide (greater than 3 %
weight) in a gaseous stream. Anhydrous hydrogen chloride.
Hydrofluoric acid. Piping over or adjacent to water and piping over
public throughways (refer to Department of Transportation and U.S.
Coast Guard regulations for inspection of over water piping).
Flammable services operating above their auto-ignition
temperature.
175. Fion Zhang/ Charlie Chong 574-7 API 570- 6.3.4.3 Class 2
Services not included in other classes are in Class 2. This
classification includes the majority of unit process piping and
selected off-site piping. Typical examples of these services
include but are not necessarily limited to those containing the
following: on-site hydrocarbons that will slowly vaporize during
release such as those operating below the flash point, hydrogen,
fuel gas, and natural gas, on-site strong acids and caustics.
176. Fion Zhang/ Charlie Chong 574-7 API 570- 6.3.4.4 Class 3
Services that are flammable but do not significantly vaporize when
they leak and are not located in high-activity areas are in Class
3. Services that are potentially harmful to human tissue but are
located in remote areas may be included in this class. Examples of
Class 3 service include but are not necessarily limited to those
containing the following: on-site hydrocarbons that will not
significantly vaporize during release such as those operating below
the flash point; distillate and product lines to and from storage
and loading; tank farm piping; off-site acids and caustics.
177. Fion Zhang/ Charlie Chong 574-7 API 570- 6.3.4.5 Class 4
Services that are essentially nonflammable and nontoxic are in
Class 4, as are most utility services. Inspection of Class 4 piping
is optional and usually based on reliability needs and business
impacts as opposed to safety or environmental impact. Examples of
Class 4 service include, but are not necessarily limited to those
containing the following: steam and steam condensate; air;
nitrogen; water, including boiler feed water, stripped sour water;
lube oil, seal oil; ASME B31.3, Category D services; plumbing and
sewers.
178. Fion Zhang/ Charlie Chong Some NDT methods used
(information) 574-7
179. Fion Zhang/ Charlie Chong Profile Radiography 574-7
180. Fion Zhang/ Charlie Chong 574-7 Profile Radiography
181. Fion Zhang/ Charlie Chong 574-7 , LT
182. Fion Zhang/ Charlie Chong 574-7 UT
183. Fion Zhang/ Charlie Chong 574-7 UT
184. Fion Zhang/ Charlie Chong 574-7 UT A-Scan
185. Fion Zhang/ Charlie Chong 574-7 UT B-Scan
186. Fion Zhang/ Charlie Chong 574-7 UT B-Scan B-Scan of
Notched Steel Sheet
187. Fion Zhang/ Charlie Chong 574-7 UT C-Scan
188. Fion Zhang/ Charlie Chong 574-7 TOFD
189. Fion Zhang/ Charlie Chong 574-7 VI
190. Fion Zhang/ Charlie Chong 574-7
http://www.sonotronndt.com/vidGallery.htm TOFD
191. Fion Zhang/ Charlie Chong ACFM 574-7
192. Fion Zhang/ Charlie Chong ACFM 574-7
193. Fion Zhang/ Charlie Chong 574-7 Thermography
194. Fion Zhang/ Charlie Chong Thermography 574-7
195. Fion Zhang/ Charlie Chong Thickness Gauging 574-7
196. Fion Zhang/ Charlie Chong Smart Pigging 574-7
197. Fion Zhang/ Charlie Chong 574-7 Smart Pigging
198. Fion Zhang/ Charlie Chong Thickness Gauging 574-7
199. Fion Zhang/ Charlie Chong 574-7 Thickness Gauging
200. Fion Zhang/ Charlie Chong 7.3 Monitoring Process Piping
574-7
201. Fion Zhang/ Charlie Chong 7.3 Monitoring Process Piping
7.3.1 General , ; (1) (2) (3) (4) A key to the effective monitoring
of piping corrosion is identifying and establishing CMLs. CMLs are
designated areas in the piping system where measurements are
periodically taken. Ultrasonic (UT) thickness measurements are
obtained within examination points on the pipe. Thickness
measurements may be averaged within the examination point. By
taking repeated measurements and recording data from the same
points over extended periods, damage rates can more accurately be
calculated or assessed. 574-7
202. Fion Zhang/ Charlie Chong 574-7 7.3.2 Piping Circuits
7.3.2.1 1. piping metallurgy; 2. process fluid and its phase (e.g.
gas, liquid, two phase, solid); . 3. flow velocity; 4. temperature;
5. pressure; 6. changes in temperature, velocity, pressure,
direction, phase, metallurgy, or pipe cross section; ,,,,,, 7.
injection of water or chemicals; 8. process fluid contaminants; 9.
mixing of two or more streams; 10. piping external conditions,
including coating/painting, insulation, and soil conditions, as
applicable; 11.stagnant flow areas (e.g. dead-legs).
204. Fion Zhang/ Charlie Chong 7.3.3 Identifying Locations
Susceptible to Accelerated Corrosion : / (,,,) CML. CML 574-7
205. Fion Zhang/ Charlie Chong 7.3.4 Accessibility of CMLs . ;
, , , . 574-7
206. Fion Zhang/ Charlie Chong 574-7 Confined space entry - .
()
207. Fion Zhang/ Charlie Chong 7.4 Inspection for Specific
Damage Mechanisms 574-7
208. Fion Zhang/ Charlie Chong 7.4 Inspection for Specific
Damage Mechanisms : injection points, process mix points,
dead-legs, CUI, S/A interfaces, service specific and localized
corrosion, erosion and erosion-corrosion, environmental cracking,
corrosion beneath linings and deposits, fatigue cracking, creep
cracking, brittle fracture, freeze damage, contact point corrosion,
dew-point corrosion. 574-7
210. Fion Zhang/ Charlie Chong 574-7 : More extensive
inspection should be applied to the injection point circuit in an
area beginning 12 in. (300 mm) upstream of the injection nozzle and
continuing for at least 10 pipe diameters downstream of the
injection point
211. Fion Zhang/ Charlie Chong 7.4.2 Process Mix Points ; , ,
NACE Publication 34101 . , , 574-7
212. Fion Zhang/ Charlie Chong 7.4.3 Dead-legs . , In hot
piping systems, the high point area can corrode due to convective
currents set up in the dead-leg. Additionally, water can collect in
dead-legs that can freeze in colder environments resulting in pipe
rupture. , , . ,,. 574-7
213. Fion Zhang/ Charlie Chong 7.4.4 CUI / 574-7
214. Fion Zhang/ Charlie Chong 7.4.4.1 Insulated Piping Systems
Susceptible to CUI : 1. those exposed to mist over-spray from
cooling water towers; 2. those exposed to steam vents; 3. those
exposed to deluge systems; 4. those subject to process spills or
ingress of moisture or acid vapors; 5. carbon steel piping systems,
including ones insulated for personnel protection, operating
between 10o F (12o C) and 350o F (175o C); CUI is particularly
aggressive where operating temperatures cause frequent or
continuous condensation and re-evaporation of atmospheric moisture;
574-7
215. Fion Zhang/ Charlie Chong 6. carbon steel piping systems
which normally operate in service above 350o F (175o C), but are in
intermittent service; (- ) 7. dead-legs and attachments that
protrude from insulated piping and operate at a different
temperature than the operating temperature of the active line; 8.
austenitic stainless steel piping systems operating between 120o F
(60o C) and 400o F (205o C) (susceptible to chloride SCC); ,-
574-7
216. Fion Zhang/ Charlie Chong 9. vibrating piping systems that
have a tendency to inflict damage to insulation jacketing providing
a path for water ingress; ( ) 10. steam traced piping systems that
can experience tracing leaks, especially at tubing fittings beneath
the insulation; - 11.piping systems with deteriorated insulation,
coatings, and/or wrappings; bulges or staining of the insulation or
jacketing system or missing bands (bulges can indicate corrosion
product buildup); ,, 574-7
217. Fion Zhang/ Charlie Chong 574-7 7.4.4.2 Typical Locations
on Piping Circuits Susceptible to CUI CUI 1. , ,,, 2. (/). 3. . 4.
. 5. , , . 6. CML/TML .
218. Fion Zhang/ Charlie Chong 7.4.5 Soil-to-air (S/A)
Interface / If the buried piping has satisfactory cathodic
protection as determined by monitoring in accordance with API 570,
excavation is required only if there is evidence of coating or
wrapping damage. If the buried piping is uncoated at grade,
consideration should be given to excavating 6 in. (150 mm) to 12
in. (300 mm) deep to assess the potential for hidden damage.
Alternately, specialized UT techniques such as guided wave can be
used to screen areas for more detailed evaluation. API 570, . , 612
, API570 9.3.1 , 574-7
219. Fion Zhang/ Charlie Chong , API570 API570, 9.3.6 External
and Internal Inspection Intervals 574-7
220. Fion Zhang/ Charlie Chong 25) Soil-to-air (S/A) interfaces
for buried piping are a location where localised corrosion may take
place. If the buried part is excavated for inspection, how deep
should the excavation be to determine if there is hidden damage?
(API574-7.4.5) a) 12 to 18 inches b) 6 to 12 inches c) 12 to 24
inches d) 6 to 18 inches 574-7 26) At concrete-to-air and
asphalt-to-air interfaces of buried piping without cathodic
protection, the inspector look for evidence that the caulking or
seal at the interface has deteriorated and allowed moisture
ingress. If such a condition exists on piping systems over ______
years old, it may be necessary to inspect for corrosion beneath the
surface before resealing the joint. (API574-7.4.5) a) 8 b) 5 c) 15
d) 10
221. Fion Zhang/ Charlie Chong 7.4.6 Service-specific and
Localized Corrosion 7.4.6.1 CML 574-7
222. Fion Zhang/ Charlie Chong 7.4.6.2 , a. downstream of
injection points and upstream of product separators (e.g.
hydroprocessor reactor effluent lines); b. dew-point corrosion in
condensing streams, (e.g. overhead fractionation); - c.
unanticipated acid or caustic carryover from processes into
non-alloyed piping systems or in the case of caustic, into
non-post-weld heat treated (PWHTed) steel piping systems;
574-7
223. Fion Zhang/ Charlie Chong d. where condensation or boiling
of acids (organic and inorganic) or water is likely to occur; e.
where naphthenic or other organic acids can be present in the
process stream. f. where high-temperature hydrogen attack can occur
(see API 941); 574-7
224. Fion Zhang/ Charlie Chong g. ammonium salt condensation
locations in hydro-processing streams (see API 932-B); h.
mixed-phase flow and turbulent areas in acidic systems, also
hydrogen grooving areas; i. where high-sulfur streams at
moderate-to-high temperatures exist; j. mixed grades of carbon
steel piping in hot corrosive oil service [450 F (232 C)] or higher
temperature and sulfur content in the oil greater than 0.5 % by
weight); / 0.5% wt 574-7 NOTE Non-silicon-killed steel pipe (e.g.
ASTM A53 and API 5L) can corrode at higher rates than
silicon-killed steel pipe (e.g. ASTM A106) in high-temperature
sulfidation environments. (e.g. ASTM A53 and API 5L) (e.g. ASTM
A106)
http://richmond.chevron.com/Files/richmond/pdf/IndustryAlertvFinal2.pdf
225. Fion Zhang/ Charlie Chong k. under deposit corrosion in
slurries, crystallizing solutions, or coke- producing fluids;/ l.
chloride carryover in catalytic reformer units, particularly where
it mixes with other wet streams; m. welded areas subject to
preferential attack; n. hot spot corrosion on piping with external
heat tracing; note 1 o. steam systems subject to wire cutting,
graphitization, or where condensation occurs. -/ 574-7 NOTE 1: In
services which become much more corrosive to the piping with
increased temperature (e.g. sour water, caustic in carbon steel),
corrosion or SCC can develop at hot spots that develop under low
flow conditions. , , .
226. Fion Zhang/ Charlie Chong 27) An example of
service-specific and localised corrosion is- API574, 7.4.6) a)
Corrosion under insulation in areas exposed to steam vents b)
Unanticipated acid or caustic carryover from processes into
non-alloyed piping c) Corrosion in deadlegs d) Corrosion of
underground piping at soil-to-air interface where it ingresses or
egresses. 574-7
228. Fion Zhang/ Charlie Chong 7.4.7 Erosion and
Erosion-corrosion Erosion can be defined as the removal of surface
material by the action of numerous individual impacts of solid or
liquid particles, or cavitation. It can be characterized by
grooves, rounded holes, waves, and valleys in a directional
pattern. Erosion is usually in areas of turbulent flow such as at
changes of direction in a piping system or down stream of control
valves where vaporization can take place. . : (1) / (2) . , .
574-7
229. Fion Zhang/ Charlie Chong This type of corrosion occurs at
high-velocity and high-turbulence areas. Examples of places to
inspect include: 1. downstream of control valves, especially where
flashing or cavitation is occurring; 2. downstream of orifices; 3.
downstream of pump discharges; 4. at any point of flow direction
change, such as the outside radii of elbows; 5. downstream of
piping configurations (welds, thermowells, flanges, etc.) that
produce turbulence particularly in velocity sensitive systems, such
as ammonium hydrosulfide and sulfuric acid systems. (, ,) , . 574-7
, , UT ()RT
230. Fion Zhang/ Charlie Chong 574-7
231. Fion Zhang/ Charlie Chong574-7 28) Erosion can be defined
as:(API574, 7.4.8) a) Galvanic corrosion of a material where
uniform losses occur b) Removal of surface material by action of
numerous impacts of solid or liquid particles c) Gradual loss of
material by a corrosive medium acting uniformly on the material
surface d) Pitting on the surface of a material to the extent that
a rough uniform loss occurs 29) A combination of corrosion and
erosion results in significantly greater metal loss that can be
expected from corrosion or erosion alone. This type of loss occurs
at: a) High-velocity and high-turbulence areas b) Areas where
condensation or exposure to wet hydrogen sulphide or carbonates
occur c) Surface-to-air interfaces f buried piping d) Areas where
gradual loss of material occurs because of a corrosive medium
232. Fion Zhang/ Charlie Chong 7.4.8 Environmental Cracking
7.4.8.1 SCC . Some piping systems can be susceptible to
environmental cracking due to: : upset process conditions CUI,
unanticipated condensation exposure to wet hydrogen sulfide or
carbonates. 574-7
233. Fion Zhang/ Charlie Chong Examples of this include the
following. 574-7 1. Chloride SCC of austenitic stainless steels
resulting from moisture and chlorides under insulation, under
deposits, under gaskets, or in crevices. 2. Polythionic acid SCC of
sensitized austenitic alloy steels resulting from exposure to
sulfide/moisture condensation/oxygen. 3. Caustic SCC (sometimes
known as caustic embrittlement). 4. Amine SCC in nonstress-relieved
piping systems. 5. Carbonate SCC in alkaline systems. 6. Wet
hydrogen sulfide stress cracking and hydrogen blistering in systems
containing sour water. 7. Hydrogen blistering and hydrogen induced
cracking (HIC) damage. This has not been as serious of a problem
for piping as it has been for pressure vessels. It is listed here
because it is considered to be environmental cracking and can occur
in piping although it has not been extensive. One exception where
this type of damage has been a problem is longitudinally-welded
pipe fabricated from plate materials.
235. Fion Zhang/ Charlie Chong 7.4.8.2 , When the inspector
suspects or is advised that specific circuits may be susceptible to
environmental cracking, he/she should schedule supplemental
inspections. : (PT, MT, WFMT), LRUT, UT, RT) . Such inspections can
take the form of surface NDE [liquid penetrant examination
technique (PT) or wet fluorescent magnetic particle examination
technique (WFMT)], UT, or eddy current examination technique (ET).
Where available, suspect spools may be removed from the piping
system and split open for internal surface examination. 574-7
236. Fion Zhang/ Charlie Chong 7.4.8.3 ,. If environmental
cracking is detected during internal inspection of pressure
vessels, and the piping is considered equally susceptible, the
inspector should designate appropriate piping spools, upstream and
downstream of the pressure vessel, for environmental cracking
inspection. When the potential for environmental cracking is
suspected in piping circuits, inspection of selected spools should
be scheduled before an upcoming turnaround. Such inspection should
provide information useful in forecasting turnaround maintenance. ,
, ,(). , , . 574-7
237. Fion Zhang/ Charlie Chong574-7 30) Environmental cracking
of austenite stainless steels is caused many times by:-
(API574-7.4.8) a) Exposing areas to high-velocity and
high-turbulence streams b) Excessive cyclic stresses that are often
very low c) Exposure to chlorides from salt water, wash-up water,
etc. d) Creep of the material by long time exposure to high
temperature and stress Q- When the potential for environmental
cracking is suspected in piping circuits, inspection of selected
spools should be scheduled; (2013/June) a) Within 6 months. b) 5
years c) 10 years d) Before an upcoming turnaround.
238. Fion Zhang/ Charlie Chong574-7 31) When the inspector
suspects or is advised that specific piping circuits may be
susceptible to environmental cracking, the inspector should:
(API574- 7.4.8) a) Call in a piping engineer for consultation. b)
Investigate the history of the piping circuit. c) Obtain advice
from a Metallurgical Engineer. d) Schedule supplemental
inspections. 32) If environmental cracking is detected during
internal inspection of pressure vessels, what should the inspector
do? (API574-7.4.8 / 2013 June) a) The inspector should designate
appropriate piping spools upstream and downstream of the vessel to
be inspected if piping is susceptible to environmental cracking. b)
The inspector should consult with a metallurgical engineer to
determine extent of the problems c) The inspector should review
history of adjacent piping to determine if it has ever been
affected. d) The inspector should consult with a piping engineer to
determine the extent of the problems.
239. Fion Zhang/ Charlie Chong 7.4.9 Corrosion Beneath Linings
and Deposits ,. 7.4.9.1 If external or internal coatings,
refractory linings, and corrosion-resistant linings are in good
condition and there is no reason to suspect a deteriorated
condition behind them, it is usually not necessary to remove them
for inspection of the piping system. , , , /. . 574-7
240. Fion Zhang/ Charlie Chong 7.4.9.2 () , .. , , . The
effectiveness of corrosion-resistant linings is greatly reduced due
to breaks or holes in the lining. The linings should be visually
inspected for separation, breaks, holes, and blisters. If any of
these conditions are noted, it may be necessary to remove portions
of the internal lining to investigate the effectiveness of the
lining and the condition of the metal piping beneath the lining.
Alternatively, ultrasonic inspection from the external surface can
be used to measure the base metal thickness. When the lining is
metallic and is designed to be fully bonded, external ultrasonic
examination can also be used to detect separation, holes and
blisters. 574-7
241. Fion Zhang/ Charlie Chong 7.4.9.3 Refractory linings used
to insulate the pipe wall can spall or crack in service, causing
hot spots that expose the metal to oxidation and creep cracking.
Periodic temperature monitoring via visual, infrared, temperature
indicating paints should be undertaken on these types of lines to
confirm the integrity of the lining. Corrosion beneath refractory
linings can result in separation and bulging of the refractory.
Microwave examination technique (MW) can examine the refractory for
volumetric flaws and for separation from the shell surface. If
bulging or separation of the refractory lining is detected,
portions of the refractory may be removed to permit inspection of
the piping beneath the refractory. Otherwise, thickness
measurements utilizing UT or profile RT may be obtained from the
external metal surface. , // ., , . MW/UT/RT . 574-7
242. Fion Zhang/ Charlie Chong 7.4.9.4 Where operating
deposits, such as coke are present on the internal pipe surface,
NDE techniques employed from the outside of the pipe such as
profile radiography , UT, and/or ET should be used to determine
whether such deposits have active corrosion beneath them. , (), UT,
ET, . 574-7
243. Fion Zhang/ Charlie Chong 574-7 32) If environmental
cracking is detected during internal inspection of pressure
vessels, what should the inspector do? (API574-7.4.9/2013 June) a)
The inspector should designate appropriate piping spools upstream
and downstream of the vessel to be inspected if piping is
susceptible to environmental cracking. b) The inspector should
consult with a metallurgical engineer to determine extent of the
problems c) The inspector should review history of adjacent piping
to determine if it has ever been affected. d) The inspector should
consult with a piping engineer to determine the extent of the
problems.
244. Fion Zhang/ Charlie Chong 574-7 33) If external or
internal coatings or refractory liners on a piping circuit are in
good condition, what should an inspector do? (API574-7.4.9/2013
June) a) After inspection, select a portion of the liner for
removal b) The entire liner should be removed for inspection c)
Selected portions of the liner should be removed for inspection d)
After inspection, if any separation, breaks, holes or blisters are
found, it may be necessary to remove portions of the lining to
determine the condition under it. Q- Refractory linings used to
insulate the pipe wall can spall or crack in service, causing hot
spots that expose the metal to oxidation and creep cracking. NDT
method undertaken on these types of lines to confirm the integrity
of the lining is; (2013 June) a) Infrared thermography b) High
temperature UT c) WFMT d) PT
245. Fion Zhang/ Charlie Chong 574-7 34) What course of action
should be followed it a coating of coke is found on the interior of
a large pipe of a reactor on a Fluid Catalytic Cracking Unit?
(API574-7.4.9/ 2013June) a) Determine whether such deposits have
active corrosion beneath them. If corrosion is present, thorough
inspection in selected areas may be required. b) The coke deposits
should be removed from the area for inspection. c) The coke
deposits may be ignored the deposits will probably protect the line
from corrosion. d) Consult with a Process Engineer and a
Metallurgist on the necessity of removing the coke deposits.
246. Fion Zhang/ Charlie Chong 574-7
247. Fion Zhang/ Charlie Chong 7.4.10 Fatigue Cracking 7.4.10.1
Fatigue cracking of piping systems can result from excessive cyclic
stresses that are often well below the static yield strength of the
material. , . (1) (2) () (3) . - 574-7 The onset of low-cycle
fatigue cracking is often directly related to the number of
heat-up/cool-down cycles experienced. For example, trunnions or
other attachments that extend beyond the pipe insulation can act as
a cooling fin that sets up a situation favorable to thermal fatigue
cracking on the hot pipe. Thermal fatigue can also occur at mix
points when process streams at different operating temperatures
combine. Excessive piping system vibration (e.g. machine or flow
induced) can also cause high-cycle fatigue damage.
248. Fion Zhang/ Charlie Chong 7.4.10.2 Fatigue cracking can
typically be first detected at points of high stress
intensification such as branch connections. Locations where metals
having different coefficients of thermal expansion are joined by
welding can be susceptible to thermal fatigue. Preferred NDE
methods of detecting fatigue cracking include PT, magnetic particle
examination technique (MT), and angle beam UT when inspecting from
the OD for ID cracking. Suggested locations for UT on elbows would
include the 3 and 9 oclock positions. Acoustic emission examination
technique (AE) also may be used to detect the presence of cracks
that are activated by test pressures or stresses generated during
the test. MT/PT/UT AE AE- : UT39 574-7
249. Fion Zhang/ Charlie Chong 7.4.10.3 It is important for the
owner/user and the inspector to understand that fatigue cracking is
likely to cause piping failure before detection with any NDE
methods. Of the fatigue cycles required to produce failure, the
vast majority are required to initiate cracking and relatively few
cycles are required to propagate the crack to failure. As such,
proper design and installation to prevent fatigue cracking are
important. , , , . , . 574-7
250. Fion Zhang/ Charlie Chong () 574-7
251. Fion Zhang/ Charlie Chong () 574-7
252. Fion Zhang/ Charlie Chong 574-7
253. Fion Zhang/ Charlie Chong 574-7 Beach marks - Macro
254. Fion Zhang/ Charlie Chong 574-7 Striation marks Striation
marks
255. Fion Zhang/ Charlie Chong 574-7
256. Fion Zhang/ Charlie Chong 574-7
257. Fion Zhang/ Charlie Chong Corrosion Fatigue 574-7
258. Fion Zhang/ Charlie Chong 574-7
http://www.me.metu.edu.tr/courses/me307/useful_info.htm
259. Fion Zhang/ Charlie Chong 574-7
http://www.fgg.uni-lj.si/kmk/esdep/master/wg12/l0200.htm
260. Fion Zhang/ Charlie Chong 574-7 35) Fatigue cracking of
piping systems may result from a) Embrittlement of the metal due to
it operating below its transition temperature b) Erosion or
corrosion / erosion that thin the piping where it cracks c)
Excessive cyclic stresses that are often well below the static
yield strength of the material d) Environmental cracking caused by
stress corrosion due to the presence of caustic, amine, or other
substance. 36) Where can fatigue cracking typically be first
detected? a) At points of low-stress intensification such as
reinforced nozzles b) At points of high-stress intensification such
as branch connections c) At points where cyclic stresses are very
low d) At points where there are only bending or compressive
stresses.
261. Fion Zhang/ Charlie Chong 574-7 37) What are the preferred
NDE methods for detecting fatigue cracking? (API574-7.4.10/ 2013
June) a) Eddy current testing ultrasonic A-scan testing, and / or
possibly hammer testing b) Liquid penetrant testing, magnetic
particle testing and / or possibly acoustic emission testing. c)
Visual testing, eddy current testing and / or possibly ultrasonic
testing d) Acoustic emission testing, hydro-testing, and / or
possibly ultrasonic testing.
262. Fion Zhang/ Charlie Chong 574-7 2013 June Paper Beach Mark
-the characteristic fracture surface marks on fatigue
fracture.
263. Fion Zhang/ Charlie Chong 7.4.11 Creep Cracking 574-7
264. Fion Zhang/ Charlie Chong 7.4.11 Creep Cracking 7.4.11.1
Creep is dependent on time, temperature, and stress. Creep cracking
can eventually occur at design conditions since some piping code
allowable stresses are in the creep range. Cracking is accelerated
by creep/ fatigue interaction when operating conditions in the
creep range are cyclic. Particular attention should be given to
areas of high stress concentration. If excessive temperatures are
encountered, mechanical property and microstructural changes in
metals can also take place, which can permanently weaken equipment.
An example of where creep cracking has been experienced in the
industry is in 1 1/4 Cr steels above 900o F (482o C). , . . , . 1
1/4 Cr steels >900 Deg F (482 Deg C). 574-7
265. Fion Zhang/ Charlie Chong 574-7
266. Fion Zhang/ Charlie Chong 574-7
267. Fion Zhang/ Charlie Chong 574-7
268. Fion Zhang/ Charlie Chong 574-7
269. Fion Zhang/ Charlie Chong 574-7 Damage mechanism in
weldment of 2.25Cr1Mo steel under creepfatigue loading
270. Fion Zhang/ Charlie Chong 574-7
271. Fion Zhang/ Charlie Chong 574-7
http://www.nationalboard.org/Index.aspx?pageID=181
272. Fion Zhang/ Charlie Chong 7.4.11.2 NDE methods of
detecting creep cracking include PT, MT, UT, RT, ET and alternating
current field measurement (ACFM), in-situ metallography and
dimensional verification (i.e. strapping pipe diameter) are other
common practices for detection. NDE volumetric examination methods,
including profile RT and UT, can be used for detection of creep
cracking. AE can be utilized to identify active creep cracking. The
examination can be conducted whilst piping is in or out of
operation. When the examination is conducted, the probability of
detecting creep cracks can be a function of crack orientation. Any
piping examined out of operation requires a pressure stimulus to
activate any damage present. PT,MT, UT, RT, ET( ACFM). () . RTUT .
AE. , . AE . 574-7
273. Fion Zhang/ Charlie Chong574-7 38) Creep is dependent on:
a) Time, temperature, and stress b) Material, product contained,
and stress c) Temperature, corrosive medium, and load d) Time,
product contained and load 39) An example of where creep cracking
has been experienced in the industry is in the problems experienced
with cracking of 1.25 % Chrome steels operating at temperatures
above ______F. a) 500 b) 900 c) 1000 d) 1200
274. Fion Zhang/ Charlie Chong 7.4.12 Brittle Fracture
574-7
275. Fion Zhang/ Charlie Chong 7.4.12 Brittle Fracture 7.4.12.1
Carbon, low-alloy, and other ferritic steels can be susceptible to
brittle failure at or below ambient temperatures. In some cases,
the refrigerating effect of vaporizing liquids such as ammonia or
C2 or C3 hydrocarbons can chill the piping and promote brittle
fracture in material that may not otherwise fail. Brittle fracture
usually is not a concern with relatively thin wall piping. Most
brittle fractures have occurred on the first application of a
particular stress level (that is, the first hydrotest or overload)
unless critical defects are introduced in service. The potential
for a brittle failure should be considered when pressure testing or
more carefully evaluated when pressure testing equipment
pneumatically or when adding any other additional loads. Special
attention should be given to low-alloy steels (especially 2 1/4
Cr-1 Mo material), because they can be prone to temper
embrittlement, and to ferritic stainless steels. , , . , C2C3 . : 2
1/4 Cr-1 Mo () . 574-7