1. SCOPE
…………………………………………………………………….
1.1 General Application
1.2 Specific Application
2. REFERENCES
………………………………………………………….
3. DEFINITIONS
4. GENERAL
5. INSPECTION REQUIREMENTS AND PROCEDURES 6. INSPECTION OF BURIED PIPING
7. ATTACHMENTS
1. Scope
1.1 General Application
This standard is to be used in conjunction with API 570 in determining the procedures for inspection of
metallic piping systems that have been in-service.
1.2 Specific Application
Lines that require inspection as described in this standard shall be identified on the Mechanical Flow
Diagrams during the design of the processing unit. The Process Design Group shall set the limits based
on corrosion/erosion concerns for a process stream. Inspection intervals shall be based on the
requirements of this standard and API 570.
2. References
The user shall use the latest editions available for the listed standards.
API 510 – Pressure Vessel Inspection Code
API Publication 920 – Prevention of Brittle Fracture of Pressure Vessels
API RP 574 – Inspection of Piping System Components
API RP 651 – Cathodic Protection of Above ground Petroleum Storage Tanks
API RP 750 – Management of Process Hazards
API 598 – Valve Inspection and Testing
ASME B16.34 – Valves-Flanged, Threaded, and Welding End
ASME B31G – Manual for Determining the Remaining Strength of Corroded Pipelines a Supplement to
ASME B31 Code for Pressure Piping
ASNT SNT-TC-1A CP-189 – Standard for Qualification and Certification of Nondestructive Testing
Personnel
ASTM G57 – Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method
NACE RP 0169 – Control of External Corrosion on Underground or Submerged Metallic Piping Systems
NACE RP 0170 – Protection of Austenitic Stainless Steels from Polythionic Acid Stress Corrosion Cracking
During Shutdown of Refinery Equipment
NACE RP 0274 – High-Voltage Electrical Inspection of Pipeline Coatings Prior to Installation
NACE RP 0275 – Application of Organic Coatings to the External Surface of Steel Pipe for Underground
Service
NFPA 704 – Identification for the Fire Hazards of Materials
3. Definitions
Use applicable definitions listed in API 570 and this standard.
Process Design Group – The organization responsible for the process development of a unit including the
determination of metallurgical requirements. The organization could be an Engineering & Construction
Company, a Process Licensor, or owner/user.
4. General
The owner/user along with the process design group of a unit shall determine the inspection program and
inspection frequencies for the piping systems they are responsible for designing. The inspection program
and inspection frequencies shall be discussed during the Metallurgical Selection. Metallurgical Selection
diagrams are an extension of the Process Flow Diagrams. The process design group shall take into
consideration piping systems that are susceptible to the following specific types and areas of concern:
a. Injection points.
b. Deadlegs.
c. Corrosion under insulation (CUI).
d. Soil-to-air (S/A) interfaces.
e. Service specific and localized corrosion.
f. Erosion and corrosion/erosion.
g. Environmental cracking.
h. Corrosion beneath linings and deposits.
i.
Fatigue cracking.
j. Creep cracking.
k. Brittle fracture.
l. Freeze damage.
5. Inspection Requirements and Procedures
5.1. An authorized API certified inspector should carry out inspection of piping systems.
5.1.1 Certification requires taking and passing an examination administered by API or a third party
designated by the API, and meeting at a minimum the following education and experience requirements.
5.1.1.1 Education and experience requirements are found in Appendix A, section A.2 of API 570.
5.1.2 Validity of the authorized API piping inspector certificate is three years from date of issuance. The
certification agency is API.
5.2 Owner/User is responsible for developing, documenting, implementing, executing, and assessing
piping inspection systems and inspection procedures that will meet the requirements of API 570. The
process design group along with the owner/user shall create the necessary documents for inspecting
requirements. Those requirements start from the Metallurgical Flow Diagrams and are then transferred to
Mechanical Piping and Instrumentation Diagrams. Procedures for assessing and reporting of findings can
be found in API 570 paragraph 4.3.1.
5.3 Preparation for inspecting of in-service piping systems can be found in API 570 paragraph 5.2. The
most important issue when inspecting in-service piping is safety. Fluids may be flammable or toxic.
Precautions should be taken to remove such fluids before inspecting piping systems tagged for inspection.
5.4 Paragraph 5.3 of API 570 discusses establishing locations for thickness measurement locations, and
identifying locations where stress concentrations are of a concern for stress corrosion cracking. The
sub-paragraphs of 5.3 in API 570 discuss in detail those specific types of deterioration for piping systems
listed in Section 4 of this standard. Those issues, if determined to be monitored, shall be included in the
Mechanical Piping & Instrumentation diagrams.
5.5 When the locations for inspection are determined, the owner/user and the process design group shall
determine what type of inspection and surveillance needed to determine the physical state of the in-service
piping. Inspection and surveillance can be any of the following or a combination of the following:
a. Internal visual inspection.
b. Thickness measurement inspection.
c. External visual inspection.
d. Vibrating piping inspection.
e. Supplemental inspection.
API 570 paragraph 5.4 through 5.11and subsequent sub-paragraphs discuss what effective measure of
inspection needs to be established in the piping design. The general piping layout and arrangement shall
be established after the surveillance locations are identified on the Mechanical Piping & Instrumentation
diagrams.
5.6 The frequency and extent of inspection shall be based on the potential for explosion, fire, toxicity,
environmental impact, and other potential effects associated with a failure. After the assessment is made,
the results can be used to establish an inspection strategy. The strategy will better define what methods of
inspection are required, and the inspection frequency.
5.6.1 A classification of piping systems must be made to establish the criticality of the system. Once
established the process design group will be able to establish the frequency of inspection when
developing the Mechanical Piping & Instrumentation diagrams. For details of the classifications see API
570 paragraphs 6.2.1 through 6.2.3.
5.7 Inspection intervals are established in API 570 paragraph 6.3. Note these are recommended
inspection intervals and may be adjusted dependent on what corrosion/erosion rates exist after the first
and subsequently scheduled inspections. The process design group along with input from the owner/user
shall create an additional legend flow diagram that addresses the intervals as described in API 570.
Attachment 1 shows required data to establish appropriate inspection records.
5.8 Corrosion under insulation is the responsibility of the owner/user. The extent of visual external and
corrosion under insulation inspections is covered by API 570 paragraph 6.4. The owner/user can fashion a
table similar to attachment 1 for data records dealing with corrosion under insulation.
5.9 Once the thickness measurements are tabulated, the piping engineer shall determine the rate of
corrosion. API 570 paragraph 7.1.1 explains how to arrive with the remaining life of a piping circuit. The
remaining life shall set the requirements for subsequent inspections base on existing corrosion rates.
6. Inspection of Buried Piping
6.1 Buried process piping is a unique case. Significant external corrosion can be caused by soil
conditions. A piping engineer cannot easily visually inspect it; therefore, special methods must be
implemented. Underground installations of process lines require that each system be holiday inspected
prior to burial. Inspection of buried process piping systems must be established by the owner/user. The
following subsections give guidance to the owner/user for the type and method of inspection, and the
frequency and extent of inspection of piping systems.
6.1.1 Types and methods of inspection are covered by API 570 paragraphs 9.1.1 through 9.1.5. Those
include:
a. Above-grade visual surveillance
b. Close-interval potential survey
c. Pipe coating holiday survey
d. Soil resistivity
e. Cathodic protection monitoring.
6.1.2 Inspection methods for buried piping systems can be evaluated by the following methods:
a. Intelligent pigging. Note: if the owner/user decides on this type of inspection, 5 diameter bends
may need to be employed. Pigs may not be able to pass through 1-1/2 diameter bends. Check with
the manufacturer for design requirements. If 5 diameter bends are employed, then detailed design
must account for such requirements.
b. Video cameras
c. Excavation
6.1.3 Frequency and extent of inspection is covered by API 570 paragraphs 9.2.1 through 9.2.6.
Recommended intervals for inspection are listed in those paragraphs.
7. Attachments
