API 653 Section 6
- answer6.1 General
-The purpose of inspection is to assure continued tank integrity.
-Periodic in-service inspection of tanks shall be performed as defined in API 653
Section 6.
-Inspections, other than those defined in 6.3 shall be directed by an authorized
inspector.
6.2 Inspection Frequency Considerations
Factors to be considered to determine inspection intervals:
-The nature of the product stored
-The results of visual maintenance checks
- answer6.2 Inspection Frequency Considerations Continued:
Factors to be considered to determine inspection intervals:
-corrosion allowances and corrosion rates
-corrosion prevention systems
-conditions at previous inspections
-the methods and materials of construction and repair
-the location of tanks, such as those in isolated or high risk areas
-the potential risk of air or water pollution
-leak detection systems
-change in operating mode (e.g. frequency of fill cycling, frequent grounding of floating
roof support legs)
-jurisdiction requirements
-change in service (including changes in water bottoms)
-the existence of a double bottom or a release prevention barrier
- answer6.2.2
Interval between inspections (both internal and external) is most influenced by its
service history unless special reasons indicate that an earlier inspection is required.
6.2.3
Jurisdictional regulations (i.e., vapor loss values, seal condition, leakage, proper diking
and repair procedures) control the frequency and interval of the inspections.
Knowledge of such regulations is necessary to ensure compliance with inspection
requirements.
- answer6.3 Inspections from the Outside of the Tank
6.3.1.1 Routine In-service Inspections can be done by:
- By owner/operator personnel
- Authorized inspectors
- Anyone who has knowledge about the tank and its operation
, 6.3.1.2 Interval of routine in-service inspections
- shall be consistent with conditions at the particular site, but shall not exceed one
month.
6.3.1.3 Routine in-service inspection:
-Shall include visual inspection on tank's exterior surfaces (leaks; shell distortions; signs
of settlement; corrosion; and condition of the foundation, paint coatings, insulation
systems, and appurtenances) and:
-Should be documented for follow-up action by an authorized inspector.
- answer6.3.2.2
Insulated tanks need to have insulation removed only to the extent necessary to
determine the condition of the exterior wall of the tank or the roof.
6.3.2.3
Tank grounding components (i.e. shunts or mechanical connections of cables)
shall be visually checked.
Practices dealing with the prevention of hydrocarbon ignition are covered by API 2003.
- answer6.3.3 Ultrasonic Thickness (UT) Inspection
6.3.3.1 The extent of Ultrasonic Thickness Inspection measurements shall be
determined by the owner/operator.
6.3.3.2
When UT is used as inspection method, intervals not to exceed the following:
- When the corrosion rate is not known, the maximum interval of UT inspection interval
shall be five years
- When the corrosion rate is known, the maximum interval shall be the smaller of
RCA/2N years or 15 years
6.3.3.3
Internal inspection of the tank shell (when the tank is out of service) can be substituted
for a program of external ultrasonic thickness measurement if the internal inspection
interval is equal to or less than the interval required in 6.3.3.2 b
- answer6.3.4 Cathodic Protection Surveys
6.3.4.1
Where exterior tank bottom corrosion is controlled by a cathodic protection system:
- periodic surveys shall be in accordance with API 651.
- The owner/operator shall review the survey results.
6.3.4.2
The owner/operator shall assure competency of personnel performing surveys.
- answer6.4 Internal Inspection
- answer6.1 General
-The purpose of inspection is to assure continued tank integrity.
-Periodic in-service inspection of tanks shall be performed as defined in API 653
Section 6.
-Inspections, other than those defined in 6.3 shall be directed by an authorized
inspector.
6.2 Inspection Frequency Considerations
Factors to be considered to determine inspection intervals:
-The nature of the product stored
-The results of visual maintenance checks
- answer6.2 Inspection Frequency Considerations Continued:
Factors to be considered to determine inspection intervals:
-corrosion allowances and corrosion rates
-corrosion prevention systems
-conditions at previous inspections
-the methods and materials of construction and repair
-the location of tanks, such as those in isolated or high risk areas
-the potential risk of air or water pollution
-leak detection systems
-change in operating mode (e.g. frequency of fill cycling, frequent grounding of floating
roof support legs)
-jurisdiction requirements
-change in service (including changes in water bottoms)
-the existence of a double bottom or a release prevention barrier
- answer6.2.2
Interval between inspections (both internal and external) is most influenced by its
service history unless special reasons indicate that an earlier inspection is required.
6.2.3
Jurisdictional regulations (i.e., vapor loss values, seal condition, leakage, proper diking
and repair procedures) control the frequency and interval of the inspections.
Knowledge of such regulations is necessary to ensure compliance with inspection
requirements.
- answer6.3 Inspections from the Outside of the Tank
6.3.1.1 Routine In-service Inspections can be done by:
- By owner/operator personnel
- Authorized inspectors
- Anyone who has knowledge about the tank and its operation
, 6.3.1.2 Interval of routine in-service inspections
- shall be consistent with conditions at the particular site, but shall not exceed one
month.
6.3.1.3 Routine in-service inspection:
-Shall include visual inspection on tank's exterior surfaces (leaks; shell distortions; signs
of settlement; corrosion; and condition of the foundation, paint coatings, insulation
systems, and appurtenances) and:
-Should be documented for follow-up action by an authorized inspector.
- answer6.3.2.2
Insulated tanks need to have insulation removed only to the extent necessary to
determine the condition of the exterior wall of the tank or the roof.
6.3.2.3
Tank grounding components (i.e. shunts or mechanical connections of cables)
shall be visually checked.
Practices dealing with the prevention of hydrocarbon ignition are covered by API 2003.
- answer6.3.3 Ultrasonic Thickness (UT) Inspection
6.3.3.1 The extent of Ultrasonic Thickness Inspection measurements shall be
determined by the owner/operator.
6.3.3.2
When UT is used as inspection method, intervals not to exceed the following:
- When the corrosion rate is not known, the maximum interval of UT inspection interval
shall be five years
- When the corrosion rate is known, the maximum interval shall be the smaller of
RCA/2N years or 15 years
6.3.3.3
Internal inspection of the tank shell (when the tank is out of service) can be substituted
for a program of external ultrasonic thickness measurement if the internal inspection
interval is equal to or less than the interval required in 6.3.3.2 b
- answer6.3.4 Cathodic Protection Surveys
6.3.4.1
Where exterior tank bottom corrosion is controlled by a cathodic protection system:
- periodic surveys shall be in accordance with API 651.
- The owner/operator shall review the survey results.
6.3.4.2
The owner/operator shall assure competency of personnel performing surveys.
- answer6.4 Internal Inspection
