nc05_04

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Tank InspectionTank Inspection

Tank InspectionTank InspectionShop Fabrication Inspection1 Material Receiving Inspection Report� Check visual (free of lamination & damage). � Check mill certificate (Heat No & Plate No).� Check dimensional (Length, Thickness, Width & Diameter).� Check thickness of plates

2 Marking� Check dimensional marking.� Check transfer heat no.

Shop Fabrication Inspection1 Material Receiving Inspection Report� Check visual (free of lamination & damage). � Check mill certificate (Heat No & Plate No).� Check dimensional (Length, Thickness, Width & Diameter).� Check thickness of plates

2 Marking� Check dimensional marking.� Check transfer heat no.


3 After Cutting� Check dimensions. (L x W x Diagonals)� Check traceability (Heat No & Plate No).� Check Stamp Marking.� Check edge preparations

4 Rolling� Check visual (free of damage).� Check edge preparation.� Check Rolling radius.

3 After Cutting� Check dimensions. (L x W x Diagonals)� Check traceability (Heat No & Plate No).� Check Stamp Marking.� Check edge preparations

4 Rolling� Check visual (free of damage).� Check edge preparation.� Check Rolling radius.

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5 Painting� Check material painting (batch no, self life, brand).� Check Ambient Condition (surface temperature & weather).� Check DFT� Perform Pull Out test

5 Painting� Check material painting (batch no, self life, brand).� Check Ambient Condition (surface temperature & weather).� Check DFT� Perform Pull Out test


6 Dimensional Inspectiona) Peaking and banding �Peaking measured using a horizontal

sweep board 36 inch (900 mm) long. Tolerance of peaking shall not exceed ½inch (12.7 mm).

�Banding measured using a straight edge vertical sweep board 36 inch (900 mm) long. Tolerance of peaking shall not exceed ½ inch (12.7 mm).


sweep board 36 inch (900 mm) long. Tolerance of peaking shall not exceed ½inch (12.7 mm).



b) Roundness �Check roundness at 0°, 45°, 90°, 135°, 180°,

225°, 270°, 325°�Radius measured at 1 foot above the bottom

corner weld shall not exceed the following tolerance:




±1¼” (32mm)≥250ft (76m)

±1” (25mm)>150 – 250ft (76m)

±¾” (20mm)>40 – 150ft (46m)

±½” (12mm)< 40 ft (12.2m)

ToleranceDiameter

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c Plumbness�Check at 0°, 45°, 90°, 135°, 180, 225°,

270°�The plumbness of the top of shell relative to

the bottom of the shell not exceed 1/200 of the total tank height.

�The out of plumbness in one shell plate (single course) shall not exceed 1/250 of the course height or as per ASTM A6.


270°�The plumbness of the top of shell relative to

the bottom of the shell not exceed 1/200 of the total tank height.


Tank InspectionTank Inspection7 VISUAL� Visual examinations shall be carried out during all stages of fabrication to

ensure that the completed fabrication meets COMPANY satisfaction and approval with particular attention being paid to th e following:

� A weld shall be acceptable by this kind of inspecti on if the conditions are fulfilled :

� The weld has no crater cracks or other surface crac ks.� The maximum acceptable undercutting is 1/64 inches of the base metal for

vertical joints, and 1/32 inches maximum for horizo ntal joints. For the welds that attach nozzles, manholes, clean-out opening, a nd permanent attachments, no undercutting exceeds 1/64 inches.

� The frequency of surface porosity in the weld does not exceed one cluster (one or more pores) in any 4 inches of length, and the diameter of each cluster does not exceed 3/32 inches.

� Welds that fail to meet the criteria given in parag raph above, shall be reworked prior to hydrostatic testing as follows :

� Defects shall be removed by mechanical means or thermal gouging processes.

� If the resulting thickness is less than minimum req uired as per hydrostatic test design conditions, re-welding is required.

� The repair weld shall be visually examined for defe cts prior to reexamined by radiography.

7 VISUAL� Visual examinations shall be carried out during all stages of fabrication to




vertical joints, and 1/32 inches maximum for horizo ntal joints. For the welds that attach nozzles, manholes, clean-out opening, a nd permanent attachments, no undercutting exceeds 1/64 inches.






Shell to bottom platesFlush type connections

Bottom platesAnnular plates

Roof plates and top angleShell plates

Not required for weldsRequired for butt welds

Radiographic Inspection


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Vertical Shell Plate joints

Requirement

Thinner shell plate is 1 spot radiograph in first 10 ft (3m) of weld of each type

<3/8 in (10 mm) thick and thickness welded by each welder or welding operator

1 additional radiography taken in each additional 100ft(30m) (without regards to the no. of welders or welding

operator) and any remaining major fraction of the vertical

weld of the same type and thickness

At least 25% of selected spot shall be at junctions of verticaland horizontal joints (minimum of 2 per tank)

1 random spot radiograph taken at each vertical joint inthe lowest course

Thinner shell plate is As above> 3/8 in (10 mm) thick but

=< 1 in (25mm) All junctions of vertical and horizontal joints (T junctions)

in plates in this thickness range shall be radiographed

In the lowest course, 2 spot radiographs shall be taken ineach vertical joint as close to the bottom as possible.

Thinner shell plate is All vertical joints shall be fully radiographed

> 1 in (25mm) All junctions of vertical and horizontal joints (T joints)

shall be radiographed

Location

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4

5

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Horizontal joints

Requirement

Based on thickness 1 spot radiography in the first 10 ft (3m) horizontal buttwelded of the same type and thickness without regards to the

number of welders or welding operators

1 spot radiograph for each additional 200 ft (60m) and

any remaining fraction of horizontal joint of same type andthickness.

Location

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Annular plate joints

Requirement

Bottom annular plates 1 spot radiograph on 10% of radial double welded butt joints

1 spot radiograph on 50% of radial single welded joints with

with back up bar preferably at the outer edge of the joint

where the shell plate and annular plate join.

Location



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Vacuum box testing/inspection of bottom plates

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Tank InspectionTank InspectionTank Calibration/StrappingTank Calibration/Strapping

Storage Tank Calibration Methods:

• API MPMS Ch. 2.2A (Std 2550) - Measurement and Calibration of Upright Cylindrical Tanks by the Manual Strapping Method

• API MPMS Ch. 2.2B - Calibration of Upright Cylindrical Tanks- OPTI, Using the Optical Reference Line Method

• API MPMS Ch. 2.2C - Calibration of Upright Cylindrical Tanks - OTM, Optical Triangulation method

• API MPMS Ch. 2.2D - Calibration of Upright Cylindrical Tanks -Using the Internal Electro-optical Distance Ranging Method

• ISO 7507






• ISO 7507

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Tank InspectionTank InspectionTank Inspection Schedule

Depending on local/product requirements

Tank out of service inspection : Every 15 years

�Tank cleaning - Steam, butterworth water wash, chemical wash, desludging etc.

�Tank bottom plate : MPI or DPI or Magnetic flux leakage (MFL) method (depending on the tank bottom construction and materials)

�Tank roof and shell plate : Thickness gauging

�Cathodic protection : To check on transformer rectifier

Tank Inspection Schedule

Depending on local/product requirements







Depending on local requirements

Out of service inspection

�Floating roof (External) Floatation/air tightness tests for pontoons, seals, floating roof drains

�Floating roof (Internal) Air tightness tests for pontoons, seals, tension wires etc.

�Valves - Hydrotest

�Pipes - Hydrotest

�Tanks - Hydrotest









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�Tank gauging : By calibration and dipping

�Tank Pressure vacuum vents : Weight tested

�Tank nozzles : DPI or MPI

�Tank spring hangers : Tightness/tension testing of buckles










Tank in service inspection : Every agreed periodic inspection

�Tank external bottom plate : MPI or DPI (depending on the tank bottom construction and materials)











Tank in service inspection�Inspection method for tank bottom plates :Acoustic emission method or Mechanical crawler with camera�High/low level alarms and shut down system etc.�Tank foundation level checks




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Tank InspectionShop Fabrication Inspection1 Material Receiving Inspection Report�Check visual (free of lamination & damage). �Check mill certificate (Heat No & Plate No).�Check dimensional (Length, Thickness, Width & Diameter). 2 Marking�Check dimensional marking.�Check transfer heat no.

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3 After Cutting�Check dimensional. �Check traceability (Heat No & Plate

No).�Check Stamp Marking.4 Rolling�Check visual (free of damage).�Check edge preparation.�Check Rolling radius.

Tank Inspection

5 Painting�Check material painting (batch no, self

life, brand).�Check Ambient Condition (surface &

whether).�Check DFT

Tank Inspection


sweep board 36 inch (900 mm) long. Tolerance of peaking shall not exceed ½ inch (12.7 mm).


Tank Inspection

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Tank Inspection

±1¼” (32mm)≥250ft (76m)

±1” (25mm)>150 – 250ft (76m)

±¾” (20mm)>40 – 150ft (46m)

±½” (12mm)< 40 ft (12.2m)

ToleranceDiameter


270°�The plumbness of the top of shell

relative to the bottom of the shell not exceed 1/200 of the total tank height.


Tank Inspection

7 VISUAL� Visual examinations shall be carried out during all stages of fabrication to




vertical joints, and 1/32 inches maximum for horizo ntal joints. For the welds that attach nozzles, manholes, clean-out open ing, and permanent attachments, no undercutting exceeds 1/64 inches.






Tank Inspection

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Tank Calibration/Strapping





















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