» 20 Feb 2012, 07:39
Storage Tank (API 650)
Shop Fabrication Inspection
1 Material Receiving Inspection Report
Check visual (free of lamination & damage).
Check certificate (keaslian, Heat No & Plate No).
Check dimensional (Length, Thickness, Width & Diameter).
2 Marking
Check dimensional marking.
Check transfer heat no.
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.
5 Painting
Check material painting (batch no, self life, brand).
Check Ambient Condition (surface & whether).
Check DFT.
Field Erection Inspection
6 Dimensional Inspection
1 Peaking banding
Peaking measured using a horizontal sweep board 36 inch (900 mm) long. Tolerance of peaking
shall not exceed ½ inch (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).
2 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:
Diameter Tolerance
< 40 ±½”
40 – 150 ±¾”
150 – 250 ±1”
≥250 ±1¼”
3 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.
7 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 the following:
A weld shall be acceptable by this kind of inspection if the conditions are fulfilled :
The weld has no crater cracks or other surface cracks.
The maximum acceptable undercutting is 1/64 inches of the base metal for vertical joints, and
1/32 inches maximum for horizontal joints. For the welds that attach nozzles, manholes, clean-
out opening, and 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 paragraph 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 required as per hydrostatic test design
conditions, re-welding is required.
The repair weld shall be visually examined for defects prior to reexamined by radiography.
8 NDT
1 Oil leak test
media solar, method spray, temperature ambient, holding period 4 hours.
2 Vacuum box test
Vacuum testing shall conduct as follows:
Vacuum testing is conveniently performed by means of a metal testing box, 6 inches wide x
30 inches long, with a glass window in the top. The open bottom is sealed against the tank
surface by a sponge-rubber gasket. Suitable connections, valves, and gauges should be provided.
Approximately 30 inches of the seam under test is brushed with a soap solution or linseed oil.
The vacuum box is placed over the coated section of the seam, and a vacuum is applied to the
box. Bubbles or foam produced by air sucked through the welded seam will indicate the presence
of porosity in the seam.
A vacuum can be drawn on the box by any convenient method, such as connection to a
gasoline or diesel-motor intake manifold or to an air ejector or special vacuum pump.
Vacuum box tested using a test pressure at least 3 psi gauge or as specified on Company
specification.
3 Radiography test
Radiographic examination method shall be in accordance with the ASME section V, Article
2.
Radiographic inspection is required for shell butt weld, annular-plate butt welds, and flush-
type connection with butt welds.
Inspection by radiographic method is not required for roof-plate or bottom-plate welds, for
welds joining roof plates to top angle, the top angle to the shell plates, shell plates to bottom
plates, or appurtenances to tanks.
Number and location of radiographic shall minimum as specified on API Standard 650,
Section 6. Vendor shall submit proposal of number and location of radiographic to
CONTRACTOR/COMPANY for review and approval.
The radiographers shall be certified by the manufacturer meeting the requirement as outlined
by ASNT Recommended Practice SNT-TC-1A and its supplement.
Vendor shall submit the radiography test result to CONTRACTOR/COMPANY for review
and approval. The penetrameter image as result of radiography shall clearly enough for visual
examination on a radiograph viewer. The acceptance criteria of radiographs result shall be
judged as specified on ASME Section VIII Div. 1, par. UW-51 (b).
Repairing defective welds shall be done by chipping or melting out the defects from one or
both side of joint, as required, and proceed with re-welding. All repaired welds are subject to be
re-tested as specified above.
4 Penetrant test
Liquid penetrant examination shall be performed in accordance to ASME Section V, Article
6.
Magnetic particle examiner shall meet the requirements on API Standard 650 par. 6.4.3.
The acceptance criteria and repair of defects shall be per ASME Section VIII, Division 1,
Appendix 8, Par. 8-3, 8-4, and 8-5.
5 Ultrasonic test
Ultrasonic examination method shall be in accordance with ASME Section V, article 5.
Ultrasonic examiner shall be qualified in accordance with as specified on API Standard 650
par. 6.3.3.
The acceptance criteria and repair of defects shall be per ASME Section VIII, Division 1,
Appendix 12, Par. 12-3 and 12-4.
gujral502
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Re: Usefull info on API 650 Storage Tanks
by arcpro » 20 Feb 2012, 09:39
A real quick reference.
Thanks.
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Re: Usefull info on API 650 Storage Tanks
by 1772 » 20 Feb 2012, 16:10
Thank you...
1772
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Re: Usefull info on API 650 Storage Tanks
by mechcolor » 20 Feb 2012, 20:28
Very comprehensive checklist.
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Re: Usefull info on API 650 Storage Tanks
by rizq » 27 Feb 2012, 06:15
how about hydrostatic testing?
-before testing:
*coating/lining perform at the after/before hydrostatic testing?
*when hydrostatic testing can be performed?
-during testing
*Settlement survey every how much percent of full water height?
*holding time during level survey minimum?
-after testing.
*settlement survey can be perform after 24 hrs holding time,and water release step by step every
25% or not?
thank's for sharing...
rizq
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Re: Usefull info on API 650 Storage Tanks
by gujral502 » 27 Feb 2012, 07:19
how about hydrostatic testing?
-before testing:
*coating/lining perform at the after/before hydrostatic testing?
HT is performed to varify the weld quality so general engineering practice is to HT the tank first
then proceed for internal coating/lining, we can coat/line the tank by sparing horizontal/vertical
welds to varify the quality during HT.
*when hydrostatic testing can be performed?
After entire tank & roof structure is completed.
-during testing
*Settlement survey every how much percent of full water height?
Empty, 25%, 50%, 75%, 100% & after 24 Hrs.
*holding time during level survey minimum?
On every %age when you observe water is settled or as general engineering practice we allow 01
to 02 Hrs.
-after testing.
*settlement survey can be perform after 24 hrs holding time,and water release step by step every
25% or not?
Yes settlement suvey is performed after 24 Hrs of holding time and water could be drained
continuously by maintaining the HT flow rate, assuring that all designated vents are in open
mode, during drain only flow rate is important.
Refer: API 650 Sec-05, Sec-08, Appendix-F (for hydro-neumatic tanks)
gujral502
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Re: Usefull info on API 650 Storage Tanks
by ben » 27 Feb 2012, 07:29
rizq wrote:how about hydrostatic testing?
-before testing:
*coating/lining perform at the after/before hydrostatic testing?
API 650 does not mention about performing the hydrostatic testing before or after the coating &
painting. In my opinion, coating & painting should be performed before hydrostatic test. The
surface would be dry enough to apply the paint easily. And for lining also, same approach should
be followed. Hydrostatic test must check the final condition of the tank. No works after
hydrostatic testing are recommended. You can consult Storage Tanks books on this to get more
points.
*when hydrostatic testing can be performed?
-during testing
*Settlement survey every how much percent of full water height?
*holding time during level survey minimum?
-after testing.
*settlement survey can be perform after 24 hrs holding time,and water release step by step every
25% or not?
As per API 650, Six sets of settlement readings are required:
a. Before start of the hydrostatic test
b. With tank filled to 1/4 test height (±600 mm [2 ft])
c. With tank filled to 1/2 test height (±600 mm [2 ft])
d. With tank filled to 3/4 test height (±600 mm [2 ft])
e. At least 24 hours after the tank has been filled to the maximum test height. This 24-hour
period may be increased to
duration specified on the data sheet if the Purchaser so requires for conditions such as:
i. The tank is the first one in the area.
ii. The tank has a larger capacity than any other existing tank in the area.
iii. The tank has a higher unit bearing load than any other existing tank in the area.
iv. There is a question regarding the rate or magnitude of settlement that will take place.
f. After tank has been emptied of test water
For more details, please refer to para 7.3.6.5
thank's for sharing...
ben
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