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[MW:10019] Tank Peaking/Banding Issue, API 650

By Materials & Welding
Dear All,

I am Abdul Wahab working in KSA as QA/QC Inspector, I have an issue
which is confusioning me. Below there is copy of Paragraph of API 650.
Plumbness, peaking, banding & flat spot discussed in this & tolerances
are provided but along with tolerance of API 650, also refering to
ASTM standards, those standards have tolerances aproximately a double
values as compared to API 650 Tolerances. Do we need to follow those
as ASTM is not a tank construction code but provide guidance about
matrial manufacturing,testing & handling etc.

We have Banding Value for 6 mm Plate of 13 mm max, can we consider a
dent as a banding problem in tank shell.

Please see below & advice.

7.5.2 Plumbness

a. The maximum out-of-plumbness of the top of the shell relative to
the bottom of the shell shall not exceed 1/200 of the total
tank height. The out-of-plumbness in one shell course shall not exceed
the permissible variations for flatness and waviness as
specified in ASTM A 6M/A 6, ASTM A 20M/A 20, or ASTM A 480M/A 480,
whichever is applicable.

7.5.4 Local Deviations

c. Flat spots measured in the vertical plane shall not exceed the
appropriate plate flatness and waviness requirements given in
7.5.2.

If there is any confusion to understand, please ask.


Abdul Wahab
Mechanical Inspector
KSA

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