Peaking & Bending Measurement of Welded Joints in Cylindrical Storage Tanks....

[jose seban]

Dear Friends,

I am making fixed roof cylindrical oil storage tanks as per Indian
Standards IS-803.In section 9.3.5 it is mentioned about circularity
and shape.There it is mentioned about verticality & circularity
tolerences.Also it is mentioned about peaking and bending of welds
there..

1.Peaking of vertical weld joints measured over an arc length of 1 m
shall not exceed 12 mmm.

2.Bending of horizontal weld joints measured by a straightedge of 1 m
length shall not exceed 12 mm.

My questions are..

1.What is meant by this peaking and bending there?
2.How we will measure these factors?
3.How would the unit "millimetre" will come for these factors
measurement?
4.Is these 2 measurements are important in tank fabrication,if I am
checking vericality & circularity properly?


Regards,

Jose Sebastian,
Quality Manager,
Adani Power Limited,
Gujrat,India.
Mob:+919687660525

[raghura...@gmail.com]

You can make a template from a steel sheet / scrap plate with radius of template equal to your tank radious with an arc length of aprx 1 mtr. place this on your tank and if you are getting greater than 12mm gap, needs rectification. Similar way use 1 mtr steel rule as straight edge to check verticality.

Your 4th point itself is an answer to your query. How do you intended to check verticality and circularity?

Sent from my Nokia phone

[kamal nathan]

Mr.Jose,

             Reply to your questions are as follows,

 

1.Peaking & banding  is nothing but the profile of the tank i.e while erecting the shell plates the curvature to be maintained.

The shell plates rolled to a radius to be maintained till the welding of joints completed.For this purpose only the curavture of joints are checked.

For vertical joints of tank curvature is called as Peaking.

For Horizontal joints it is called a Banding.Banding is also called a straightness.

2.These can be measured by making a template of 1 mtrs length.Template shall be of a  wooden board .Mark the radius of the tank shell in an wooden board and cut accordingly.One side of the template shall be used for peaking and the other side straight side shall be used for banding.There is no specific requirement for making a template just make for easy handling

3.Keep the template-straight side on the centre of horizontal joints so now you will find half(500mm)on one shell course and remaining half on the other shell course.Take the measuring scale and measure the gap between joints.

                 Keep the template-radius side on the centre of vertical joints and measure the peaking so now you will find half(500mm)on one shell course and remaining half on the other shell course.Take the measuring scale and measure the gap between joints.
4.Peaking & banding are the important parameters to be checked while constructing a tank because circularity & verticality is checked but at the same time on the tank weld joints Peaking & banding are checked to maintain the profile and to avoid local buckling of weld joints.

 

Regards,

 

R.Kamalanathan,

Manager-Quality Control,

LANCO INFRATECH LIMITED,

VIZAG,INDIA

 

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[Jorge Mejía Lema]

Please,refer to API 650 Eleventh Edition, Addendum 2008, Numeral 7.5.2 Plumbness, 7.5.3 Roundness and 7.5.4 Local Deviations. All are very importand mesurement.
Regards,

jml

2010/5/31 jose seban <jose...@gmail.com>

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Jorge Mejia Lema.
Especialista IV Mecánico.
Gerencia Tanques.
PBX: +57 (1) 3215801 Ext. 4094
FAX: +57 (1) 3215913
Cell: 3174793091
Carrera 11 No.71-73 Piso 10
ITANSUCA PROYECTOS DE INGENIERIA Ltda.
Bogotá, Colombia, Sur América
 

[GOPU NAIR]

Dear Mr. Jose Sebastin   The sket you attached itself is self explanatory.  Distortion at the longitudial weld and circuferential weld are measured with these templates and it shall not exceed the figure you have given. For further clarification please feel free to call me on 09892193345 ( Mumbai)   Gopu --- On Mon, 31/5/10, Jorge Mejía Lema <jmeji...@gmail.com> wrote:

[sethurama lingam]

Dear friend,
As per ur question no :1 in vessel fab. Or tank the long seam assembly
you must check the peak in or peak out then only find the seam fit up
came inside or gone out side before welding and at that time of weld
visual. Simple you can make D/2 or D/4 template fixed inside gap find
in middle of temp. That is peak out that is directly take and if u
find out one side fix one side and measure other end and divided by 2
u will get peak in.

Point no :2circular seam fit up you can fix top ,seam and bottom area
you can check the circularity as well as check the verticality as per
the code u r given divided the circle by 8 deg. And drop the plumb at
1m above the seam or top of the tank as u wish.

I think it will help lot..sure.

Sethuramalingam.P
Acpcpl

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Regards

Sethu Ramalingam.p