peaking measurement method

[mechfabricator]

can anybody let me know how we must measure peaking, when we use the template,we can fit the template in one side to shell and measure the distance between other side of template and shell.
in this case it seems that peaking is half of this distance, is this correct or not.

 

[bimr]

What is specified? Your Contract should spell out the tolerances.

American Petroleum Institute (API) Publication 650, Standard for Welded Steel Tanks for Oil Storage, paragraph 5.5.3 specifies that with a horizontal sweep board 36 inches long, peaking shall not exceed 1/2 inch.

Peaking is when the vertical shell weld or weld joint is not properly fitted and it makes a peak at the joint. Sometimes this is caused because the shell plate wasn't properly rolled. The radius of the tank in that area will not be correct. It is checked by cutting a 36 inches long board to the outside radius of the tank, holding the board against the weld, and measuring the distance between the board and the tank shell. If the weld or joint holds the board more than 1/2 inch from the shell, then the joint has too much peaking.

 

[mechfabricator]

thank you for your valuable hints, I would like to know the detail of peaking
measurement.
please take a look at enclosed file, which method is correct, a or b?
thank you.

 

[Duwe6]

Method A. You use a Radius Board the same way.

 

[Syahar1975]

Agree with Duwe6.

Method A is the correct one.

 

[mechfabricator]

thank you if the a method is correct our inspector has reported both banding and peaking twice!
we have a 20m fixed supported storage tank which plumbness and roundness and levelness are ok, but in 4 point peaking and banding was measured in b method and reported as 40 mm.
what is your opinion?
thank you

 

[Duwe6]

Of course it failed when measured wrong! That method magnifies the peaking. This is as dumb as moving over a decimal point, to change the tolerance from 13mm to 1.3mm.

 

[Syahar1975]

All dimensional check (peaking, banding, plumbness, radius) shall be within tolerance per the code.

If we can not meet the tolerance we have to fix it.

Off course there was some cases that the client or QC manager or tank designer will accept as it is.

Syah