7/27/2019 Waviness Tolerance 18.01.10

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Clarification for Allowable / Permissible waviness tolerance for Built-up

Structural Member

Reference: MBMA 2006 Edition (Metal Builders Manufacturers Association)

With respect to the permissible tolerance set forth by MBMA (Metal Builders

Manufacturers Association) Section IV, Common Industry Practices, figure 9.2a and

table 9.2, pgs. 346 348. That the permissible tolerance for waviness shall be

calculated as f = D / 72. Where f is the permissible tolerance allowed; D is the

depth of the web; and 72 is a constant value.

f

actl web web centerline

Therefore, f shall be the calculated as the permissible tolerance and shall be

measured from the web center line to the peak of waviness. However, as a

common inspection practice and to be more feasible, waviness can be measured

from peak to peak or from crop to crop of the plate waviness. In this case,

calculated permissible tolerance shall be multiplied by 2.

This brief explanation has been prepared based on the permissible and allowable

tolerance set forth by MBMA for better understanding.

For example:

For a beam with a web height D = 500 mm The maximum allowable waviness from

peak to peak shall be calculated as follows.

Maximum allowable waviness from Peak to Peak = 2 f

f= D/72

Hence 2f = 500/72 * 2 = 13.9mm.

Therefore, the maximum allowable tolerance for waviness from peak to peak is

13.9mm

2f