Fabrication and Installation - Offshore Structures: Design, Construction and Maintenance - page 309

The vertical level of braces within a horizontal plane should be within ± 13

●

1

mm ( ±

2 inch) of the construction drawings.

The vertical distance between plan bracing elevations should be within ± 13 ●

1

mm ( ±

2 inch) of the construction drawings.

Tubular Member Tolerance
For tubular members with thicknesses of 50 mm (2 inches) or less, the differ-
ence between the major and minor outside diameters (the out-of-roundness) at
any point of a tubular member should not exceed the smaller of 1% of the
diameter or 6 mm ( 4 inch).
For tubular members with thicknesses of more than 50 mm (2 inches), the
difference between the major and minor outside diameters at any point of a tu-
bular member should not exceed 12.5% of the wall thickness.
For tubular members with a diameter of 1200 mm or more, and a thickness
of 100 mm or less, the difference between the major and minor outside di-
ameters at any point of a tubular member may increase to 13 mm ( 2 inch), pro-
vided the tolerance on the circumference is less than 6 mm ( 4 inch).
The difference between the actual and nominal outside circumferences at
any point of a tubular member should not exceed the smaller of 1% of the nom-
inal circumference or 13 mm ( 2 inch).
Figure 5.8 presents the tolerances for the straightness of tubular members
and beams, based on ISO, which are:

3

Straight to be within ± 10 mm ( ±

8 inch) for length

≤ 12 m ●

1

Straight to be within ± 13 mm ( ±

2 inch) for length

> 12 m.

●

L ± 50 mm (2”)

Change in
thickness

L + 25 mm
(1”)

Joint can within
member

Centerline
from design

Actual
centerline

Tolerance on straightness
± 10 mm for lengths = 12 m;
+ 13 mm for length > 12 m

FIGURE 5.8 Tolerances for positioning of cans within members and straightness of members.