Straightness tolerances (T) should not exceed those shown in the tables below. The tolderance (T) for any 3-foot length (1 metre) is measured as shown in Figure 1. The total tolerance, the maximum curvature in the total length, is measured as shown in Figure 2. The table applies to lengths no exceeding 22 feet (6.7 metres).
The tolerances shown apply to annealed and heat-treated tubes up to 302 Brinell maximum. Heat-treated tubes with Brinell hardness over 302 maximum up to 401 maximum have tolerance (T) twice the values shown in the tables.
| Specified Size |
Maximum Curvature in any 3 feet |
Maximum Curvature in Total Lengths of 5 feet or more |
Maximum Curvature for Lengths under 5 feet |
|
| OD 5 inches and smaller Wall thickness, over 3% of OD |
0.030 inch |
0.020 inch x (length in feet) ÷ 3 |
Ratio of 0.010 inch per foot |
| OD over 5 inches to 8 inches inclusive Wall thickness, over 4% of OD |
0.045 inch |
0.030 inch x (length in feet) ÷ 3 |
Ratio of 0.015 inch per foot |
| OD over 8 inches to 11 inches inclusive Wall thickness, over 4% of OD |
0.060 inch |
0.045 inch x (length in feet) ÷ 3 |
Ratio of 0.020 inch per foot |
| Specified Size |
Maximum Curvature in 1 metre |
Maximum Curvature in Total Length of 1.5 metres or more |
Maximum Curvature for Lengths under 1.5 metres |
|
| OD 125 mm and smaller Wall thickness, over 3% of OD |
.85 mm |
.55 mm x length in metres |
Ratio of .85 mm per metre |
| OD 125 mm to 200 mm inclusive Wall thickness, over 4% of OD |
1.25 mm |
.85 mm x length in metres |
Ratio of 1.25 mm per metre |
| OD over 200 mm to 280 mm inclusive Wall thickness, over 4% of OD |
1.65 mm |
1.25 mm x length in metres |
Ratio of 1.65 mm per metre |