ABS Grade DH32 Marine Steel Plate Tolerance Standards and Qu...
- May 07, 2026
Knowledge
ABS Grade DH32 Marine Steel Plate Tolerance Standards and Quality Control
I. Thickness Tolerances
| Plate Thickness | Tolerance |
|---|---|
| ≤ 10 mm | ±0.5 mm |
| 10 - 20 mm | ±0.8 mm |
| 20 - 50 mm | ±1.0 mm |
| > 50 mm | ±1.5 mm |
Rationale: Inconsistent thickness can cause fluctuations in weld penetration and stress concentration, thereby reducing the local strength of the hull.
II. Width Tolerance
| Plate Width | Tolerance |
|---|---|
| ≤ 2000 mm | ±5 mm |
| > 2000 - 3000 mm | ±8 mm |
| > 3000 mm | ±10 mm |
Rationale: To ensure controllable assembly gaps between plate sections and sections, thereby reducing the need for on-site cutting adjustments.
III. Length Tolerance
| Plate Length | Tolerance |
|---|---|
| ≤ 10000 mm | ±10 mm |
| > 10000 mm | ±15 mm |
Rationale: Same as for width tolerance: to ensure controllable assembly gaps and reduce on-site cutting and correction.
IV. Flatness Tolerance
| Plate Thickness | Tolerance |
|---|---|
| ≤ 20 mm | ≤ 3 mm/m |
| > 20 mm | ≤ 5 mm/m |
Rationale: Exceeding flatness tolerances can cause welding distortion and angular distortion, increasing correction costs and affecting the hull’s appearance and assembly accuracy.
V. Key Quality Control Points
1. Rolling Control
A four-roll reversible finishing mill is used in conjunction with an in-line thickness gauge to achieve closed-loop control of thickness throughout the process.
2. Levelling Process
Perform hot levelling followed by cold levelling to ensure the flatness of the plates meets requirements.
3. Individual Plate Inspection
Each plate undergoes the following tests:
Dimensions, flatness, appearance, and ultrasonic testing (UT).
4. Certification Documents
The following documents are provided:
ABS Material Certificate, furnace batch number, mechanical properties report, and non-destructive testing report.
VI. Common Issues and Mitigation
1. Thickness Deviations
Prioritise supply with a negative tolerance (e.g. -0.3/+0 mm) to avoid on-site welding repairs.
2. Flatness Deviations
Cold levelling and a secondary inspection are required, with particular attention to be paid to thick plates.
3. Edge and Corner Deformation
Pad and protect all four edges during packaging, and stack plates horizontally; implement anti-deformation measures during transport.
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