Pipeline Cold Bending Service

Understanding our workflow helps project planners coordinate pipe delivery, inspection hold points, and shipping schedules.

Step 1: Material Receiving and Verification

Incoming pipes are inspected against mill certificates for:

• Grade designation and heat number

• Outside diameter and wall thickness measurements

• Surface condition (no unacceptable defects per API 5L)

• End preparation and bevel condition

Pipes failing incoming inspection are segregated and reported to the customer for disposition.

Step 2: Bend Planning and Marking

Based on the customer’s bend schedule, each pipe is marked with:

• Bend location (distance from pipe end)

• Direction of bend (vertical or horizontal plane)

• Target angle

• Reference to isometric drawing number

Step 3: Machine Setup

The appropriate bending die is installed based on pipe diameter. CNC parameters are programmed including:

• Clamp pressure (calculated from pipe D/t ratio)

• Feed increment length

• Target angle with springback compensation

Step 4: Incremental Bending

The bending process uses incremental advancement:

• Pipe advances 1–3 inches per cycle

• Hydraulic ram applies bending force

• Angle is measured after each increment

• Process repeats until target angle achieved

This incremental method controls ovality and prevents wrinkling, particularly for thin-wall pipes.

Step 5: In-Process Inspection

Digital protractors verify bend angle immediately after forming. Any deviation beyond tolerance triggers adjustment of CNC parameters for subsequent bends.

Step 6: Final Inspection

Each completed bend undergoes:

• Angle verification (tolerance ±0.5°)

• Ovality measurement at bend apex, mid-point, and end

• Visual inspection for wrinkles, cracks, or surface damage

• Wall thickness measurement at intrados and extrados (sampling plan)

Step 7: Marking and Documentation

Each bend receives a unique traceability number. Inspection data is recorded and linked to the original pipe mill certificate.