ERW tube defect atlas

Where it originates

Originates at the weld point; root causes often begin at slitting (edge condition) and the fin pass (edge presentation).

What to record first

Record whether the seam is fully unbonded or intermittent, where along the length it appears, and whether it begins at a strip join, a setup change, or mid-coil.

First checks

1. Verify strip edge condition and slitting history for the affected coil
2. Review edge presentation into the weld point: fin pass condition and seam guiding
3. Check weld monitoring records against the time the symptom began

Full investigation sequence

• Verify strip edge condition and slitting history for the affected coil
• Review edge presentation into the weld point: fin pass condition and seam guiding
• Check weld monitoring records against the time the symptom began
• Confirm squeeze-out/upset evidence is consistent along the affected length
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates in the weld vee — the interaction of heat input, speed, and edge condition at the instant of bonding.

What to record first

Note how the indication was detected (test response, flattening behavior, appearance), whether it is continuous or periodic, and its position relative to strip joins.

First checks

1. Compare monitoring trends (power, speed, temperature signals) around the occurrence window
2. Review destructive test results (flattening/flare) on adjacent samples
3. Check for coolant or contamination reaching the weld vee

Full investigation sequence

• Compare monitoring trends (power, speed, temperature signals) around the occurrence window
• Review destructive test results (flattening/flare) on adjacent samples
• Check for coolant or contamination reaching the weld vee
• Verify material identity — chemistry changes can shift weldability at fixed practice
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

The seam was made on the mill, but the split usually reveals itself where downstream stress is applied: sizing, flaring, bending, or end forming.

What to record first

Record whether the split occurred on the mill, at sizing, or at a downstream operation (flaring, bending, end forming), and photograph the fracture faces before handling.

First checks

1. Determine the operation that opened the seam and the stress it applies
2. Review weld quality evidence for the mother tube (tests, monitoring)
3. Check whether the split follows the bond line or the adjacent heat-affected zone

Full investigation sequence

• Determine the operation that opened the seam and the stress it applies
• Review weld quality evidence for the mother tube (tests, monitoring)
• Check whether the split follows the bond line or the adjacent heat-affected zone
• Trace the affected pieces to coil, join, and production window
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates in the weld zone during welding or the cooling that immediately follows it.

What to record first

Distinguish continuous cracking from periodic; record orientation (longitudinal in the seam vs transverse), and whether it appears before or after sizing.

First checks

1. Review cooling practice and any interruption around the occurrence window
2. Check strip chemistry and hardness records for the affected coil
3. Examine whether cracking correlates with heavier upset or bead-removal depth

Full investigation sequence

• Review cooling practice and any interruption around the occurrence window
• Check strip chemistry and hardness records for the affected coil
• Examine whether cracking correlates with heavier upset or bead-removal depth
• Review any downstream cold work applied before the crack was found
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates in the forming section and seam guiding immediately before the weld point.

What to record first

Measure or photograph the radial offset between strip edges at the seam; record whether it is constant, drifting, or periodic with roll rotation.

First checks

1. Check strip width and camber records for the affected coil
2. Review forming section condition and documented setup against the approved record
3. Inspect seam guiding and last-pass presentation

Full investigation sequence

• Check strip width and camber records for the affected coil
• Review forming section condition and documented setup against the approved record
• Inspect seam guiding and last-pass presentation
• Correlate drift with coil changes, joins, or tooling temperature
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates at the weld squeeze; strip thickness variation upstream changes it at fixed practice.

What to record first

Record inside and outside upset condition, symmetry, and whether the change coincided with a speed, material, or setup change.

First checks

1. Compare actual upset evidence with the product's bead-condition requirement
2. Review squeeze settings history in the approved setup record (do not adjust without authority)
3. Check strip thickness records — thickness shifts change upset at fixed practice

Full investigation sequence

• Compare actual upset evidence with the product's bead-condition requirement
• Review squeeze settings history in the approved setup record (do not adjust without authority)
• Check strip thickness records — thickness shifts change upset at fixed practice
• Verify bead removal tooling condition if flash-controlled product is being run
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates at the scarfing station immediately after welding.

What to record first

Describe the mark (gouge, step, chatter along the seam path), measure remaining wall if possible, and record whether it is continuous or intermittent.

First checks

1. Inspect scarfing tool condition, support, and documented position
2. Check for tool chatter correlating with speed or vibration events
3. Verify remaining wall against the drawing requirement at the seam

Full investigation sequence

• Inspect scarfing tool condition, support, and documented position
• Check for tool chatter correlating with speed or vibration events
• Verify remaining wall against the drawing requirement at the seam
• Review whether the condition follows tool changes or specific setups
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates at any tooling or guide contact point along the line; the repeat interval identifies the rotating component.

What to record first

Photograph with scale; record whether the mark is on OD or ID, its position around the circumference, and the repeat interval if periodic.

First checks

1. Match any repeat interval to roll or tool circumferences on the line
2. Inspect suspect tooling surfaces for transferred material
3. Review coolant condition, filtration, and debris evidence

Full investigation sequence

• Match any repeat interval to roll or tool circumferences on the line
• Inspect suspect tooling surfaces for transferred material
• Review coolant condition, filtration, and debris evidence
• Check incoming strip surface for pre-existing pickup or scale
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates at a fixed contact point — guides, liners, turned rolls, cutoff transfer, or post-line handling.

What to record first

Record position (constant clock position suggests a fixed contact point), depth impression, and where along the line it first appears on stopped equipment.

First checks

1. Walk the line for a fixed contact: guides, worn liners, turned rolls, cutoff transfer
2. Check whether the scratch begins at a specific stand or after cutoff/handling
3. Compare against surface acceptance criteria before disposition

Full investigation sequence

• Walk the line for a fixed contact: guides, worn liners, turned rolls, cutoff transfer
• Check whether the scratch begins at a specific stand or after cutoff/handling
• Compare against surface acceptance criteria before disposition
• Verify packaging and bundling are not the origin for field complaints
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates in rotating-component vibration — drives, bearings, cutoff engagement, or scarfing tool support.

What to record first

Record the repeat pitch, orientation, and whether the pattern is on OD, ID, or the seam path only; note line speed at occurrence.

First checks

1. Convert repeat pitch and line speed to a frequency and compare to rotating components
2. Inspect drive condition, roll bearings, and cutoff engagement
3. Check scarfing tool support if marks follow the seam path

Full investigation sequence

• Convert repeat pitch and line speed to a frequency and compare to rotating components
• Inspect drive condition, roll bearings, and cutoff engagement
• Check scarfing tool support if marks follow the seam path
• Review whether marks appear only above certain speeds
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Introduced at sizing, straightening, cutoff, or handling; cut-end distortion is a separate phenomenon.

What to record first

Measure maximum and minimum diameter at agreed locations away from cut ends; record orientation relative to the weld and whether ends differ from mid-length.

First checks

1. Confirm the measurement method and location match the governing requirement
2. Check whether ovality is introduced at sizing, straightening, cutoff, or handling
3. Review sizing section condition against the approved setup record

Full investigation sequence

• Confirm the measurement method and location match the governing requirement
• Check whether ovality is introduced at sizing, straightening, cutoff, or handling
• Review sizing section condition against the approved setup record
• Distinguish tube ovality from end distortion caused by cutoff
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates in forming/sizing alignment and straightener practice, often driven by strip camber.

What to record first

For shaped tube, measure twist per unit length per the agreed method; record whether it is constant or varies with coil position.

First checks

1. Verify strip camber and coil-set records for the affected material
2. Review forming and sizing alignment against documented setup
3. Check straightener condition and documented practice

Full investigation sequence

• Verify strip camber and coil-set records for the affected material
• Review forming and sizing alignment against documented setup
• Check straightener condition and documented practice
• Correlate onset with coil changes or setup events
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates at the straightener or downstream handling and storage.

What to record first

Measure deviation over the agreed gauge length on a qualified surface; record direction consistency and whether cut length changes the result.

First checks

1. Confirm measurement method (surface plate, supports, gauge length) before reacting
2. Review straightener setup history and tooling condition
3. Check whether bow direction correlates with seam position or strip camber

Full investigation sequence

• Confirm measurement method (surface plate, supports, gauge length) before reacting
• Review straightener setup history and tooling condition
• Check whether bow direction correlates with seam position or strip camber
• Evaluate handling and rack storage as post-production contributors
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel

Where it originates

Originates in the shaping passes of the sizing section, influenced by strip width variation.

What to record first

For squares and rectangles, record which corners deviate, whether the condition is constant along the length, and how radii were measured.

First checks

1. Confirm corner requirements and measurement method from the drawing/PO
2. Review shaping pass condition and documented setup
3. Check strip width records — width variation redistributes material at corners

Full investigation sequence

• Confirm corner requirements and measurement method from the drawing/PO
• Review shaping pass condition and documented setup
• Check strip width records — width variation redistributes material at corners
• Compare all four corners to isolate a single-stand contribution
• Inspect only with equipment stopped, isolated, and verified safe
• Escalate conclusions and changes to qualified personnel