How to Specify Slit Steel Coil on a Purchase Order — Line-by-Line Guide

Most coil disputes happen because the purchase order (PO) was vague.

Buyers often write:

“914 mm slit coil, 0.7 mm GI”

That is not a complete specification.

When slit coil is underspecified, disputes arise over:

• Width tolerance

• Burr height

• Camber

• Coating mass

• Mechanical properties

• Packaging

• Traceability

A professional PO protects:

• Production stability
• Inspection leverage
• Warranty position
• Claim enforceability

This guide explains exactly how to specify slit coil line-by-line so your PO is technically enforceable and commercially clear.

1. The Core Rule of Slit Coil Purchasing

You are not just buying:

Steel.

You are buying:

Material + geometry + mechanical performance + slitting quality + packaging + documentation.

Every one of those must be defined.

2. Section 1 — Material Grade & Standard

Specify clearly:

• Standard (ASTM / EN / JIS etc.)
• Grade designation
• Forming grade or structural grade

Example:

• ASTM A653 CS Type B
• or
• EN 10346 DX51D

Do not assume supplier knows your forming requirements.

3. Section 2 — Thickness (Nominal & Tolerance)

Specify:

Nominal thickness
Applicable tolerance standard

Example:

0.70 mm nominal thickness
Mill tolerance per ASTM A653

If coating included in thickness, clarify:

“Thickness inclusive of metallic coating.”

Ambiguity here creates claims issues.

4. Section 3 — Slit Width & Tolerance

Specify clearly:

• Nominal slit width
• Permissible deviation
• Measurement method

Example:

Slit width: 914 mm ±0.5 mm
Measured flat, excluding burr

If application critical (tube mill):

±0.3 mm maximum deviation.

Without tolerance defined, width disputes weaken.

5. Section 4 — Burr Requirement

For forming-sensitive applications:

Specify burr control.

Example:

Maximum burr height 5% of material thickness.

If burr direction important:

“Consistent burr orientation required.”

Most buyers omit this — then struggle with cracking.

6. Section 5 — Camber & Flatness

Camber tolerance example:

Maximum 1 mm in 2000 mm length.

Flatness:

No visible edge wave exceeding application tolerance.

Flatness definitions prevent subjective disputes.

7. Section 6 — Coating Type & Mass (If Coated)

Specify:

Coating type (Z, AZ, etc.)
Coating mass designation

Example:

• Z275 galvanized
• or
• AZ150 Galvalume

If painted:

Include paint system and thickness.

Do not write simply “galvanized.”

Coating mass defines corrosion life.

8. Section 7 — Mechanical Properties

Specify minimum values if forming-critical:

• Minimum yield strength
• Minimum tensile strength
• Minimum elongation

Example:

Minimum elongation 20%

If not specified, mill minimum standard applies — may not match your forming needs.

9. Section 8 — Coil Dimensions

Specify:

• Coil ID (e.g., 508 mm or 610 mm)
• Maximum coil OD
• Maximum coil weight

Example:

• 508 mm ID
• Max OD 1500 mm
• Max 5 MT per coil

This affects:

• Uncoiler compatibility
• Handling equipment
• Safety

Omitting this creates operational problems.

10. Section 9 — Slitting Requirements

Add slitting-specific instruction:

• Clean cut edges
• No excessive edge rollover
• Knife maintained
• No oil contamination (if required)

If surface sensitive (painted):

Protective interleaf if required.

Slitting quality must be written into PO.

11. Section 10 — Packaging Requirements

Specify:

• Export packaging
• Moisture protection
• Vapor barrier
• Edge protection
• Strapping configuration

Example:

Seaworthy packaging with anti-corrosion wrap.

Improper packaging causes rust claims.

12. Section 11 — Documentation

Require:

• MTC / MTR
• Heat number traceability
• Coil tag matching documentation

Example:

MTC must accompany shipment and match coil heat number.

Without documentation, enforcement weakens.

13. Section 12 — Inspection & Claims Clause

Include:

Inspection window
Claim procedure

Example:

Claims must be submitted within 7 days of receipt with documented evidence.

Clear claim terms prevent argument.

14. Section 13 — Quantity & Yield Note

Specify:

Total tonnage
Number of slit strands expected (if relevant)

Example:

Slit from 1250 mm master coil to maximize yield per agreed layout.

This prevents supplier from choosing inefficient layout.

15. Example Slit Coil Specification Line

Example structured PO line:

• ASTM A653 CS Type B
• 0.70 mm nominal thickness (inclusive of coating)
• Z275 coating
• Slit to 914 mm ±0.5 mm (excluding burr)
• Maximum burr 5% thickness
• 508 mm ID
• Max 5 MT per coil
• Camber ≤1 mm per 2 m
• Seaworthy export packing
• MTC required per heat number

This is enforceable.

16. Common PO Mistakes

• Writing only width and thickness
• Not defining tolerance
• Ignoring burr
• Not specifying coil ID
• Ignoring packaging
• No documentation requirement

Incomplete PO shifts power to supplier.

17. When to Tighten Specification

Tighten specs when:

• Tube mill production
• High-strength steel
• Snap-lock roofing
• Laser welding
• Precision decking

Do not over-specify for basic agricultural panels.

Match specification to risk level.

FAQ Section

Should burr be specified?

Yes.

Is camber important to define?

Yes.

Should coil ID be included?

Always.

Do I need to specify coating mass?

Yes.

Is width tolerance necessary?

Absolutely.

Should packaging be defined?

Yes.

Can I rely on standard mill tolerances?

Only if acceptable for your application.

Should mechanical properties be written?

For forming-critical jobs, yes.

Is documentation mandatory?

Yes.

Can vague PO weaken claims?

Very much.

Conclusion

Specifying slit coil correctly is not optional.

It determines:

• Production stability
• Inspection authority
• Claim enforceability
• Supplier accountability

A professional PO defines:

• Material grade
• Thickness & tolerance
• Width & tolerance
• Burr & camber
• Coating
• Mechanical properties
• Coil dimensions
• Packaging
• Documentation
• Claim terms

If it is not written, it is not enforceable.

Clear specification protects your production — and your margin.