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.