Aug 20, 2026News & Insights

Proof Coil Chain: The Complete Guide to Grade 30 Welded Chain

This guide explains what proof coil chain is, how it is made, its standard specifications, common applications, and how it compares with higher-strength chains

Proof coil chain is one of the most widely used welded chains in general industrial, agricultural, and hardware applications. It is the entry-level strength grade in the welded chain family, designed for non-lifting tasks where cost efficiency and moderate strength are the primary requirements.

This guide explains what proof coil chain is, how it is made, its standard specifications, common applications, and how it compares with higher-strength chains such as high test, transport, and alloy chain.

What Is Proof Coil Chain?

Proof coil chain is a welded steel chain manufactured from low-carbon steel. The name "proof coil" comes from the fact that the chain is proof-tested during production to a fraction of its minimum breaking strength — a basic quality check that verifies the welds are sound.

It is classified as Grade 30 chain, meaning it has a minimum breaking stress of approximately 300 N/mm². This is the lowest strength grade among common welded chains, but it is perfectly adequate for general-purpose securing, agricultural, and light industrial use.

Material and Manufacturing

Proof coil chain is made from low-carbon steel wire, typically equivalent to Q195 or Q235 grades in China. The manufacturing process involves:

Wire drawing — steel rod is drawn to the required wire diameter

Link forming — wire is bent into interlocking links

Welding — each link is electric-welded at the joint

Proof testing — the chain is subjected to a short proof load test to verify weld integrity

Surface finishing — typically electro-galvanized, hot-dip galvanized, or self-colored

The chain is not heat-treated after welding, which keeps production costs low but also limits its strength compared with heat-treated grades such as Grade 70 or Grade 80.

Surface Finishes

Proof coil chain is available in several surface finishes to suit different environments:

Finish	Characteristics	Typical Use
Self-colored (raw)	Natural steel with light oil coating	Indoor use, budget-sensitive applications
Electro-galvanized	Bright silver appearance, moderate corrosion resistance	General outdoor, hardware retail
Hot-dip galvanized	Matte grey, thicker zinc layer (50–80 μm)	Agricultural, outdoor, wet environments
Zinc-plated with yellow chromate	Golden yellow finish, good corrosion resistance	General-purpose, visual identification

For most outdoor applications, electro-galvanized is the standard choice. For harsh or wet environments, hot-dip galvanized offers significantly better protection.

Grade 30 Proof Coil Chain Specifications

Working load limits and breaking strengths vary by diameter and manufacturer, but typical values for standard proof coil chain are:

Diameter (inch)	Diameter (mm)	Working Load Limit (lbs)	Breaking Strength (lbs)
1/8"	3 mm	400	1,600
3/16"	5 mm	800	3,200
1/4"	6 mm	1,300	5,200
5/16"	8 mm	1,900	7,600
3/8"	10 mm	2,650	10,600
1/2"	13 mm	4,500	18,000
5/8"	16 mm	6,900	27,600

These values are approximate and based on a 4:1 safety factor. Always confirm the exact WLL with the manufacturer's specification sheet.

Common Applications

Proof coil chain is a general-purpose workhorse. Typical uses include:

Application	Why Proof Coil Chain Is Used
Agricultural	Light towing, fence gates, livestock chains, implement securing
General hardware	Clotheslines, dog tie-outs, gate chains, swing chains
Light industrial	Machine guards, barrier chains, low-stress conveyor applications
Construction	Temporary fencing, sign hanging, light duty securing
Retail & DIY	Packaged chain for home and garden use

Important: Proof coil chain is not suitable for overhead lifting. Any lifting application requires Grade 80 or Grade 100 alloy chain tested and certified to EN 818-2 or equivalent standards.

Proof Coil vs. High Test vs. Transport vs. Alloy Chain

Property	Proof Coil (Grade 30)	High Test (Grade 43)	Transport (Grade 70)	Alloy (Grade 80/100)
Material	Low-carbon steel	Medium-carbon steel	Heat-treated carbon steel	Alloy steel, quenched & tempered
Heat treatment	None	None or minimal	Yes	Yes
Approximate strength	300 N/mm²	430 N/mm²	700 N/mm²	800–1000 N/mm²
Typical use	General securing, agriculture	Truck tie-down, towing	Heavy-duty cargo securement	Lifting, heavy lashing
Relative cost	Lowest	Low	Medium	High

Standards and Certification

Proof coil chain is manufactured to various national and international standards. The most relevant include:

NACM Welded Steel Chain Specifications — the North American reference for welded chain grades and proof testing

ASTM A413 — specification for carbon steel chain

ISO 1835 — international standard for short-link chain (non-lifting)

DIN 5685 — German standard for round steel chains

Buyers should verify that the chain is proof-tested and, where required, marked with the grade or manufacturer's identification.

How to Choose the Right Proof Coil Chain

Step 1: Determine the Application

General purpose, light loads → Proof coil is appropriate

Heavy cargo tie-down on trucks → Upgrade to Grade 70

Overhead lifting → Do not use proof coil; use Grade 80 or 100

Step 2: Match the Working Load

Select a diameter whose WLL comfortably exceeds the maximum load with an appropriate safety margin. For dynamic applications, use at least double the static requirement.

Step 3: Select the Surface Finish

Indoor → self-colored

Outdoor general → electro-galvanized

Wet, agricultural, coastal → hot-dip galvanized

Step 4: Confirm Packaging and Length

Proof coil chain is commonly supplied in drums, pails, reels, or cut lengths depending on the customer's retail or industrial needs.

Safety and Maintenance

Even though proof coil chain is not used for lifting, basic care extends its service life:

Inspect regularly for weld cracks, bent links, or excessive rust

Replace if link wear exceeds 10% of original diameter

For outdoor use, choose galvanized finish and rinse occasionally

Boyuan Metal Supply Capability

Boyuan Metal supplies proof coil chain in Grade 30 with diameters from 3 mm to 16 mm, available in:

Electro-galvanized, hot-dip galvanized, or self-colored finish

Short link, mid link, or long link configurations

Standard drums, pails, reels, or custom cut lengths

Custom packaging, branding, and barcoding for retail distribution

Mill test certificates with every shipment

We also supply higher-grade chains — Grade 43 high test, Grade 70 transport, and Grade 80/100 alloy — for customers who need a full range from one supplier.