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日本語The direct answer is that G80 chain is stronger than G70 chain. A G80 chain of the same nominal diameter carries a higher working load limit, breaks at a higher applied force, and is manufactured from heat-treated alloy steel rather than carbon steel. The two grades are not interchangeable, and the difference matters far more than a number on a tag.
G70 chain is built primarily for cargo securement and transport work. G80 chain is the minimum grade accepted for overhead lifting in most regulated workplaces. Understanding the material, rating, and application differences between the two grades helps buyers, riggers, and maintenance teams specify the correct chain the first time. This guide explains what the grades mean, how they compare in controlled tests, and how to apply that knowledge without over-specifying or under-specifying your chain.
What Do the Chain Grades Mean?
Chain grade designations such as G70, G80, G100, and G120 are shorthand labels for the strength class of a welded steel chain. They indicate the minimum performance level the chain must meet, including tensile strength, proof load, and elongation behavior. The number in the grade name is a practical reference to the nominal strength class of the material. In simple terms, the grade tells you how much load the chain can handle and under what conditions it may be used.
G70 Chain Grade
G70, often called transport chain or truck chain, is a heat-treated carbon steel chain developed for securing cargo on trucks, trailers, and rail cars. Its combination of strength, ductility, and wear resistance makes it well suited for tie-down systems and load binding.
G80 Chain Grade
G80 is an alloy steel chain that has been heat treated to achieve a higher strength-to-weight ratio. It is the most common grade used for overhead lifting and rigging, including chain slings and lifting assemblies. Many national standards require alloy steel chain for suspended loads.
G100 and G120 chains provide even higher working load limits than G80 at the same diameter and are increasingly specified for heavy-haul tie-downs and compact lifting assemblies. However, G80 remains the default alloy grade in most lifting standards, and the practical question for most buyers is still G70 versus G80.
Material and Manufacturing Differences
The core difference between G70 and G80 lies in the steel composition and the heat treatment process.
- G70 material: medium-carbon steel with limited alloy content. The chain is hardened by quenching and tempering after welding.
- G80 material: low-alloy steel with additions of chromium, molybdenum, and manganese. These alloying elements improve hardenability and raise the yield point of the finished links.
- G70 process: links are flash-welded from bar stock, heat treated, and calibrated to final pitch. The process produces a strong, ductile chain suited to tension loads.
- G80 process: after welding and heat treatment, G80 chain is proof-loaded and submitted to hardness and dimensional checks that are more demanding than those applied to G70.
The practical result is that a G80 chain of the same diameter is stronger and more fatigue-resistant than a G70 chain. G70, by contrast, is generally more economical and offers high ductility, which is advantageous in tie-down work where chains are tensioned and released repeatedly. Wear resistance also differs. The harder surface of G80 alloy chain resists abrasion from rough loads and deck edges better than G70, while operators often prefer G70 for applications that require frequent manual handling.
G70 Transport Chain for Tie-Down and High-Ductility UseThis G70 chain is presented alongside a comparison of working load and breaking force, making it a practical choice for applications that require repeated tensioning and economical durability.View Product →Strength Comparison: Working Load Limit and Breaking Force
Two numbers matter most when comparing chain strength: the working load limit (WLL) and the minimum breaking force. The WLL is the maximum load the chain should be asked to carry under normal service conditions. The breaking force is the load at which the chain is expected to fail. The table below compares typical published values for 10 mm chain, which corresponds approximately to 3/8 inch.
| Property | G70 Transport Chain | G80 Alloy Chain |
|---|---|---|
| Material | Heat-treated carbon steel | Heat-treated alloy steel |
| Working load limit | 6,600 lb (3,000 kg) | 7,100 lb (3,200 kg) |
| Minimum breaking force | 28,200 lb (12,800 kg) | 35,100 lb (15,900 kg) |
| Proof load test | Not always required | Routinely applied |
| Typical use | Cargo securement | Overhead lifting and rigging |
In this example, G80 chain provides roughly 25 percent more breaking force than G70 chain at the same diameter. The gap can grow in larger diameters because the alloy structure allows G80 to retain its strength properties in thicker cross-sections. The exact numbers vary slightly between manufacturers because each producer publishes test data within the allowed standard range, but the ranking does not change: G80 always sits above G70 in load capacity for the same size. Breaking force is not the only indicator of strength. G80 also has a higher yield point, meaning it resists permanent stretch better than G70 under repeated heavy loads. That matters in lifting, where elongation of a sling leg can change the load distribution in a multi-leg assembly.
G80 Alloy Chain with Higher Breaking Force and Yield PointHighlighted after load-capacity comparisons, this G80 chain offers roughly 25 percent more breaking force than G70 at the same diameter, suiting lifting and heavy-load applications.View Product →Strength in Practice: Elongation, Fatigue, and Shock Loads
A higher rating on paper only matters if the chain behaves predictably in the real world. Three behaviors separate G70 and G80 in service.
- Elongation: G70 chain tends to stretch more noticeably before failure, giving operators visible warning of an overloaded tie-down. G80 is engineered for lower elongation under load, which is essential in lifting because stretch in a sling leg changes the load distribution.
- Fatigue resistance: repeated loading and unloading slowly weakens any chain. Alloy steel with proper heat treatment resists micro-damage better than carbon steel. For frequent heavy cycles, such as daily lifting in a workshop, G80 has a longer useful life.
- Shock loading: a sudden jerk can produce a force several times higher than the static load. The higher yield point of G80 helps it resist permanent deformation from momentary overloads, while a G70 link may bend and bind.
These differences explain why operators often describe G80 as the stronger grade even when both chains have the same diameter. The alloy chain does not deform as early and returns to its original shape more reliably after a moderate overload.
Application Differences: Transport versus Lifting
The primary application determines which grade is appropriate.
G70 for Cargo Securement
G70 is used in tie-down assemblies on heavy trucks, trailers, agricultural equipment, and rail cars. The chain connects to load binders, ratchet binders, and hooks to hold cargo in place during transit. In this role the chain experiences repeated tension, vibration, and occasional shock loads. G70 offers enough strength for these conditions at a lower cost than alloy chain.
G80 for Overhead Lifting
G80 is the prevalent grade for overhead lifting applications such as chain slings, crane attachments, and suspended tool handling. It is the base grade required by many industrial safety rules for any chain used to suspend a load above personnel or equipment. The higher working load limit and improved fatigue resistance provide a greater safety margin when a failure could cause injury or property damage.
Why You Should Not Swap Them
- Using G70 in an overhead lifting application can exceed the intended safety factor and may lead to sudden failure under shock loading.
- Using G80 for tie-down work is technically safe but often unnecessary; the higher cost provides little benefit in straight-line tension.
- Mixing grades in one assembly is dangerous because the lowest-rated component determines the assembly rating.
Rule of thumb: if a load is suspended above the ground or above personnel, choose an alloy chain such as G80. If the load is resting on a trailer and only needs to be held in position, G70 is the conventional choice.
How to Identify G70 and G80 Chain
Chain grades are marked on the links themselves. Most welded chain manufacturers imprint a grade mark on every link or at regular intervals along the length.
| Grade | Typical link mark | Typical tag wording | Common use |
|---|---|---|---|
| G70 | 7 or 70 | Transport chain or Grade 70 chain | Cargo securement |
| G80 | 8 or 80 | Alloy chain or Grade 80 chain | Overhead lifting and rigging |
Relying on visual appearance alone is not sufficient. A rusty or painted chain can hide its marking, so verify the grade from the attached tag or the delivery certificate before use in a critical application. When a marking is unreadable, treat the chain as ungraded and remove it from service. Routine inspection is also part of grade management. Before every important lift or long trip, measure the chain pitch, look for bent links, cracks, or corrosion, and replace any chain that shows visible damage. A damaged G80 chain can perform worse than a new G70 chain of the same diameter.
Standards and Hardware Compatibility
Chain grades are defined by standards so that a buyer in one country can be confident that a chain with a given mark performs the same as a chain produced elsewhere. G70 transport chains are manufactured to carbon steel transport chain specifications that control material, heat treatment, and minimum breaking forces. G80 alloy chain is manufactured to alloy chain standards such as ASTM A391 in North America and equivalent documents in other markets.
Compliance also affects hardware. Hooks, binders, and connecting links carry their own working load limits, and an assembly is no stronger than its weakest component. When G80 chain is used with G70-rated hardware, the hardware rating governs. In practice, G70 transport chain is often supplied with Grade 80 hooks and connectors, because a small-diameter Grade 80 hook offers sufficient strength at a competitive price. The assembly rating must still be checked on the tag.
How to Choose the Right Grade for Your Job
Selecting between G70 and G80 requires answering a few clear questions:
- Is the chain going to support a suspended load? If yes, choose G80 or a higher alloy grade.
- What is the maximum load during service? The working load limit of the chain must meet or exceed the expected force.
- Which standard applies in your market? Local regulations may require a specific grade for certain applications, especially overhead lifting.
- What hardware will the chain connect to? Hooks, binders, and connectors have their own working load limits and must be matched to the chain grade.
- Are there environmental factors such as moisture, chemicals, or abrasive wear? These affect the grade choice, surface treatment, and inspection frequency.
For buyers evaluating multiple applications, the practical message is simple: when strength and safety margins matter most, G80 is stronger; when economy and tie-down performance matter most, G70 is the standard choice. Cost follows grade closely. G70 transport chain costs less per meter than G80 alloy chain because the base material is cheaper and the testing program is less intensive. G80 costs more, but the premium buys a higher working load limit, so a smaller-diameter G80 chain can sometimes replace a larger G70 chain. When the required working load limit is high, the total installed cost of G80 may actually be lower than that of a thicker G70 chain.
For a more detailed discussion of how steel chains are rated and selected, see our heavy-duty steel chain selection guide.
Common Misconceptions About Chain Grades
- Myth: G70 and G80 use the same steel. G70 is a carbon steel chain; G80 is an alloy steel chain with added elements that improve strength and hardenability.
- Myth: the grade number is the working load limit in hundreds of pounds. The number refers to the strength class, not a direct load rating. Always read the working load limit on the tag or the test certificate.
- Myth: a higher grade is always the best purchase. Higher grades cost more and can be stiffer and harder to handle. Choosing G80 for a simple tie-down job adds cost without adding value.
- Myth: any chain with the same grade mark is identical. Manufacturing quality, dimensional control, and testing procedures vary between producers. Buy from a documented source and keep certificates for traceability.
Being able to explain the strengths and limits of G70 and G80 prevents costly mistakes. Both grades are legitimate products with clearly defined roles. The best chain is not the highest grade; it is the grade that matches the load, the application rules, and the operating environment.
Frequently Asked Questions
Q1: Is G80 chain always stronger than G70 chain?
Yes. At any given nominal diameter, a properly manufactured G80 chain has a higher working load limit and a higher minimum breaking force than a G70 chain. This is the result of the alloy steel composition and the more demanding heat treatment and proof testing used for G80.
Q2: Can I use G70 chain for overhead lifting?
No. G70 chain is intended for cargo securement and transport applications. It does not meet the material and rating requirements for overhead lifting under most industrial safety regulations. Use G80 or a higher alloy grade whenever a load is suspended above personnel or equipment.
Q3: What does the number in the grade name mean for G80?
The number is a label referring to the strength class of the chain. A G80 chain corresponds to a nominal strength class of 80, which means it is manufactured and tested to the minimum breaking force limits required for grade 80 alloy chain in the applicable standard. The number is not the working load limit.
Q4: Why is G80 chain more expensive than G70 chain?
G80 chain uses higher-cost alloy steel, requires additional heat treatment, and is subjected to more stringent proof testing and quality control. These processes increase material and production costs, and the premium buys a higher working load limit and a greater safety margin for lifting applications.
Q5: Can G80 chain be used for towing or recovery work?
Yes. G80 alloy chain is strong enough for towing and recovery within its working load limit. However, it has lower elongation than G70, so it absorbs less shock during a hard pull. For general towing, G70 remains the more common choice because it is more forgiving and more economical.
