17
Sep
Understanding Chain Grades
Knowing the difference between Grades is essential when selecting the right chain for your lift or application.
Chain is a durable and versatile tool for lifting and is more commonly used for lifting goods in Australia than in other parts of the world, certainly more so than in Europe.
We know the strength of a chain by its Grade. The Grade of chain is determined by the mean stress in the chain at the minimum breaking load. The higher the grade, the smaller and lighter the chain for a given working load. It makes a big difference: Grade 120 chain has a 50% increase in working load limit compared to a similar size chain in Grade 80, allowing a reduced size of chain depending on the working load required.
Carbon and alloy steel chain
Welded chain falls into two categories:
1. Carbon steel chain (most commonly used for tie down and container securement purposes and not recommended for overhead lifting)
2. Alloy steel chain (unlike carbon chain, all graded alloy steel chain is recommended for overhead lifting)
Grade is important when it comes to the difference between carbon and alloy chain. The biggest difference between Grades of chain is that carbon steel chain (Grade 30, 43, and 70) is not recommended for overhead lifting, while alloy steel chain (Grade 80, 100, and 120) is recommended for use in sling assemblies and overhead lifting applications.
(However, chain slings made from alloy steel are not suitable for use in acidic environments as this can cause hydrogen embrittlement.)
Manufacturers are now developing Grade 140 and 160 for the Australian market in other industries that will soon find their way into the lifting industry. These chain systems are being developed within Europe but the manufacturers are specifically targeting the Australian market.
Australia has already recognised the value of using Grade 100 for overhead lifting with the revision of standards related to chain slings for lifting purposes. The Australian Standards: ‘AS 3775.1: 2014 Chain Slings for Lifting Purposes – Part 1 – Product Specification’, and ‘AS 3775.2: 2014 Chain Slings for Lifting Purposes – Part 2 – Care & Use’ have both been extended to include Grade 100 systems as well as Grade T(80) systems and similarly the scope within AS 3776: 2015 Lifting Components for Grade T(80) has been extended to include Grade V(100).
In Australian Standard ‘Chain slings for lifting purposes—Grade T(80) and V(100)’ the quality grading system provides for the variations in mechanical properties of the finished product. Each grade is identified by a letter in the series T(80) or V(100) which allows for positive identification and easy selection.
The five common types of chain
Grade 60 Stainless Steel
Grade 70 Transport Chain
Grade 80
Grade 100
Grade 120
G60
SUITABLE FOR LIFTING?
Grade 60 Stainless Steel
RELEVANT STANDARD
AS 2321 DIN 5688
DESCRIPTION
Grade 60 stainless steel lifting chains and accessories can be used in different corrosive environments and at higher temperatures compared to normal lifting accessories. It is typically used in pump stations and marine environments.
G70
SUITABLE FOR LIFTING?
Grade 70 Transport Chain
RELEVANT STANDARD
AS 4344
DESCRIPTION
Also known as transport chain, Grade 70 chain is designed for use as a tie down chain or lashing for transportation. It has a gold chromate finish to help resist corrosion from continuous exposure to the elements and the rigours of road use. It is too brittle for lifting.
G80
SUITABLE FOR LIFTING?
Grade 8 Grade 80 Grade T Alloy Chain
RELEVANT STANDARD
AS 2321
DESCRIPTION
Grade T(80) chain is designed for industrial lifting applications. It is made from alloy steel; it is hardened and tempered. It has a high resistance to impact and is the most economical of the three chain grade types that are suitable for overhead lifting.
G100
SUITABLE FOR LIFTING?
Grade 10 Grade 100 Grade V Alloy Chain
RELEVANT STANDARD
AS 2321
DESCRIPTION
Grade V(100) chain is generally used for chain slings with 25% higher lifting capacity than G80. Manufactured from hardened and tempered allow steel, it has a high resistance to impact and wear. It is now becoming the most common chain used for manufacturing chain slings.
G120
SUITABLE FOR LIFTING?
Grade 12 Grade 120
RELEVANT STANDARD
N/A Must comply with AS 2321 or ISO 16877
DESCRIPTION
Grade 120 chain is specifically designed for extreme overhead lifting applications. It is made from an ultra-premium quality, high strength alloy steel and has a 50% increase in working load limit as compared to a similar size chain in Grade 80. It is typically used where manual handling or weight is a critical factor.
Note that several different Grades of material are used for lifting equipment, which results in slings, crane hooks, shackles, and other lifting components varying considerably in size for a given capacity. Care shall be taken to ensure the compatibility of the ancillary equipment used to sling the load, both in size and capacity. An intermediate link or shackle may be required to allow for a suitable compatibility between components.
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