Appendix B - Chain | NZ Transport Agency Waka Kotahi

Current standards

AS/NZS 4344.
BS 4942 is six parts and titled: Short link chain for lifting purposes. This standard incorporates the following ISO standards – 1834, 1835, 1836, 3075, 3076, 3077.

The requirements of the above standards are essentially the same. In the following any significant difference in the contents of these standards will be stated; minor differences will be ignored.

The standards detail the minimum requirements for compliance, eg details of such as: manufacture dimensions marking material composition testing procedure mechanical properties certification.

Identification

The features by which a chain may be identified are:

its dimensions, ie size
marking.

Chain size

The size of the chain refers to the nominal diameter of the material from which the link is made. The standards specify the maximum and minimum limits of the diameter of the material for every nominal chain size. These limits on material size are roughly ±5 percent of the normal diameter.

To obtain the chain size, the material from which the link is made should be measured:

either on the straight portion of the unwelded leg of the link
or, if both legs of the link are welded, on the straight portion of the link adjacent to the weld
in two positions at right angles in the same plane; the dimension is to be taken as the mean of the two measurements.

Marking

Grade marking

The letters L, M, P, S and T are used to designate the strength grade of the chain. The letter designating the particular strength grade must be stamped or embossed on either every twentieth link or every 1 metre of chain, whichever is the lesser.

The marking must not:

coincide with a weld
be situated where the material is displaced by the weld
be situated on the extrados (the extrados is the outer curved surface of the link).

Identification marking

The following marks must be legibly and permanently displayed either on the links of each manufactured chain length or on metal tabs which are permanently attached to each end of each manufactured chain length:

the manufacturer’s name or trademark
the lot number or other reference mark which indicates the order against which the chain was supplied.

PWB Chain markings and specifications – pre 1997

PWB AS/NZS4344:1995 Chain markings and specifications – 97/98 onwards

The chain tables are reprinted by permission from the Lifting Equipment Engineers New Zealand Inc.

Chain strength

Note: With respect to the Minimum breaking strength and elongation of chain table:

Tonne = kN 9.81
AS/NZS 4344 lists the preferred chain sizes in mm as follows: 6, 7, 7.3, 8, 10 and 13
The table does not give the breaking strengths of chains larger than 16mm; these larger sizes are considered too clumsy for normal load securing purposes.

Minimum breaking strength and elongation of chain table