AD 520: Amendment to Table 8 in the MPS-Bolts (issue 14)

The BCSA has reviewed the requirements for impact test for machined test pieces in Table 8 of the Model specification for the purchase of structural bolting assemblies and holding down bolts (MPS-Bolts) following discussions with bolt suppliers. Currently Table 8 requires a sample size of three bolts, per manufacturing lot, for property classes up to and including 8.8, and five bolts for property class 10.9, see table below.

For bolts used in normal UK temperatures (T), (i.e. minimum -15°C), a sample size of one bolt, per manufacturing lot, for any property class, was found to be more appropriate. This is in line with Table 9 of the MPS-Bolts. For bolts used in temperatures below -15°C but above -50°C, a sample size of three bolts, per manufacturing lot, for all property classes should be specified. For bolts used below -50°C, the purchaser should discuss the sample size with a bolt metallurgist and consider increasing the sample size. The new sample size should be communicated to the bolt supplier on the purchase order.

It is the responsibility of the purchaser to confirm the sample size at the time of order, otherwise it will be assumed that the fasteners will not be used at service temperatures below -15°C.

The revised Table 8 for evaluation of the impact strength should read as the table below.

Contact: Ana M. Girão Coelho
Telephone: 020 7747 8127
Email: ana.girao-coelho@bcsa.org.uk