BS A 327:1998 Nuts, bihexagonal, self-locking, with counterbore and MJ threads, classifications: 1100 MPa (at ambient temperature)/425 degreesC, 1100 MPa (at ambient temperature)/650 degreesC, 1210 MPa (at ambient temperature)/425 degreesC, 1210 MPa (at ambient temperature)/730 degreesC, 1550 MPa (at ambient temp

standard by BSI Group, 07/15/1998