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Love letter to contractor speaking about steel specifications

posted Jun 16, 2018, 8:06 AM by jeffery jim

Steel specification and grading have evolved for the past twenty years and at time, contractors and suppliers never updated their brochures in their submission. In this case, the specification for steel reinforcement bar which have been superseded twice are submitted and the followings are the reply on their submission.

"Apart from that, we found out that the product still make reference to BS 4449:1997 which is superseded twice by revision 2005 and 2009. The main issue is the grade of the steel bar which specified grade 250 and 460 for 1997 edition as shown in Table 1 - Preferred Nominal sizes. The recent 2005 and 2009 editions specified the high tensile properties to be graded as B500 (with yield strength of 500MPa) with three different ductility classes (A, B, C) based on total percentage elongation.

Drawings produced Ref:XXX by XXX stated the use of 460MPa as high tensile reinforcement bars, however we recommend this to be replaced by 500MPa as recommended by BS 4449:2009 or referred as BS 4449:2005+A2:2009. XXX is recommended to purchase BS 4449:2005+A3:2016 which is in-place for making references. The reason behind this recommendation is due to reduced partial safety factor for BS EN 1992-1-1 and BS8110:1997 Amendment Nov.2005.

The other change in BS4449 is the omission of the mild steel of grade 260MPa which shall be covered under BS EN 10080:2005 – Steel for reinforcement concrete – weldable reinforcing steel – general where the scope shall cover the followings (under Clause 1.1 & Clause 5);
· Bars, coils (rod, wire) and de-coiled products;
· Sheets of factory-made machine-welded fabric; and
· Lattice girders

As for compliance to MS 146 Hot Rolled Steel Bars for the Reinforcement of Concrete – Specification, the submitted product data sheet indicates the superseded Malaysia Standard which complies with the 2006 (third) edition which lists deformed bar for both 460MPa and 500MPa without the three classes of ductility as per 2014 (fourth) edition."