Counting steel, pipe and cable: by weight, length or piece

Rebar arrives by the tonne, pipe by the piece and cable by the metre, but the accountant's ledger has one unit, and the counters on site use yet another. If site materials are measured in different ways the figures can never be matched. To make the numbers stand up, decide first which unit each material is counted in, how it is measured and how to read the tolerance.

Fix the base unit and the conversion first

Each material has a single base unit, consistent with the accounting records (1C or another system) and with the purchase unit, and the conversions are listed:

• Rebar: often booked in tonnes, but also understood by pieces and length.
• Pipe: by piece, or by metre.
• Cable: by metre, usually on whole drums, sometimes as a remnant.
• Sections and plate: by tonne or by piece.

Write the conversions in a table, for example "rebar of this size, 12 metres a bar, theoretical weight 0.888 kg per metre". Without a conversion table the counter counts pieces, the accountant counts tonnes, and the figures never meet.

Steel: weigh or count

Weighing suits loose material and tied bundles. It is the most direct, but it needs a weighbridge or platform scale, and the weight of ties and timber spacers must be deducted. Counting pieces suits steel supplied in fixed lengths, converted by theoretical weight.

An example: 12 mm deformed bar has a theoretical weight of about 0.888 kg per metre. (A reference value derived from cross-section and density; actual weight follows the product standard and the contract.) At 12 metres a bar, that is about 10.66 kg, so 100 bars are equivalent to about 1.066 tonnes.

Weighed weight often differs from theoretical weight. How much deviation is acceptable depends on the contract and the product standard, and should be agreed by the project and finance. What matters is using the same method throughout the project, not weighing this time and counting the next.

For bundled deliveries, check the piece count and weight on the bundle tag, then open a few bundles to verify. Before weighing, test the scale with a known weight and do not use it if the error is large.

Pipe: count pieces, measure offcuts

Pipe in fixed lengths is counted by piece, and cut offcuts are recorded by length. Set a rule for offcuts: those above a certain length (such as 1 metre, decided by the project) are stored apart as "remnants" with their length recorded, and shorter ones are treated as scrap.

For example, 200 pipes of 6 metres make 1,200 metres. Another 14 remnants average 2.5 metres, making 35 metres. Remnants are stored apart from whole pipes and must also agree with the issue records.

Check diameter, wall thickness and material: pipes that look alike but differ in specification are the easiest to mix up.

Cable: drums, metres and labels

For whole drums, read the label: type, specification, length. For a part-used drum there are three ways to find the length left:

• Read the metre marks: many cables carry consecutive length markings on the outer sheath every metre, so subtract the first reading from the last.
• Weigh and calculate: gross drum weight minus the empty drum, divided by the weight per metre.
• Measure: pay out the cable and measure it. It is the most accurate and the slowest.

An invented example: a drum weighs 410 kg gross and the empty drum 60 kg, so the cable is 350 kg. This type weighs 1.25 kg per metre, so about 280 metres remain. (Figures are illustrative.) Weighing carries an error margin, so note the method.

Making the figures stand up

• State on the count sheet the way of measuring (weighed, counted or measured), the scale or tape used and the conversion factor.
• Store remnants and odd lengths apart and register them apart.
• Compare like with like. Changing the method creates "false differences".
• Agree beforehand with the project manager and finance the range accepted between theoretical and measured values.
• When weighing, have two people present, and read the figure aloud, record it and photograph it.
• Rain and mud add weight to steel, so clean the surface or note the weather in the record.

In short

The hard part of counting site materials is how to measure them. UzWarehouse's project and site warehouse counts check issue, return and transfer records, agree units and basis with you before counting, and count each warehouse in turn.