How rate calculation works

Two steps, kept separate

Sizing and pricing are different problems and the tools treat them that way. First the preset works out what the plant needs — how many tanks, how big, how many pumps at what duty. That part is engineering arithmetic and does not involve money at all. Then, if you want it to, the rate book puts a figure against each line.

You can use the first half on its own. Switch the rate mode to I’ll enter my own and every rate box empties, leaving a clean take-off to send out for quotation.

The two anchors

There is no price feed behind these tools and there is not going to be one. Instead every estimated rate is built from two numbers a buyer in this trade already knows for their own city:

• Fabricated mild steel, per kg — plate delivered, cut, rolled and welded. Not the bare mill rate: roughly the mill rate plus the shop work on it.
• Skilled labour, per day — one day of fabrication or erection labour.

Both are on screen and editable, seeded per country and dated September 2026. Change the steel rate and every line moves with it. That is the point: engineering ratios hold while absolute prices drift with the market, the exchange rate and the season.

How a line is priced

rate = mass × steel rate × grade multiple
     + install days × labour rate

Every line shows the mass and the days it used, under the equipment name, so you can check the arithmetic without leaving the page. A 50 m³ mild steel tank reads:

Rate from 3,601 kg + 6 days labour
3,601 × 400 + 6 × 2,500 = 1,455,400

Weight versus steel-equivalent mass

This is the distinction most worth understanding, because the same column means two different things depending on the line.

For something fabricated — a tank, a vessel, a silo — the mass is its actual steel weight, computed from real geometry. A cylindrical tank at a height-to- diameter ratio of 1.5, shell plus both ends, at the plate thickness given:

D = ∛(4V / 1.5π)          H = 1.5 D
area = πDH + 2 × (π/4)D²
mass = area × thickness × 7850 kg/m³

For something bought in — a pump, a tractor, a compressor — the mass is a price proxy: what that item costs, expressed as the weight of fabricated plate that would cost the same. A machine runs two to four times its own weight in those terms, because it is machining, bearings and a motor rather than plate and weld. A 60 hp tractor prices like seven tonnes of plate work and weighs two.

Which is why the Total weight column shows a dash on bought-in lines, and why the job total is labelled steel to fabricate. It is the tonnage your fabricator handles, not the weight of the delivered plant.

Material grade

Where the choice is real, an oil-contact material picker offers mild steel, SS 304 or SS 316. Stainless is priced at 3.2× mild steel — that covers the plate, which runs three to four times, and the slower, more careful shop work it needs. 316 carries a further quarter on top.

Some lines ignore the picker on purpose. Crude tankage and utilities stay mild steel whatever you choose, because nobody builds them in stainless. An acid splitting tank, a deodoriser and a hydrogenation converter stay 316 or lined whatever you choose, because hot dilute sulphuric acid eats 304 and so does 240 °C under vacuum.

Shop-built or site-erected

About 15 tonnes is what goes down a road in one piece. Past that a tank is built where it stands — plate, rings and welders to site — which is a different price, a different programme and usually a different contractor. Any line over that weight is marked site-erected so it does not slip through as a delivered item.

Rounded sizes

Vessel volumes snap to sizes a fabricator would actually build, on a ladder of preferred numbers a third or less apart. So a small change in throughput may leave a vessel on the same figure — a 5 m³ tank genuinely serves a range of duties — but it will never sit still across a large one.

What the totals mean

• Material — the mass portion of every line, at the steel rate and grade multiple.
• Labour — install and erection days at the labour rate. It does not include shop fabrication, which is already inside the steel rate.
• Quotation total — the two together, counting only lines that have a rate against them.

Type over any rate and yours is used instead; the line stops being marked estimated and the split is apportioned the way that line’s estimate divided. In manual mode the split disappears entirely, because a rate you typed is one number with no material-and-labour division of its own.

The PDF

The report carries the inputs it was built from, every group as a table, the totals, and — in estimate mode — a How the estimate was built section listing both anchors, the stainless multiple and the review date. Estimated rates are marked est. Money is written with the ISO code rather than the symbol, because the report uses a base-14 font that cannot encode ₨, ₹, ৳ or ؋ — a symbol would silently vanish and leave a bare number.

What is always excluded

Every tool lists its own exclusions in its Questions section, but these are never included anywhere: civil work and foundations, buildings and structure, the electrical substation and MCC, boilers and steam distribution unless named, effluent treatment, freight, insurance, duties and taxes, erection supervision, commissioning, spares and your margin.