Rest in Peace, Hand Factors (1958–2026)

The equipment-factor method served estimators faithfully for almost seven decades. It has earned its retirement — and Kpex’s ISBL tool is the reason why.

A short obituary

In 1947–48, Hans & Lang proposed a beautifully simple idea in a series of three articles: multiply total delivered equipment cost by a single factor — 3.10 for solids processing, 3.63 for mixed, 4.74 for fluids — and you had a plant estimate. Lang himself admitted there was no statistical ground for the numbers: his database held 14 plants, of which only 6 were ever built. In 1958, W. E. Hand refined the idea in “From Flow Sheet to Cost Estimate” (Petroleum Refiner): instead of one factor for the whole plant, use a different factor per equipment type. A fractionating column installs at about 4.0 times its purchase cost; a heat exchanger at 3.5; a compressor at 2.5. That single insight made him a household name in cost engineering.

Read the fine print, though. Hand’s factors covered only seven equipment types typical of the petrochemical industry, were built on F.O.B. carbon-steel pricing, explicitly excluded exotic materials and high-pressure services, and left contingency out (he suggested adding 10% on top). The factors were refreshed by AACE International in 1992 — and that was, essentially, the last service. The refineries Hand measured belong to a world of carbon steel, moderate pressures and 1950s construction labor. Yet in 2026, ISBL estimates are still being multiplied out of that world, carrying the accuracy of a Class 4/5 exercise: roughly −30% to +50%.

Why averages can’t compete with MTOs

A factor is an average of history. It cannot see that your pump is stainless rather than carbon steel, that your column operates at high pressure, or that your exchanger sits three meters from its pipe rack instead of thirty. Every one of those realities changes the bulks — piping, civil, steel, electrical, instrumentation — and the factor flattens them all into one number you cannot audit. When a reviewer asks “where did the piping cost come from?”, the honest answer is: from 1958.

What Kpex does instead

Comparative research on factorial techniques reached a telling conclusion: whether an estimate lands close to actual construction cost depends less on which factors you apply than on the database behind the method. That is precisely the bet Kpex makes.

The ISBL tool in Kpex inverts the logic. Instead of multiplying equipment cost by an average, it derives a material take-off from each equipment item. The platform’s Module A database holds 204 equipment cost models and its still growing — rotating, static, heat transfer, material handling and packages — and each model generates its own MTO for the bulks that surround it: piping, valves and specialties, civil works, structural steel, electrical and instrumentation.

The result is an Inside Battery Limits estimate built the way the plant will actually be built — equipment by equipment, quantity by quantity — with every line traceable back to a model and a dataset, not to a multiplier older than the pocket calculator.