Piping Work Estimator — Gas Plant / GOSP

Plant Definition

Inputs

Plant type — sets density & effort presets

Major equipment count (vessels, exch., pumps, comp., cols.)

Engineering phase

Site / service complexity — MH multiplier

Tonnage units

Estimating norms & assumptions

Defaults are planning-grade industry heuristics, pre-set by plant type. Override any value to calibrate against your own historical job data.

Lines per equipment

Avg line length (m)

Avg pipe weight (kg/m)

Isometrics per line

Spools per isometric

Valves per line

Flanges per line

Fittings per metre

Support spacing (m)

Welds per metre

Stress-critical lines (%)

MH per isometric (all-in)

MH per stress package

Contingency / growth (%)

Eng. rate ($/MH, optional)

Estimate

Class 4 · −30%…+50%

Bulk pipe

—

Isometrics

—

Total man-hours

—

Bulk Material Take-Off

Engineering Deliverables

Man-Hour Breakdown

Activity	MH

Read before use. This is a Class 4/5 conceptual estimate. Quantities scale linearly from major-equipment count via editable density norms; they are not a substitute for a model-based MTO once a 3D model exists. Tonnage uses a single blended pipe weight (kg/m) — set it to a representative size mix for your plant. Calibrate every norm against your own closed-out job data before committing numbers.

Technical References & Basis of Estimate

BOE

This tool produces an equipment-factored estimate — AACE Class 5–4 methodology. It cannot reach detailed-design accuracy (Class 3 or better) without a 3D-model take-off. References are grouped by how directly they support the output: the framework and accuracy classes are standards-based; the labour and quantity norms draw on published estimating literature; the cascade density ratios are practitioner planning figures you must calibrate.

A · Methodology & accuracy framework — standards

AACE International RP 18R-97 — Cost Estimate Classification System, As Applied in EPC for the Process Industries (rev. 7 Aug 2020).

Defines the equipment-factored method this tool uses, and the Class 5→1 accuracy bands shown in the phase selector.

AACE International RP 17R-97 — Cost Estimate Classification System (generic parent practice).

The classification principles that 18R-97 extends to process plants.

18R-97 accuracy classes — full table

Class	Definition maturity	Typical use	Method	Typical accuracy
5	0–2%	Concept screening	Capacity-factored, parametric, analogy	−50% … +100%
4	1–15%	Feasibility, option select	Equipment-factored, parametric	−30% … +50%
3	10–40%	FEED, budget / FID	Semi-detailed unit costs, assembly items	−20% … +30%
2	30–75%	Detailed design, control / bid	Detailed unit costs, forced take-off	−15% … +20%
1	65–100%	Execution, check / tender	Detailed unit costs, full MTO	−10% … +15%

Highlighted row = what this tool produces. An equipment-factored estimate is Class 4 by method, whatever the project phase. Note FEED by maturity sits at Class 3 — but you only reach Class 3 accuracy with a model-based MTO, not equipment factors. Values are typical at an 80% confidence interval (process-industries, 18R-97) and must be confirmed by project-specific risk analysis. Source: AACE 18R-97.

B · Quantity & man-hour data — published literature

Page, J. S. — Estimator's Piping Man-Hour Manual, 5th ed. Gulf Professional Publishing / Butterworth-Heinemann, 1999.

Basis for the fabrication, erection, weld, fitting, flange and support relationships. Note: this is construction labour, not engineering design hours.

ISBN 0-88415-259-6

Storm, K. K. — Industrial Piping and Equipment Estimating Manual. Gulf Professional Publishing.

Supporting material take-off and quantity norms for process piping.

Towler, G. & Sinnott, R. — Chemical Engineering Design, 6th ed. Butterworth-Heinemann (Elsevier), 2019.

Factorial (Lang / Hand factor) estimating — the basis for treating bulk piping as a factor of equipment count.

C · Cascade density ratios — practitioner norms (calibrate)

Lines per equipment · isometrics per line · spools per iso · MH per iso · stress-critical line %.

Typical contractor and project-controls planning figures — not published in any single standard. Engineering design man-hour rates in particular are proprietary contractor / IPA-type benchmarks. Override every value in the assumptions drawer against your own closed-out job data before relying on the output.

Governing design codes — scope context

ASME B31.3 Process Piping · ASME B31.8 Gas Transmission & Distribution Piping · ASME B31.4 Liquid Pipelines.

Codes governing the design of the piping being estimated. They set the scope, not the estimating norms.

ZEPHRUM KONSULTAN · PIPINGPRO ACADEMY · ENGINEERING TOOLS SUITE