Skip to content
Glossary

The vocabulary every engineering document workflow runs on.

Plain-English definitions of the terms that govern engineering, procurement, fabrication, process safety, and turnaround work. Each entry explains the term in operational language and traces it back to the critical engineering documents — drawings and data tables — that Armeta contextualizes.

All terms

16 terms. One document dependency.

EPC and FEED define how projects are contracted and engineered. HAZOP, PHA, MOC, and PSI define how process safety is governed. MTO, BOM, pipe specs, P&IDs, isometrics, line lists, from-to lists, PFDs, LDAR, and turnaround define the operational record. Every one of them ultimately reads from, or writes to, the engineering documents Armeta contextualizes.

A.1
EPC

Engineering, Procurement, and Construction

The contract model under which a single contractor delivers a completed, operating facility to the owner — dominant across industrial capital projects.

Read the definition
A.2
FEED

Front-End Engineering Design

The engineering phase between conceptual design and detailed engineering — where project cost, schedule, and scope are locked in for the EPC contract.

Read the definition
A.3
HAZOP

Hazard and Operability Study

The structured PHA methodology that uses guide words to systematically identify hazards at every node of a process. The dominant PHA method for complex continuous processes.

Read the definition
A.4
LDAR

Leak Detection and Repair

The EPA regulatory program under which facilities handling VOC and HAP streams systematically monitor equipment for fugitive emissions and repair detected leaks within specified timeframes.

Read the definition
A.5
MOC

Management of Change

The OSHA PSM requirement under 29 CFR 1910.119(l) to formally manage every change to a covered process — and one of the most frequently cited PSM elements in enforcement.

Read the definition
A.6
MTO

Material Take-Off

The structured inventory of equipment, piping, and components extracted from engineering drawings — and one of the most consequential numbers on any industrial project.

Read the definition
A.7
P&ID

Piping and Instrumentation Diagram

The master engineering drawing for every process system — equipment, piping, valves, instruments, and every interconnection that defines how the facility is built, operated, and maintained.

Read the definition
A.8
PHA

Process Hazard Analysis

The systematic evaluation of hazards OSHA PSM requires under 29 CFR 1910.119(e). Must be revalidated at least every five years; HAZOP is the most common methodology.

Read the definition
A.9
PSI

Process Safety Information

The documentation package OSHA PSM requires on every covered process — the factual foundation on which PHA, MOC, Mechanical Integrity, and Pre-Startup Safety Review all depend.

Read the definition
A.10
Turnaround

Turnaround

The planned, scheduled shutdown during which major equipment is opened, inspected, maintained, and replaced — the most consequential operational event outside of a major incident.

Read the definition
B.1
Isometric

Piping Isometric Drawing

The 3D-representation drawing used to fabricate, install, and inspect individual pipe spools — the document that governs piping material take-off and shop fabrication.

Read the definition
B.2
PFD

Process Flow Diagram

The high-level engineering drawing that shows major equipment, principal process streams, and operating conditions — the basis on which P&IDs and detailed engineering are developed.

Read the definition
B.3
Line List

Line List

The tabular master record of every piping line in a process unit — line number, size, material spec, insulation, operating and design conditions, and from-to connectivity. The structured complement to the P&ID and isometric.

Read the definition
C.1
BOM

Bill of Materials

The structured, itemized list of every component required to fabricate and install a piping spool or system — the atomic unit from which the aggregate piping MTO is built.

Read the definition
C.2
Pipe Spec

Pipe Specification

The engineering document defining approved materials, components, ratings, and construction requirements for every piping line in a given service and pressure-temperature range. Encoded in every line number.

Read the definition
C.3
From-To List

From-To List

The tabular record of where every piping line begins and ends — the connectivity backbone that ties P&IDs, isometrics, and line lists into a single engineering knowledge graph.

Read the definition

These definitions are written for engineers, project managers, and operations teams who already work with industrial drawings — not as introductions, but as crisp references that connect each term to the workflows it governs and the regulatory frameworks it sits inside.

Your documents, your data

Start with ten of your own documents.

Vocabulary defines the conversation. The fastest way to see what each of these terms looks like when your engineering documents — drawings and data tables alike — are structured, current, and document-traceable is to run Armeta on your actual archive.