Engineering Glossary

A professional standards organisation for the oil and gas industry. API publishes over 700 standards and recommended practices covering equipment specifications, materials, and safe operating procedures for upstream, midstream, and downstream operations.

An engineering standards organisation that publishes widely adopted codes such as the ASME Boiler & Pressure Vessel Code (BPVC) and ASME B31 piping codes. ASME certification is often a contractual requirement for pressure vessels, piping systems, and lifting equipment.

A principle stating that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure. Derived from conservation of energy for ideal (inviscid, incompressible) flow: P + ½ρv² + ρgh = constant along a streamline. Applied in pipe sizing, venturi meters, and aerofoil design.

An intelligent 3D model-based process that provides architecture, engineering, and construction (AEC) professionals with the tools to plan, design, build, and manage buildings and infrastructure. BIM enables clash detection, quantity take-off, and lifecycle asset management before construction begins.

A comprehensive list of all components, sub-assemblies, raw materials, and quantities needed to manufacture a product or construct a facility. In engineering, a BOM is used for procurement, cost estimation, and spare parts planning.

The use of software to create, modify, and optimise engineering drawings and 3D models. Common platforms include AutoCAD, SolidWorks, CATIA, and Revit. CAD files are the primary deliverable for mechanical, civil, and electrical design.

The formation and violent collapse of vapour bubbles in a liquid when local pressure drops below the liquid's vapour pressure. In pumps, cavitation causes erosion, vibration, and noise. It is avoided by ensuring sufficient Net Positive Suction Head (NPSH) at the pump inlet.

A branch of fluid mechanics using numerical methods to simulate and analyse fluid flow, heat transfer, and associated phenomena. CFD is used for HVAC design, combustion modelling, pipeline simulation, and aerodynamic analysis of structures.

A valve used to regulate the flow of a fluid by varying its opening in response to a signal from a controller. Control valves are the final control element in most process loops. Key specifications include Cv (flow coefficient), valve type (globe, ball, butterfly), and actuator type (pneumatic, electric).

A project management algorithm that identifies the longest sequence of dependent tasks — the critical path — which determines the minimum project duration. Any delay to a critical path activity directly delays the project end date. Used widely in EPC projects.

The time-dependent, permanent deformation of a material under sustained mechanical stress, particularly at elevated temperatures. Creep is a critical design consideration for high-temperature components such as turbine blades, pressure vessels, and furnace tubes.

A computerised control system for a process or plant in which controllers are distributed throughout the facility rather than centralised. A DCS coordinates continuous processes such as oil refining, chemical production, and power generation. It interfaces with field instruments via I/O modules.

A contract model in which a single contractor is responsible for all detailed design (engineering), purchasing of equipment and materials (procurement), and building the facility (construction). The owner receives a completed, functional asset. Common in oil & gas, petrochemical, and power generation projects.

The ratio of the maximum load a structure or component can withstand to the actual working load applied. A factor of safety above 1.0 provides a safety margin for uncertainties in material properties, loads, and manufacturing quality. Typical values range from 1.5 to 4 depending on the application and consequence of failure.

Testing performed at the manufacturer's facility before equipment is shipped to site. FAT verifies that the equipment meets design specifications and operates correctly under simulated conditions. Witnessing FAT is typically required by the client or certifying authority.

A numerical technique for solving structural, thermal, and fluid problems by dividing a complex geometry into a mesh of finite elements. FEA is used to calculate stress, strain, displacement, and temperature distribution in components. Common software: ANSYS, Abaqus, and NASTRAN.

The detailed design phase that follows conceptual engineering and precedes EPC contracting. FEED produces sufficiently detailed documents — process design basis, equipment datasheets, plot plans, cost estimates — to enable a bankable capital cost estimate (±10–15%) and a final investment decision (FID).

A systematic method for identifying all ways in which a product or process can fail, evaluating the effects of each failure, and prioritising corrective actions by risk priority number (RPN = Severity × Occurrence × Detectability). FMEA is used in design reviews and process qualification.

A resistance term added to heat exchanger calculations to account for the reduction in heat transfer caused by deposits (scale, corrosion products, biological growth) on heat transfer surfaces over time. TEMA standards specify fouling factor values for different process fluids.

A standardised system (ASME Y14.5 / ISO 1101) for defining and communicating engineering tolerances on engineering drawings. GD&T specifies allowable variation in form, orientation, location, and runout of features, ensuring that manufactured parts function as intended when assembled.

A material's resistance to permanent surface deformation. Common measurement scales: Rockwell (HRC/HRB — indentation with cone or ball), Brinell (HB — large ball indenter, for castings), and Vickers (HV — diamond pyramid, precise and versatile). Hardness correlates with tensile strength for many steels.

A structured, systematic examination of a process or operation to identify potential hazards and operability problems. A multidisciplinary team applies guide words (No, More, Less, Reverse, Other Than) to process parameters (flow, temperature, pressure) and evaluates deviations on P&IDs.

The reduction in total hydraulic head caused by friction and minor losses (fittings, valves) as fluid flows through a pipe system. Major (friction) head loss is calculated using the Darcy-Weisbach equation: h_f = f(L/D)(v²/2g). Used in pump sizing and pipe network analysis.

Equipment designed to transfer heat between two or more fluids at different temperatures without mixing them. Types include shell-and-tube (most common in oil & gas), plate-and-frame, air-cooled, and double-pipe. Designed to TEMA or ASME standards.

The technology and systems used to provide thermal comfort and acceptable indoor air quality. HVAC design covers load calculations, equipment selection (chillers, AHUs, FCUs), duct sizing, and controls. Standards include ASHRAE 90.1 (energy efficiency) and ASHRAE 62.1 (ventilation).

An equivalent diameter used in fluid mechanics calculations for non-circular ducts or partially filled pipes. Defined as D_h = 4A/P, where A is the cross-sectional flow area and P is the wetted perimeter. Used to calculate Reynolds number and friction factor for rectangular or annular channels.

The international standards body for electrical, electronic, and related technologies. Key IEC standards include IEC 60364 (electrical installations), IEC 61511 (functional safety for process industries), and IEC 60079 (equipment for explosive atmospheres). IEC standards are widely adopted across the Middle East and Asia.

A worldwide federation of national standards bodies that develops and publishes international standards across engineering, manufacturing, and management. Relevant standards include ISO 9001 (quality management), ISO 14001 (environmental management), and ISO 45001 (occupational health and safety).

A 3D piping drawing that shows a single pipeline in isometric projection, including all fittings, valves, supports, dimensions, and weld numbers. Isometrics are the primary shop fabrication and site construction documents for piping systems. They are extracted from 3D CAD models (PDMS, SP3D) or drawn manually.

A globally used green building rating system developed by the US Green Building Council. Buildings are scored on energy efficiency, water use, indoor air quality, materials, and site sustainability. Certification levels: Certified, Silver, Gold, and Platinum.

The effective average temperature difference between two fluid streams in a heat exchanger, used in the fundamental heat transfer equation Q = U × A × LMTD. LMTD accounts for the varying temperature profile along the exchanger length and depends on the flow arrangement (co-current or counter-current).

A calculation that determines the steady-state voltages, current magnitudes and directions, and power flows throughout an electrical power system under specified loading conditions. Also called power flow analysis. Used in electrical area classification studies, cable sizing, and protection relay coordination.

An assembly of one or more enclosed sections containing motor starters, variable frequency drives (VFDs), feeder breakers, and bus bars used to control electric motors. MCCs are engineered to IEC or NEMA standards and include protection devices for motor overload, short circuit, and earth fault.

The three engineering disciplines responsible for the systems inside a building. Mechanical covers HVAC and fire protection, Electrical covers power distribution and lighting, and Plumbing covers water supply and drainage. MEP coordination (often via BIM) prevents clashes between systems during construction.

A formal process that ensures changes to processes, equipment, procedures, or facilities are systematically reviewed for safety implications before implementation. MOC is a requirement of process safety management (PSM) regulations and helps prevent accidents caused by poorly managed modifications.

Also called the second moment of area (I). A geometric property of a cross-section that describes its resistance to bending. A higher I value means greater stiffness. For a rectangular section: I = bh³/12. Tabulated values are published for standard steel sections (I-beams, channels, hollow sections) in AISC or SCI handbooks.

The average time elapsed between two consecutive failures of a repairable system or component, measured under normal operating conditions. MTBF = Total operating time / Number of failures. It is a key metric in reliability-centred maintenance (RCM) studies and spare parts optimisation.

The average time required to restore a failed system or component to full operation, including diagnosis, repair, and verification. MTTR = Total downtime / Number of repairs. Reducing MTTR increases equipment availability (Availability = MTBF / (MTBF + MTTR)).

Testing techniques that evaluate the properties of a material or component without causing damage. Methods include Ultrasonic Testing (UT), Radiographic Testing (RT / X-ray), Magnetic Particle Testing (MPI), Dye Penetrant Testing (DPI), and Eddy Current Testing. NDT is mandatory for welds in pressure vessels and pipelines.

A measure of the absolute pressure at the pump suction inlet above the fluid's vapour pressure. NPSHa (available) must always exceed NPSHr (required by the pump) to prevent cavitation. NPSHa depends on liquid level, suction pipe friction losses, and fluid vapour pressure at operating temperature.

A composite metric measuring how effectively manufacturing equipment is used relative to its full potential. OEE = Availability × Performance × Quality. World-class OEE is typically ≥85%. It identifies losses due to unplanned downtime, speed reduction, and product defects.

A schematic diagram showing all process equipment, piping, instrumentation, and control systems in a process plant. P&IDs use standardised symbols (ISA 5.1 / ISO 10628-2) to represent vessels, pumps, valves, heat exchangers, and instruments. They are the primary reference document for HAZOP studies, operations, and maintenance.

A 3D plant design software platform widely used in oil & gas, petrochemical, and power industries for piping, structural, and equipment modelling. PDMS (by AVEVA) enables clash detection, automatic isometric generation, and material take-off. Comparable platforms include Intergraph SP3D and Bentley OpenPlant.

A project management tool that analyses the tasks involved in completing a project, especially the time needed. PERT uses three duration estimates for each activity (optimistic, most likely, pessimistic) to calculate an expected duration and identify the critical path under uncertainty.

A diagram showing the major process equipment, primary flow streams, operating conditions (temperature, pressure, flow rate), and material balance for a process. The PFD is developed before the P&ID and serves as the process engineering baseline document.

A ruggedised industrial computer used to automate discrete or sequential process control. PLCs execute ladder logic or function block programs and interface with field devices (sensors, actuators) via digital and analogue I/O modules. Used in manufacturing, water treatment, and utilities.

The negative ratio of transverse strain to axial strain when a material is subjected to uniaxial stress. For most metals, Poisson's ratio is 0.25–0.35. For steel it is approximately 0.30. It is used in multiaxial stress analysis and finite element modelling.

A structured process used to determine what must be done to ensure any physical asset continues to fulfil its intended functions. RCM identifies failure modes, their causes and consequences, and selects the most appropriate maintenance task — preventive, predictive, or run-to-failure.

A dimensionless number that predicts the flow regime of a fluid in a pipe or over a surface. Re = ρvD/μ, where ρ = density, v = velocity, D = hydraulic diameter, μ = dynamic viscosity. Re < 2300: laminar; 2300–4000: transitional; Re > 4000: turbulent. Named after Osborne Reynolds (1883).

Testing performed at the installation site after equipment has been installed and commissioned, verifying that it functions correctly in the actual operating environment. SAT follows FAT and confirms that transportation, installation, and integration have not affected equipment performance.

A control system architecture that uses computers, networked data communications, and graphical user interfaces to provide supervisory-level management of field equipment — typically across large geographic areas such as pipelines, power grids, or water distribution networks.

A discrete level (SIL 1–4) assigned to a safety instrumented function (SIF) that defines the required probability of failure on demand (PFD). Determined through a Layer of Protection Analysis (LOPA). SIL verification is performed per IEC 61511 to ensure adequate risk reduction.

A simplified notation for representing a three-phase power system using a single line for each three-phase circuit. SLDs show the arrangement of transformers, buses, circuit breakers, protective relays, and main cable runs. They are the primary reference for electrical system design and protection coordination.

The maximum stress a material can withstand while being stretched before fracturing. Also called Ultimate Tensile Strength (UTS). Determined from a tensile test (stress-strain curve). Structural steel typically has a UTS of 400–550 MPa. Used in material selection and stress analysis.

A material property (k, W/m·K) that quantifies how well it conducts heat. High k (copper ≈ 385 W/m·K, aluminium ≈ 205 W/m·K) is desirable for heat exchangers. Low k (mineral wool ≈ 0.04 W/m·K) is required for thermal insulation. Used in Fourier's law: q = -k∇T.

An electronic device that controls the speed of an AC motor by varying the frequency and voltage of the power supply. VFDs provide significant energy savings on variable-torque loads (fans, pumps) because power consumption is proportional to the cube of rotational speed. Also called a Variable Speed Drive (VSD) or inverter.

A measure of a fluid's resistance to deformation at a given rate. Dynamic (absolute) viscosity μ is measured in Pa·s (or centipoise, cP). Kinematic viscosity ν = μ/ρ, measured in m²/s (or centistokes, cSt). Viscosity is critical for pump selection, pipe sizing, and heat exchanger design.

The stress at which a material begins to deform plastically (permanently). Below the yield strength, deformation is elastic and reversible. Allowable design stress in pressure vessel codes (ASME BPVC) is typically a fraction of yield strength to maintain elastic behaviour under operating conditions. Mild steel yield strength ≈ 250 MPa.