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Engineering Blog

Insights from
the Field

Technical articles on process engineering, simulation, process safety, and project management — written by engineers with over 100 years of combined upstream oil & gas experience.

Hazard &Risk Assess.LOPA /SIL Class.SRSDesignSISBuild & FATProof test / MoC loopSIL 1–3IEC 61511 Safety Lifecycle
SafetyEC&I

Functional Safety Management to IEC 61511: The Full Lifecycle Explained

SIL classification is just one step in a much longer process. IEC 61511 defines a complete safety lifecycle — from hazard identification through design, installation, proof testing, and eventual decommissioning. Understanding the full lifecycle is essential for anyone managing safety instrumented systems in the process industry.

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Time →Pressure →Normal op.ESDMAWPPSV lifts50% MAWP targetStableHYSYS Dynamics
EngineeringSimulation

Dynamic Simulation in HYSYS: When Steady-State Isn't Enough

Steady-state simulation answers the design question: what does the process look like at normal operating conditions? Dynamic simulation answers the operational question: what happens when it doesn't. Here is when you need HYSYS Dynamics and what it can tell you that a steady-state model cannot.

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Zone 0Zone 1Zone 21.5 m3 mIIC — HydrogenIIB — EthyleneIIA — PropaneGas GroupsIEC 60079 / ATEX
EC&ISafety

Electrical Area Classification: Zone 0, Zone 1, and Zone 2 Explained

Electrical area classification determines what electrical and instrumentation equipment can be safely installed where. Getting it wrong puts facilities at risk of ignition. Getting it right — without being excessively conservative — keeps projects on budget and avoids equipment proliferation.

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XV-001XV-002P-001ESD-2AlarmPAHHLALLTAHHFSLManual×××××××××××CAUSESEFFECTS →
EC&IEngineering

Cause and Effect Matrices: How to Structure a C&E for a Production Facility

The cause and effect matrix is the document that translates your P&ID interlocks into testable, auditable logic. A well-structured C&E prevents commissioning surprises, supports SIL verification, and gives operations a clear reference for every trip and alarm on the plant.

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RECIPROCATINGinout↕ strokePositive DisplacementvsCENTRIFUGALGasin →outDynamic / High RPM
Engineering

Reciprocating vs Centrifugal Compressors: How to Choose the Right Machine

Compressor selection is one of the most consequential decisions in a gas processing project. Choosing the wrong machine type leads to poor turndown, excessive maintenance, or a compressor that simply cannot meet the duty. Here is how to make the right call.

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Pre-FEEDFEEDFIDDetailedEPC±40%±20%±5%Project Phases
EngineeringProject Management

What Is a FEED Study and Why Does It Matter?

Front End Engineering Design is the engineering phase that turns a concept into a fundable project. Done well, it defines scope, cost, and schedule with enough accuracy to get investment approved. Done poorly, it creates expensive problems in detailed design.

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InletGasOilWaterGASOILWATER
EngineeringSimulation

How to Size a Three-Phase Production Separator

Three-phase separators are among the most common pieces of equipment in upstream oil and gas. Sizing them correctly requires balancing gas capacity, liquid retention time, and water droplet settling — and knowing which constraint governs your design.

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HAZOPNODENO FLOWMORELESSREVERSEAS WELL ASOTHER THAN
EngineeringSafety

Running an Effective HAZOP: Ten Lessons from the Field

A HAZOP study is only as valuable as the quality of its findings — and a poor facilitation can turn a critical safety exercise into an expensive rubber stamp. Here are ten lessons from years of leading and participating in HAZOP workshops across onshore and offshore projects.

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Modular EPF SkidWellWellheadSep.3-PhaseComp.GasExportMeterWater Tx
EngineeringProject Management

Early Production Facilities: Design Principles for Fast-Track Upstream Projects

An Early Production Facility is not simply a smaller, simpler version of a full field development. It is a different type of engineering problem — one that demands a different set of design decisions, trade-offs, and delivery priorities.

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SISAlarmBPCSSIL — SafetyBPCS Alarm +Basic Process ControlHazardProtection Layers (LOPA)
EngineeringSafety

SIL Determination Using LOPA: A Practical Guide for Process Engineers

Safety Integrity Level determination is a core requirement for any Safety Instrumented Function protecting against a major hazard. LOPA provides the quantitative link between the hazardous event frequency and the risk reduction required from the SIS — but applying it correctly requires understanding several concepts that are frequently misunderstood.

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Temperature →Pressure →PcLiquidVapor2-PhaseTcP-R EOS1976
EngineeringSimulation

Why Peng-Robinson EOS is a Good Choice in HYSYS

The Peng-Robinson equation of state is the go-to thermodynamic model in Aspen HYSYS for hydrocarbon systems. Here's why it earns that position — and where its limits lie.

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Set PressureProcess ↑Relief →SpringDisc & Seat
EngineeringSafety

Why Routine Maintenance for Pressure Relief Valves (PSVs) is Non-Negotiable

A PSV that passes its installation inspection is not a PSV that will perform reliably five years later. Here is why routine maintenance is a safety-critical obligation, not a scheduled inconvenience.

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Q =β × Hρ × CpA = QKd√(2gΔP/ρ)β = expansion coeff.Kd = discharge coeff.API 520 / API 526Orifice sizes: D–T
EngineeringSafetySimulation

How to Size a Token Relief Pressure Relief Valve (PSV)?

Token relief PSVs protect systems against minor, predictable overpressure scenarios. Sizing them correctly requires understanding the specific relief case — and why an oversized valve can be just as problematic as an undersized one.

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CLOSEDCLOSEDHeat sourceToken PSVP ↑Blocked-in liquidThermal expansion → pressure buildup → token PSV lifts
EngineeringSafetySimulation

When is a Token Relief PSV Needed?

Not every overpressure scenario requires a full-scale relief valve. Understanding when a token relief PSV is the right engineering solution — and when it is not — is a fundamental process safety skill.

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