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.
Subscribe via RSSAPI 520 — Vapour Relief Orifice
A = W / (C · Kd · Kb · Kc)
· √(T · Z / (M · P₁))
C = 0.03948 · √(k · (2/(k+1))^((k+1)/(k-1)))
Kd = discharge coefficient (typ. 0.975)
Concept Selection for Marginal Fields — MOPU vs FPSO vs Fixed Platform vs Subsea Tieback
The development concept is the single decision that determines a marginal field's economics — and it is made when you know the least. A framework for choosing between a fixed platform, an FPSO, a MOPU, and a subsea tieback, and the drivers that actually decide it.
Darren StrengersEmergency Depressurisation and Blowdown — The API 521 15-Minute Rule
Depressure to 50% of design pressure within 15 minutes — the rule everyone quotes and few derive. Working through where it comes from, how the fire case sets the load, how the blowdown orifice gets sized, and why auto-refrigeration quietly drives your material selection.
Jose CampinsFuel Gas and Vapour Recovery — Making an Early Production Facility Self-Sufficient
An EPF wants to run on its own gas and flare as little as possible. The fuel gas system feeds the power plant; the vapour recovery unit claws back the flash gas you would otherwise burn. Both are small systems with outsized consequences if they are wrong.
Jose CampinsStorage and Offloading Without an FPSO — FSOs, CALM Buoys, and Shuttle Tankers
When a MOPU or fixed platform has no export pipeline, the crude has to be stored on the water and handed to a tanker. The storage-and-offloading system is its own engineering problem — and it is what quietly sizes the whole development.
Darren StrengersPigging Philosophy and Pig Launcher / Receiver Design
A pipeline you cannot pig is a pipeline you cannot inspect, clean, or batch-treat. The philosophy choice — utility pigs, intelligent pigs, or no pigging — sets the launcher and receiver design, and that design is permanent. Here is the framework that gets it right at the front end.
Ian BissettCrude Stabilisation and RVP/TVP Control — Multi-Stage Flash vs the Stabiliser Column
Get the vapour pressure wrong and the storage tank breathes hydrocarbons, the tanker rejects the cargo, or you leave stock-tank barrels in the gas. A working guide to RVP, TVP, and the two ways to hit the spec on a weight-limited topside.
Jose CampinsMaterial Selection for Sour Service — NACE MR0175 in Plain Language
NACE MR0175 / ISO 15156 governs metal selection wherever H₂S can crack steel. The standard runs to several hundred pages — the operating principles fit on one. A practical guide to partial-pressure thresholds, qualified materials, and the audit trail the operator needs to defend the choice.
Ian BissettGreenfield vs Brownfield CAPEX Estimating: AACE Class Progression in Practice
AACE cost estimate classes describe the maturity of the estimate, not the quality of the engineering behind it. Understanding the difference is what separates a useful estimate from a number that will be wrong in expensive ways.
Darren StrengersWhat an Independent Engineering Review of a MOPU Actually Checks
A MOPU is a leased, converted asset with a history you did not write, on a schedule that skipped steps. Before an operator accepts it, an independent review tests the offering against the requirements, the standards, and the regulator — across six dimensions that decide whether it is fit for the field.
Darren StrengersSand Erosion Management Beyond API 14E — DNV-RP-O501 in Practice
API 14E's C-factor is a screening tool, not a sand model. When solids are in the stream, the controlling component is the choke or the first elbow downstream — and DNV-RP-O501 is the framework that actually sizes them.
Jose CampinsALARP Demonstration in Practice
ALARP is two letters at the end of a safety case and an obligation that runs through every design decision. The UK Health and Safety at Work Act expects gross disproportion in the cost-benefit comparison — what that means in practice, and where designs go wrong.
Ian BissettPre-Commissioning: Flushing, Drying, and Nitrogen Purging in Practice
Pre-commissioning is where construction quality is verified and hidden defects surface. Flushing, drying, and nitrogen purging are the three operations that most commonly determine whether commissioning starts on time or starts late.
Darren StrengersFlare Radiation and Siting — API 521 Thermal Contour Analysis
The flare is sized by the header; the flare stack is sized by radiation. Working through API 521 Table 5, the Brzustowski-Sommer model, and how the 1500 BTU/hr·ft² contour ends up setting the plot plan.
Jose CampinsMOPU and EPF Lifecycle: Lease, Convert, Operate, Demobilise
A Mobile Offshore Production Unit is a financial instrument as much as it is a piece of engineering. Its lifecycle — acquisition, conversion, operation, redeployment — is what makes early production economic, and what makes it hard.
Darren StrengersCommissioning and Start-Up Sequencing for Oil and Gas Facilities
Most schedule overruns at the end of a project are not engineering or construction problems — they are commissioning problems caused by sequence decisions made months earlier. Getting the sequence right is the work.
Darren StrengersTwo-Phase Pipeline Flow Regimes and Slug Catcher Sizing
Long-distance multiphase pipelines do not flow as homogeneous mixtures — they flow as stratified, slug, annular, or mist regimes depending on conditions. The slug catcher exists because terrain-induced slugs are unavoidable in real pipelines, and getting it right is the difference between a steady production train and one that trips on every pig.
Jose CampinsBrownfield Tie-In Engineering: Hot Tap vs Shutdown Planning
Every brownfield modification eventually comes down to one decision: tie in live, or take the plant down. The choice drives cost, schedule, risk, and the rest of the engineering scope — and it must be made early.
Darren StrengersControl Valve Sizing — Cv, Choked Flow, and Trim Selection
A control valve undersized by 20% will hunt, a valve oversized by 50% will throttle on the seat. ISA 75 / IEC 60534 gives the equations — choosing the right Cv, trim, and characteristic is the part that takes judgement.
Robin Charles BinnerGas Sweetening with Amines — MDEA, MEA, DEA, and Mixed Solvents
Sour gas containing H2S or CO2 fails sales spec, corrodes carbon steel, and is fatal to operators at low concentrations. Amine gas sweetening is the proven defence — but selecting the right amine, designing the absorber, and protecting the regenerator from thermal degradation requires more than dropping MDEA into a flowsheet.
Jose CampinsAPI 14E Erosion Velocity and Sand Management in Early Production
API 14E gives a one-line correlation that has sized offshore piping for forty years — and is now the most argued-about equation in subsea engineering. Here's what the C-factor really represents, when the conservative limit is right, and where modern guidance moves it.
Jose CampinsBow-Tie Analysis — Threats, Barriers, and Consequences
HAZOP finds hazards. LOPA quantifies their frequency. Bow-tie analysis sits between them — visualising the prevention and mitigation barriers between every threat and every consequence, and exposing where a single failure leaves the system unprotected.
Jose CampinsCentrifugal Pump Sizing and NPSH
Pump cavitation destroys impellers, drops capacity, and shakes piping apart — all because the suction pressure didn't quite clear vapour pressure. NPSH is the calculation that prevents it. Done correctly, the pump runs for twenty years; done badly, it eats itself in six months.
Jose CampinsChoosing the Right Property Package: An EOS Selection Guide
Process simulators offer dozens of thermodynamic models and the wrong choice silently corrupts every result downstream. This is a service-by-service guide to picking the right one — cubic EOS, activity coefficient, GERG, CPA, electrolyte — and knowing when each fails.
Jose CampinsFlare Network Sizing and API 521 Blowdown
Once individual PSVs are sized, the relief load has to land somewhere. API 521 governs the contingency selection, simultaneous relief logic, and depressurisation rate that together determine the flare header, knock-out drum, and stack.
Jose CampinsHydrate Prediction and MEG Injection
Gas hydrates form in cold high-pressure pipelines, plug flowlines completely, and shut down production for weeks. The defence is thermodynamic inhibition with MEG or methanol — calculated from a phase envelope, dosed continuously, regenerated, and recycled. Get the rate wrong and the line plugs anyway.
Jose CampinsTEG Gas Dehydration — Designing the Contactor and Regenerator
Triethylene glycol dehydration is the workhorse of pipeline gas conditioning. The contactor, the regenerator, and the lean-rich exchanger together drive the water dewpoint — and a handful of design choices determine whether the unit holds spec or limps along on chemicals.
Jose CampinsSCADA, DCS, or PLC — Which Control System Does Your Upstream Facility Need?
SCADA, DCS, and PLC are not interchangeable acronyms for the same thing. Each has a distinct architecture, a distinct strength, and a context where it clearly outperforms the alternatives. Getting this decision right at FEED stage saves significant cost and avoids painful redesign at commissioning.
Robin Charles BinnerHow to Size a Restriction Orifice Plate
Restriction orifices appear throughout upstream process systems — on bypass lines, compressor recycles, chemical injection headers, and pressure letdown applications. They are simple devices, but they are frequently undersized, oversized, or sized without checking for cavitation. Here is a rigorous approach to getting the calculation right.
Jose CampinsHAZOP vs HAZID: Choosing the Right Study for Your Project
Both appear on project safety study schedules, and both are called 'hazard studies'. But a HAZOP and a HAZID address different questions at different stages. Confusing the two — or substituting one for the other — leaves serious gaps in your safety case.
Jose CampinsWhy Every Process Plant Needs a HAZOP
A HAZOP is not a box-ticking exercise — it is the most effective tool available for identifying process safety gaps before they become incidents. Here is why it is non-negotiable, what it uncovers, and what happens when it is skipped.
Jose CampinsFunctional 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.
Robin Charles BinnerDynamic Process Simulation: 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 dynamic simulation and what it can tell you that a steady-state model cannot.
Jose CampinsElectrical 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.
Robin Charles BinnerCause 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.
Robin Charles BinnerReciprocating 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.
Jose CampinsWhat 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.
Jose CampinsHow 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.
Jose CampinsRunning 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.
Jose CampinsEarly 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.
Darren StrengersSIL 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.
Robin Charles BinnerWhy Peng-Robinson EOS is a Good Default Choice
The Peng-Robinson equation of state is the go-to thermodynamic model in commercial process simulators for hydrocarbon systems. Here's why it earns that position — and where its limits lie.
Jose CampinsWhy 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.
Jose CampinsHow to Size a Thermal Relief Pressure Relief Valve (PSV)?
Thermal 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.
Jose CampinsWhen is a Thermal Relief PSV Needed?
Not every overpressure scenario requires a full-scale relief valve. Understanding when a thermal relief PSV is the right engineering solution — and when it is not — is a fundamental process safety skill.
Jose Campins