TL;DR
A shutdown survey oil & gas program delivers millimetre-accurate tie-in dimensional control, fit-check, and as-built capture during the planned turnaround when an LNG train, refinery unit, or gas plant stops production. With major turnarounds deferring tens of millions of dollars in output and running on a fixed, immovable window, survey work that drifts onto the critical path is the most expensive line on the job. Industrial Spatial Solutions plans, mobilises, and executes hazardous-area shutdown surveys across Australian oil and gas facilities so measurement never becomes the bottleneck.
Key takeaways
- LNG and refinery turnarounds are scheduled years out and measured in days, not hours: a refinery major turnaround typically runs 30–60 days and an LNG train turnaround 20–40 days, with deferred production and fixed labour costs that make every shift on the critical path worth six figures or more.
- The high-value shutdown survey scopes in oil and gas are brownfield tie-in dimensional control, spool and module fit-up, heat-exchanger bundle and tower-internals fit-check, vessel and tank shell surveys, and rapid as-built laser scanning of process areas opened only during the outage.
- A Leica RTC360 captures a dense pipe rack or exchanger row to ±2–5 mm at 10 m in minutes per setup; critical flange-to-flange and bolt-pattern control is held to ±1–2 mm with total station or laser tracker — the band where a spool either bolts up or returns to the workshop.
- All work proceeds under hazardous-area classification (AS/NZS 60079) and permit-to-work, with datums tied to plant control or MGA2020 / GDA2020 and AHD so shutdown measurements reconcile against the engineering model and prior records.
- Scope locked before isolation, control re-verified ahead of the outage, and crews inducted and permitted for the site — these three things separate a turnaround that restarts on schedule from one that overruns at full burn rate.
Why oil & gas shutdowns demand precision surveying
Process plant runs continuously until a planned turnaround stops it, and the operator stops it reluctantly. Australia's LNG trains — the North West Shelf, Pluto, Gorgon, Wheatstone, and Prelude in Western Australia, Ichthys and Darwin LNG in the Northern Territory, and the three Curtis Island trains at Gladstone — each defer enormous revenue when offline. The Ampol Lytton and Viva Energy Geelong refineries, the Cooper and Surat basin gas plants, and the Bass Strait facilities are no different: a turnaround is a multi-million-dollar event executed against a window fixed months or years in advance, often coordinated with cargo schedules and catalyst or refractory campaigns that cannot move.
Shutdown surveying in this environment differs fundamentally from greenfield or routine work. There is no flexibility in the schedule, and almost no flexibility in access. The surveyor measures when the area is isolated, gas-freed, and permitted — not before — and the result must be issued before the next mechanical or fabrication step can proceed. A spool cannot be released for fabrication until the tie-in flange faces are measured; a heat-exchanger channel cannot be boxed up until the bundle and tubesheet fit is verified; a replacement valve or vessel cannot be set until its envelope is confirmed against the surrounding steel. Survey is woven into the turnaround sequence, and a delayed measurement delays everything downstream of it.
The consequences of error are concentrated and expensive. A spool fabricated to a stale 1990s isometric that does not bolt up at the tie-in burns days of standby across an entire shutdown crew. A new module set to the wrong line fouls a pipe rack and forces rework on the deck — the most expensive place to discover a clash. The discipline that prevents this is unglamorous: a verified plant control network, a current point cloud instead of legacy drawings, and a survey methodology agreed before the gate opens.
| Do | Don't |
|---|---|
| Laser scan the tie-in zone before the turnaround and design the spool against the point cloud | Trust decades-old P&IDs and isometrics as the basis for new spool fabrication |
| Hold critical tie-in dimensional control to ±1–2 mm with total station or laser tracker | Accept tape-and-eye field dimensions for flange-to-flange spool fabrication |
| Re-verify the plant control network and datum before isolation | Mix local arbitrary grids between pre- and post-work surveys |
| Capture a full scan of every process area while it is open and accessible | Re-mobilise after recommissioning when the only access window has closed |
Oil & gas shutdown survey applications
Hydrocarbon turnarounds concentrate the most demanding dimensional survey work into the tightest window of an asset's year. The applications below recur across LNG trains, refineries, gas-processing plants, and tank farms.
Brownfield tie-in dimensional control
The single highest-value shutdown survey scope in oil and gas is tie-in dimensional control. Before a new line, module, or unit can be connected, the existing flange faces, bolt patterns, and pipe positions must be measured as they actually are — not as the drawings say. ISS captures the tie-in geometry to ±1–2 mm with total station or laser tracker, supplies it to the fabricator, and verifies the finished spool before it goes to the deck. This is where stale as-builts are replaced with reality and where fit-up rework — the single biggest cause of shutdown overrun — is designed out.
Spool, skid, and module fit-up
Modular construction and pre-fabricated spools only deliver schedule savings if they mate first time. ISS provides dimensional control of skids, modules, and spool pieces against the design model so that steel fabricated in a Perth or Gladstone yard bolts up to the live plant. Critical flange-to-flange and bolt-circle checks are held to ±1–2 mm — the tolerance band where a spool either fits or comes back across the country.
Heat-exchanger and tower-internals fit-check
Shell-and-tube exchangers, fired heaters, and fractionation towers are opened during turnarounds for bundle pulls, tube-sheet work, tray replacement, and packing changes. ISS measures channel and shell geometry, nozzle orientation, and internal clearances so bundles, trays, and internals fit on reinstallation without field modification — work that must be signed off before the equipment is boxed up and the next step in the sequence can start.
Vessel, tank, and structural shell surveys
In-service inspection campaigns under API 653 (tanks) and pressure-equipment integrity work drive shell roundness, verticality, plumb, and settlement surveys during outages. ISS captures tank and vessel shells, confirms nozzle and manway positions, and supports re-rating and repair decisions with defensible geometry, all referenced to the verified plant datum.
Rapid as-built laser scanning of opened process areas
When a process area is isolated and opened, it is frequently the only window in years in which it is fully accessible. A Leica RTC360 captures a process module, pipe rack, exchanger row, or compressor house in minutes per setup, producing a registered point cloud for clash detection, spool generation, and future revamp design. See outage survey services for the full scope.
Key point: The turnaround is usually the only time the inside of a live process area can be measured at all. Scanning everything that is open — regardless of immediate need — turns a one-off shutdown cost into a reusable digital as-built that pays back on the next tie-in, integrity audit, or capital revamp, when re-access would mean another isolation.
How ISS executes an oil & gas shutdown survey
ISS structures every turnaround around a sequence designed to keep survey off the critical path and inside the permit system.
1. Scope definition (well ahead of isolation). We review the turnaround work pack and schedule, flag every survey-dependent activity, and run a site visit to assess access, hazardous-area zoning, line of sight, and control requirements. The output is an agreed survey methodology and program aligned to the shutdown network.
2. Control re-verification (before isolation). Brownfield plant modified over decades often carries multiple local grids and inconsistent benchmarks. ISS re-establishes and verifies the plant control network against MGA2020 / GDA2020 with AHD heights while the area is still accessible, so every later deliverable shares one defensible coordinate system.
3. Pre-shutdown baseline and scan. Tie-in geometry, equipment positions, and clearances are captured as the reference against which fabricated components and post-work measurements are compared.
4. In-shutdown execution. The surveyor attends in sequence with the mechanical and fabrication crews — continuous standby for tight tie-in fronts, scheduled attendance for specific fit-checks on longer turnarounds — measuring as each work front is isolated and permitted, and issuing results before the next step.
5. Post-shutdown verification and reporting. Final fit-up and as-built confirmation before recommissioning, with deviation tables and point-cloud deliverables issued in your coordinate system and in formats compatible with AVEVA E3D, Navisworks, SmartPlant, and Revit.
ISS owns its instruments and scanners, so there is no waiting on hire equipment, and crews hold current hazardous-area awareness, confined-space, and working-at-heights certifications for the environments we enter.
Equipment and tolerances
Shutdown survey gear has to be reliable, portable, and suited to congested, hot, classified plant. ISS deploys instruments selected for that environment, calibrated annually to traceable standards and carried with regional backups so a single instrument fault never stalls a turnaround.
- Leica RTC360 laser scanner — around 2 million points per second for rapid as-built capture of process modules, pipe racks, and exchanger rows, with typical registered accuracy of ±2–5 mm at 10 m.
- Leica TS16 total station — 1" angular precision with ATR automatic target recognition for tie-in dimensional control, spool fit-up, and shell surveys where ±1–2 mm is required on critical interfaces.
- Laser tracker — for the tightest dimensional control on modules, skids, and machinery interfaces, delivering accuracy in the tens of microns over short ranges where a bolt-up either works or it doesn't.
- FARO arm and reflectorless measurement — close-range fit-check and measurement to inaccessible points without target access inside vessels and channels.
- CASA Part 101 certified RPAS — flare-tip, stack, and elevated-structure inspection and context capture across large plant footprints, flown under operator approvals.
Typical tolerances on oil and gas shutdown work: critical tie-in and spool dimensional control to ±1–2 mm, tighter again with a laser tracker over short ranges; terrestrial laser scanning at roughly ±2–5 mm at 10 m; control and alignment networks at the millimetre level. AUD cost scales with scope and access — a single-day scan of an opened process area typically runs from a few thousand dollars, while a full turnaround dimensional-control and scanning program is scoped and fixed-priced per project once access is confirmed.
Regulatory and safety standards
Oil and gas shutdown environments are among the most hazardous survey workplaces in Australian industry — classified hazardous areas, residual hydrocarbons, confined spaces, heavy lifting, simultaneous operations, and constant time pressure. Survey work proceeds only under the operator's permit-to-work system, with intrinsically safe or hot-work-permitted equipment and procedures suited to classified zones under the AS/NZS 60079 series. Tank and vessel scopes align to API 653 and API 650 inspection practice, pipeline tie-ins to AS 2885, and instrument calibration follows AS/ISO metrology practice with deliverables traceable from field observation to final report under an ISO 9001 quality system.
Before mobilisation, ISS surveyors complete site-specific induction, task-based risk assessment, and the relevant confined-space and hot-work permits, and brief against the shutdown coordinator's communication plan. Coordinate and height work is referenced to GDA2020 / MGA2020 and AHD so survey data reconciles cleanly with the engineering model and integrity records.
Key point: The most common shutdown survey failure we are called in to fix is not measurement error — it is access and datum. A surveyor who cannot enter the vessel because the gas-free certificate is not issued, or who measures against a local grid that no longer matches the plant model, loses hours the turnaround cannot give back. Verifying the datum and planning permitted access is survey work, done before isolation.
Frequently asked questions
What is a shutdown survey in oil and gas?
A shutdown survey is precision measurement carried out during a planned turnaround or outage of an LNG train, refinery unit, gas plant, or tank farm. It covers pre-shutdown baselines and scans, in-shutdown tie-in dimensional control and fit-check, and post-shutdown as-built verification before recommissioning. The defining feature is the fixed, immovable window: every measurement is sequenced against mechanical and fabrication work, under the permit system, so it never delays the restart.
How far ahead should we book an oil & gas shutdown surveyor?
As early as the turnaround work pack is firm — typically months out for major LNG and refinery shutdowns, given they are planned years in advance. Early engagement allows scope definition, a pre-shutdown site visit, hazardous-area and permit documentation, control re-verification, and crew scheduling. Tie-in dimensional control in particular should be locked in early, because fabricated spools depend on field geometry measured before the steel is cut.
Can ISS survey inside a live plant, or only during the shutdown?
Both. Laser scanning is non-contact and much brownfield capture is done with the plant running, subject to access and hazardous-area permits — which is exactly how we recommend capturing tie-in zones before the turnaround. Work inside isolated, gas-freed process areas and vessels is sequenced into the shutdown itself, and our crews can work around the clock during the outage to fit the available window.
What accuracy does ISS achieve on shutdown work?
Critical tie-in and spool dimensional control is held to ±1–2 mm using total station and laser tracker methods, and tighter again with a laser tracker over short ranges. Terrestrial laser scanning is typically ±2–5 mm at 10 m, which suits revamp design and clash detection. All work ties to the plant control network or MGA2020 with AHD so results reconcile against the engineering model and prior records.
Will the survey data import into our engineering software?
Yes. ISS delivers point clouds in E57, LAS/LAZ, RCP/RCS, and web-viewable TruView, plus extracted 2D drawings (DWG/DGN) and deviation reports where needed. These import directly into AVEVA E3D, Navisworks, SmartPlant, and Revit, and all data is supplied in MGA2020 with full datum documentation.
Request a quote
A turnaround at full burn rate is the wrong place to discover your survey support is under-prepared. ISS plans the scope, re-verifies plant control, mobilises inducted and permitted crews with our own instruments, and delivers tie-in dimensional control, fit-check, and as-built data inside the window — so your LNG train, refinery unit, or gas plant restarts on schedule. We support shutdowns and turnarounds across LNG, refining, gas processing, and tank-farm operations Australia-wide, from the Pilbara LNG coast and Curtis Island to Darwin, the Cooper and Surat basins, and the Geelong and Brisbane refineries. Call 0407 057 015 or request a quote online to scope your next turnaround.
Related: Oil & gas surveying services | Outage survey services | Shutdown survey services Australia