LNG and gas processing
LNG commissioning, run per train instead of per plant.
Liquefaction scopes carry the densest loop testing and the longest preservation windows in the industry, and the operator gates start-up one train at a time. Deskely keeps the records, the certification ladder and the readiness number at that same level.
- Certification level
- Per train
- Record density
- Loop and machine
- Preservation window
- 24–36 months
- Operator gate
- PSSR
Choose your project type
The problem
A liquefaction train is not one commissioning scope. It is several thousand, gated in a fixed order.
Pre-treatment, refrigeration, liquefaction, storage and loading each behave like their own project. Between them sit tens of thousands of instrument loops, hundreds of rotating machines and a utilities scope that has to be live long before any of them can be tested.
The volume is only half of it. The compressor cannot be run before its lube oil system is commissioned, which cannot be commissioned before its instrument loops are proven, which cannot be proven before the loop's field devices are calibrated and installed. On a spreadsheet that dependency lives in somebody's head.
When the operator asks whether train two can take feed gas, they are asking whether a specific list of subsystems has earned RFSU — and every one of those subsystems has to be provable on its own.
The certification ladder
Four gates stand between steel and feed gas in the cold box.
Each gate is issued at subsystem level, per train, and none of them are claimed on a status update.
- 01
Mechanical completion
All A and B records signed, static tests complete, loop checks proven to the DCS marshalling cabinet.
Construction manager and commissioning lead
- 02
RFSU
Enforced by the register, not reviewed against it afterwards.
MC held, no open Category A punch, preservation current on every tag in the subsystem.
Commissioning manager, countersigned by operations
- 03
PSSR
RFSU on all subsystems feeding the train, safety-critical devices proof-tested, evidence pack exported.
Operator PSSR panel
- 04
First cargo
Loading arm cryogenic and ESD interface tests, custody meter proving, tank gauging calibration.
Terminal superintendent and buyer's surveyor
Setting up the register
Loop and machine registers drafted from the drawing set, not typed from it.
An LNG register is built from P&IDs, loop diagrams, line lists, cable schedules and vendor equipment lists — and on a two-train scope it is a year of senior engineering time if it is done by hand.
Deskely's parser reads the document set and drafts the tag register, normalising tag formats and keeping the drawing reference behind each tag. Where a line list and a revised P&ID disagree, the conflict is shown side by side for an engineer to settle rather than silently picking one.
Because the register is structured by system and subsystem from the start, the per-train breakdown the operator will gate against already exists before the first ITR is issued.
Preservation
Cold boxes and compressors sit for years before they ever run.
On a greenfield LNG project, main refrigerant compressors, pumps and motors are installed early and then wait — often two to three years — for the plant around them to be finished. Each needs its own routine the whole time: shaft rotation, nitrogen blanket pressure checks, insulation resistance, desiccant changes, lube oil sampling.
Those routines run per tag and on their own cadence, independent of the commissioning sequence. An overdue cycle appears the day it is overdue rather than during a handover review, and each completed cycle carries the name, role and timestamp of whoever performed it.
That record is what settles a warranty conversation with a machine vendor three years later: a filtered log of every cycle on that tag with signatures against it, not an assurance that preservation was maintained.
Scale, in numbers
What a two-train scope actually runs through the register.
15,000–25,000
instrument and machine tags per train
24–36 mo
typical rotating-equipment preservation window
3–5
distinct commissioning phases per train
1
readiness number per train, derived from records
Who owns what
Trains, jetty and utilities are usually different contracts.
The register does not care who is contracted to whom; it cares which party owns which tag.
EPC / lead contractor
Process trains, utilities, mechanical completion and RFSU submission
Signs
A/B/C records, MC and RFSU certificates
Rotating equipment vendors
Compressor and turbine works tests, site acceptance
Signs
Vendor test certificates, run logs
Marine / jetty contractor
Loading arms, custody metering, ship–shore ESD link
Signs
Cryogenic and interface test records
Operator commissioning team
PSSR, hydrocarbon introduction approval
Signs
Reviewed evidence pack, PSSR minutes
Preservation crew
Idle-equipment routines from installation to start-up
Signs
Signed preservation cycle logs per tag
Terminal / buyer surveyor
First cargo acceptance
Signs
Meter proving and loading arm certificates
What a train's dossier actually holds
The records the operator opens before hydrocarbon reaches the cold box.
An LNG train is accepted on a specific set of witnessed results, not on a general assurance that testing took place. Each one is produced by a named party at a fixed point in the sequence and stays attached to the tag it belongs to.
Cryogenic leak test record
Piping and joints hold integrity at liquefaction temperature before feed gas is introduced
During cold commissioning of the affected train
Cold box dry-out and purge log
Moisture and air have been removed from the main cryogenic heat exchanger before start-up
Immediately ahead of first cool-down
Custody metering proving certificate
The export meter factor and uncertainty are accepted before commercial loading begins
Before first cargo
Loading arm ESD interface test
The arm disconnects safely on a ship-shore emergency shutdown signal
During jetty commissioning, re-verified before first cargo
Compressor string test report
The main refrigerant compressor train performs to design across its operating envelope
At the vendor works, ahead of site installation
Boil-off gas system commissioning record
Vapour recovery and re-liquefaction respond correctly to tank pressure
During storage and loading system commissioning
Jetty, cargo and commercial acceptance
First cargo is a commercial event, and the loading arms, meters and ship–shore link have to be proven before the carrier arrives.
Liquefaction gets the attention, but the export jetty is where an LNG project actually earns money: cryogenic loading arms, custody transfer metering, tank gauging, boil-off gas handling and the ship–shore emergency shutdown link all have to be tested, witnessed and signed before a carrier is accepted alongside.
These systems are usually built by a different contractor on a different schedule, and their records tend to live in a separate marine package. When first cargo slips, it is often because a metering certificate or an ESD interface test that nobody was tracking turns out to be missing.
Deskely holds the jetty, the arms, the metering skid and the tank gauging system in the same register as the liquefaction trains, so first cargo readiness is one status, and the buyer's and terminal's evidence requirements are an export rather than a search.
Terminology on this scope
Words this page uses the way an LNG project actually uses them.
- RFSU
- Ready for start-up: a subsystem has been commissioned and is safe to take process feed.
- Cold box
- The insulated structure housing the main cryogenic heat exchanger where natural gas is liquefied.
- Boil-off gas (BOG)
- Gas that vaporises from stored LNG due to heat ingress, handled by dedicated compression and recovery systems.
- Custody transfer metering
- The metering skid whose calibration and proving certificates set the commercial quantity of LNG sold.
- Ship–shore link
- The emergency shutdown and communication interface between the jetty and the LNG carrier during loading.
- PSSR
- Pre-start-up safety review: the operator's final gate before hydrocarbon is introduced to a train.
- Preservation routine
- A scheduled maintenance cycle protecting idle equipment between installation and commissioning.
How it runs
How an LNG scope is set up in Deskely.
The structure is decided once, at the start, and then everything else is a consequence of it. Getting the train and subsystem breakdown right is most of the work.
- 01
Break down by train and utility
Systems and subsystems are created per train, with shared utilities held separately so a common scope does not block a single train's certification.
- 02
Draft the register from drawings
P&IDs, loop diagrams and equipment lists are parsed into a tag register with drawing references retained, then reviewed and corrected by a completions engineer.
- 03
Assign ITR templates by tag type
Loops, valves, machines and vessels each get their A, B and C record templates, so a twenty thousand tag scope is populated without building forms one by one.
- 04
Start preservation at installation
Routines and cadences are attached to rotating equipment and instruments as they are installed, running in parallel with construction for as long as the wait lasts.
- 05
Run field capture on tablets
A, B and C records are completed at the tag, offline where necessary, with photos and signatures that keep the time they were taken.
- 06
Gate MC and RFSU per subsystem
Certificates issue only when the records beneath them allow it, and each train's readiness number is derived from those certificates rather than reported alongside them.
FAQ
Questions about LNG scopes.
Keep reading
Oil and gas commissioning
The full sector view: certification ladder, preservation, handover and the terminology behind them.
Read morePreservation
Per-tag routines on their own cadence, with overdue cycles surfaced continuously rather than at handover.
Read moreCertificates
MC, RFSU and handover certificates issued from signed records, with the gates enforced by the data.
Read moreOther oil and gas scopes: FPSO and floating production, Brownfield tie-ins and turnarounds, Fixed platforms and jackets, Subsea tie-backs, Refineries and petrochemical, Pipelines and compressor stations, Terminals, tank farms and jetties, Hydrogen, ammonia and carbon capture, Decommissioning and late life.
