Pipelines, compressor and pump stations
Pipeline pre-commissioning where the test record stays with the section.
A transmission scope is not one asset. It is a linear spread of test sections, block valve stations, pig traps and compressor or pump stations, each with its own hydrotest, cleaning, gauging, drying and tie-in evidence. Deskely holds that evidence against the section and the station it belongs to, so acceptance by the pipeline operator is a query rather than an archive search.
- Structure
- Test sections and stations
- Record types
- Hydrotest, gauging, drying
- Spread
- Linear, multi-crew
- Operator gate
- Acceptance for gas-in
Choose your project type
The problem
The spread moves on and the evidence stays behind.
A pipeline crew works forward. Welding, coating, lowering-in, backfill and testing all advance along the route, and by the time a section is being hydrotested the crews that built it are kilometres away. The record for that section is produced by a different party at a different time to almost everything else in the project.
The weld book sits with the fabrication contractor, the NDT reports with the inspection company, the coating holiday-test survey with a third-party surveyor, the hydrotest charts with the testing subcontractor, and the station ITRs with the mechanical and electrical subcontractors on site. None of them are wrong; they are just never in the same place at the same time.
The reckoning comes at operator acceptance. For one kilometre post the operator wants the weld map, the NDT release, the pressure and temperature charts, the gauging plate result and the dryness measurement together. Assembling that from five parties after the fact is what turns a physically finished pipeline into one that still cannot go into gas.
Scale of a transmission scope
The numbers a route actually runs on.
A cross-country line is not sized in tags the way a plant is — it is sized in kilometres, sections and stations, and the register has to hold both scales at once.
- Test section length
- 3–15 km
- Between block valve stations or pig traps
- Hydrotest hold time
- 4–24 hours
- Per section, per code and design pressure
- Golden welds
- 1 per tie-in
- Each carries its own NDT release and repair history
- Dryness target
- ≤ -10°C dew point
- Typical pipeline-grade specification before nitrogen pack
- Station count
- 1 per 80–150 km
- Compressor or pump stations on a typical transmission route
- Land parcels
- 50–400+
- Reinstatement and compensation tracked per parcel, not per section
One register
Test sections and stations in the same hierarchy.
The register is drafted from the alignment sheets, the line list, the station P&IDs and the instrument index, so the linear scope and the station scope live in one hierarchy instead of two systems that meet only in a status report.
A test section carries its own tags — line pipe, block valves, pig traps, cathodic protection test posts — with kilometre references retained from the drawings they were parsed from. A compressor or pump station is broken into subsystems the same way any plant is, because that is what it is.
Each contractor works only in their own scope. The welding contractor signs weld and NDT records, the testing subcontractor signs pressure charts, the station subcontractors sign their ITRs, and progress rolls up without anyone exporting a spreadsheet to anyone else.
The pre-commissioning ladder
A section cannot be pressure tested on evidence that does not yet exist beneath it.
The sequence is fixed by physics, not by procedure, so the system enforces the order rather than trusting a schedule to describe it.
- 01
Mechanical completion (section)
Weld map complete, NDT releases signed, coating holiday test passed
Construction contractor, witnessed by client inspector
- 02
Cleaning and gauging pass
Pig run completed, gauging plate free of deformation
Testing subcontractor
- 03
Hydrotest acceptance
Pressure and temperature stabilisation criteria met for the hold period
Testing subcontractor, countersigned by client
- 04
Dewatering and drying sign-off
Dew point measurement within specification
Testing subcontractor
- 05
PSSR (station)
Pressure equipment register complete, all station ITRs signed
Independent competent person
- 06
RFO / gas-in readiness
All sections and stations on the route accepted, tie-in golden welds closed
Pipeline operator
Section acceptance
Cleaning, gauging, testing and drying as a sequence that cannot be shuffled.
Pre-commissioning a section follows a fixed order: clean, gauge, fill, pressure test, dewater, dry, then nitrogen or air pack for hold. Each stage produces a record, and each stage depends on the one before it having been signed off, not merely reported as finished.
Deskely enforces that order at the section. A gauging plate result showing deformation blocks the pressure test above it. A hydrotest that fails its stabilisation criteria cannot be signed to a pass. A dew point measurement outside specification keeps the section short of ready, regardless of what the schedule says.
Where a section is retested, the previous attempt is kept rather than overwritten. That history is what an integrity engineer needs five years later when a repair is planned at the same kilometre post, and it is what makes a pressure test defensible in front of a regulator.
Who signs what
Six parties, one section record.
A transmission scope routinely has more independent signing parties per kilometre than a plant has per unit.
Welding & coating contractor
Weld map, NDT release, coating holiday test
Signs
Weld log, radiography report, holiday detector trace
Testing subcontractor
Cleaning, gauging, hydrotest, dewatering, drying
Signs
Pressure/temperature charts, gauging result, dew point log
Station EPC / subcontractors
Compressor, pump, metering and control system ITRs
Signs
Loop tests, function tests, PSSR pack
Cathodic protection contractor
CP test post readings, coating repair at tie-ins
Signs
Potential survey, close-interval survey
Land / right-of-way agent
Parcel access, reinstatement, compensation close-out
Signs
Landowner sign-off, reinstatement photographs
Pipeline operator
Route acceptance, gas-in authorisation
Signs
RFO certificate against the full route register
Stations
A compressor station is a plant sitting on a pipeline, delivered last and gated first.
Gas turbine or motor-driven compressors, filtration, coolers, metering, fire and gas, ESD and the station control system carry the same record density as any process facility — and they are usually the last thing on the route to finish and the first thing the operator gates on.
Machine packages arrive with vendor works test results and their own commissioning procedures. Those records attach to the tags they belong to, so a vendor's string test and the site's loop tests read as one history instead of a folder sitting alongside a database.
Preservation matters here more than anywhere else on the route. A compressor delivered eighteen months before gas-in has a nitrogen blanket, a rotation routine and a lube system to keep alive, and the proof of that is what stops a warranty conversation from becoming a dispute.
Where transmission schedules actually slip
Four failure modes that are specific to a linear spread.
Golden weld left open at a tie-in
A single unreleased NDT report at a tie-in weld can hold an entire multi-kilometre section short of certification.
Tie-in welds tracked as their own tags, blocking section sign-off until closed.
Retest history overwritten
A failed hydrotest attempt gets discarded once the retest passes, leaving no record for a future repair at the same chainage.
Every attempt retained against the section, not just the final pass.
Station preservation lapse
Compressor packages sit idle for over a year before gas-in with no visible preservation cadence.
Per-tag preservation routines with overdue cycles surfaced continuously.
Unclosed land parcel blocks handover
A single unresolved reinstatement or compensation item on one parcel holds up final route acceptance.
Parcel and crossing records tracked in the same register as the technical evidence.
What a section is accepted on
The records that follow the pipe long after the crew has moved on.
Because a test section's evidence is produced by five separate parties working weeks apart, acceptance depends on six specific records lining up under the same kilometre reference, rather than on a general statement from any one contractor that their portion of the section is finished.
Pigging and gauge plate record
The bore is clear of obstruction and free of deformation before pressure testing
Immediately before hydrotest
Hydrotest pressure chart
The section holds design pressure for the full hold period without loss
During the section's pressure test
Weld NDT and radiography report
Every weld, including golden welds at tie-ins, meets the code acceptance criteria
After welding, before coating and lowering-in
Cathodic protection commissioning record
The pipeline's corrosion protection system delivers the design potential along the route
After energising, before RFO
Coating holiday-test survey
The external coating has no breaks that would expose bare steel after burial
Before lowering-in
Dryness measurement log
The section meets its dew point specification before it is packed for hold
After dewatering, before nitrogen or air pack
Right of way and reinstatement
A pipeline is accepted along a route, and the route runs across land that has to be handed back in the condition it was found.
Alongside welding, coating and hydrotest evidence, a pipeline project carries a parallel record set per land parcel: access agreements, pre-condition surveys, topsoil separation photographs, drainage and fencing reinstatement, and crop or disturbance compensation closed with the owner. Special crossings — rivers, road bores, rail and protected land — each carry their own permit, method statement and as-built set, usually with a different authority as the counterparty.
The handover dossier exports per test section and per station in the structure the operator retains, with weld map, NDT release, coating survey, pressure and temperature charts, gauging result, drying record, ITRs, punch position and preservation history under the tags the operator will keep using. Sections can be accepted progressively as they are proven, which is what allows a line to be commissioned in stages instead of everything being gated behind the last kilometre.
Years later the same query still works: open the tag or the kilometre post and the chain is there, signed, timestamped and traceable to the drawing revision it was built from — and no parcel is left untracked because it never carried a weld number.
How it runs
How a pipeline scope is set up in Deskely.
The structure follows the route and the stations on it, so the record is always addressable by the thing the operator points at.
- 01
Break the route into test sections
Sections between block valves and pig traps become the certifiable units, with kilometre references from the alignment sheets retained on every tag.
- 02
Structure stations as subsystems
Compressor, pump, metering and block valve stations are broken into subsystems and certified on the same ladder as any process plant.
- 03
Draft the register from drawings
Alignment sheets, line lists, station P&IDs and the instrument index are parsed into tags with drawing references kept for engineer review.
- 04
Scope each contractor by access
Welding, NDT, coating, testing and station subcontractors sign only their own records, and progress rolls up with no import step.
- 05
Sequence the pre-commissioning gates
Cleaning, gauging, pressure test, dewatering and drying are ordered so a stage cannot be signed before the evidence beneath it exists.
- 06
Accept and export per section
Sections and stations are certified as they are proven, and the dossier exports in the operator's retention structure at any point.
FAQ
Questions about Pipelines scopes.
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