Method Statement: Pipeline Pigging, Cleaning and Gauging Prior to Testing/Commissioning – Method Statement

Purpose

This method defines the procedures, resources, quality controls, and HSE measures for pipeline pigging, mechanical cleaning, and gauging prior to hydrostatic testing or commissioning.

Scope of Work

• Prepare and verify pipeline section limits and isolation for pigging.
• Set up and leak-test pig launcher and receiver assemblies.
• Select, assemble, and run cleaning pigs and a gauging plate pig.
• Control pigging pressures, flows, and speed; implement pressure relief and venting.
• Track pigs and manage safety exclusion zones.
• Receive and inspect debris; classify, collect, and dispose of waste.
• Inspect and evaluate gauging plate acceptance.
• Compile QA/QC records, hold/witness points, and cleaning reports.

Pipeline Applicability

• Onshore transmission/distribution pipelines for gas or liquids, carbon steel or CRA-lined, DN ≥ 4 in [Verify per project specifications].
• Pre-commissioning cleaning prior to hydrotest (liquid lines) or prior to gas-in (gas lines) [Verify per project commissioning plan].

Exclusions

• Full hydrostatic testing and drying after hydrotest (covered under separate method).
• In-line inspection (ILI) tool runs beyond basic gauging (covered under separate method).

• Approved method statement, risk assessment, and ITP.
• Permits to Work (PTW) approved: excavation/open trench (if any), pressure testing/pigging, hot work (if applicable), lifting, confined space (if applicable) [Verify per project HSE plan and local regulations].
• Line identified and section limits confirmed against P&IDs, alignment sheets, and isometrics. All tie-ins/branches isolated, blinds/spades installed per blind list and tagged.
• Verify pipeline free of open ends; vents and drains identified and controlled; check valve orientation confirmed.
• ESD/ESV and isolation valves function-tested as applicable; lock-out/tag-out (LOTO) established.
• Launcher/receiver closures inspected; seals/O-rings in good condition; interlocks operate.
• Instruments calibrated (pressure, temperature, data logger); calibration within 6 months [Verify].
• Emergency response plan briefed; muster points and exclusion zones established (min 15 m around launcher/receiver; increase as required by risk assessment) [Verify per site constraints].
• Utilities and services available (power, air, nitrogen/water as planned, lighting).
• Waste management plan approved; containers for debris and contaminated materials staged.
• Toolbox talk held; roles, communication protocol, and hand signals agreed.
• Weather and wind direction checked to plan venting and noise mitigation; community notifications arranged if needed.

Task-specific hazards and controls

• Hazard: Stored energy/overpressure during pigging and at closures
• Likely consequence: Catastrophic release, projectile pig, serious injury/fatality.
• Engineering/procedural control: PRVs set ≤90% of lowest rated component; calibrated gauges; slow pressurization/depressurization; interlocked closures with pressure equalization valves; enforce exclusion zone ≥15 m around launcher/receiver (increase if pneumatic or high pressure) [Verify per project HSE plan and local regulations].
• Required PPE: Hard hat, safety glasses/face shield, hearing protection, gloves, FR clothing, safety boots.
• Collective preventive measure: Physical barriers, danger tape, signage "No entry – pressure operations"; spotter to enforce line-of-fire control.

• Inspection/permit/supervision: PTW for pressure operations; Supervisor authorization before opening; PRV calibration certs verified by QA/QC.

• Hazard: Inert gas (N2) asphyxiation and oxygen deficiency

• Likely consequence: Unconsciousness, fatality.
• Engineering/procedural control: Use gas detectors (O2/LEL); vent to height; position downwind; avoid confined spaces; purge plans reviewed; continuous atmospheric monitoring during venting.
• Required PPE: Personal gas monitor, standard PPE; SCBA available for emergencies.
• Collective preventive measure: Establish upwind muster; ventilation and windsock; training on asphyxiation hazards.

• Inspection/permit/supervision: Gas test logs; HSE supervision during purging/venting; PTW with confined space controls if applicable.

• Hazard: Hydrocarbon gas presence/ignition (if product residues)

• Likely consequence: Fire/explosion, burns.
• Engineering/procedural control: Gas-free test <10% LEL before opening closures; use non-sparking tools; bond/ground equipment; hot work controls when needed; use flame arrestor on vent if specified.
• Required PPE: FR clothing, anti-static gear, gloves, eye/face protection.
• Collective preventive measure: Hot work permits; fire watch with extinguishers; keep ignition sources >15 m away.

• Inspection/permit/supervision: LEL logs; fire watch checklist; hot work PTW.

• Hazard: Noise from venting/compressors

• Likely consequence: Hearing damage.
• Engineering/procedural control: Acoustic silencers on vents; plan venting during low-sensitivity periods; maintain distance.
• Required PPE: Class 5 earplugs/earmuffs.
• Collective preventive measure: Noise assessment and zoning.

• Inspection/permit/supervision: HSE noise monitoring where required.

• Hazard: Dropped objects during pig handling/lifting

• Likely consequence: Crush injuries.
• Engineering/procedural control: Certified lifting gear; taglines; no hands under load; use pig trolleys.
• Required PPE: Helmet with chin strap, gloves, safety boots.
• Collective preventive measure: Exclusion under load; lifting plan and appointed person.

• Inspection/permit/supervision: Lifting certificates; pre-lift check; permit to lift if required.

• Hazard: Manual handling/ergonomics

• Likely consequence: Strains/sprains.
• Engineering/procedural control: Use mechanical aids; team lifts; break down components where possible.
• Required PPE: Gloves, supportive footwear.
• Collective preventive measure: Manual handling training; rotate tasks.

• Inspection/permit/supervision: Supervisor oversight.

• Hazard: Pressurized hose/connection failure

• Likely consequence: Whiplash, impact injury.
• Engineering/procedural control: Restrain hoses; whip-checks; rated fittings; secure routing away from walkways; pressure test hoses prior to use.
• Required PPE: Eye/face protection, gloves.
• Collective preventive measure: Barriers and trench plates where hoses cross access.

• Inspection/permit/supervision: Hose inspection tags; pressure rating check.

• Hazard: Traffic and mobile plant at site

• Likely consequence: Collision/run-over.
• Engineering/procedural control: Traffic management plan; segregated pedestrian routes; banksmen for reversing.
• Required PPE: Hi-vis clothing.
• Collective preventive measure: Signage and speed limits.

• Inspection/permit/supervision: Daily traffic brief by Supervisor.

• Hazard: Adverse weather (wind during venting)

• Likely consequence: Gas drift to occupied areas.
• Engineering/procedural control: Monitor wind; suspend venting if wind direction unsafe; extend exclusion zone.
• Required PPE: As standard.
• Collective preventive measure: Windsock installation.
• Inspection/permit/supervision: HSE approval before venting.

• Emissions from venting: Use silencers and, where required, temporary flare/thermal oxidizer to minimize hydrocarbon release [Verify per local regulations]. Plan venting during favorable wind; record vent durations/volumes.
• Waste debris handling: Collect solids in sealed containers; segregate metal fragments; classify as non-hazardous/hazardous per Waste Management Plan. Track weights and disposal manifests; no on-ground dumping.
• Liquid effluents (if water push/cleaning): Contain and sample for oil-in-water, pH, TSS; discharge only to permitted system with limits [Verify per permit]. Use filtration/oil-water separation if needed.
• Noise: Acoustic silencers, schedule high-noise activities during daytime; maintain complaint log for community interfaces where applicable.
• Spills/leaks: Spill kits staged; drip trays under connections; immediate containment and reporting per SPCC/site procedures.
• Wildlife/vegetation: Protect nearby habitats; no venting/blowdown directed toward fauna or crops; reinstate ground protection mats after works.
• Housekeeping: Maintain clean work area; remove temporary materials after completion; waste tracking per ISO 14001 practices.

Quality Controls

• Calibration: Pressure gauges/data loggers calibrated within 6 months; accuracy ≤1% FS. PRVs with valid bench-set certificates (±5%).
• Dimensional checks: Gauging plate diameter = 95% of nominal ID ±0.5 mm [Verify]; pig OD 0.5–1% over ID [Verify]. Records with traceable calipers/micrometers.
• Tracking verification: Pre-run function test of signallers and transmitter. Continuous tracking log with timestamps at each checkpoint.
• Speed/DP control: Record distance and time between signallers to calculate pig speed; maintain within 0.5–1.0 m/s [Verify]. Record DP and line pressure; investigate spikes.
• Cleanliness acceptance: Two consecutive cleaning runs show (a) debris mass change ≤5%, (b) total debris ≤0.05 kg/km [Verify], and (c) foam/effluent visibly clean. Alternative project criteria to govern if different [Verify per project specifications].
• Gauging acceptance: No tears/cuts >10 mm; no flattening/ovalization >10% of gauging plate diameter; no severe gouges/burrs. If non-conforming, identify probable location using tracking times/distances; raise NCR; correct defect and repeat run.
• Documentation: Pig Run Logs, Debris Logs with weights/photos, Gauging Inspection Reports, Calibration Certificates, PRV set sheets, Pressure/Speed plots, ITRs with signatures of Contractor, Client, and TPI (as applicable).
• Nonconformance: NCR raised for deviations; corrective action approved prior to continuation. Hold points cannot be passed without written release.

• Sample Pig Run Log (fields: date, pig type, transmitter ID, start/stop times, checkpoint times, DP, pressure, speed, remarks).
• Debris Log Template (weights, photos, waste classification, manifest number).
• Gauging Plate Dimensional Inspection Form (target, actual, instrument used, tolerance, sign-offs).
• Calibration Certificate Register (gauges, data logger, PRVs, gas detectors).
• PRV Bench Set Sheet.
• Launcher/Receiver Leak Test ITR.
• Tracking Setup and Function Test Checklist.
• Risk Assessment and Job Hazard Analysis (JHA).
• Emergency Response Plan (pig stuck, overpressure, gas detection, spill).
• Site Layout showing exclusion zones, vent stack, traffic plan.