1. Equipment inventory & weight data collection

• Conduct systematic walk-down surveys across all platform levels cellar deck, main deck, mezzanine deck, top deck, and helideck to identify and document all permanent and installed equipment items.
• Collect, verify, and reconcile available vendor data sheets, equipment schedules, piping and instrument diagrams (P&IDs), single-line diagrams (SLDs), electrical area classification drawings, and maintenance records to extract confirmed equipment weights and dimensions.
• Where original documentation is absent, incomplete, or unreliable, apply recognised engineering estimation methods density-volume calculation, analogous equipment databases, vendor catalogue comparison and document all assumptions with explicit uncertainty bounds.
• Account for 30 years of as-built modifications: retrofitted equipment, piping re-routes, added spools, clamps, doublers, instrumentation additions, and any temporary or permanent weight additions not reflected in the original design basis.
• Establish, populate, and maintain a structured Equipment Register covering all disciplines: structural steel, mechanical, piping and valves, electrical, instrumentation and controls, HVAC, fire and gas, telecom, and civil/architectural items.
• Compile fluid inventory (process, utility, marine) including pipe contents, vessel hold-up volumes, and variable liquid loads for each operating scenario (normal operations, shutdown, survival condition).

2. Weight & centre-of-gravity (CoG) analysis

• Calculate the weight and CoG of every item in the equipment register referenced to the platform grid and elevation coordinate system agreed with the structural lead.
• Produce a deck-by-deck weight summary table distinguishing: dead load D1 (permanent structural steel), dead load D2 (permanently installed equipment and systems), live loads L (variable and operational), fluid loads, and any accidental or temporary loads.
• Determine the overall topside operating weight and its CoG in all three axes, and compare against the original platform design weight and rated deck load capacities.
• Apply contingency and uncertainty allowances consistent with the NORSOK Z-014 weight data quality classification system (DQ0 through DQ5), clearly stating the confidence level associated with each weight entry.
• Identify weight-critical or large-mass items (heavy rotating equipment, storage vessels, large valve stations, module packages) and provide their precise location coordinates and bearing points for accurate node loading in the structural model.
• Prepare distributed load maps (kN/m ) for each deck plate for use in the finite element model, in addition to point-load schedules at structural nodes.

3. Field survey & measurement

• Lead or participate in offshore field campaigns; physically measure equipment envelopes, pipe diameters, wall thicknesses, and structural member dimensions where engineering drawings are unavailable or unverified.
• Coordinate with platform operations and maintenance teams to access nameplate data, installed weight certificates, pre-installation rigging records, and lifting operation reports held at site.
• Photograph, sketch, and dimension all undocumented items, maintaining a fully traceable and auditable field data package that can withstand third-party verification.
• Liaise with inspection, corrosion, and materials engineers to incorporate significant material losses (wall thinning, corroded members, weld repairs) or added material (corrosion protection systems, repair clamps) into the weight model.
• Coordinate with operations to identify and quantify any temporary equipment, lay-down areas, or stored materials routinely present on each deck that represent recurring live loads.

4. Multidisciplinary coordination

• Coordinate with the lead structural engineer to ensure that topside weight data is delivered in the exact format, reference system, and phasing required for the finite element model (SACS, USFOS, ANSYS, or equivalent).
• Interface with process, piping, electrical, and instrumentation discipline leads to gather and validate discipline-specific weights and spatial data.
• Support the marine warranty surveyor or certifying authority with weight justification and CoG documentation as required for the life-extension approval process.
• Participate in project technical review meetings, hazard identification workshops, and peer reviews as required.
• Respond to requests for information (RFIs) and technical queries from the structural analysis team and the client's engineering authority.

5. Weight control report (WCR) authoring

• Author and formally issue the Weight Control Report as a key project deliverable, covering: scope and methodology; survey findings and data quality assessment; assumptions and limitations; itemised weight register; deck-by-deck and total topside weight summary; CoG coordinates; contingency breakdown; and comparison against design basis and rated capacities.
• Prepare supporting appendices: field survey photographs and marked-up drawings, vendor data sheets, calculation sheets, and the full itemised register in a format suitable for client records.
• Clearly flag any areas where the current topside weight exceeds the original rated deck load or design environmental weight envelope, and provide recommendations for structural mitigation or load reduction.
• Present WCR findings to the project team and client, facilitating discussion on weight exceedances, structural implications, and recommended actions.
• Issue weight data in a software-compatible format for direct import into the structural re-analysis model as agreed with the project lead.

6. Quality assurance & compliance

• Ensure all weight data, calculations, and reports are prepared, checked, and formally approved in accordance with the project Quality Management Plan and Document Control procedures.
• Maintain full traceability from every weight entry to its primary source (vendor document), secondary estimate (calculation), or engineering assumption with the applicable data quality class recorded.
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