Design Basis Memorandum
Checklist (Excel)

A design basis memorandum (DBM), also called Basis of Design (BoD) or Basic Engineering Design Data (BEDD), is the FEED-stage document that fixes every assumption the engineering team will use throughout detail design. It defines feedstock, product slate, capacity, site conditions, applicable codes, utility specifications, HSE design philosophy, material selection philosophy, sparing philosophy, and sustainability targets. The DBM is the contractual baseline against which design deviations are tracked through Management of Change. Every discipline (Process, Piping, Mechanical, Electrical, Instrumentation, Civil) references the DBM at FEED and detail-design start. Without a frozen DBM, downstream design rework is unavoidable.

Required sections: project identification, plant location and site conditions (ambient temperature, humidity, elevation, seismic zone, wind speed), feedstock and product definition with ranges, plant capacity (nameplate, turn-down, design margin), stream-day vs calendar-day basis, battery limit definition, tie-in points (for brownfield), applicable codes and standards, utility conditions (steam, CW, IA, N2, power), effluent and emission specs, HSE design philosophy (HAZOP / SIL / LOPA), process control philosophy, material selection per NACE MR0175 (sour service), sparing philosophy, plot plan philosophy per OISD-118, sustainability and carbon targets, currency and units, open-issues register, and sign-off. The template includes all sections.

Pathnovo, an engineering document intelligence platform, ingests legacy DBMs, FEED reports, licensor process packages, client URS documents, and prior project DBM precedents, then consolidates them into one unified DBM matrix. Conflicting assumptions across documents are surfaced as flagged rows for client decision. Hold items and open issues are extracted automatically. Typical turnaround is 48 hours from document upload to consolidated DBM checklist. Output is configurable to your client template (EIL, L&T, Tata Projects, Worley, Technip Energies, Bechtel formats pre-configured). See the engineering document consolidation workflow for the full pipeline.

Three terms for the same FEED-stage deliverable. Design Basis Memorandum (DBM) is the term common in Indian EPC and Middle East EPC contracts. Basis of Design (BoD) is the term common in US and European EPC contracts. Basic Engineering Design Data (BEDD) is the term sometimes used by process licensors (Honeywell UOP, Shell GBV, Axens, Lummus) for the licensor-issued process data package. All three define the same content: frozen design assumptions for detail engineering. Pathnovo handles all three naming conventions in the same template. See the engineering document consolidation reference for the unified handling.

The Applicable Codes section of the DBM fixes which codes apply to each discipline: ASME Section VIII Div 1 or Div 2 for pressure vessels, ASME B31.3 for process piping, API 610 for centrifugal pumps, API 617 for compressors, API 650 / 620 for storage tanks, IEC 61511 for safety instrumented systems, ISA 5.1 for instrumentation symbology. Indian projects add IS codes, OISD-118 for refinery layout, IBR (Indian Boiler Regulations) for steam-side scope, PESO compliance for pressure equipment in hydrocarbon service, and CCOE for tank farm. Every datasheet, MR, and detail drawing inherits the code basis from the DBM. See the ASME B31.3 reference and OISD-118 reference for code reference structure.

Brownfield DBMs must reference both the as-built basis (the original plant DBM) and the revamp basis (new feedstock, new capacity, new product slate). The Tie-In Points section is critical, listing every battery-limit interface to the existing plant with operating conditions, line tag, valve tag, and pipe spec from the existing line list. Indian PSU brownfield revamps (IOCL, BPCL, HPCL refinery expansions) must also reconcile the existing OISD-118 plot plan compliance with revamp expansion plot needs. The template includes both an Existing-Basis column and a Revamp-Basis column for side-by-side comparison.

Downstream consumers: Process discipline uses feedstock, capacity, and codes for PFD, P&ID, HMB, and equipment datasheets. Piping discipline uses utility conditions and codes for piping material specs (PMS) and stress analysis criteria. Mechanical discipline uses code basis and site conditions for vessel and exchanger thermal-mechanical design. Electrical discipline uses utility power conditions for SLD and load list. Instrumentation discipline uses control philosophy for I/O list and SIS design. Civil discipline uses seismic and wind data. The DBM is the single contract-frozen reference every discipline pulls from. Any deviation is logged in the Management of Change register. See the Management of Change reference.