# Engineering Context for EPC and Process Plants

The harder problem is not that change happens — it is proving why it changed, when it changed, and what it affected.

> The real unit of change is not a document. It is a time-linked chain of engineering evidence.

## A design change rarely closes in one file.

Owner requirements, design criteria, TQs, Owner Clarifications, CRS, drawing and model revisions, and transmittals stack on the same issue. EPC teams must re-read which objects, systems, and spaces were touched — and on what evidence the review rested.

## Where design and review work stalls today

- Finding the real object behind a clause or tag means cross-checking drawings, models, and lists by hand.
- Revision diffs show what changed, but not which systems, spaces, or re-reviews are in scope.
- TQ, CRS, responses, and send history do not stay joined to the issue, so impact discussions lose footing.
- Without Viewpoint, object, revision, and clause packaged together, the same judgment is hard to reconstruct.

## Why Engineering Change Intelligence is needed

Requirements and clauses, the Process Rich Tag Graph, target objects, Spatial Graph neighborhoods, drawing and model revisions, TQ / Owner Clarification / CRS, and Evidence Snapshots must share one time axis. People and AI need the same identities, revisions, and relationships before review support is meaningful.

## From requirement to change-impact review

Engineering Change Intelligence keeps this chain intact so design and commercial review stay grounded.

1. **Owner Requirement / Design Criteria** — Where the change starts
2. **Clause / Requirement** — Document clause as the unit of interpretation
3. **PIDEX / Process Rich Tag Graph** — Normalize process identity and relationships
4. **Tag Resolver → target object** — The real engineering object a tag points to
5. **S3DX / Spatial Graph** — Spatial and hierarchy context for large models
6. **Spatial Resolver → neighborhood** — Relationships and space that must be reviewed
7. **Drawing / Model Revision** — Deliverables that applied at that point in time
8. **TQ / Owner Clarification / CRS** — Issue, response, and comment history
9. **Evidence Snapshot** — Review evidence package
10. **Change-impact review support** — Then engineer judgment and approval

## Four workflows EPC teams run every week

### A. Design Change Impact Review

Read how a requirement or clause change reaches objects, surrounding systems and space, and which drawings or models must be re-reviewed — as an evidence chain.

- Requirement / clause change
- Target object
- Surrounding system and spatial impact
- Affected drawings/models and evidence chain

### B. Revision Deviation Review

Beyond what changed: which tags, systems, and spaces are affected, and what must be re-reviewed.

- What changed
- Affected tags / systems / spaces
- What must be re-reviewed

### C. Repetitive Design Review Assistance

From document clause to object to surrounding space, AI surfaces candidate issues; the engineer decides.

- Clause → object → space
- AI finds candidate issues
- Engineer decides

### D. Engineering Deliverables

L3D Emit turns model views into reusable deliverables for detailed design and review.

- SAT / 3D Solid DWG / 2D output where applicable
- Coordinate-true backgrounds and Evidence

## What this workflow actually uses

Not a product inventory — the roles each piece plays in the Engineering Change Intelligence chain.

### Primary

- **PIDEX**: Connects P&ID and records into a Process Rich Tag Graph and review outputs.
- **S3DX**: Publishes large models as Spatial Graph and 3D Tiles so spatial context stays current.
- **L3D Vue**: Reviews 1D, 2D, 3D, and relationships in one workspace.
- **Spatial Resolver**: Selects the neighborhood and relationships that must be reviewed around a target.

### Secondary

- **L3D Emit**: Turns model views into engineering deliverables, 2D backgrounds, and Evidence.
- **Evidence Snapshot**: Packages object, revision, clause, and Viewpoint as traceable review evidence.
- **nanochat** (future): Future local Engineering Agent runtime (design stage). Not central on this page.

## What AI does — and what engineers close

AI understands, analyzes, identifies candidates, and supports review. Final judgment and approval stay with authorized engineers.

We do not claim approval, CRS closure, entitlement, litigation outcomes, 100% automatic mapping, or hallucination-free AI. Focus stays on tracing impact, supporting review, and connecting evidence.