Most cGMP process problems are decided on the drawing, not on the job site. A dead leg that fails cleaning validation, a transfer line sized for the wrong turndown, a skid that cannot be maintained without breaking the sterile boundary: each is a design decision that becomes expensive only after the steel is in the air. Paul Industries provides process engineering services for hygienic systems, and because the same company then fabricates, installs and qualifies the work, the design is made by people who will have to build it and prove it.
What a process design package contains
Design for regulated process systems is not a single drawing set. It is a sequence, and each stage exists to close a class of decision before the next stage depends on it.
| Phase | What it decides | Typical deliverables |
|---|---|---|
| User requirement specification | What the system must do, in the owner’s words, with the regulatory basis and the critical quality attributes named | URS, regulatory basis memo, critical aspects list |
| Basis of design | The engineering answer to the URS: capacities, grades, materials, utilities, control philosophy | Basis of design document, block flow diagram, utility load summary |
| Process design | How the process actually flows, what each stream is, where the boundaries sit | Process flow diagrams, mass and energy balance, line list |
| Detailed design | Every component, size, slope, instrument and connection | P&IDs, equipment and instrument schedules, piping specification, valve list |
| 3D and layout | Whether the system fits, drains, and can be operated and maintained | 3D model, clash review, general arrangement, isometrics, spool drawings |
| Qualification support | How the built system will be shown to meet the URS | Design qualification, traceability matrix, specification for turnover documentation |
The URS is the document that decides the project
A weak user requirement specification is the most common root cause of an expensive process project. It usually fails in one of three ways. It states equipment rather than requirements, which locks in a solution before the engineering is done. It omits the operating range, so a system sized for nominal flow cannot hold velocity at minimum batch size. Or it leaves the regulatory basis implicit, so nobody establishes early whether the water is USP Purified Water or Water for Injection, whether the room is classified, and which predicate rules apply. We write requirements as testable statements, because every line in the URS eventually has to be demonstrated in qualification, and a requirement that cannot be tested is a requirement that will be argued about at handover.
Where hygienic design differs from general industrial design
Ordinary process engineering optimizes for throughput, pressure drop and capital cost. Hygienic design adds a constraint that outranks all three: every product-contact surface must be cleanable and, where required, sterilizable, and that must be provable. That single constraint drives slope so lines drain, dead-leg length under the ASME BPE limit, diaphragm and zero-static valves at branches, surface finish specified as a measured Ra rather than a description, orbital welds wherever a head fits, and documentation that survives an audit years later. It also means a line cannot simply be made bigger to solve a pressure problem, because velocity governs cleaning. In clean-in-place circuits the design target is a scouring velocity through every branch of the circuit, which means the circuit boundary is a design decision, not an operating one.
Design-build vs design-bid-build for regulated work
In design-bid-build an engineering firm produces a package, the owner tenders it, and a contractor prices exactly what is drawn. It gives a clean competitive bid and an independent designer. It also puts a commercial boundary between the person who drew the system and the person who has to make it work, and in hygienic work that boundary is where slope, support, access and weld sequence problems surface as change orders. In design-build the same party designs and constructs, so constructability is decided while it is still cheap to change and there is one accountable party through qualification. The trade is transparency: the owner sees fewer competing prices and must specify more carefully at the URS stage. For a tightly scheduled cGMP project with an experienced owner team, design-build usually wins on total installed cost and schedule. For a large greenfield facility with multiple trade packages, an independent designer is often worth the coordination cost.
Designing so that qualification is cheap
Validation cost is largely set during design. Instruments that will be calibration points need to be accessible and identified early. Sampling points have to exist where the protocol will sample, not where the pipe happened to allow. Circuit boundaries must match the way cleaning will be validated, because a worst-case circuit that was never drawn cannot be tested. Where a risk-based approach under ASTM E2500 is used, the critical aspects are identified in design and the commissioning evidence is written to be leveraged into qualification rather than repeated. A design that ignores this produces a system that works and a qualification that takes months. Our validation and commissioning team reviews the P&IDs before they are issued for construction for exactly this reason.
3D modelling and what a clash review is really for
A 3D model is often sold as a way to avoid pipes hitting ducts. That is the least valuable thing it does. The high-value checks are whether every line drains in the direction the P&ID claims, whether valves can be reached and rebuilt without a lift, whether a filter housing can be opened in the space provided, whether a transfer panel is reachable from the operator’s position, and whether insulated lines still clear structure once the insulation is on. Those are the conditions that make a system either maintainable or permanently irritating, and they are almost free to fix in the model.
What to require from a process engineering provider
- A URS written as testable requirements, with the regulatory basis and the critical quality attributes stated, not implied.
- A piping specification that names material grade, surface finish as a measured Ra limit, fitting standard and weld acceptance criteria, rather than the phrase sanitary construction.
- P&IDs that show slope direction, drain points, circuit boundaries and sterile boundaries, not just connectivity.
- A line list and valve list that an estimator and a validation engineer can both work from.
- A 3D model with a documented clash and access review, including maintenance envelopes and insulated dimensions.
- A design qualification or equivalent record that traces each URS requirement to the design feature that satisfies it and the test that will prove it.
- Named engineering responsibility for the pressure-retaining design basis under ASME B31.3, and the code stamp where a vessel is involved.
- A defined change process for the period between issued-for-construction and turnover, because undocumented field changes are what break a traceability matrix.
- Deliverables in a format the owner can maintain afterward, with native files included, not only PDFs.
Scaling the effort to the project
Not every project needs every deliverable. A single skid replacement inside an existing suite may need a URS, a P&ID, a tie-in drawing and a qualification plan. A new water system needs the full sequence because the loop touches every room it serves. The judgement is which decisions are irreversible: anything that sets a building penetration, a utility capacity, a room classification or a validated boundary deserves engineering before it is bought, and anything reversible can be resolved in the field. We scope engineering that way rather than selling a fixed document set.
What Paul Industries does
Paul Industries provides sanitary process engineering and process design services for pharmaceutical, biotech, medical device, food, beverage and personal-care facilities across the United States: user requirement specifications, basis of design, process flow diagrams and P&IDs, equipment and line sizing, materials and surface finish specification to ASME BPE, 3D modelling with clash and access review, isometrics and spool drawings, and design qualification support. Because we self-perform fabrication, installation, orbital welding, passivation and IQ/OQ/PQ, the design is produced by the party that carries it through to a qualified system, and the turnover package is planned from the first drawing rather than assembled at the end.
Standards referenced: ASME BPE · ASME B31.3 · ASTM E2500 · 21 CFR 211 · ISO 14644-1
Frequently asked questions
What do process engineering services include for a hygienic system?
They include the user requirement specification, basis of design, process flow diagrams, mass and energy balance, P&IDs, equipment and line sizing, materials and surface finish specification, instrumentation and control scope, 3D modelling with clash and access review, isometrics and spool drawings, and the design qualification record that traces requirements to the features that satisfy them.
How is sanitary process engineering different from general process engineering?
General process engineering optimizes throughput, pressure drop and capital cost. Sanitary process engineering adds a constraint that outranks those: every product-contact surface must be cleanable, provably so. That drives drainable slope, dead-leg limits, valve selection, measured surface finish, weld method and a documentation trail, and it means a line cannot be oversized to fix pressure because velocity governs cleaning.
What should a user requirement specification contain?
Testable statements of what the system must do, the regulatory basis, the critical quality attributes, capacity and the full operating range including minimum batch, required utilities, the cleaning and sterilization expectation, documentation requirements and the acceptance criteria. Naming a specific piece of equipment in a URS is usually a mistake, because it fixes a solution before the engineering that should choose it.
Do I need a URS for a small equipment replacement?
Usually yes, but a short one. Even a single skid swap has requirements that must be demonstrated afterward: capacity, utility connections, cleaning expectation, controls integration and the qualification scope. A two page URS prevents the common outcome where a replacement is installed and then nobody can state what it was supposed to achieve.
What is the difference between design-build and design-bid-build on a cGMP project?
Design-bid-build separates the designer from the builder, which gives an independent design and competitive pricing, but puts a commercial boundary where constructability problems appear. Design-build keeps design and construction with one party, so buildability is resolved while it is still cheap and one party is accountable through qualification, at the cost of fewer competing prices.
How does design affect validation cost?
Heavily. Sampling points, instrument accessibility, circuit boundaries and the ability to reach worst-case locations are all fixed by the drawing. A system designed without the protocol in mind produces a working plant and a slow, expensive qualification, because tests have to be improvised around what was built rather than executed against what was planned.
What is design qualification and is it still required?
Design qualification is the documented verification that the proposed design meets the user requirements and the applicable regulations. It is still expected in traditional qualification approaches. Under a risk-based approach following ASTM E2500 the same verification happens as design review against critical aspects, with commissioning evidence leveraged rather than repeated, but the underlying requirement to show the design satisfies the URS does not go away.
What should be on a P&ID for a hygienic system that is not on an ordinary one?
Slope direction and value, low points and drain valves, cleaning circuit boundaries, the sterile boundary and its isolation valves, instrument tag numbers matching the calibration program, transfer panel or valve matrix arrangement, and identification of product-contact versus utility service. Connectivity alone is not enough to build or validate from.
Can you design a system another contractor will build?
Yes. Design can be delivered as a standalone package for competitive tender, including the specification, drawings and qualification plan. It is worth telling the design team at the outset that the package will be tendered, because a package written for bid needs tighter specification language than one where the designer will also build.
How detailed should a piping specification be?
Detailed enough that two bidders cannot legitimately price different things. Name the material grade and dual certification where needed, the fitting and tube standard, surface finish as a measured Ra limit for product contact and for the exterior, the weld method and acceptance criteria, inspection percentage, and the passivation and documentation requirements. The phrase sanitary construction is not a specification.
What is a clash and access review, and why does it matter more than clash detection?
Clash detection finds geometry that overlaps. An access review asks whether the system can be operated and maintained: can a valve be rebuilt in place, can a filter housing be opened, can an instrument be removed for calibration, does an insulated line still clear structure. Those are the issues that make a plant workable, and they are nearly free to fix in a model.
Who is responsible for the code design of piping and vessels?
The engineering party that takes design responsibility under ASME B31.3 for the process piping, and the vessel manufacturer for code stamped vessels under ASME Section VIII. That responsibility should be named in the contract rather than assumed, particularly on projects where the owner supplies some equipment and the contractor supplies the rest.
Do you provide industrial process engineering services outside pharmaceutical work?
Yes. The same engineering applies in food, beverage, dairy, brewing, nutraceutical and personal-care plants, with the regulatory spine changing rather than the engineering. The cleanability, drainability, material and documentation logic is common; what differs is which rule governs and how much documentation the plant is required to keep.
What deliverable formats should I insist on?
Native editable files as well as PDFs: the 3D model, the P&ID source files, the line and instrument lists as spreadsheets, and isometrics. A facility that only receives PDFs pays to recreate the model the first time it modifies the system, which is usually within a few years.
Related: Turnkey Process Systems — Single-Source Design, Build & Validate · Sanitary Process Piping Installation (ASME BPE) · Validation & Commissioning (IQ/OQ/PQ) · Requesting Bids for Stainless Steel Process Piping Installation · How to Choose a Process-Piping Contractor · Process Equipment & Systems Companies: How to Choose a Single-Source Provider · Request a quote