Good clean-in-place (CIP) system design ensures every product-contact surface is reached with the right flow, temperature, chemistry, and time – without disassembling the equipment. Paul Industries designs and builds CIP systems and integrates them with your process piping so no dead leg is missed.
The elements of CIP design
- Coverage: spray devices sized for full wetted-surface contact in tanks and vessels
- Flow: turbulent velocity in pipe to clean the walls (not just fill them)
- The CIP cycle: pre-rinse, caustic wash, intermediate rinse, acid wash, final rinse
- Controls: recipe management for repeatable, validated cycles
Why integration matters
A CIP skid is only as good as its reach. Designing CIP alongside the process piping ensures the loop actually cleans every dead leg, instrument, and valve – which is exactly where split-scope projects fail cleaning validation.
Related: CIP/SIP systems · CIP vs SIP · How to choose a CIP/SIP company · Request a quote
Frequently asked questions
What is involved in clean-in-place system design?
CIP system design engineers spray coverage, flow velocity, cycle sequencing, drainability, and chemistry for the specific equipment to be cleaned. It sizes pumps, heat exchangers, and piping, minimizes dead legs, and plans validation. Paul Industries designs the system to prove repeatable, coverage-verified cleaning.
How is spray coverage designed in a CIP system?
Coverage is designed by selecting spray balls or rotary spray devices positioned so cleaning solution reaches every internal surface, including heads, agitators, baffles, and nozzles. Coverage is then confirmed physically with riboflavin testing. Missed surfaces are a leading cause of cleaning failure.
What flow velocity is needed for CIP piping?
Piping circuits are designed for turbulent flow, commonly targeting around 1.5 meters per second (roughly 5 feet per second), to generate the scrubbing action that removes soil from tube walls. Undersized pumps or oversized lines drop velocity below the threshold and leave residue.
Why is drainability critical in CIP design?
Any pooled cleaning solution or rinse water left in low spots dilutes chemistry, harbors organisms, and defeats sterility if SIP follows. Lines are sloped to low-point drains and vessels designed to self-drain fully. Poor drainage is a common root cause of failed cleaning.
How are dead legs handled in CIP system design?
Dead legs are stagnant branches where flow can’t scrub, so residues survive. Good design minimizes branch length (ASME BPE guidance limits dead-leg length relative to diameter), uses zero-static valves, and orients tees for flushing. Paul Industries designs dead legs out rather than accepting them.
What is riboflavin coverage testing in CIP design?
Riboflavin (a fluorescent vitamin) is sprayed onto interior surfaces, the CIP cycle is run, and surfaces are inspected under UV light for any remaining fluorescence. Residual glow reveals uncleaned spots, verifying that the designed spray coverage actually reaches every surface.
How do I choose between single-pass and recirculating CIP design?
Single-pass (single-use) sends solution to drain after one pass, simpler and cheaper to build but higher water and chemical use. Recirculating recovers and reuses solution, cutting utility cost for frequent cleaning at higher equipment complexity. Cleaning frequency and utility cost drive the choice.
How are cleaning cycle parameters set during design?
Design sets pre-rinse, wash, and rinse phases with target flow, temperature, chemical concentration, and contact time based on the soil’s solubility. These are proven in development and locked in validation. The parameters, not just the hardware, determine whether cleaning succeeds.
What standards guide CIP system design?
Design follows ASME BPE for hygienic piping and dead-leg limits, ASTM A967/A380 for passivation, and USP <1231> for the water quality feeding the system, all under cGMP. These references keep surfaces cleanable, corrosion-resistant, and drainable. Paul Industries designs to each.
How is CIP capacity and pump sizing determined?
Pump size is set by the highest simultaneous demand across the circuits being cleaned, delivering required velocity and spray-device pressure. Heat-exchanger capacity is sized to reach and hold cycle temperature. Undersizing starves coverage; oversizing wastes energy and utilities.
How does CIP design account for multi-product facilities?
Multi-product design supports validated changeover cleaning to carryover limits between products, with recipe management per product and worst-case bracketing for validation. Residue limits and cycle parameters are set for the hardest-to-clean product so all others are covered.
What materials and finishes are specified in CIP design?
Product-contact surfaces are typically 316L stainless, orbital-welded, and electropolished or mechanically polished to a hygienic finish, then passivated. Smoother finishes shed soil and drain better. Paul Industries specifies finish to the cleanability and regulatory needs of the process.
How is CIP return and waste flow designed?
The return path must remove spent solution and rinse without air-locking or flooding, using a return pump or gravity drain sized to match supply. Waste routing plans for chemical neutralization. Poor return design floods vessels and disrupts the cycle.
How does CIP design integrate with SIP?
When SIP follows, the shared skid must supply clean steam, drain condensate, and provide steam-rated valves alongside CIP components. Design coordinates the two so a cleaned, fully drained vessel can be sterilized without redesign. Paul Industries designs combined CIP/SIP skids.
What are common CIP design mistakes?
Frequent mistakes include undersized pumps that miss velocity, spray devices with shadowed coverage, unaddressed dead legs, inadequate slope for drainage, and cycle parameters too weak for the soil. Paul Industries designs against each and verifies with coverage testing. Call 201-450-8280.
How do I get a CIP system designed for my equipment?
Provide P&IDs, tank and equipment geometry, product and soil types, cleaning limits, and utilities. Paul Industries engineers coverage, velocity, drainability, and cycle parameters, then fabricates, installs, and validates the design as one contractor. Call 201-450-8280.
What is involved in CIP system design?
Spray-device coverage, turbulent flow, cycle chemistry and temperature, and controls for repeatable, validated cleaning – all coordinated with the process piping.
What are the steps in a CIP cycle?
Typically pre-rinse, caustic wash, intermediate rinse, acid wash, and final rinse, with parameters validated for your product.
Why does CIP need to be designed with the piping?
So the loop reaches every dead leg, valve, and instrument. Cleaning coverage is a system-design problem, not just a skid.
Do you build CIP systems?
Yes – Paul Industries designs, builds, and integrates CIP systems and supports cleaning validation nationwide.
Design your CIP system
Paul Industries is a single-source supplier, installer, and validator – one accountable partner from design through documented startup. Tell us about your project and we will scope it.
The four design parameters that decide whether a CIP cycle works
Cleaning is delivered by four variables acting together — often called TACT: Time, Action (mechanical shear), Concentration and Temperature. Weakness in one has to be paid for in another. The most common design failure is a circuit that cannot deliver mechanical shear, which then gets compensated for with more chemistry, more heat and a longer cycle, permanently.
| Parameter | Design target | Why it matters |
|---|---|---|
| Flow velocity in pipe | Minimum 5 ft/s (1.5 m/s); 5–7 ft/s typical target | Below this, cleaning depends on diffusion rather than shear |
| Velocity in larger lines | ~7 ft/s for 3 in and above | Maintains turbulence as diameter grows |
| Upward-flowing branches | 10 – 14 ft/s where air removal is needed | Prevents trapped air blocking contact |
| Flow regime | Reynolds number above 4,000 | Laminar flow leaves an undisturbed boundary layer at the wall |
| Spray device coverage | ≥0.5 GPM per ft² of vessel surface | Sets the pump and supply sizing for tanks |
| Dead legs | L/D below 2, measured from the inside wall of the run | Unswept volume receives effectively zero shear |
| Drainability | Continuous slope, no low points | Retained solution carries over and dilutes the next step |
Chemistry: concentration and temperature by step
| Step | Chemistry | Concentration | Temperature | Removes |
|---|---|---|---|---|
| Pre-rinse | Water | — | Ambient to warm | Gross soil; recovered where possible |
| Caustic wash | Sodium hydroxide | 1 – 4% | 65 – 80 °C | Proteins, fats, organic soils |
| Intermediate rinse | Water | — | Ambient | Caustic carryover |
| Acid wash | Nitric, phosphoric or citric | 0.5 – 1.5% | Warm | Mineral scale, water hardness, beerstone |
| Final rinse | PW or WFI as service requires | — | Ambient to hot | All residues |
| Sanitisation | Peracetic acid, or hot water | 100 – 200 ppm PAA | Hot water above 82 °C | Microbial load |
Caustic before acid, not the reverse. Caustic lifts the organic layer; running acid first fixes protein onto the surface and makes the whole cycle less effective.
How you prove the cycle actually worked
| Verification | Method | Typical acceptance |
|---|---|---|
| Spray coverage | Riboflavin under UV light at 365 nm | 100 – 200 ppm applied; no fluorescence remaining |
| Chemical removal | Final rinse conductivity | Approaching incoming water; ≤1.3 µS/cm at 25 °C for WFI service |
| Organic residue | Final rinse total organic carbon | ≤500 ppb per USP <643> |
| Surface residue | Swab sampling against a MACO-derived limit | Set by cleaning validation, not by the CIP skid |
| Cycle parameters | Recorded flow, temperature, conductivity, time per step | Within the ranges proven during qualification |
Riboflavin coverage testing is what demonstrates the design works. Swab and rinse sampling against acceptance limits is what demonstrates the process works. They are different exercises and both belong in the qualification file.
Instrumentation the cycle has to have
- Flow measurement on the supply, accurate to about ±2%, because velocity is the parameter you cannot infer
- Conductivity on supply and return, to control chemical concentration and confirm rinse-down — resolution to roughly ±0.1 µS/cm at the rinse end
- Temperature at the return, not just at the heater, because the return is what proves the whole circuit reached temperature
- Pressure to confirm spray device performance
- Return-line verification that flow actually returned, so a diverted or blocked circuit cannot silently pass
- Records retained per circuit per cycle — on a cGMP system under 21 CFR Part 11 where captured electronically
Single-use versus reuse skid design
| Single-use (Type I) | Reuse (Type II) | |
|---|---|---|
| Solution handling | Made up, used once, drained | Recovered to tanks and re-used |
| Tanks required | One, or none with inline dosing | Separate caustic, acid, rinse and recovery |
| Water and chemical use | Highest | Substantially lower per cycle |
| Capital cost | Lower | Higher |
| Cross-contamination risk | Lowest — nothing is carried between products | Requires control, and often precludes multi-product use |
| Best fit | Multi-product, high-potency, pharmaceutical | Single-product, high cycle count, food and beverage |
Design errors we are called in to correct
- Pump sized for the tank, not the circuit. The longest, largest-diameter circuit sets the pump duty. Sizing on an average leaves the worst circuit below 5 ft/s permanently.
- Dead legs at points of use and instrument tappings, which no amount of chemistry reaches.
- Cleaning to a timer rather than to an endpoint. Conductivity and TOC endpoints let a cycle finish when the circuit is clean.
- Inline dosing without feedback control, so concentration drifts with supply pressure and nobody knows.
- Shared return lines that allow one circuit’s soil into another.
- No recorded return temperature, so a circuit that never reached temperature passes on the heater reading.
- Spray devices selected by tank volume instead of by surface area and coverage rate.
Check the velocity in a specific line
The 5 ft/s minimum above is a velocity, not a flow rate, so it changes with line size. Our pipe and tube volume calculator converts between the two for hygienic tube and NPS pipe, and reports the flow each size needs to reach 5 ft/s – about 9 gpm in 1 in tube, 43 gpm in 2 in and 101 gpm in 3 in. It also returns the line volume and wetted surface area used when sizing the chemical charge.