What equipment challenges arise when scaling up PEF production?

Michaël Dreesen · 07 Nov 2026

60+ years of experience
120+ employees
Units up to 10 m diameter
Up to 1,000 tons

When PEF production moves from pilot to industrial scale, the main equipment challenges are corrosion, pressure and temperature control, dimensional precision and line integration. Polyethylene furanoate is made by polycondensation of furandicarboxylic acid (FDCA) and ethylene glycol, a process that places heavy demands on the vessels, reactors and heat transfer equipment around it. These challenges rarely appear on a laboratory bench. They emerge when wall thicknesses grow, material costs rise and a single fabrication error can stop an entire line. The sections below answer the most common questions about scaling up PEF production and the equipment decisions behind it.

Why do PEF treatment chambers fail at industrial scale?

PEF treatment chambers fail at industrial scale mainly because small-scale designs do not transfer linearly. Higher throughput brings more aggressive media exposure, greater thermal loads, thicker walls and tighter dimensional demands. Weaknesses that stayed hidden in pilot equipment, such as local corrosion, weld defects or poor temperature uniformity, become critical failure points.

A pulsed electric field system and a PEF polymer line are different things, so it helps to be precise. In the polymer context, the “chamber” is usually a reactor or vessel in which esterification and polycondensation take place. In the pulsed electric field context, a treatment chamber exposes a product to short, high-voltage pulses. Both share the same scale-up logic: geometry, material and fabrication quality must hold up under continuous operation.

Typical failure drivers include:

Corrosion under process conditions: acidic intermediates and elevated temperatures attack materials that looked adequate in short pilot runs.
Thermal gradients: larger volumes make uniform temperature control harder, which affects product quality and stresses the vessel.
Fatigue and cycling: repeated start-ups and shutdowns load welds and nozzle connections more than steady operation does.
Scaled geometry errors: a design copied at larger size without mechanical re-evaluation can create stress concentrations.

The practical lesson is to treat scale-up as a mechanical redesign, not an enlargement.

Which materials hold up in industrial PEF equipment?

Titanium is the most established material for corrosion-resistant PEF equipment, with grades such as Ti Grade 1 and Ti Grade 2 used for solid vessels and as cladding on carbon steel. Zirconium, Hastelloy and tantalum serve more severe conditions. The right choice depends on the process medium, temperature and pressure.

Solid titanium delivers excellent corrosion resistance, but at large dimensions the material cost climbs quickly. This is why clad pressure vessels are widely used. A carbon steel shell carries the mechanical load, while an inner layer of titanium or another corrosion-resistant alloy protects against the process medium. Explosion-clad plate is a common route to this construction.

When comparing options, weigh these factors:

Corrosion behaviour in the actual process medium, including impurities and by-products
Operating temperature and the strength the material retains at that temperature
Weldability and the availability of qualified fabrication procedures
Total lifecycle cost rather than purchase price alone

Fabricating titanium and other reactive metals also requires controlled conditions. Contamination during welding can undermine the very corrosion resistance the material was chosen for, so fabrication know-how matters as much as the material grade itself.

How do pressure and temperature affect PEF equipment design?

Pressure and temperature set the wall thickness, material selection, nozzle reinforcement and joint design of PEF equipment. Higher pressure demands thicker walls and more rigorous calculation, while elevated temperature reduces allowable material strength. Together they determine whether the equipment is classified and certified under codes such as PED and ASME.

Design codes translate operating conditions into mechanical requirements. Pressure equipment is typically designed to PED or ASME rules, and for demanding duty, supplementary analysis is common. Finite element analysis, fatigue analysis and thermal analysis help confirm that the design survives real operating cycles, not only the steady design point.

Temperature creates two separate concerns. First, allowable stress drops as temperature rises, which pushes wall thickness up. Second, temperature differences between the inner layer and the structural shell in clad equipment create differential expansion that the design must accommodate. Ignoring this is a frequent cause of cladding problems.

For scale-up, the key step is to define the full operating envelope early, including upset conditions, start-up and shutdown, and cleaning cycles. Designing only for normal operation leaves the equipment exposed during the transients that cause most damage.

What fabrication tolerances matter when scaling up PEF?

The tolerances that matter most in PEF scale-up are roundness and straightness of large shells, weld quality, cladding integrity, nozzle alignment and internal surface condition. At large diameters and thick walls, small deviations compound, affecting the fit of internals, sealing, process performance and the ability to assemble the equipment on site.

Dimensional precision becomes harder as equipment grows. A shell that is slightly out of round complicates the fit of agitators, seals and internals. Misaligned nozzles create piping stress. Poor weld profiles on the process side can trap material and accelerate corrosion.

Work through these checkpoints during fabrication planning:

Confirm the forming method and its effect on clad layer integrity.
Define weld procedures and qualification for each material combination.
Specify non-destructive examination scope, including cladding bond checks.
Set tolerances for roundness, flange faces and nozzle orientation.
Plan heat treatment and verify distortion control afterwards.
Agree inspection and documentation requirements before fabrication starts.

Involving the fabricator during design pays off here. Features that look simple on a drawing can be costly or risky to build, and a design adjusted for manufacturability often reduces both schedule and risk.

How should PEF equipment be integrated into a full line?

PEF equipment should be integrated by defining interfaces between vessels, agitators, drives, seals, heat exchangers and instrumentation early in the design. A coordinated mechanical scope avoids mismatches, such as a drive that does not suit the vessel loads or a seal system incompatible with the process conditions.

A PEF line is a chain of linked equipment, and the weakest interface sets the reliability of the whole. Reactors need agitation and sealing suited to viscous, high-temperature media. Heat exchangers must match the thermal duty and the corrosion profile of the surrounding vessels. Instrumentation must read accurately in the actual conditions.

Consider these integration points:

Mechanical interfaces

Agitator shafts, seal housings and lubrication systems depend on precise alignment with the vessel. Load paths from drives into the structure should be calculated, not assumed.

Thermal and process interfaces

Shell-and-tube heat exchangers, preheaters and condensers must be specified consistently with the reactor materials, so galvanic or compatibility issues do not appear at the connections.

Where one party handles several of these components, interface risk drops because fewer handovers occur.

When should a PEF scale-up use a custom fabricator?

A PEF scale-up should use a custom fabricator when equipment is large, heavy or thick-walled, uses titanium, zirconium or clad construction, has tight tolerances, or falls outside standard catalogue designs. First-of-a-kind equipment is a strong signal, since there is no proven standard to copy.

Standard fabrication suits simple equipment in common materials. Scale-up of a newer process is different. The process is still maturing, the operating window may shift, and the mechanical design must stay flexible while meeting certification requirements.

Look for a fabricator that can show:

Documented experience with the required materials and clad construction
In-house mechanical engineering to translate process requirements into buildable designs
Capacity for the size and weight of the equipment
Relevant certification, such as ISO 9001, PED and ASME

Choosing on technical fit and reliability, rather than price alone, usually lowers total project risk, since failures in critical equipment cost far more than the fabrication premium.

How Coek helps with PEF production scale-up

Coek Engineering is a Belgian manufacturer of custom, critical pressure equipment, and its work covers many of the challenges described above. Coek has fabricated solid titanium Grade 2 pressure vessels for PEF applications, and has more than 30 years of experience with clad construction using titanium, zirconium, Hastelloy and other demanding materials.

Coek supports PEF scale-up projects with:

Custom reactors, pressure vessels and shell-and-tube heat exchangers in exotic and clad materials
In-house mechanical engineering that turns customer process requirements into manufacturable equipment, including FEA, fatigue and thermal analysis
Fabrication of equipment up to 10 metres in diameter and approximately 1,000 tons
Integrated scopes that can combine reactors with agitators, drive systems, seals, lubrication systems and instrumentation
ISO 9001, PED and ASME certification

If you are planning a PEF scale-up and need a fabrication partner for demanding equipment, contact the Coek team to discuss your project requirements.

Frequently Asked Questions

How do I get started planning equipment for a PEF scale-up project?

Start by defining the full operating envelope: normal operating conditions, start-up and shutdown, upset scenarios and cleaning cycles. Then collect corrosion data for your actual process medium, including impurities and by-products, and use it to shortlist materials. Engage a fabricator with in-house mechanical engineering at this stage, because early input on manufacturability and code requirements (PED or ASME) typically saves time and cost later.

What is the most common mistake when scaling PEF equipment from pilot to industrial size?

The most common mistake is simply enlarging the pilot design without a fresh mechanical evaluation. Wall thickness, thermal gradients, nozzle loads and weld stresses do not scale linearly, so a copied design can introduce stress concentrations and temperature non-uniformity. Re-run the design calculations and supporting analysis (FEA, fatigue, thermal) for the new size rather than extrapolating from pilot results.

How can I tell whether clad construction or solid titanium is the better choice?

Compare the material cost against the mechanical demands. Solid titanium suits smaller or thinner equipment where the cost premium is manageable, while clad construction (a carbon steel shell with a titanium or other alloy inner layer) is usually more economical for large, thick-walled vessels. Also consider differential thermal expansion between the layers and the availability of qualified welding procedures for the clad material. Evaluate total lifecycle cost, not just purchase price.

What should I do if corrosion appears in equipment that performed well during pilot trials?

First identify the corrosion type and location, such as general attack, crevice corrosion at welds or localized attack in stagnant zones. Review whether process conditions at scale differ from the pilot, such as higher temperatures, longer residence times or different impurity levels. Check fabrication quality as well, since weld contamination or poor weld profiles on the process side can undermine a correctly chosen material. The findings will indicate whether you need a material upgrade, a design change or improved fabrication controls.

Which inspections and tests should I specify for critical PEF pressure equipment?

Specify non-destructive examination of welds, including cladding bond checks for clad equipment, plus dimensional verification of roundness, flange faces and nozzle orientation. Add pressure testing in line with PED or ASME requirements and confirm material traceability and welding procedure qualifications. Agreeing the inspection and documentation scope with the fabricator before fabrication starts avoids disputes and rework later.

How can I reduce interface risk when a PEF line includes reactors, agitators, seals and heat exchangers?

Define the interfaces early and calculate load paths from drives and agitators into the vessel structure rather than assuming them. Make sure materials in heat exchangers, reactors and connections are compatible to avoid galvanic issues, and confirm seal systems suit the process temperature and viscosity. Using a single supplier for several components reduces handovers, which lowers the chance of mismatches between equipment.

How early should a fabricator be involved in a first-of-a-kind PEF project?

As early as possible, ideally during basic or conceptual design. For first-of-a-kind equipment there is no proven standard to copy, and the process window may still shift as the technology matures. Early fabricator involvement helps keep the design flexible, adjust details for manufacturability and certification, and avoid features that look simple on a drawing but are costly or risky to build.