1-805-484-2992
Quotes - Engineering - SalesThe Product Picks the Construction
Once the duty is known, the construction is chosen by what the product will tolerate and what the hygiene class demands. Thin, clean liquids at close approach go to gasketed plates. Higher pressures, steam service and pharma water go to shell-and-tube. Viscous, fibrous or particulate product goes to tube-in-tube. Where product must never reach the utility side, a double tubesheet or a double-wall plate is added on top of whichever construction was chosen.
The three pages in this branch take those decisions one at a time, with the numbers that separate a comfortable selection from a marginal one.
Talk to an Application Specialist
Three Decisions in This Branch
Plate vs shell-and-tube vs tube-in-tube
- The same duty sized three ways, with the viscosity, particulate, pressure and approach-temperature lines that move a product from one construction to the next, and the footprint and cleaning consequences of each.
When you need a double tubesheet
- A short decision tree for the pharma and high-value-product buyer: where a tube-to-tubesheet leak would go, what it would cost, and when the second tubesheet is required rather than optional.
Steam, hot water or glycol utility
- Plant steam against culinary steam, the case for a 185 to 195 F hot water loop on heat-sensitive product, chilled water against propylene glycol, and how each utility is controlled so the product does not burn on or freeze.
Gasketed plates below 500 cP, tube-in-tube above it or with particles over an eighth of an inch, shell-and-tube for pressure, steam and pharma water.
Three thresholds settle most sanitary selections.
Where each construction is strongest
A gasketed plate unit gives the highest coefficient per square foot and the closest approach, opens for inspection, and grows or shrinks by adding plates, which is why it dominates HTST, juice, beer and wort duty. A sanitary shell-and-tube carries higher pressure and temperature, tolerates steam on the shell side, and can be built with a double tubesheet, seal-welded tubes and full ASME documentation, which is why it dominates WFI, clean steam and CIP heating. A tube-in-tube passes whatever fits through the inner tube, sauce, fruit prep, yogurt with fruit, egg, and is drained and cleaned end to end without disassembly.
The lines that move a duty
Viscosity above about 500 cP takes a product out of a standard plate pack; the pressure drop needed to keep the channels turbulent becomes more than a sanitary pump will give. Particles larger than an eighth of an inch or fibers that bridge a plate gap take it out of standard plates as well, though a wide-gap plate will handle pulp and small particulates. Pressures above roughly 150 psig, or any duty with steam on the utility side, favor shell-and-tube. A required 2 to 3 F approach favors plates or a long counterflow tube-in-tube; shell-and-tube wants 10 F or more.
Single or double barrier
Shell-and-tube with a single tubesheet, and single-wall plates, keep product and utility apart by one joint or one plate. That is normal food-grade practice with a potable utility. Where the utility is boiler water with treatment chemicals, or the product is WFI, a parenteral, a cell culture medium or a product where one contaminated batch outweighs the cost of the exchanger, the second barrier is specified: a double tubesheet with a vented gap, or double-wall plates with a vented interspace. Either one makes a leak visible before it becomes a mixing event.
Utility is part of the construction
The utility decides wall temperature, and wall temperature decides whether a dairy product burns on, a juice loses flavor, or a protein denatures on the surface. Plant steam at 150 psig on a milk heater is a burn-on machine unless it is throttled hard; a 190 F hot water loop is gentle and controllable. On the cold side, chilled water at 34 to 40 F will cool milk to 38 F but will not cool wort to 50 F fast enough on a hot day, so brewers run propylene glycol at 20 to 30 F. Extraction cold traps run at minus 40 F and need a construction rated for it. Call and talk it through with an engineer: 1-805-484-2992
Common FAQs
For clean, low-viscosity product at a close approach it usually is, because it needs the least surface. Once the product needs a wide gap, a double-wall plate, or a coefficient allowance for heavy fouling, the plate count rises and a sanitary shell-and-tube or tube-in-tube can come in lower. We price both when it is close.
Not economically. A shell-and-tube is normally sized at a 10 F or larger approach. Pushing it to 3 F multiplies the surface several times over. If the process needs a tight approach and the product will not run in plates, a long counterflow tube-in-tube is the better route.
Pulp, seeds, small particulates and fibrous juices up to roughly a quarter inch run well in wide-gap plates and keep the plate coefficient. Larger pieces, high viscosity, and products that must not be sheared go to tube-in-tube, which is also easier to clean and drain with chunks in the product.
It adds a few inches of length for the second tubesheet and vent gap and a modest amount to the cost, but it does not change the thermal size. The tube count, length and passes are set by the duty exactly as on a single-tubesheet unit.
Yes, in a shell-and-tube or tube-in-tube with the steam on the utility side, provided the steam is throttled to keep the wall temperature within 15 to 20 F of the product on dairy and similar products. Where steam could contact product, or product could enter a condensate return, culinary steam or a hot water loop is specified instead.
Related
Sizing & Selection
Plate vs Shell & Tube vs Tube-in-Tube
One duty, three constructions, and the six questions that pick between them.
+ Learn More
Sizing & Selection
When You Need a Double Tubesheet
Where a tube-to-tubesheet leak would go, what it would cost, and whether the second sheet is required.
+ Learn More
Sizing & Selection
Steam, Hot Water or Glycol Utility
The utility sets the wall temperature, and the wall temperature decides whether the product survives the pass.
+ Learn More
