A shell and tube heat exchanger is a closed vessel in which one fluid flows through a bundle of tubes while a second fluid flows around those tubes inside a cylindrical shell, so heat moves through the tube walls without the two streams mixing; Paul Industries installs, pipes, inspects, cleans, repairs and hydrostatically tests these exchangers in process plants nationwide. This guide is for the engineer specifying one, the operator running one and the buyer comparing quotes: flow paths, parts, the TEMA code on the nameplate, the main constructions, sizing, materials, the pressure vessel code and what decides service life.
How does a shell and tube heat exchanger work?
It works by dividing the two fluids between two separate pressure spaces: the tube side, made up of the heads and the inside of the tubes, and the shell side, the space between the tubes and the shell wall. Heat travels from the warmer fluid through a film on that side, through the tube wall and through a film on the other side into the cooler fluid. The shell and tube heat exchanger working principle is ordinary conduction and convection across thin metal, repeated over hundreds or thousands of tubes until the surface matches the duty.
Three things set how much heat crosses: the temperature difference, the tube surface area and the overall heat transfer coefficient, which combines both film coefficients, the wall and any fouling layer. Designers raise the coefficient by keeping both fluids turbulent, with multiple tube passes on the tube side and baffles that force the shell fluid back and forth across the tubes.
Counterflow and multi-pass flow
With one straight pass each, entering at opposite ends, the exchanger runs in true counterflow, the most effective arrangement. Most real units send the tube fluid down half the tubes and back through the other half while the shell fluid makes one pass, so part of the surface runs counterflow and part parallel flow. The effective temperature difference is then somewhat lower, and designers account for it with a correction factor, F.
Shell and tube heat exchanger parts and what each one does
Every unit is built from the same short list of components: a shell, a tube bundle, one or two tubesheets, baffles held by tie rods and spacers, a front head (channel or bonnet), a rear head or shell cover, and nozzles connecting both sides to plant piping.
| Part | What it does | Where trouble usually starts |
|---|---|---|
| Shell | Pressure boundary for the shell-side fluid | Erosion opposite an unprotected inlet nozzle |
| Tubes | The heat transfer surface, straight or U-bent | Pitting, inlet-end erosion, wear at baffle holes |
| Tubesheet | Drilled plate holding the tube ends and separating the two sides | Leaking tube joints, crevice corrosion |
| Baffles | Steer shell-side flow across the tubes and support them | Enlarged holes, bypass leakage, tube fretting |
| Front head | Distributes tube-side fluid; partition plates form the passes | Partition gasket leaks that short-circuit passes |
| Rear head or cover | Closes the far end, enclosing any floating head | Hidden floating head gasket leaks |
| Nozzles and impingement plate | Connect piping; the plate shields tubes from the inlet jet | Piping loads cracking nozzle welds |
| Expansion joint | Shell bellows absorbing shell-to-tube growth on some fixed designs | Fatigue cracking from excess cycling |
Here is a diagram of shell and tube heat exchanger construction, written as the path each fluid takes through a removable-bundle unit with two tube passes:
- Tube-side fluid enters the front head nozzle and fills the channel below the pass partition plate.
- It enters the first-pass tubes through the front tubesheet and runs the length of the bundle.
- It turns in the rear head or the U-bends and returns through the second-pass tubes.
- It leaves the upper half of the channel through the outlet nozzle, on the end where it entered.
- Shell-side fluid enters a shell nozzle, strikes the impingement plate and spreads into the bundle.
- Segmental baffles push it across the tubes, through each baffle window and across again.
- It exits the far shell nozzle; vents sit at the high points and drains at the low points of each side.
What are baffles in shell and tube heat exchanger construction?
Baffles are plates set across the bundle at intervals so the shell-side fluid flows across the tubes rather than along them, raising its velocity and heat transfer coefficient, and they also support the tubes against sagging and vibration. The usual form is the single-segmental baffle, a disc with one segment cut away. TEMA sets minimum baffle spacing at one-fifth of the shell inside diameter or 2 inches, whichever is greater. Baffle cut can range from about 15 to 45 percent of shell diameter, but published design guidance recommends 20 to 35 percent; outside that band, dead zones or bypass take over. Wider spacing lowers pressure drop but lengthens unsupported spans, which is what drives tube vibration.
The tubesheet and the tube joints
The tubesheet in heat exchanger construction is the thick plate drilled with one hole per tube end; it carries the full pressure difference between the sides. Tubes are fixed by expanding (rolling) the tube against the hole, often into grooves, by welding the tube end to the tubesheet face, or by welding and then expanding. Every joint is a possible leak path. Where cross-contamination is unacceptable, a double tubesheet adds a vented gap, as explained in our sanitary heat exchangers guide.
Tube layout patterns: triangular and square pitch
Tube layout is the hole pattern in the tubesheet, defined by the pitch (center-to-center spacing) and the angle the rows make with shell-side flow; four patterns are used, at 30, 60, 90 and 45 degrees. Read the table as a text diagram of the tubesheet face.
| Layout | How the holes line up | Minimum pitch | Shell-side lanes | Typical choice |
|---|---|---|---|---|
| Triangular, 30 degrees | Rows offset half a pitch; three neighbors form a triangle pointing into the flow | 1.25 x tube OD | None | Clean shell side, most tubes per shell |
| Rotated triangular, 60 degrees | Same triangle, one side facing the flow | 1.25 x tube OD | None | Clean shell side |
| Square, 90 degrees | Straight rows and columns, lanes parallel to flow | 1.25 x OD or OD plus a 1/4 in (6 mm) lane, whichever is larger | Yes | Fouling shell side, removable bundles |
| Rotated square, 45 degrees | Square grid turned to present a diamond to the flow | Same as square | Yes, diagonal | Fouling shell side needing more turbulence |
Triangular layouts fit roughly 15 percent more tubes into a given shell than square ones at the same pitch ratio. Under the square rule, 20 mm tubes go on a 26 mm pitch to keep the 6 mm lane, while 25 mm tubes go on 31.25 mm because 1.25 times the diameter is already wider. Tubes of 3/4 inch and 1 inch outside diameter are the most popular sizes in process plants.
TEMA heat exchanger types: front head, shell and rear head letters
TEMA describes every exchanger with three letters for the front head, the shell and the rear head, so a BEM is a bonnet front, single-pass shell and fixed tubesheet rear. The letters come from the Standards of the Tubular Exchanger Manufacturers Association, which buyers cite alongside the pressure vessel code.
| Position | Letter | Meaning and typical reason |
|---|---|---|
| Front head | A | Channel with removable cover: tubes reachable without disturbing piping |
| Front head | B | Bonnet: clean tube side, fewer gaskets, lower cost |
| Front head | C, N | Channel integral with tubesheet, removable cover; N is also fixed to the shell |
| Front head | D | Special high-pressure closure, such as feedwater heaters |
| Shell | E | One-pass shell, general service |
| Shell | F | Two-pass shell with longitudinal baffle, for temperature crosses |
| Shell | G, H, J | Split, double split and divided flow, for low shell pressure drop and condensing |
| Shell | K | Kettle reboiler with vapor space above the bundle |
| Shell | X | Cross flow, very low pressure drop vapor duties |
| Rear head | L, M, N | Fixed tubesheet, matching the A, B and N fronts |
| Rear head | P, W | Outside packed floating head; externally sealed floating tubesheet |
| Rear head | S | Floating head with split backing ring |
| Rear head | T | Pull-through floating head |
| Rear head | U | U-tube bundle |
Datasheets commonly show BEM or NEN (fixed), BEU or AEU (U-tube), AES or AET (floating head) and AKT or BKU (kettle). Reading the code tells you what can be cleaned and inspected before you look at the price.
TEMA classes R, C and B
TEMA also defines three mechanical classes. Class R covers the severe requirements of petroleum and related processing and demands the heaviest construction. Class C covers the moderate requirements of commercial and general process service, where most utility and light industrial units sit. Class B covers chemical process service. Naming a class is how a buyer makes two bids comparable, because a TEMA C and a TEMA R unit of the same duty are different purchases.
Types of shell and tube heat exchanger: fixed tubesheet, U-tube, floating head and kettle
The constructions differ in how they let tubes and shell grow at different rates as temperatures change, and that one decision sets cleanability, cost and allowable temperature difference.
| Construction | Thermal expansion | Tube inside cleaning | Shell side cleaning | Relative cost |
|---|---|---|---|---|
| Fixed tubesheet (L, M, N) | Needs a shell expansion joint if differential is large | Easy, straight tubes | Chemical only | Lowest without expansion joint |
| U-tube (U) | Each tube bends freely | Difficult in the bends | Bundle removable | Close to fixed |
| Floating head (S, T, P, W) | Rear tubesheet slides in the shell | Easy, straight tubes | Bundle removable | Highest |
| Kettle (K shell) | Usually U-tube or floating bundle | Depends on bundle | Bundle removable | High, oversized shell |
Fixed tubesheet
Both tubesheets are welded to the shell, which is why the design is also called a fixed tube heat exchanger. It has the fewest gasketed joints, any tube can be replaced, and tube interiors are easy to brush or rod. When tubes run much hotter or colder than the shell, though, a shell bellows becomes necessary and most of the cost advantage disappears. Because the bundle never comes out, the shell-side fluid should be clean or chemically cleanable.
U-tube
A U-tube shell and tube heat exchanger has one tubesheet and hairpin tubes that expand independently, so no expansion joint is needed and the bundle can be withdrawn to clean the tube outsides. The tight inner bends resist mechanical cleaning, and inner-row tubes cannot simply be swapped, so leaks are usually plugged. That makes the U-tube heat exchanger a natural fit for steam heating, where the tube-side fluid is clean and temperature differences are large.
Floating head
A floating head shell and tube heat exchanger fixes one tubesheet and lets the other move inside the shell, so the bundle expands freely and comes out for cleaning on both sides; it is the most versatile and most expensive construction. The S type bolts its head to a split backing ring, keeping the shell tight to the bundle; the T type pulls straight through, at the cost of a larger shell. Outside packed P and W designs are limited to nonhazardous fluids at moderate conditions, about 570 psi and 570 degrees F in published guidance.
Kettle
A kettle places the bundle low in an oversized K shell so liquid boils around the tubes and vapor separates above before leaving the top nozzle, as in reboilers and flooded evaporators.
Which fluid goes on the tube side?
As a rule of thumb, the higher pressure, more corrosive or more fouling fluid, including cooling tower water, goes in the tubes, while viscous liquids and condensing steam go on the shell side; then confirm the chosen construction can be cleaned where the dirt will be.
| Fluid property | Usual side | Why |
|---|---|---|
| High pressure | Tubes | Small tubes and heads hold pressure with less metal than a large shell |
| Corrosive | Tubes | Only tubes, tubesheets and channels need the costly alloy |
| Fouling, tower water | Tubes | Straight tubes can be brushed; velocity is easier to hold |
| Viscous | Shell, if baffles make it turbulent | Cross-flow beats laminar flow inside tubes |
| Condensing steam | Shell | Vapor space and easy condensate drainage |
| Hazardous | Tubes | Fewer external gasketed joints |
Hot or cold placement follows these rules rather than any convention: a steam heater has its hot fluid on the shell side, while a tower-water oil cooler has its cold fluid in the tubes. A fixed tubesheet only makes sense with a clean shell-side fluid and a U-tube only with a clean tube-side fluid; when dirt lands on the side that cannot be mechanically cleaned, budget for a floating head.
Tube passes and shell pass arrangements
Tube passes are the number of times the tube fluid travels the exchanger’s length, set by partition plates in the heads; one, two, four, six and eight are usual. Doubling passes at the same tube count doubles velocity, lifting the coefficient roughly with velocity to the 0.8 power but pressure drop roughly with its square, so passes are added until allowable pressure drop is used. Published practice keeps liquid velocity in tubes between about 1.0 m/s (3.3 ft/s) and 2.5 to 3.0 m/s (8 to 10 ft/s), and allows roughly 7 to 10 psi of liquid pressure drop per shell.
When the cold fluid must leave hotter than the hot fluid leaves, a temperature cross, F falls sharply in a single E shell with two tube passes. The fixes are an F shell, which behaves like two shells in series, or several E shells in series. An F factor below about 0.75 signals the wrong arrangement rather than too little area.
Shell and tube heat exchanger design basics
Every thermal design starts with a datasheet listing flow, inlet and outlet temperatures, properties, allowable pressure drop and fouling resistance for each fluid, plus design pressure and temperature per side. The designer then picks a TEMA type, tube size, layout, length, passes and baffle spacing, iterating until the surface fits both pressure drop limits. The shell and tube heat exchanger calculations in that loop cover heat balance, mean temperature difference, film coefficients, overall coefficient, area and pressure drop.
How to size shell and tube heat exchanger surface area
Size the surface with Q = U x A x F x LMTD: find duty Q from a heat balance, the log mean temperature difference from the four terminal temperatures, F from the TEMA chart for the pass arrangement, estimate U, and solve for A. For water, duty in Btu/h is 500 x gpm x temperature change in degrees F. A 1,000,000 Btu/h water-to-water duty with U of 200 Btu/h ft2 F, LMTD of 40 degrees F and F of 0.9 needs about 139 square feet before margin. Our LMTD calculator handles the temperature math. Design coefficients including fouling run around 140 to 265 Btu/h ft2 F (800 to 1,500 W/m2K) for water to water and 265 to 700 Btu/h ft2 F (1,500 to 4,000 W/m2K) for steam heating water. For steam, read saturation temperature and latent heat from our saturated steam table; at 15 psig steam condenses near 250 degrees F and releases about 945 Btu per pound.
Fouling factors and overdesign
A fouling factor is extra thermal resistance added to each side so the unit still meets duty once deposits form. TEMA-based tables give 0.001 h ft2 F/Btu for treated cooling tower water below 240 degrees F and three times that for untreated water. Those values rest on thin data, and stacking them on a percentage margin yields an exchanger that runs slow when new and fouls faster. Realistic allowances and a stated overdesign work better.
The mechanical design of shell and tube heat exchanger shells, tubesheets, heads and flanges then follows the pressure vessel code and TEMA class, which set wall thicknesses and corrosion allowance.
Materials: stainless steel, carbon steel, duplex and other alloys
Materials are chosen side by side: shell parts for the shell fluid, tubes and tubesheets for both fluids, channels for the tube fluid, so mixed construction such as a carbon steel shell with stainless tubes is common. A carbon steel shell and tube heat exchanger is the economical choice for steam, condensate, oils, hydrocarbons and treated closed-loop water, where corrosion is low and predictable and a corrosion allowance covers it.
A stainless steel shell and tube heat exchanger, usually 304L or 316L, is specified when the fluid must stay free of iron pickup, attacks carbon steel, or is cleaned with caustic and acid, and throughout food, dairy, pharmaceutical and high-purity water service. The weakness of 300-series grades is chloride stress corrosion cracking, commonly cited above about 140 degrees F (60 degrees C) with chlorides and tensile stress present. Duplex 2205, with a pitting resistance number commonly given as 34 to 38 against roughly 24 to 26 for 316L, is used where 300-series would crack or pit, and its strength allows thinner walls. Titanium, copper-nickel and nickel alloys cover seawater and aggressive chemicals.
Sanitary versions add polished tubes, drainable layouts, hygienic connections and often double tubesheets, built to ASME BPE where pharmaceutical service requires it; the sanitary guide linked above covers them, and our dairy heat exchanger and pasteurizer page shows them in service.
Is a shell and tube heat exchanger a pressure vessel?
Yes, in most industrial service it is, and in the United States it is normally designed, built, inspected and stamped under ASME Boiler and Pressure Vessel Code Section VIII, Division 1. Division 1 covers vessels operating above 15 psig and excludes those at or below 15 psi or with an inside diameter of 6 inches or less, though such units can still be stamped if the owner wants it. Each side is its own pressure chamber with its own design conditions, and the tubes and tubesheets are common elements shared by both.
Part UHX holds the tubesheet rules for U-tube, fixed and floating designs. The standard hydrostatic test under UG-99 is at least 1.3 times maximum allowable working pressure, adjusted by the ratio of allowable stress at test temperature to that at design temperature, applied to each side. TEMA works alongside the code on tolerances, baffle and tie rod sizes and minimum thicknesses, and local jurisdictions set registration and inspection rules. After repair or reassembly, a pressure test of each side proves integrity; see our hydrostatic testing page.
Shell and tube heat exchanger uses in plant systems
Plants rely on these units for steam heaters, condensers, chiller evaporators and condensers, process coolers on tower water or glycol, oil coolers, heat recovery interchangers and reboilers: anywhere pressure, temperature or fouling would strain a gasketed plate.
- Steam heaters. A shell and tube steam heat exchanger, usually a U-tube bundle with steam on the shell side, heats process water, building water and CIP solutions; condensate drainage decides how well it performs, tying it to the steam piping around it. Clean steam generators use stainless versions, covered under clean steam systems.
- Chillers. Water-cooled chillers commonly use shell and tube evaporators and condensers with water in the tubes and refrigerant in the shell, which is why chiller maintenance includes tube brushing and eddy current testing; our industrial process chillers guide explains the cycle.
- Coolers and heat recovery. Product, oil and jacket water coolers on tower water, chilled water or glycol, and interchangers that preheat a cold feed with a hot product, all part of the plant utilities a site runs on.
You will find a shell and tube heat exchanger in industry sectors from refining and power to food processing, where it handles hot water sets, CIP heating and viscous products, as our food and beverage heat exchangers page describes.
Fouling, inspection and the cleaning methods used in industry
Fouling is the buildup of scale, biological growth, corrosion products, sediment or process deposits on heat transfer surfaces, and it shows first as rising pressure drop and a falling overall coefficient, well before the outlet temperature misses setpoint. Trending approach temperature and each side’s pressure drop against the datasheet shows when a bundle needs attention and which side is dirty.
Industry methods for tube interiors include chemical circulation, brushes or scrapers propelled by water, rotating rods and high-pressure water lancing, often called hydro-blasting. Shell-side deposits come off by chemical circulation on fixed bundles or, on removable square-pitch bundles, by pulling the bundle and lancing down the lanes. Inspection uses eddy current testing on nonferrous and stainless tubes, remote field or ultrasonic methods on carbon steel, borescopes and pressure or helium leak tests. Leaking tubes are plugged at both ends, and once plugs consume the surface margin the usual industry step is retubing or a new bundle. Our heat exchanger repair page covers field service.
Shell and tube heat exchanger life expectancy
Shells and heads commonly last decades, while tube bundles may need plugging, retubing or replacement much sooner, depending mostly on water chemistry, velocity and operating cycles. ASHRAE’s equipment service-life table lists a 24-year median for shell-and-tube heat exchangers in building HVAC service, which ASHRAE itself treats as dated survey data, useful for budgeting rather than prediction. At the other extreme, published corrosion case histories show carbon steel tubes in aggressive service failing within one or two years.
| What shortens life | How it shows up | What extends life |
|---|---|---|
| Poor cooling water treatment | Scale, under-deposit pitting, slime | Controlled treatment, filtration, tube inspection |
| Tube velocity too high | Erosion at tube inlets | Velocity within design range, inlet inserts |
| Tube velocity too low | Fast fouling, settling in bottom passes | Right-sized passes, no chronic oversizing |
| Flow-induced vibration | Tube wear at baffle holes | Correct baffle spacing, staying within rated flow |
| Thermal cycling | Tube joint leaks, cracked welds | Controlled warm-up and cool-down |
| Condensate backup in steam heaters | Water hammer, tube and baffle damage | Proper trapping, vacuum breakers, drainage |
| Chlorides on 300-series stainless | Stress corrosion cracking | Duplex or higher alloys |
| Freezing during shutdown | Split tubes | Draining idle units, glycol where exposed |
Shell and tube heat exchanger advantages and disadvantages
The advantages are tolerance of high pressure and temperature, wide material choice, suitability for steam, phase change and dirty fluids, and code-stamped construction; the disadvantages are more surface and floor space for the same duty, wider approach temperatures, greater weight and the need for tube-pull space.
| Advantages | Disadvantages |
|---|---|
| High pressures and temperatures on both sides | Lower coefficient than corrugated plates, so more area |
| Suits condensing, boiling and vapors | Temperature crosses need multiple shells |
| Tolerates particulates, especially in tubes | Clearance equal to bundle length for removal |
| Few gaskets on welded designs | Heavier, larger foundations and rigging |
| Single tubes can be plugged to restore service | Fixed capacity; more surface means another shell |
| Resists pressure surges better than thin plates | Shell side of fixed bundles hard to inspect |
Choosing between shell and tube and a plate heat exchanger
For clean liquid-to-liquid duties at moderate pressure where a close approach matters, such as glycol to chilled water, a gasketed plate unit is usually smaller and cheaper and can be extended with more plates. Steam, high pressure, high temperature, large particulates or gasket-attacking fluids point to shell and tube. The full comparison is on our plate heat exchanger page.
Shell and tube heat exchanger service from Paul Industries
Paul Industries sets, pipes and starts up shell and tube exchangers within steam, chilled water, glycol, process cooling and high-purity systems, using shop-fabricated stainless and carbon steel spools and skids. On existing units our crews inspect, clean (including chemical and CIP cleaning), replace gaskets, repair leaks, hydrostatically test and reassemble, for planned outages or emergency calls, nationwide. See our heat exchanger repair page for field service, and send a datasheet, nameplate photo or problem description to request a quote.
Standards referenced: TEMA Standards (Tubular Exchanger Manufacturers Association) · ASME Boiler and Pressure Vessel Code Section VIII Division 1 · ASME Section VIII Division 1 Part UHX · ASME BPE · ASHRAE Handbook HVAC Applications
Frequently asked questions
In a shell and tube heat exchanger, which side is hot?
Either side can carry the hot fluid; the choice follows fluid properties, not temperature. Steam heaters put the hot steam on the shell side so condensate drains freely, while many process coolers put hot, high-pressure process fluid in the tubes and tower water on the shell side. When temperature matters most, the hotter fluid often goes in the tubes so only the smaller tube-side parts need high-temperature design and less heat escapes through the shell.
What is shell and tube heat exchanger fouling and what causes it?
It is a layer of deposit on the tube surfaces that adds thermal resistance and narrows flow paths. Common causes are hardness scale from heated water, biological slime in tower water, corrosion products, suspended solids that settle at low velocity and process deposits such as polymerized oils or protein. Temperature at the tube wall matters: scale forms fastest where the wall is hottest.
Are shell and tube heat exchangers counterflow?
Only a single-pass shell with single-pass tubes runs in pure counterflow. Most units have two or more tube passes, so the flow is partly counterflow and partly parallel, and the mean temperature difference is corrected with the F factor. Shells in series or an F shell bring performance close to true counterflow.
What does a pass mean in a shell and tube exchanger?
A pass is one trip of a fluid along the length of the exchanger. A two-pass tube side sends fluid down half the tubes and back through the other half, so both nozzles sit on the front head. Shell passes are created by a longitudinal baffle, as in the TEMA F shell.
What do BEM, AES and BEU mean on a datasheet?
They are TEMA codes. BEM is a bonnet front, single-pass shell and fixed tubesheet rear. AES is a removable channel cover, single-pass shell and split-ring floating head, the common choice for dirty fluids on both sides. BEU is a bonnet front, single-pass shell and U-tube bundle, typical for steam heaters.
What is a temperature cross?
A temperature cross happens when the cold fluid outlet temperature is higher than the hot fluid outlet temperature. It is possible in counterflow but forces a low F factor in a single 1-2 shell, so the duty is split across shells in series or an F shell is used.
Why do U-tube bundles always have an even number of tube passes?
Each tube enters and leaves through the same tubesheet, so the fluid always returns to the front head. Every hairpin adds two passes worth of travel, giving two, four or more passes with both tube-side nozzles on the channel.
What is an impingement plate?
It is a plate under the shell inlet nozzle that takes the force of the incoming jet so it does not hit the tubes directly. It is used where the inlet carries high-velocity liquid, two-phase flow or vapor such as steam, which would otherwise erode or vibrate the first rows of tubes.
What are tie rods and spacers?
Tie rods are rods screwed into the stationary tubesheet that run the length of the bundle, and spacers are pipe sleeves on those rods between baffles. Together they hold every baffle at its design spacing and give the bundle the rigidity to be pulled and handled.
What tube sizes are used in shell and tube exchangers?
Process plants mostly use 3/4 inch and 1 inch outside-diameter tubes, with 5/8 inch and smaller in compact units on clean duties and larger tubes for very dirty or viscous fluids. Tube wall thickness is often given as a BWG gauge and is checked against the pressure vessel code for the design pressure.
What causes tube vibration in a shell and tube exchanger?
High shell-side velocity across tubes that are supported too far apart. Vortex shedding and fluid-elastic instability make the tubes move against the baffle holes, wearing through the wall. The cure is designing baffle spacing and support plates for the actual flow, and not running the shell side well above its rated flow.
Can a leaking tube be plugged and the exchanger kept in service?
Yes, leaking tubes are commonly plugged at both ends with tapered or mechanical plugs after the leak is located by a pressure or leak test. Each plugged tube removes surface and raises velocity in the rest, so the number of plugs is tracked against the remaining design margin.
How is a shell and tube exchanger hydrostatically tested?
Each side is filled with water, vented of air, and pressurized to the test pressure while the other side is left open or drained so any leak is visible. Testing the shell side with the tube side open shows leaks at tubes and tube joints; testing the tube side shows channel, partition and tube leaks.
What is the difference between TEMA class R, C and B?
Class R is for petroleum and related processing and requires the heaviest construction. Class C is for commercial and general process service and permits lighter construction. Class B is for chemical process service. The class affects minimum thickness, corrosion allowance, tube pitch details and bolting.
When is a kettle shell used?
A kettle is used when liquid must boil on the shell side and the vapor must separate before it leaves, as in reboilers, steam generators heated by a process stream and flooded evaporators. The enlarged shell above the bundle gives the vapor room to disengage from the liquid.
Can a shell and tube heat exchanger be installed vertically?
Yes. Vertical units save floor space and suit some condensers, thermosiphon reboilers and sanitary exchangers that must drain completely. They need venting and drainage arranged for the vertical orientation, and overhead clearance or a removal plan for the bundle.
What information is needed to quote a shell and tube exchanger?
Flow rates, inlet and outlet temperatures, fluid properties or identities, allowable pressure drop and fouling allowance for each side, plus design pressure and temperature, materials, the TEMA type and class, code stamping, connection sizes and orientation, and any space limits for bundle removal.
How efficient is a shell and tube heat exchanger?
Thermal efficiency is usually expressed as effectiveness, the actual heat transferred divided by the maximum possible for the inlet temperatures. A well-designed unit can reach a high effectiveness, but closing the approach further takes rapidly more surface, so most are designed to an economic approach rather than the closest possible.
Related: Plate Heat Exchanger · Sanitary Heat Exchangers: Types & How They Work · Sanitary Heat Exchanger Installation & Service · LMTD Calculator and Heat Exchanger Sizing · Dairy Heat Exchangers And Pasteurizers · Food And Beverage Heat Exchangers · Request a quote