Frequently Asked Questions
Technical & Product Information

Selecting the right heat exchanger involves evaluating several interconnected factors. API Heat Transfer’s engineering team works with customers through this process, but here are the primary criteria to consider:

1. Fluid characteristics — Are the fluids clean, fouling, viscous, or corrosive? What are the flow rates on each side?
2. Thermal requirements — What are your inlet and outlet temperatures? What is the required heat duty (kW or BTU/hr)?
3. Pressure and temperature limits — What are the maximum operating pressure and temperature for each fluid stream?
4. Material compatibility — Corrosive fluids may require stainless steel, titanium, or specialty alloys
5. Sanitary requirements — Food, beverage, dairy, and pharmaceutical applications require FDA/3-A compliant designs
6. Maintenance access — How often will the unit need to be cleaned or serviced?
7. Space constraints — Is a compact footprint required?
8. Budget — Both capital cost and long-term operating cost should be factored in

Once these parameters are defined, our engineers evaluate which technology — plate, shell and tube, air-cooled, or a pre-engineered thermal system — delivers the optimal balance of performance, reliability, and total cost of ownership for your specific application. Contact our team to begin the selection process.

API Heat Transfer provides heat transfer solutions across a broad spectrum of industries worldwide. Our product portfolio and engineering expertise are designed to meet the unique thermal management challenges of each sector.

Industries we serve include:

• Food and Beverage — Pasteurization, heating, cooling, evaporation, and dealcoholization systems
• Dairy — Sanitary heat exchangers for pasteurization and processing
• Chemical and Petrochemical — High-pressure, corrosion-resistant designs for demanding process environments
• Oil and Gas — Compressor cooling, lube oil cooling, and gas processing applications
• Power Generation — Steam surface condensers, turbine oil coolers, and cooling systems
• Industrial Compressed Air — Aftercoolers, intercoolers, and moisture separators
• Mobile and Off-Highway Equipment — Aluminum and copper-brass radiators and cooling packages for construction, agriculture, and mining equipment
• HVAC and Refrigeration — Brazed plate and semi-welded heat exchangers for refrigerant applications
• Pharmaceutical — Hygienic thermal systems meeting strict regulatory standards
• Data Centers — High-performance cooling for mission-critical infrastructure
• Alternative Energy — Heat transfer solutions for hydrogen, solar, and geothermal applications

If you don’t see your industry listed, contact us — API Heat Transfer’s breadth of technology and custom engineering capabilities means we can solve thermal challenges across virtually any market.

Plate heat exchangers come in three primary configurations, each suited to different operating conditions and maintenance requirements:

Gasketed Plate Heat Exchangers

These use elastomeric gaskets to seal the plates together. The primary advantage is ease of maintenance — plates can be disassembled, inspected, cleaned, and re-gasketed without specialized tools. They are also thermally expandable: capacity can be increased simply by adding plates. Gasketed designs are ideal for moderate pressures (typically up to 25 bar) and temperatures, and are widely used in food and beverage, HVAC, and general industrial applications. They are not suitable for very high pressures or aggressive chemical compatibility concerns with gasket materials.

Brazed Plate Heat Exchangers

In brazed designs, the plates are permanently joined using a brazing material (typically copper or nickel) in a furnace, eliminating the need for gaskets. This creates an extremely compact, robust unit capable of handling higher pressures than gasketed designs. Brazed plate heat exchangers are cost-effective and popular for refrigeration, HVAC, fluid power, and industrial applications where compactness and reliability are priorities. Because they are permanently bonded, they cannot be disassembled for mechanical cleaning.

Welded Plate Heat Exchangers

Fully welded or semi-welded plate heat exchangers (such as API’s SIGMAWIG technology) are designed for the most demanding applications — high pressures, extreme temperatures, and highly aggressive or hazardous fluids. Semi-welded designs weld pairs of plates together, using gaskets only on the shell side, allowing one fluid side to handle aggressive media. Fully welded designs eliminate all gaskets for the highest pressure and chemical resistance. These units are common in chemical, petrochemical, and refrigerant applications.

API Heat Transfer manufactures all three configurations across our SIGMA and SIGMABRAZE product lines.

The choice between air cooling and liquid cooling depends on your site conditions, operating environment, and long-term operating costs.

Air-Cooled Heat Exchangers are best when:

• Water is scarce, expensive, or unavailable at your site
• You want to eliminate the cost and complexity of cooling water treatment and water systems
• Your application involves mobile or off-highway equipment (construction, mining, agriculture)
• Ambient temperatures are cool enough to achieve the required process outlet temperatures
• You want to minimize environmental impact by avoiding water consumption

Liquid-Cooled Heat Exchangers (using water, glycol, or other coolants) are best when:

• The required process outlet temperature is close to or below ambient air temperature — air cooling cannot cool below ambient
• Space is limited and a compact footprint is required
• Ambient temperatures are very high, making air cooling insufficient
• Precise temperature control is required
• The application involves high heat loads in a small footprint

In many industrial plants and mobile applications, both technologies are used together — liquid-cooled exchangers handle primary process cooling while air-cooled units serve as the final rejection point to atmosphere.

API Heat Transfer designs and manufactures both air-cooled and liquid-cooled heat exchangers, and our engineering team can help you evaluate the optimal approach for your site and application.

Fouling is the accumulation of unwanted deposits on heat transfer surfaces, and it is one of the most significant factors affecting heat exchanger performance and operating costs. Understanding fouling mechanisms is the first step in managing them.

Common Types of Fouling:

Scaling (Crystallization Fouling) — Dissolved minerals (primarily calcium carbonate and calcium sulfate) precipitate out of solution when water is heated, forming a hard scale on heat transfer surfaces. This is the most common fouling type in water-side applications.

Biological Fouling — Microorganisms (bacteria, algae, biofilms) grow on heat transfer surfaces, particularly in cooling water systems operating at warm temperatures. Biofilm acts as an insulating layer and dramatically reduces heat transfer efficiency.

Particulate Fouling — Suspended solids, silt, or debris deposit on surfaces, particularly at low-velocity zones.

Corrosion Fouling — Corrosion products from system piping accumulate on heat transfer surfaces.

Chemical Reaction Fouling — Chemical reactions at the heat transfer surface produce deposits (common in food processing and petrochemical applications).

Prevention Strategies:

• Water Treatment — Proper treatment with scale inhibitors, biocides, and corrosion inhibitors is the most cost-effective prevention strategy
• Filtration — Upstream strainers and filters remove particulates before they reach the heat exchanger
• Velocity Optimization — Maintaining sufficient fluid velocity prevents particulate settling and reduces biological growth
• Material Selection — Selecting appropriate materials for wetted surfaces reduces corrosion fouling
• Regular Monitoring — Tracking pressure drop and thermal performance allows early detection before fouling becomes severe
• Product Selection — Plate heat exchangers with wider gap designs or turbulent flow patterns resist fouling better in certain applications

API Heat Transfer’s engineering team can recommend products and design features optimized to minimize fouling risk for your specific fluids and application.

API Heat Transfer manufactures heat exchangers across a wide range of pressure and temperature capabilities, spanning multiple product families and technologies.

General Capability Ranges by Technology:

Gasketed Plate Heat Exchangers — Typically rated up to 25 bar (360 psi) and temperatures from -20°C to 180°C (-4°F to 356°F), depending on gasket material selection.

Brazed Plate Heat Exchangers (SIGMABRAZE) — Rated for higher pressures than gasketed designs, typically up to 45 bar (650 psi), making them suitable for refrigerant and high-pressure fluid power applications.

Welded and Semi-Welded Plate Heat Exchangers (SIGMAWIG) — Designed for the most demanding conditions, capable of operating at pressures up to 40+ bar and temperatures up to 350°C (660°F) depending on configuration.

Shell and Tube Heat Exchangers — Our BASCO® and Whitlock shell and tube product lines are engineered for high-pressure, high-temperature service common in turbine, compressor, oil and gas, and power generation applications. Ratings vary significantly by design and are engineered to TEMA and ASME standards.

Air-Cooled Heat Exchangers — Available in a wide range of pressure ratings to match process requirements.

Important Note: Specific pressure and temperature ratings depend on the exact model, material of construction, gasket or seal type, and applicable design code (ASME, PED, etc.). For critical applications, our engineers will review your operating parameters and recommend a solution designed and certified to meet your requirements. Contact our technical team with your specifications for precise ratings.

Material selection is one of the most important factors in heat exchanger design. The right material must resist corrosion from both process fluids and utility fluids while meeting pressure, temperature, and code requirements. API Heat Transfer offers a wide range of material options across our product lines.

Metals Commonly Available:

Carbon Steel — Cost-effective for non-corrosive applications with water, steam, and oil. Widely used in shell and tube designs.

Stainless Steel (304 & 316/316L) — Excellent corrosion resistance for food, beverage, dairy, pharmaceutical, chemical, and marine applications. 316L offers enhanced resistance to chloride-containing fluids.

Duplex and Super Duplex Stainless Steel — Higher strength and improved corrosion resistance versus standard stainless, used in aggressive chemical and offshore applications.

Titanium — Outstanding resistance to seawater, chlorides, and many aggressive chemicals. Commonly specified for marine, desalination, and chemical applications where stainless steel is insufficient.

Hastelloy and Other Nickel Alloys — Used in highly aggressive chemical environments, including strong acids and oxidizing media.

Copper and Copper Alloys (Admiralty, Cupronickel) — Traditional materials for shell and tube heat exchangers in water and steam service; Cupronickel offers seawater resistance.

Aluminum — Lightweight and thermally conductive; widely used in air-cooled heat exchangers for mobile equipment and compressed air applications.

Specialty Coatings and Linings — Available for specific corrosion or contamination protection requirements.

Material selection should always consider both process and utility fluid compatibility, operating temperature, pressure, and applicable regulatory standards (FDA, ASME, etc.). API Heat Transfer’s engineering team can advise on the optimal material for your application.

Deciding between repairing an existing heat exchanger and replacing it is an important operational and financial decision. Several factors should be evaluated together.

Indicators That Repair May Be Sufficient:

• Minor gasket or seal leaks — Gasket replacement in a gasketed plate heat exchanger is a routine, cost-effective maintenance procedure
• Localized tube damage in a shell and tube unit — Individual tubes can be plugged or replaced without replacing the entire unit
• Fouling-related performance loss — If the unit has been restored to design performance after cleaning, the equipment itself may still be serviceable
• The unit is relatively new and otherwise in good condition

Indicators That Replacement Should Be Considered:

• Repeated failures in the same location suggest a systemic issue with the design or material
• Extensive tube bundle corrosion or plate erosion that cannot be cost-effectively repaired
• The unit’s design pressure or temperature rating no longer meets current operating requirements
• The original design is obsolete and replacement parts are no longer available
• Energy efficiency improvements — modern heat exchanger designs may offer significantly better thermal performance, reducing operating costs enough to justify replacement
• Regulatory or code compliance — an older unit may not meet current safety standards or sanitary requirements
• Total repair cost exceeds 50-60% of replacement cost — at this threshold, replacement typically makes more economic sense

API Heat Transfer offers a complete aftermarket parts and service program, as well as a retrofit and replacement evaluation service to help you make the most cost-effective decision for your operation. Contact our service team for an assessment.

Yes. Custom engineering is a core competency at API Heat Transfer and a key differentiator from suppliers offering catalog-only products.

While we offer a broad range of pre-engineered, standard-catalog heat exchangers for common applications, many industrial processes involve unique combinations of fluids, pressures, temperatures, space constraints, or regulatory requirements that demand a purpose-designed solution.

Our Custom Engineering Capabilities Include:

• Thermal and mechanical design using industry-leading software including ASPEN and HTRI for accurate performance modeling
• Material selection for corrosive, high-purity, or specialty fluid applications
• Custom dimensions, nozzle configurations, and connection orientations to fit existing plant footprints
• Integrated thermal systems combining multiple heat transfer technologies in a single skid-mounted package
• Proprietary plate designs across our SIGMA product family, with unique channel geometry optimized for specific applications
• Custom tube profiles through our ARUP/Thermasys tubing division, including an in-house tool shop and prototype mill
• Sanitary, pharmaceutical-grade, and ATEX-rated designs for regulated industries

Our team of experienced thermal engineers works directly with customers to understand their process requirements and develop a solution that optimizes thermal performance, material selection, maintainability, and total cost of ownership.

Whether you need a single custom unit or an ongoing supply relationship for OEM integration, API Heat Transfer has the engineering resources and manufacturing capabilities to deliver. Contact our applications engineering team with your specifications to get started.

Lead times at API Heat Transfer vary depending on the product type, level of customization, current production capacity, and order complexity. Here is a general guide:

Pre-Engineered Standard Catalog Products:

Our standard, catalog heat exchangers — including many BASCO® shell and tube models, SIGMA brazed plate units, and standard air-cooled products — typically ship in 2–6 weeks from order confirmation, depending on stock availability and order volume.

Semi-Custom and Modified Standard Products:

Products requiring non-standard nozzle sizes, material upgrades, or minor dimensional modifications typically require 4–10 weeks depending on the specific modifications and material procurement lead times.

Fully Custom-Engineered Heat Exchangers:

Custom-designed units, engineered thermal systems, or products built to specific project specifications generally require 8–20 weeks or more, reflecting the time required for engineering design, customer approval of drawings, material procurement, fabrication, testing, and inspection.

Rush Orders:

API Heat Transfer understands that unplanned equipment failures can create urgent production needs. Our team works to accommodate expedited requests where possible — contact our sales team directly to discuss priority options for emergency replacement situations.

Factors That Can Affect Lead Time:

• Specialty material procurement (titanium, Hastelloy, duplex alloys)
• Third-party inspection or witnessing requirements
• ASME code stamp and documentation requirements
• Special testing requirements (helium leak testing, radiographic inspection, etc.)

For accurate lead time information on a specific product or project, contact our sales team with your requirements.

Yes. API Heat Transfer maintains a dedicated aftermarket parts and service division to support the full lifecycle of our heat transfer equipment.

Aftermarket Parts:

We supply genuine replacement parts for the complete range of API Heat Transfer products, including our legacy brands (BASCO®, Whitlock, Schmidt, Thermal Transfer Products, and others). Available parts include:

• Replacement gaskets (all materials: NBR, EPDM, Viton, PTFE, and more)
• Tube bundles and replacement tubes
• Plate packs and individual plates
• Shell components and end covers
• Nozzles, connections, and hardware
• Complete unit replacements

Parts are available for both current production models and many legacy units, even those no longer in active production. Contact our aftermarket team with your unit serial number or nameplate data for parts identification.

Technical Support and Field Service:

Our team can provide technical guidance on maintenance procedures, troubleshooting, and performance evaluation. Field service support is available for inspection, repair, and recommissioning of heat transfer equipment.

Performance Audits and Upgrades:

If an aging unit is underperforming, our engineering team can evaluate whether a re-rating, retrofit, or full replacement provides the best path forward. In many cases, existing units can be upgraded with modern plate or tube designs that significantly improve thermal efficiency and reduce energy consumption.

To reach API Heat Transfer’s aftermarket team, call 1.877.274.4328 or email sales@apiheattransfer.com.

API Heat Transfer has been designing and manufacturing heat transfer equipment since 1879 — a heritage that reflects over 145 years of engineering experience, innovation, and industry knowledge. Several factors distinguish us in a competitive global market:

Unmatched Product Breadth

API Heat Transfer offers one of the broadest product portfolios in the industry, spanning plate heat exchangers (gasketed, brazed, semi-welded, and fully welded), shell and tube heat exchangers, air-cooled heat exchangers, integrated thermal systems, and specialty evaporation and dealcoholization systems. This means customers can find the optimal technology for their application from a single, trusted supplier.

Deep Engineering Expertise

Our team of thermal engineers brings decades of real-world application experience across virtually every industrial market. We don’t just sell products — we solve problems. Our use of advanced thermal design software (ASPEN, HTRI) and proprietary design tools ensures accurate performance modeling before manufacturing begins.

Global Manufacturing and Support

With multiple manufacturing facilities and a worldwide network of sales and service support, API Heat Transfer delivers locally with global engineering resources behind every product.

Proprietary Technology

Our SIGMA plate heat exchanger family, SIGMABRAZE brazed plate products, SIGMAWIG welded plate technology, and SIGMASTAR climbing-film evaporators represent decades of proprietary innovation. Our ARUP/Thermasys tubing division develops custom tube profiles not available from standard suppliers.

Commitment to Innovation

We continuously invest in research and development — from advanced thermal system designs for data centers and clean energy applications to specialty food and beverage processing systems. API Heat Transfer is positioned to solve the thermal challenges of today and the future.

As digital infrastructure and electrified transportation grow rapidly, thermal management has become a critical engineering challenge in both data centers and electric vehicle (EV) battery systems. API Heat Transfer has developed specialized solutions to address these demanding applications.

Data Center Cooling:

Modern data centers require highly reliable, energy-efficient cooling for servers, power electronics, and supporting infrastructure. API Heat Transfer offers:

• Liquid Cooling Solutions — Plate heat exchangers for liquid-to-liquid cooling loops, enabling the precise temperature control that high-density computing requires
• Free Cooling / Economizer Integration — Heat exchangers that allow data centers to leverage cool ambient conditions to reduce or eliminate mechanical refrigeration, dramatically improving Power Usage Effectiveness (PUE)
• Waste Heat Recovery — Systems that capture rejected heat from data center cooling loops for reuse in building heating or other applications
• High-Reliability Design — Our products are engineered for continuous duty in mission-critical environments where uptime is paramount

EV and Battery Thermal Management:

Electric vehicles require precise battery temperature management to maximize range, performance, charging speed, and battery life. Batteries that run too hot degrade rapidly; batteries that run too cold lose performance. API Heat Transfer supports this market with:

• Compact, Lightweight Aluminum Heat Exchangers — Optimized for the weight and space constraints of mobile vehicle platforms
• Liquid Cooling Plates and Systems — For direct battery thermal management
• Powertrain Cooling — Thermal management of electric motors, inverters, and power electronics
• Customized OEM Solutions — Engineered to fit specific vehicle packaging requirements

Contact our applications team to discuss how API Heat Transfer can support your data center or EV thermal management program.

Yes. API Heat Transfer actively supports the global transition to clean energy by providing heat transfer solutions for a growing range of renewable and alternative energy applications.

Hydrogen Production and Processing:

The hydrogen economy requires heat exchangers at multiple points in the production, compression, and distribution chain. Whether for green hydrogen produced via electrolysis or blue hydrogen with carbon capture, API Heat Transfer provides heat exchangers engineered for the specific pressure, temperature, and material compatibility requirements of hydrogen service.

Geothermal Energy:

Geothermal power plants and heating systems rely on heat exchangers to transfer energy from geothermal brine to working fluids or district heating systems. The corrosive, high-mineral-content nature of geothermal fluids demands careful material selection — API Heat Transfer’s engineering team has experience specifying appropriate materials (titanium, high-alloy stainless) for these challenging environments.

Solar Thermal Energy:

Concentrated solar power (CSP) plants and solar thermal heating systems use heat exchangers to transfer heat from solar collectors to power generation or storage systems. API Heat Transfer supplies heat exchangers for these applications across a range of operating temperatures.

Biogas and Bioenergy:

Anaerobic digestion and biogas upgrading processes require heat exchangers for feedstock preheating, digester temperature control, and gas cooling. Our plate heat exchanger product lines are well suited for these applications.

Zero-Alcohol Beer and Food Processing:

API Heat Transfer’s Schmidt brand holds original patents for vacuum rectification dealcoholization technology — a process that enables the production of non-alcoholic and low-alcohol beverages without compromising flavor quality. This technology is used globally to meet growing consumer demand for alcohol-free products.

Contact API Heat Transfer to discuss how our engineering team can support your clean energy project with custom-designed or standard heat transfer solutions.