Your Heat Exchanger Is Specified by TEMA Class Before Anyone Reads Your Brochure

Chemical and process engineers specify heat exchangers by TEMA class (R/C/B) and ASME BPVC Section VIII design code. If your content does not reference TEMA by class, ASME by division, and HEI or API 660 where applicable, you are invisible to the engineers who write the specification. We build heat exchanger marketing that speaks the language of thermal design engineers.

Request a Content Audit →See TEMA Type Comparison

$22.7BGlobal heat exchanger market (Grand View Research, 5.8% CAGR)

TEMA RClass R — Refinery, severe service. The highest TEMA standard. API 660 supplements.

ASME VIIIASME BPVC Section VIII Div 1 — the core pressure vessel standard for heat exchangers

3:1Manufacturers with TEMA/ASME reference content win 3× more engineer inquiries

Heat Exchanger Type Comparison — TEMA Classes and Plate Types

Type	Design Standard	Pressure Range	Fouling Factor (hr·ft²·°F/Btu)	Typical LMTD Ft	Best Application	Buyer
Shell & Tube — TEMA R	TEMA R + API 660 + ASME VIII Div 1	Full vacuum to 6,000+ psig	0.0005–0.003	0.70–0.85	Refinery, petrochemical, high-pressure steam, severe service	Process / Refinery Engineer
Shell & Tube — TEMA C	TEMA C + ASME VIII Div 1	Up to 600 psig (standard)	0.001–0.005	0.70–0.85	Chemical processing, general industrial, HVAC	Chemical / Process Engineer
Shell & Tube — TEMA B	TEMA B + ASME VIII Div 1	Moderate (chemical service)	0.001–0.004	0.70–0.85	Chemical process (intermediate between C and R)	Chemical Engineer
Gasketed Plate & Frame (PHE)	ASME VIII Div 1, EN 13445, PED	Up to 350 psig	0.0002–0.001	0.90–0.98	HVAC, district cooling, food processing, low-fouling fluids	HVAC / Mechanical Engineer
Brazed Plate (BPHE)	ASME VIII Div 1, PED, UL (refrigeration)	Up to 725 psig	0.0001–0.0005	0.92–0.98	Refrigeration, condensing boilers, hydronic separation, heat pumps	HVAC / Refrigeration Engineer
Welded / Semi-Welded Plate	ASME VIII Div 1, EN 13445	Up to 600 psig	0.0002–0.001	0.88–0.95	Chemical, aggressive fluids, high-temperature, ammonia	Chemical / Process Engineer

Sources: TEMA 10th Edition (2024), ASME BPVC Section VIII Div 1 (2023), API 660 (2020), HEI Standards for Shell and Tube Heat Exchangers (2022). Fouling factor ranges per TEMA Section RGP-RCB-4. LMTD correction factors per TEMA Section RCB-4.2 for 1-2 pass configuration.

Expert Insight: Jakub Gałęga — CEO, Digital Pilot

"Heat exchanger marketing is one of the most standard-reference-dependent sectors I have worked in. The specifying engineer does not search for 'heat exchanger manufacturer' — they search for 'TEMA R shell and tube heat exchanger ASME VIII Div 1 600 psig'. If your product page does not contain those exact standard references with the correct TEMA class, they scroll past your result to a competitor whose content matches their spec vocabulary. The manufacturers who publish TEMA/ASME-referenced comparison tables dominate search results by a wide margin. I recommend every heat exchanger manufacturer publish at minimum a TEMA class selection guide, a fouling factor reference table, and a material compatibility chart referenced to ASME Section II."

Jakub Gałęga on LinkedIn →

Heat Exchanger Applications by Industry — Standards, Types, and Duty

Industry	HE Type	Design Standard	Typical Duty	Key Parameters
Refinery / Petrochemical	TEMA R Shell & Tube	API 660 + ASME VIII + TEMA R	Crude preheating, FCC slurry, reformer feed	6,000 psig, 650°C, fouling 0.0005–0.003
Chemical Processing	TEMA C/B Shell or Welded Plate	TEMA + ASME VIII, EN 13445	Reactor cooling, solvent recovery, distillation	600 psig, 400°C, aggressive fluids
HVAC / District Cooling	Gasketed PHE	ASME VIII, EN 13445, PED	Chilled water, condenser water, hydronic separation	350 psig, 150°C, compact footprint
Refrigeration / Heat Pumps	Brazed Plate (BPHE)	PED, UL, ASME VIII	Evaporator, condenser, gas cooler, desuperheater	725 psig, NH₃ / CO₂ / R-410A
Food & Beverage / Dairy	Gasketed PHE (EHEDG)	3-A SSI 74-07, EHEDG, NSF/ANSI 51	Pasteurisation, CIP heating/cooling, UHT	CIP compatible, Ra ≤0.8 μm, EPDM gaskets
Power Generation	Feedwater Heater / Condenser	HEI, ASME VIII	Feedwater heating, steam condensing, lube oil cooling	High vacuum, large surface area, titanium tubes

Sources: TEMA 10th Edition (2024), HEI Standards for Shell and Tube Heat Exchangers (2022), EHEDG Doc 32, 3-A SSI 74-07, PED 2014/68/EU.

Five Decision-Makers in Heat Exchanger Procurement

Heat exchanger procurement involves a buying committee of at least five stakeholders, each with veto power over different aspects of the specification and purchase.

Stakeholder	Role	Veto
Chemical / Process Engineer	Writes the heat transfer specification. Selects TEMA class, design pressure, materials, fouling factor, LMTD, allowable ΔP.	Primary spec veto
Thermal Design Engineer	Performs thermal rating. Calculates required surface area, confirms baffle configuration, tube count, passes. Validates vendor proposals against TEMA/ASME.	Technical veto
Procurement / Supply Chain	Manages vendor qualification, TEMA/ASME compliance verification, commercial terms, lead time, shipping logistics.	Commercial veto
Project / EPC Contractor	Selects heat exchanger as part of overall plant design. Evaluates cost, delivery schedule, field service capabilities, long-lead items.	Project veto
Maintenance / Reliability Engineer	Evaluates MTBF, ease of cleaning (tube bundle removal clearance), gasket availability, corrosion monitoring access, retubing cost.	Operational veto

Heat Exchanger Specification Guide — Seven Parameters Every Engineer Defines

1. Duty (Q)

Heat transfer rate in kW or MMBtu/hr. Derived from mass flow × specific heat × temperature difference. The starting point for all thermal design.

2. Flow Rates

Shell-side and tube-side mass flow (kg/s, lb/hr) or volumetric flow (GPM, m³/hr). Determines velocity, heat transfer coefficient, and pressure drop.

3. Temperatures

Inlet/outlet temperatures for both streams. Defines LMTD and temperature approach. Critical for material selection (tube sheet design temp).

4. Fouling Factor

Resistance to heat transfer due to deposit buildup. Per TEMA Section RGP-RCB-4. Directly adds surface area margin. Range: 0.0001–0.005 hr·ft²·°F/Btu.

5. Allowable ΔP

Maximum permitted pressure drop on each side. Typically 5–15 psi for liquids, 2–8 psi for gases. Governs baffle selection, tube count, shell diameter.

6. TEMA Class

R (refinery/severe), C (commercial), or B (chemical). Determines minimum design margins, corrosion allowance, baffle spacing limits, tube sheet thickness.

7. Materials

Shell, tube sheet, channel, tube material selection per ASME Section II. Carbon steel (SA-516 Gr 70), SS 304/316, Hastelloy, Titanium, Duplex. Corrosion allowance typically 1.6–3.2 mm.

8. Code Compliance

ASME BPVC Section VIII Div 1 (U-Stamp), EN 13445 (PED), or other local codes. Determines inspection requirements, NDT levels, certification paperwork.

9. Nozzle Sizing

Inlet/outlet nozzle diameters per API 660 (refinery) or TEMA RCB. Velocity limits for erosion prevention: max 3 m/s for liquids, 30 m/s for gases.

Reference: TEMA 10th Edition (2024), ASME BPVC Section VIII Div 1 (2023), API 660 (2020), HEI Standards (2022).

Fouling Factor Reference Table — Per TEMA 10th Edition (RGP-RCB-4)

Fluid / Service	Fouling Factor (hr·ft²·°F/Btu)	Fouling Factor (m²K/W)	TEMA Class
Crude oil (desalted, tube side)	0.0005	0.000088	R
Crude oil (shell side, reduced)	0.002–0.003	0.000352–0.000528	R
Cooling water (treated, closed loop)	0.001	0.000176	C / R
Cooling water (cooling tower, untreated)	0.003	0.000528	C
Steam (non-condensing)	0.0005	0.000088	C / R
Condensing steam (oil-bearing)	0.001	0.000176	C
Process gas (industrial)	0.001	0.000176	C / B
Refrigerant (liquid, clean)	0.0001	0.000018	B / PHE
Food / Dairy (CIP cleaned)	0.0002	0.000035	PHE
Engine lube oil	0.001	0.000176	C

Source: TEMA 10th Edition (2024), Section RGP-RCB-4, Tables RCB-4.1 through RCB-4.5. Fouling factors are design margins and actual values depend on fluid quality, operating temperature, and velocity.

NBS / CSI MasterFormat Specification Clause — Heat Exchanger

Add your product as a named spec in new construction and retrofit projects. Below is a template NBS clause for Division 23 00 00 (HVAC) or 40 00 00 (Process Piping):

/* MASTERFORMAT DIVISION 23 21 13 — HYDRONIC PIPING SPECIALTIES */

HEAT EXCHANGER, SHELL-AND-TUBE:

A. Design per TEMA Class R, ASME BPVC Section VIII Div 1.

B. Duty: 8,000 kW (27.3 MMBtu/hr).

C. Shell side: 650 psig @ 340°C, Crude oil, fouling 0.0005.

D. Tube side: 600 psig @ 320°C, Steam, fouling 0.0005.

E. Material: SA-516 Gr 70 shell, SA-240 TP 304L tubes.

F. Nozzles per API 660, gaskets spiral-wound.

G. [Manufacturer] [Model] as specified herein.

When your product model number appears in the spec clause, procurement is required to purchase from your quote. This is the end goal of all heat exchanger content marketing.

Generative Engine Optimization (GEO) for Heat Exchanger Manufacturers

When a chemical engineer asks ChatGPT "What is the allowable pressure drop for a TEMA R shell and tube heat exchanger in crude service?" or "Compare TEMA R vs TEMA C class heat exchanger design", structured technical content determines whether your brand is cited or ignored. We structure content with:

FAQPage schema — 8+ questions with TEMA/ASME-specific answers cited to published editions
Article schema — with datePublished and author (Jakub Gałęga) for authoritativeness
Service schema — with areaServed listing key refinery and chemical markets (US, GB, DE, NL, PL, IT, CH, AE, SG)
E-E-A-T signals — references to TEMA 10th Ed, API 660, ASME VIII, HEI — quoted by edition year

Manufacturers with structured technical content are 3× more likely to be cited in AI-generated specification shortlists. Source: internal analysis of 240 B2B manufacturing sites (2025).

Frequently Asked Questions

What TEMA class is required for a refinery shell and tube heat exchanger?

Refinery and petrochemical service requires TEMA Class R, which is the most stringent TEMA classification. Class R covers severe service conditions including high pressure (up to 6,000+ psig), high temperature (up to 650°C), and cyclic operation. API 660 supplements TEMA R with additional requirements for refinery heat exchangers, including minimum tube sheet thickness, corrosion allowance, and nozzle loading. Marketing content for refinery applications must reference both TEMA R and API 660 (2020 edition) to align with procurement vocabulary. Source: TEMA 10th Edition (2024), Section R — Refinery Class; API 660 (2020) Shell-and-Tube Heat Exchangers for Petroleum, Chemical, and Gas Industry Services.

What is the typical fouling factor for crude oil in a shell and tube heat exchanger?

Per TEMA 10th Edition, the recommended fouling factor for crude oil is 0.0005 hr·ft²·°F/Btu (0.000088 m²K/W) for clean, desalted crude on the tube side, and 0.001–0.002 hr·ft²·°F/Btu (0.000176–0.000352 m²K/W) for crude on the shell side. For reduced crude or coker gas oil, fouling factors of 0.002–0.004 hr·ft²·°F/Btu apply. These values directly determine the required surface area — a 0.0005 increase in fouling factor typically adds 15–25% additional surface area. TEMA provides the definitive fouling factor table in Section RGP-RCB-4 which is referenced in virtually every heat exchanger specification.

How does the baffle cut affect heat transfer in a shell and tube exchanger?

Baffle cut — the segmental opening in a baffle — directly controls shell-side cross-flow velocity and heat transfer coefficient. A 25% baffle cut (standard for most TEMA R and C applications) provides high cross-flow velocity, improved heat transfer, and reduced fouling at the cost of higher pressure drop. A 35% cut reduces shell-side ΔP by approximately 40% but lowers the shell-side film coefficient by 15–20%. TEMA Section RCB-4.3 specifies baffle spacing and cut limits: minimum spacing is 1/5 of shell ID, maximum spacing is shell ID. For marketing content, a comparison of baffle configurations (single-segmental vs double-segmental vs no-tubes-in-window) demonstrates deep engineering knowledge.

What is the maximum design pressure for a TEMA C class heat exchanger?

TEMA Class C (Commercial) is typically designed for pressures up to 600 psig (41.4 barg) and temperatures up to 750°F (400°C). However, TEMA Class C does not define explicit pressure limits — the governing constraint comes from ASME BPVC Section VIII Div 1 which provides the design code for the pressure vessel. In practice, TEMA C heat exchangers are used in general chemical processing, HVAC, and light industrial applications where design pressures remain below 600 psig. Above this threshold, TEMA R with API 660 supplements is typically specified. Per ASME BPVC Section VIII Div 1 (2023), the maximum allowable working pressure (MAWP) depends on material strength, corrosion allowance, and joint efficiency — not TEMA class alone.

How do I calculate the required surface area for a plate heat exchanger?

The fundamental heat transfer equation Q = U × A × LMTD × Ft governs surface area selection. For a gasketed plate-and-frame heat exchanger (PHE): (1) Determine duty Q (kW or MMBtu/hr) from process conditions, (2) Calculate log mean temperature difference (LMTD) from inlet/outlet temperatures, (3) Apply Ft correction factor (typically 0.90–0.98 for counterflow PHE vs 0.70–0.85 for shell-and-tube 1-2 pass), (4) Estimate overall heat transfer coefficient U (3,000–7,000 W/m²K for water-water PHE vs 200–800 W/m²K for shell-and-tube), (5) Solve for A = Q / (U × LMTD × Ft). The higher U and Ft values of PHEs make them 2–4× more compact than shell-and-tube for the same duty. Standards: ASME VIII Div 1, EN 13445, PED 2014/68/EU.

What is the difference between gasketed and brazed plate heat exchangers?

Gasketed plate heat exchangers (PHE) use elastomer gaskets between plates, allowing disassembly for cleaning, plate addition/removal, and service. Maximum operating temperature is limited by gasket material (EPDM: 150°C, Viton: 200°C, NBR: 140°C). Maximum pressure: 350 psig. Brazed plate heat exchangers (BPHE) use copper or nickel braze at plate contact points, creating a sealed, non-serviceable core. BPHEs handle higher pressures (up to 725 psig) and temperatures (up to 300°C for copper braze, 550°C for nickel braze). BPHEs dominate refrigeration, condensing boiler, and heat pump applications. PHEs dominate HVAC, district cooling, food processing, and chemical duties requiring periodic cleaning. EHEDG certification is available for hygienic PHE designs.

What is the allowable pressure drop for a shell and tube heat exchanger in a chemical plant?

Typical allowable pressure drop for shell-and-tube heat exchangers in chemical processing: shell side: 5–10 psi (35–70 kPa) for liquids, 2–5 psi (14–35 kPa) for gases/vapours. Tube side: 5–15 psi (35–100 kPa) for liquids, 2–8 psi (14–55 kPa) for gases. These limits are specified by the process engineer during thermal design and directly influence shell geometry (baffle cut and spacing), tube diameter and length, number of passes, and nozzle sizing. Exceeding allowable ΔP requires a larger shell or multiple exchangers in series. A well-designed TEMA R/C exchanger typically allocates 40–50% of total allowable ΔP to the shell side and 50–60% to the tube side. Reference: TEMA Section RCB-4, HEI Standards (2022).

How does EN 13445 differ from ASME BPVC Section VIII for heat exchanger design?

EN 13445 (European standard for unfired pressure vessels) and ASME BPVC Section VIII Div 1 (US standard) both govern heat exchanger design but differ in several key areas: (1) Material groups — EN 13445 uses EN material designations vs ASME SA/SA-xxx. (2) Design margins — ASME VIII uses 3.5:1 safety factor on tensile strength vs EN 13445 using 2.4:1 on Rm at room temperature, leading to slightly thinner walls under EN. (3) Testing — EN 13445 requires more extensive NDT for higher testing groups. (4) PED compliance — EN 13445 is harmonized with EU PED 2014/68/EU, which is mandatory for heat exchangers installed in the EU. (5) TEMA remains the design standard for shell-and-tube internals regardless of which pressure vessel code is used. For global manufacturers, maintaining both ASME U-Stamp and PED CE certification is the standard approach.

Win More Heat Exchanger Specifications with TEMA-Referenced Content

45-minute conversation with Jakub Gałęga about your current content gap vs competitors.

Request a Content Audit →