TEMA (Tubular Exchanger Manufacturers Association Standards)
TEMA is the trade association standard for shell-and-tube heat exchangers, defining the three-letter type designation that identifies the front head, shell, and rear head configuration of every shell-and-tube exchanger (BEM, AEL, NEN, AKT, BES, AEW, and dozens of other combinations). The standard also defines minimum design and construction requirements scoped by service class: TEMA R (refinery service), TEMA C (commercial service), TEMA B (chemical process service). The current edition is TEMA 10th edition (2019).
How is the TEMA three-letter type read?.
The first letter identifies the front head (A, B, C, D, N): A is a channel head with bolted cover (most common, allows tube access without piping disconnection); B is a bonnet head (welded or integral with the shell); C is a channel head integral with the tubesheet; D is a high-pressure closure; N is a channel integral with the tubesheet and a removable cover. The middle letter identifies the shell (E, F, G, H, J, K, X): E is a single-pass shell (most common); F is a two-pass with longitudinal baffle; G is a split flow; H is a double split flow; J is a divided flow; K is a kettle reboiler; X is a crossflow. The third letter identifies the rear head (L, M, N, P, S, T, U, W): L, M, N are stationary heads; P, S, T are floating heads with various sealing arrangements; U is U-tube; W is a packed-tube floating head.
What does TEMA R vs. TEMA C vs. TEMA B require differently?.
TEMA R (refinery service) requires the most conservative design margins, mandates impact testing for low-temperature service, and imposes the strictest welding and inspection requirements. TEMA C (commercial service) is the lightest specification and is used in non-hazardous service such as water-water or oil-water exchangers in commercial buildings. TEMA B (chemical process service) sits between R and C and is the default for chemical and petrochemical service where the rigor of R is not required. Most projects specify R or B; a vendor bidding a TEMA C exchanger for refinery service would not be accepted.
What does a TEMA datasheet carry?.
The TEMA datasheet structures bid-stage and as-built exchanger documentation. Process-side data: shell-side and tube-side flow rates, inlet and outlet temperatures, pressures, design pressure, design temperature, fouling factors. Construction data: TEMA type, shell ID, tube count and length, tube outer diameter and wall thickness, tube material, shell material, tubesheet material, baffle count and spacing. Mechanical data: design code (ASME Section VIII), corrosion allowance, hydrotest pressure, weights. Performance data: heat duty, LMTD, UA, fouling factor margins. Per-bid customization (testing requirements, NACE compliance, post-weld heat treatment) goes in a notes block.
Frequently asked.
What is the difference between TEMA and API 660?
API 660 is the API standard for shell-and-tube exchangers in petroleum and petrochemical service; it is more restrictive than TEMA R on materials, fabrication, and inspection. Specifications for refinery exchangers often cite both standards: TEMA for the type designation and basic construction, API 660 for the petroleum-specific requirements layered on top.
Are plate-frame exchangers covered by TEMA?
No. TEMA covers shell-and-tube exchangers only. Plate-and-frame, plate-fin, brazed-aluminum, and spiral exchangers are governed by other standards (ASME PHE, vendor proprietary standards). The TEMA type designation does not apply to non-shell-and-tube configurations.
What does TEMA say about thermal design?
TEMA provides minimum mechanical design and construction requirements but does not prescribe thermal design methods. Thermal design (LMTD calculation, fouling factor selection, vibration analysis) is done with HTRI, Aspen EDR, or comparable thermal-rating software. The thermal design output is presented on the TEMA datasheet, but the calculation procedure is the vendor's or the licensor's responsibility.
Does TEMA cover air-cooled exchangers?
No. Air-cooled exchangers are governed by API 661 (Air-Cooled Heat Exchangers for General Refinery Service). TEMA covers shell-and-tube exchangers only. API 661 has its own datasheet structure and is the relevant standard for fin-fan and aerial cooler equipment in process service.