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.
What TEMA, Tubular Exchanger Manufacturers Association Standards means.
TEMA emerged in the 1940s as the U.S. Shell-and-tube exchanger industry consolidated common construction rules. The three-letter type designation, front head, shell, rear head became the universal shorthand for exchanger configuration. BEM is a fixed-tubesheet exchanger with a bonnet front head and a stationary rear head. AES is a floating-head exchanger with a channel front head and a split-ring floating rear head. AKT is a kettle reboiler with a channel front head and a U-tube bundle. The service classes, R, C, B carry progressively tightening design conservatism. R is most rigorous, C is least. Most U.S. Process industry exchangers are TEMA R or TEMA B. Commercial HVAC and utility services use TEMA C.
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.
Common questions
What is the difference between TEMA and API 660.
Are plate-frame exchangers covered by TEMA.
What does TEMA say about thermal design.
Does TEMA cover air-cooled exchangers.
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