TEMA Selection

Chapter from the Heat Exchangers Design Guide.

SHELL & TUBE TYPE SELECTION — TEMA

TEMA Front-End Head Types

Type	Letter	Description	Removable Bundle?	Gasket Type	Advantages	Limitations	Typical Use
Channel & Removable Cover	A	Bolted bonnet, removable cover	N/A (head type)	Confined gasket	Easy tube-side cleaning	Multiple gasket surfaces	Most common, clean tube-side
Bonnet (integral cover)	B	One-piece bonnet	N/A	Fewer gaskets	Fewer leak points, cheaper	Must disconnect piping to inspect	Low fouling tube-side
Channel Integral w/ Tubesheet	C	Welded to tubesheet	Must be removable shell	N/A	No shell-tubesheet gasket	Shell removal for bundle pull	High pressure (>1500 psig)
Special High-Pressure	D	Heavy-duty bolted	N/A	Special high-P gasket	Extreme pressure service	Very expensive, long lead	HP reactors, lethal service
Channel Integral w/ Tubesheet	N	Welded, fixed tubesheet	No (fixed)	N/A	Leak-free, lowest cost	Cannot pull bundle	Clean service both sides

TEMA Shell Types

Type	Letter	Flow Path	Passes	Advantages	Limitations	Typical Use
One-Pass	E	Single pass through shell	1	Simple, low cost	Limited LMTD efficiency	Most applications
Two-Pass (Long Baffle)	F	Split shell, 2 passes	2	Pure countercurrent	Long baffle leakage, difficult fabrication	True countercurrent needed
Split Flow	G	Feed at center, exit both ends	1	Low shell ΔP	Complex internals	Thermosiphon reboilers
Double Split Flow	H	Two split-flow sections	1	Very low shell ΔP	Rarely used	Large condensers
Cross Flow	J	Flow across bundle	1	Lowest shell ΔP	Low heat transfer coefficient	Vacuum condensers
Kettle	K	Large shell, pool boiling	1	High vaporization duty	Large shell diameter	Kettle reboilers
Cross Flow (multi-pass)	X	Multiple tube passes, crossflow	1	Very low shell ΔP	Baffling required	Very large condensers

TEMA Rear-End Head Types

Type	Letter	Description	Bundle Removable?	Expansion Provision	Cost	Best For
Fixed Tubesheet	L/M/N	Welded to shell	No	Expansion joint if ΔT > 50°F	Lowest	Clean shell-side, no bundle pull
Outside Packed Floating Head	P	Packing gland on floating head	Yes	Floating head slides	Moderate	Moderate P&T, accessible
Pull-Through Floating Head	T	Flanged floating head	Yes (pull-through)	Head floats freely	High	Dirty both sides, easy maintenance
Split Ring Floating Head	S	Split backing ring	Yes (remove shell cover)	Ring allows float	Moderate-High	Most common floating head type
U-Tube	U	U-bend tubes	Yes	Tubes expand freely	Low-Moderate	Clean tube-side, high ΔT OK

Common Type Combinations

Designation	Configuration	Application	Advantages	Notes
BEM	Fixed tubesheet	Clean service, process-to-process	Lowest cost, no expansion joint if ΔT small	Most common in refinery
AES	Split-ring floating head	Moderate fouling both sides	Pull bundle for inspection, A-head for tube access	Standard refinery workhorse
AET	Pull-through floating head	Heavy fouling both sides	Easy bundle removal	Higher cost, larger shell diameter
BEU	U-tube, bonnet head	Clean tube-side, high ΔT	Free thermal expansion, lower cost than floating	Cannot mechanically clean tube-side
AKU	Kettle reboiler, U-tube	Reboiler service	High duty, self-regulating level	Large footprint, high liquid inventory
BEJ	J-shell, fixed tubesheet	Vacuum condenser	Very low shell-side ΔP	Fixed — clean service only

Source: Heat_Exchangers_Design_Guide_v1.xlsx · sheet “TEMA Selection”

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