TEMA Datasheet: 15 Inputs That Prevent Redesign Loops
Key Takeaways
- Most heat exchanger redesign loops start with incomplete datasheet inputs, not vendor incompetence — freeze 15 critical fields before AFC release.
- TEMA now emphasizes using one unit system consistently (SI or US Customary) for design and fabrication — mixing units triggers recalculation spirals.
- Treat "datasheet revision issued" as a milestone in the EPC schedule, not an administrative afterthought.
- The rear-head type (fixed/floating/U-tube) should follow from maintenance and cleaning assumptions, not habit — freeze those constraints first.
Why Datasheets Cause Redesign Loops
If your shell-and-tube heat exchanger keeps getting re-quoted, redesigned, or re-reviewed, it's usually not because the vendor "can't design." It's because the datasheet inputs weren't frozen (or the unit system changed midstream).
TEMA has updated its Heat Exchanger Specification Sheet to better define design requirements and notes that US Customary and SI units are provided, but one unit system should be used consistently for design and fabrication. Source: TEMA Standards
Freeze the TEMA datasheet inputs early — duty, temperatures, allowable ΔP, fouling, materials, corrosion allowance, and mechanical type — then lock the unit system and tie deliverables to a document register before fabrication.
15 Inputs EPC Teams Should Freeze (No "TBD")
These are the fields that, if left as "TBD" or changed after AFC, will trigger redesign loops, drawing revisions, and schedule pain:
| # | Input | Why It Matters |
|---|---|---|
| 1 | Heat duty (required / fouled / clean) | Drives thermal sizing & surface area |
| 2 | Shell-side inlet/outlet temperature | LMTD calculation basis |
| 3 | Tube-side inlet/outlet temperature | LMTD calculation basis |
| 4 | Shell-side flow rate (min/normal/max) | Velocity, ΔP, vibration checks |
| 5 | Tube-side flow rate (min/normal/max) | Velocity, erosion, ΔP checks |
| 6 | Allowable pressure drop (shell + tube) | Constrains baffle spacing & tube count |
| 7 | Fouling factors (shell + tube) | Excess area & cleaning strategy |
| 8 | Design pressure & design temperature (shell + tube) | Wall thickness, flange rating, material selection |
| 9 | Corrosion allowance (if used) | Additional wall thickness & weight impact |
| 10 | Fluid properties at operating cases | Density, viscosity, phase behavior at each condition |
| 11 | Materials (shell, tubes, tubesheet, baffles) | Cost, lead time, weldability, corrosion resistance |
| 12 | Tube OD, thickness, length, layout preference | Heat transfer coefficient & mechanical integrity |
| 13 | TEMA configuration / rear-head preference | Maintenance, expansion, cleaning philosophy |
| 14 | Cleaning & maintenance assumption | Bundle pull? Mechanical cleaning? Chemical only? |
| 15 | Codes/inspection basis + hold points | ITP, witness plan, third-party requirements |
Tip: If you need a ready-to-use datasheet template, TEMA provides spec sheets in both unit systems: Metric (PDF) | US Customary (PDF)
Freeze Rules That Keep Schedules Stable
- Freeze datasheet inputs before AFC (approved-for-construction) release
- Freeze one unit system for the whole exchanger package
- Treat "datasheet revision issued" as a milestone in the EPC schedule
- Mixing SI and US Customary units leads to repeated recalculation, drawing revisions, and approval loops
- Leaving any of the 15 inputs as "TBD" after AFC virtually guarantees a redesign cycle
Fixed Tubesheet vs Floating Head vs U-Tube: EPC Decision Table
EPC buyers don't want a textbook lecture on exchanger construction. You want a selection that won't blow up your schedule later — especially when cleaning, thermal expansion, or fouling reality hits.
| Option | Best When | Watch Outs | EPC Questions to Freeze |
|---|---|---|---|
| Fixed Tubesheet | Clean service, stable temps, simpler maintenance | Shell-side cleaning limits; expansion stress risk if ΔT is high | Cleaning method, ΔT envelope, fouling factors |
| Floating Head | You need bundle pull & mechanical cleaning | More parts/complexity; higher cost | Bundle pull clearance, lifting method, maintenance access |
| U-Tube | Big thermal expansion; tube bundle can flex | Tube-side mechanical cleaning constraints; U-bend inspection considerations | Cleaning method, inspection plan, spare bundle strategy |
How to Use This in an RFQ
Instead of specifying "floating head because we always do," write what EPC actually needs:
- Is tube-side mechanical cleaning required?
- Is shell-side cleaning required?
- What is the operating ΔT envelope and upset case?
- Is bundle pull possible at site (clearance + lifting)?
- What is the acceptable maintenance strategy and downtime?
Why This Prevents Redesign Loops
Vendors redesign after RFQ when they discover:
- Cleaning requirement conflicts with the initial rear-head assumption
- Thermal expansion is worse than expected
- Site layout prevents bundle pull
If you freeze the maintenance assumption early, mechanical selection becomes straightforward.
Need a TEMA heat exchanger quotation for your project?
Lmart delivers TEMA-compliant shell & tube heat exchangers (ASME U-Stamp, PED/CE) with GA drawings and budget pricing within 48 hours.
Downloads & Resources
- TEMA Datasheet Template (Metric): Download PDF
- TEMA Datasheet Template (US Customary): Download PDF
- Vendor Data Book Index (PDF)
- ITP Hold Points Checklist (PDF)
- Delivery Milestones Map (PDF)
Summary
Redesign loops on shell-and-tube heat exchangers are almost always a datasheet problem, not a vendor competence problem. Freeze the 15 critical inputs before AFC, lock one unit system, and treat the datasheet revision as an EPC milestone. When specifying the rear-head configuration, start from maintenance and cleaning reality — not from habit.
Lmart holds ASME U-Stamp, PED/CE Mark, and 6 classification society approvals (DNV, BV, CCS, ABS, LR, NK).
103-mu campus in Zhangjiagang · 38,000 m² workshop · 300+ staff · 15,000 T/year fabrication capacity
Last reviewed: March 5, 2026 · Technical accuracy verified by Lmart Engineering Dept.
Frequently Asked Questions
Do we need to specify the exact TEMA type at RFQ stage?
Not always. But you should at least freeze the maintenance/cleaning assumption and thermal expansion constraints — those choices drive the rear-head type and mechanical design decisions. Let the vendor optimize from there.
Why does unit system consistency matter so much?
Because mixing SI and US Customary assumptions leads to repeated recalculation, drawing revisions, and approval loops. TEMA explicitly emphasizes using a single system consistently for design and fabrication. One datasheet revision for a unit-system change can cost 2–4 weeks of schedule.
Which of the 15 inputs causes the most redesign?
In practice, fouling factors and allowable pressure drop are the most common late-change triggers. They directly affect tube count, baffle spacing, and shell diameter — changes that cascade through GA drawings, nozzle loads, and foundation design.
What standards apply to TEMA heat exchanger datasheets?
The primary references are: TEMA (10th or 11th edition) for the specification sheet format and construction classification; ASME Section VIII Division 1 for pressure design; API 660 for refinery/petrochemical service. For marine applications, classification society rules (DNV, BV, CCS, ABS) apply additionally. Lmart fabricates to all of these standards.
What documentation does Lmart deliver with a heat exchanger?
Standard deliverables include: Manufacturer's Data Report (MDR), material certificates (3.1/3.2 per EN 10204), NDE reports (RT/UT/PT/MT as applicable), hydrostatic test report, GA drawings, thermal design datasheet, and O&M manual. For ASME units: U-1A form + National Board registration. For marine units: classification society certificate.
Can Lmart handle both metric and US Customary unit datasheets?
Yes. Lmart's engineering team works with both unit systems daily, serving clients in Asia, the Middle East, Europe, and the Americas. The key is to agree on one system per project at RFQ stage and maintain it through fabrication and documentation.
Ready to Discuss Your Heat Exchanger Project?
Lmart delivers TEMA-compliant shell & tube heat exchangers — fixed tubesheet, floating head, and U-tube configurations — with ASME U-Stamp and PED/CE certification. Technical proposals with GA drawings and budget pricing within 48 hours.