Inspection requirements should be defined before fabrication, not assembled after the exchanger is finished. The applicable code establishes mandatory controls, while the purchaser may add project-specific witness points, NDT, PMI, dimensional checks and documentation. If these requirements are introduced after the purchase order, they can require rework or become impossible to verify retrospectively.
1. Build the Inspection and Test Plan around manufacturing sequence
An ITP should follow the actual fabrication route: drawing approval, incoming material, cutting/forming, welding, NDT, heat treatment where required, tube/tubesheet work, assembly, pressure testing, coating, dimensional inspection, nameplate/marking and packing. For each activity identify the governing procedure, acceptance criteria, record produced and inspection status: review, surveillance, witness or hold.
A hold point means work cannot proceed without release; use it only where necessary. Excessive hold points can delay fabrication without improving quality if the purchaser cannot attend promptly.
2. Material traceability: link certificates to the physical parts
Material certificates are useful only if the heat/lot identity remains traceable to the finished component. The quality system should control transfer of markings after cutting. For alloy components, the purchaser may additionally require PMI. The RFQ should define the PMI population and method rather than saying only “PMI required.”
| Record | Purpose | Typical review point |
|---|---|---|
| Material certificate / MTR/MTC | Chemistry/mechanical properties and heat identity | Before fabrication or at incoming inspection |
| Material traceability map | Links heat numbers to pressure parts | During/final fabrication dossier |
| PMI report | Field verification of alloy identity | After fabrication as specified |
| Consumable certificates | Controls welding filler materials | Welding dossier |
3. Welding documentation: WPS, PQR and welder qualifications serve different roles
The WPS tells production welders how to make the weld. The PQR records the procedure qualification test supporting the WPS. Welder or welding-operator qualification records show that personnel are qualified for the applicable process/range. Purchasers often ask for “WPS/PQR/WPQ” as one line item, but the review should confirm that the qualifications actually cover the production joint and materials.
A weld map can link major welds to WPS, welder identification, NDT and repair records. This is especially useful on pressure vessels with multiple material groups or extensive examination requirements.
4. NDT scope must come from the code plus purchase specification
Visual examination, radiography, ultrasonic testing, magnetic-particle testing and liquid-penetrant testing have different applications and limitations. The extent of examination affects design joint efficiency in some code cases and also affects fabrication sequence. Do not assume that 100% RT is automatically “better” for every joint; the required method should match joint geometry, code rules and project risk.
Define acceptance criteria, personnel qualification basis, report format and whether purchaser/third-party review is required. If digital radiography or advanced UT is requested, state it explicitly.
5. Tube-to-tubesheet joints need their own quality plan
Heat exchangers contain hundreds or thousands of repetitive joints that may dominate leak risk. Inspection should match the joint type: expanded, seal welded, strength welded, grooved or combined. Controls can include tube-hole preparation, expansion procedure, expansion measurement/control, weld procedure qualification, visual/PT examination where applicable and leak testing.
If mixing between shell and tube fluids is unacceptable, the purchaser should define leak-tightness expectations and test method before manufacture.
6. Heat treatment and forming records
When PWHT or other heat treatment is required by code, material, thickness or project specification, retain furnace charts/thermocouple records and identify the treated item. Forming of heads or other components may require dimensional and material-property controls depending on the code and degree of forming.
7. Pressure testing: define medium, pressure, temperature and witness point
The code and approved calculation determine test requirements. The ITP should identify test pressure, test medium, metal/fluid temperature limits, hold time per procedure, calibrated gauges, venting/draining method and acceptance criteria. Pneumatic testing introduces higher stored energy and requires specific justification and controls where permitted.
For exchangers, clarify whether shell side and tube side are tested separately and how differential pressure across tubes/tubesheets is controlled during the sequence.
8. Dimensional inspection is critical for installation success
- Overall length, shell diameter and orientation.
- Nozzle size, class/rating, facing, projection and angular orientation.
- Support/saddle centerlines, elevations and anchor-bolt holes.
- Channel and cover removal clearances.
- Bundle pull direction and required maintenance space.
- Flange-face alignment and flatness where specified.
- For replacement units: all interface dimensions designated “must match.”
9. Surface treatment, coating and cleanliness
Coating systems should identify surface preparation standard, product, dry-film thickness, color, cure and inspection method. Stainless and high-alloy equipment may require contamination controls rather than painting. For oxygen, pharmaceutical, food or special gas service, cleanliness requirements can become a separate controlled process and should not be assumed.
10. Final data dossier: agree the index before production starts
A robust final dossier can include approved drawings, design calculations where contractually required, material records, traceability, WPS/PQR/WPQ, weld map, NDT reports, PWHT charts, PMI, pressure-test certificate, dimensional report, coating report, calibration records, nameplate copy, ITP release, packing list and code-specific certificates/data reports. Not every project needs every document.
Specify whether the dossier needs native files, searchable PDF, signed/stamped copies, document numbering and a master index. Large EPC projects may have strict document-control templates that add real engineering hours.
11. Code-specific records should be named explicitly
For ASME Section VIII Division 1 certified vessels, the applicable Manufacturer’s Data Report form is part of the Code documentation process. For PED projects, the technical documentation and EU Declaration of Conformity depend on the selected conformity-assessment route; Notified Body certificates/reports apply where the module requires their involvement. These are not interchangeable documents.
12. Suggested purchaser ITP hold/witness strategy
- Review: drawings, calculations/datasheets, WPS/PQR, NDT procedures, material certificates.
- Witness selectively: material identification/PMI, key NDT, tube-to-tubesheet qualification, dimensional inspection.
- Hold where consequential: final pressure test or code/third-party hold points required by contract.
- Final release: document dossier substantially complete, punch items closed, marking and packing verified.
Frequently asked questions
Is an ITP required by ASME for every heat exchanger?
The code and the manufacturer quality system impose required controls, but a purchaser-style ITP with witness/hold points is a contractual project document. Define it in the purchase specification if you need it.
What is the difference between WPS and PQR?
The WPS provides production welding instructions; the PQR documents the qualification test that supports the procedure. Welder qualification is a separate record for personnel.
Should I require 100% PMI?
Only if project risk/specification justifies it. Define which materials/components/welds are included and the accepted method. A vague PMI requirement causes disputes.
Can the final dossier be agreed after fabrication?
It can, but some evidence may no longer be obtainable. Agree the document index before manufacture so records are generated at the correct stages.
Why is dimensional inspection especially important for replacement exchangers?
Because a code-compliant pressure vessel can still fail the project if nozzle centers, supports or interface dimensions do not match the existing plant.
Related technical guides
Standards and references
The following official or industry technical resources were checked when preparing this guide. Always verify the edition and project-specific requirements before design or procurement.
Need a technical review before you send the RFQ?
Send the available datasheet and drawings to yifan.zhang@trilee.cn. TriLee can review manufacturability, missing inputs and quotation scope for custom shell-and-tube heat exchangers and related pressure equipment.