CRN Material Documentation: MTRs and Substitution

By Kopfkino Consulting Corp. · Published September 11, 2026 · Updated October 17, 2026 · 9 min read

Material documentation for a CRN dossier starts with the specifications on the frozen drawing, not with mill test reports collected later. How to manage MTRs and substitution risk.

Material documentation for a Canadian CRN dossier starts with the specifications named on the frozen drawing and in the calculations, not with mill test reports collected after fabrication. The registered design must use materials permitted by the construction code and consistent with the MDMT and impact assessment, and the manufacturer's quality program is what later ties mill certificates to heat numbers. Substituting a "similar" plate after the design is registered is a design change, not a purchasing convenience. Expedited 24-hour and 48-hour review can check that specified materials, MDMT, and quality certificates agree. It cannot recreate missing traceability on a vessel already built without heat numbers, and it cannot issue a CRN.

The 24-hour and 48-hour options are expedited engineering review, technical validation, documentation review, dossier preparation, and submission-readiness services. They are not a promise that a provincial regulator, authority having jurisdiction, or registration body will issue a CRN within 24 or 48 hours.

What is material documentation for CRN, and what is an MTR?

Material documentation is the set of records showing which materials the registered design specifies and which materials the physical equipment actually contains. At design registration it is dominated by material specifications (for example, ASME/ASTM designations such as SA-516 Grade 70 plate or SA-105 forgings) stated on the drawing and used in the calculations. A mill test report (MTR, mill certificate) is the producer's document certifying a specific heat's chemistry and mechanical properties; MTRs become critical at fabrication, inspection, and any as-built recovery, where traceability from the registered specification to the installed plate must be demonstrated.

How this article relates to Kopfkino's material-selection page

Kopfkino's material-selection and impact-testing service page covers the engineering choice of materials for Canadian low-temperature service. MDMT determination and Charpy impact qualification. This article covers the documentation side: what the dossier must say about materials, how specifications flow from drawing to purchase to nameplate, and why substitutions are registration events. Read the service page for selection; use this page to audit the paperwork.

Design dossier versus fabrication dossier

Design registration (CRN) typically needs:

  • Material specifications on the drawing for each pressure part
  • Impact-test designation or a stated exemption basis consistent with the MDMT
  • Corrosion-allowance and overlay/cladding notes
  • Bolting and gasket materials where they form part of the registered closure
  • The manufacturer's quality-program certificate (the RBQ requires proof of a manufacturing quality-control program for boilers and vessels; TSSA National Service asks for quality-program evidence)

Fabrication and inspection typically need:

  • MTRs tied to heat numbers
  • Traceability maps
  • PMI records where specified
  • Data reports

Do not confuse the two sets, and do not claim an AHJ never looks beyond the specification line. Some jurisdictions and owners ask for more material evidence at design registration, especially for exotic materials; confirm with the applicable authority having jurisdiction.

Specify first, buy second, register the specification

The registered design names the material; purchasing then buys that material. The reverse (buying leftover plate and "making it work") is how substitutions become revisions. A 24-hour review should see one specification (for example SA-516-70, or an impact-tested variant where MDMT requires it) on the drawing, in the calculations, and in the conditions table. "CS" or "or equivalent" is not a specification. If winter service needs impact-tested product, put the impact designation on the drawing before the mill order.

MDMT is a material problem

A datasheet stating MDMT −40 °C with a material specification not qualified for that temperature is not submission-ready, the review stops there. Impact-test requirements follow the construction code's rules for the material, thickness, and MDMT; do not invent exemption curves or energy values in a transmittal. Mining, Prairie, and northern energy equipment fails this check constantly (Expedited CRN Documentation Review for Mining Equipment and Mining & Remote Energy CRN Planning in Canada). Confirm the adopted code edition and AHJ expectations for low-temperature service.

Substitution risk: revisions, variances, and as-built recovery

After a CRN is issued, changing grade, product form, or impact class is not a purchase-order tweak. AHJs distinguish pre-construction design revisions from post-construction changes, which follow alteration, repair, or variance paths. TSSA, for example, administers a variance process in Ontario for items that do not fully comply with O. Reg. 220/01, and other jurisdictions have their own alteration/revision routes. Confirm the current process with the applicable AHJ before changing any registered material. If the unit is already built from the wrong heat, that is an as-built recovery (Emergency CRN Support for Equipment Already Fabricated and Post-Fabrication CRN Challenges: As-Built Differences, Alterations, Variances, and Rerates), not an expedited-review product.

Traceability is a quality-program output

MTRs are produced and controlled by the quality program the AHJ asked to see at design registration. A certificate for Plant A does not make Plant B's heats trustworthy. If a vessel is already built without heat-number traceability, no 48-hour review can reconstruct metallurgy; options narrow to the AHJ's as-built, rerate, or used-equipment paths, where present condition and examination evidence can become the design basis (TSASK publishes rerating guidance; confirm current requirements with the applicable AHJ).

Overlays, cladding, linings, and bolting

  • Corrosion-resistant overlay and cladding are pressure-part materials, not paint: show them on the drawing and in the calculations as the code requires.
  • Rubber or brick linings in mining vessels (Mining & Remote Energy CRN Planning in Canada) change corrosion allowance and inspection notes; they do not remove the steel from registration.
  • Bolting and gaskets that form part of the registered closure belong in the material table; substituting bolting in the field is a design change where the registered closure assumed a specific grade.

Sour service and owner specifications

Sour-service requirements (for example NACE/ISO 15156) and similar owner specifications are not CRNs, but they change hardness limits, welding, and material selection, which are CRN inputs. Put the owner specification next to the drawing in the dossier, and do not invent clause numbers in the transmittal. A sweet-service material table filed into a sour plant is a specification failure.

Foreign designations and "equivalent" tables

European and Asian mills often quote EN or JIS designations. Canadian CRN calculations typically need ASME (or another adopted construction code) material identities, allowable stresses, and MDMT rules. An "equivalent" table in a sales email is not a code basis. Either purchase ASME-designated product, or provide an AHJ-acceptable reconciliation with allowables and impact basis, which is engineering work, not a 24-hour paperwork fix. PED material dossiers are supporting evidence, not a substitute specification. The review should stop on "P355GH or equivalent SA-516" until the registered specification is exactly one specification.

Expedited-service relevance

24-hour: check specifications against MDMT, drawing, and calculations for agreement. 48-hour: clean a material table across a package with many sub-vendors. Not a 48-hour product: reconstructing traceability for a painted vessel with no heat numbers.

Practical scenario

A fabricator, after quoting, substitutes normalized SA-516-70 for the as-rolled grade "for winter service" on a Saskatchewan-bound vessel. The engineering instinct may be right, but if the filed drawing says the as-rolled grade without impact testing, the registration state is now wrong. The correct sequence is to freeze the impact-tested specification in the design, confirm MDMT by calculation, then buy steel. A 24-hour documentation review before the mill order is far cheaper than a post-fabrication rerate.

Documentation checklist

  • Material specifications on the drawing, matching the calculations
  • MDMT basis and impact-test designation or exemption basis
  • Overlay/cladding details where applicable
  • Bolting and closure materials
  • Quality-program certificate covering the actual fabrication plants
  • Sub-vendor material specifications for packaged vessels
  • No "or equivalent" without a defined, registered equivalent
  • An as-built MTR plan if the equipment is already fabricated

Common mistakes

  1. Specification versus MDMT mismatch
  2. "Or equivalent" filed as a registered material
  3. Quality certificate for the wrong plant
  4. Changing grade after filing
  5. Assuming PED/EN material files replace ASME designations in a Canadian CRN

Frequently Asked Questions

What material documents should be in a CRN dossier?

At design registration: material specifications for each pressure part on the drawing, the MDMT basis with impact-test designation or exemption reasoning, closure and bolting materials where applicable, and the manufacturer's quality-program certificate. MTRs become critical at fabrication, inspection, and as-built recovery. Some AHJs or owners request additional material evidence for exotic alloys; confirm the destination AHJ's current expectations before filing.

What happens if we substitute a different material after fabrication?

Treat it as a design change or an as-built discrepancy, never as a purchasing footnote. Depending on timing and jurisdiction, the path is a design revision before construction, or an alteration/variance/rerate process afterward (Emergency CRN Support for Equipment Already Fabricated and Post-Fabrication CRN Challenges: As-Built Differences, Alterations, Variances, and Rerates). The substituted heat's MTRs, traceability, and any additional examination become central evidence. Hiding the substitution risks the registration and, more importantly, the equipment's integrity file.

Do we attach mill test reports to the CRN application?

Follow the destination AHJ's current instructions. Many design-registration filings need clear specifications more than heat-by-heat MTRs, because the equipment is not yet built; used-equipment, rerate, and as-built paths typically need substantially more material evidence. Dumping hundreds of MTR pages into an application is not a substitute for a clean specification table on the drawing. Confirm format and content with the applicable AHJ.

Can one vessel CRN cover two materials, such as carbon steel or stainless?

Only if both materials sit inside the registered design envelope and the calculations genuinely cover both, thickness, allowables, MDMT, and corrosion allowance for each option, shown as a defined option table on the registered drawing. "Or stainless" in a quotation is not an envelope. Otherwise the variants are separate designs or require a structured multi-design registration strategy (Standardizing Products for Multiple Provinces: CRN Risk Management for Repeatable Equipment Families).

What if the mill certificate shows a different specification than the drawing?

Stop fabrication until it is resolved: it is either a substitution (follow the design-change path) or a documentation error (correct the paperwork under quality-program control). Never proceed to nameplate stamping against an unresolved heat. The registered design, the purchased material, and the MTR must describe the same specification; a mismatch discovered after the CRN is issued becomes an alteration or as-built problem.

Key Takeaways

  • Specify materials as part of the registered design; buy to the specification.
  • MDMT is a material problem as much as a calculation problem.
  • Substitution after registration is a revision, not a purchase-order tweak.
  • Expedited review checks agreement across drawing, calculations, and certificates.
  • AHJs register the design, not the purchase order.

Next Steps

If you are a foreign manufacturer, OEM, or package supplier preparing equipment for a Canadian oil and gas, mining, or industrial project, send the current drawing set, calculations, code basis, and quality documentation for a completeness and submission-readiness review. Contact us to send your package for a completeness and submission-readiness review.

Related Guides

Sources

Regulatory references in this article were checked against publicly available authority pages as of 11 September 2026. Confirm current requirements with the applicable AHJ.

Topics: CRN Registration, CRN Documentation, CRN Material Documentation

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