Frequently Asked Questions

CRN submissions can be confusing and difficult. Knowing the requirements and doing your best to meet them before submission is always your best approach. This page is a top level introduction. Other articles on our website contain more in depth information and specific guidance.

Need Help? Pressure Vessel Engineering provides design and CRN registration services – see our advertisement at the bottom of the page.

Frequently Asked Questions

Frequently asked questions on the registration of vessels and fittings. PRINT EXPAND SHRINK LINK

Frequently Asked Questions

Here are some of the most common CRN related questions we get:

Scope and Registration

What gets registered? Both Canada and the United States use the ASME Section VIII-1 code for pressure vessel construction but Canada has a CSA B51 standard that provides a more restrictive definition of what a PRESSURE VESSEL is. Canada also registers FITTINGS – items that in other countries would be considered too small to need registering. Likewise we also register many PIPING SYSTEMS in Canada. All vessels, fittings and piping systems need to be built under appropriate quality control programs.

Who Does the Registration? Each province does its own registration and provides a CRN number which is put on the vessel nameplate. The Atlantic Canada provinces and the northern territories have joined together to use one registration organization, ACI Central. We have 13 provinces and territories, but to register across all of Canada, you must register with 7 Organizations or Jurisdictions.

When Should I Apply for a CRN? The CRN should be applied for before construction begins. To quote B51 “Acceptance and registration shall be obtained before construction is commenced.” For a manufacturer who has a finished vessel, and has been told on the shipping date that the vessel is bound for Canada, this can be a problem. In reality, this requirement varies by jurisdiction, for example the Ontario vessel act offers this alternative: “4.(2) A person who submits a design submission for registration may commence construction of the boiler, pressure vessel, fitting or piping before the submission is registered if the person assumes all risks related to the construction, whether for an installation or alteration.” The more time you allow for the registration the better.

What happens if I don’t apply for a CRN? There are a large number of fittings, piping systems and pressure vessels in use in Canada that require CRNs but were never registered. These products are often uncovered during authorized inspector visits or insurance audits. If a product is discovered while it is in use, then someone has to go through the effort to get it registered at that point. If it cannot be registered then it must be replaced. If it is a safety concern then it must be shutoff until registered or replaced.

I manufacture a fitting that will have my customer’s name on it, not mine. How do I register it? The logos that will be affixed to the product need to be indicated on the statutory declaration. Multiple logos can be registered. If the logos will not fit on the box on the statutory declaration page, put them on an additional page.

Do I need a CRN for a pump? No.

Do I need a CRN for an air compressor? No – but volume bottles between compressor stages and air receiver cylinders need CRNs.

Do I need a CRN for hydraulic components? No – except in circumstances of high operating temperatures. This varies by province.

Do I need a CRN for pneumatic cylinders? No.

Do I need a CRN for bolting or gaskets? No. Bolting and/or gasket information may be required by the connection manufacturer to calculation their design for CRN registration. For example, M & Y values for gaskets or allowable strengths for bolting material.


How long can I manufacture Pressure Vessels to my CRN? The CRN affixed to a vessel is valid for the life of the vessel. For a manufacturer, the CRN can be used until the code changes enough to require the design to be changed, or until design changes are desired.

How long can I manufacture Fittings to my CRN? The CRN for a fitting is valid for 10 years. After that time, the design must be re-registered. For a fitting registered across Canada, all the CRNs expire once the first CRN expires. The expiry date is written on the documentation you get back from your jurisdictions. Fittings in use remain in use even if the fitting CRN expires – identical parts are required for maintenance and repair. If different parts are used then the registration needs updating.

Code Revisions

Do I need to update my pressure vessel calculations with each code revision? Manufacturers have to re-run or review the calculations with each new code release to confirm that the design is still valid. The authorized inspector confirms that the calculations are current or reviewed. This is also how it is done for National Board fabrication.

Do I need to update my fitting calculations with each code revision? Calculations are not normally updated until it is time to re-register the design.

Design Changes

I need to modify a registered vessel. Do I need to re-register it? If the calculations do not need to be updated then the answer is probably no – example, addition of a nozzle identical to one already on the vessel that is not too close to another nozzle – then you will probably not need to re-register it. You must contact your local authorized inspector. Note: work must be performed by a company with a valid QC certificate like an ASME “R” stamp.

Can I change the operating conditions on my vessel without re-registering it? Maybe – if the calculation set does not need to be re-run because of the change, then you might not need to re-register it. Call your jurisdiction.


Does my fitting have to be made of code listed materials? Sometimes – see Unlisted Materials

Can I make my fitting from plastic? Yes – see Registration of Plastic Fittings


Is my quality control system acceptable?

Pressure Vessels and Boilers: ASME U stamps are required for pressure vessels signed off by National Board Inspectors. See TSSA’s list of acceptable inspection agencies.

Piping: requirements vary by province, see the QC section on the Piping QC Requirements Page?

Fittings: two things must be met :

1) the requirements of B51 Annex F “Quality control program for manufacturers of fittings” must be met, and

2) the program must be 3rd party audited (although this is not a requirement of CSA-B51, this is mandatory). Various 3rd party audited programs can be acceptable ranging from ISO, TUV, Mil Spec, ASME LLoyds, ABS, Det Veritas and provincial B51 programs. The party doing the auditing must be acceptable to the reviewer.

See TSSA document Guidelines for the Registration of Non-nuclear Fittings in the Province of Ontario for further information.  Usually a QC program is accepted based on the scope as written on the certificate without review of the actual program. Sometimes the scope as declared on the certificate is not clear or acceptable leading to a review of the actual program. For example many TSSA B51 piping programs only cover the scope of manufacturing piping systems and can not be used for the manufacture of fittings. Remember that the program only has to cover those items of the B51 Annex F that actually apply to the manufacture of the fitting being registered. For example it is not required to have a program cover welding if the fitting is made only by machining. From B51-14 “The program that the manufacturer uses shall be suited to its circumstances and reflect the complexity of the products produced.”

Can I have more than one manufacturer build fittings for me under one CRN? Each fabricator would need to declare their own statutory declarations and provide proof of a suitable QC program. If the jurisdictions can register them together they will, otherwise separate numbers will be issued. This is most likely to work if each fabricator was a different branch of the same company.

Can I have more than one manufacturer build vessels for me under one CRN? Yes, all provinces except Saskatchewan allow this. The registration covers the design and assigns it to an owner. The authorized inspector will determine that an adequate QC program and suitable quality control procedures will be followed during the construction. Note that this assumes that all manufacturers have a legal right to build the vessel granted by the owner of the design. See Move or Name Change for more information.

Do I need to label the CRN number on my vessel? Yes – stamp the CRN number on the code nameplate. On my fitting? No, but the manufacturers logo (as shown on the statutory declaration form) must be visible.

Can I build more than one piping system from my piping registration? No – piping systems are registered to an installed address. Unless the installed address remains the same, then each identical copy would need re-registering. Update: Alberta and Ontario have methods of registering mobile piping systems.

Do I need to hydrostatically test my fitting? Hydrostatic or pneumatic test requirements for a fitting depend on the standard that the fitting is designed to:

  • B31.3 piping – “Prior to initial operation and after completion of the applicable examinations required by para. 341, each piping system shall be tested to ensure leak tightness.” (345.1)
  • B16.5 flanges – “Flanges are not required to be pressure tested” (8.1) however, if the item is a flanged fitting, then “each flanged fitting shall be given a shell pressure test” (8.2.1)
  • B16.9 fittings – “Hydrostatic testing of wrought fittings is not required by this standard.” (10)
  • B16.34 valves – “Each valve shall be given a shell test…” (7.1)
  • VIII-1 vessels – “A hydrostatic test shall be conducted on all vessels…” (UG-99(a)).

Moving Equipment

I have a used vessel that was registered in another province. Do I need to re-register it to move it to my province? Yes – you need to submit the original calculations and drawings or re-create calculations and drawings if the originals cannot be found. Requirements vary, but most commonly the calculations need to be re-run using original year of construction stress allowables, but using the latest code rules. A photograph of the nameplate and the manufacturer’s data report are required. Used vessels usually need inspection like ultrasonic testing to prove that the vessel is still adequate.

I have a new vessel from another country. Can I get it registered in Canada? Maybe – are the calculations and drawings available? Is the code of construction acceptable? It is usually not worth the effort if non-ASME codes and materials are used.

I am importing a machine from another country that has a piping system that needs registering. Can I do this or do I need to scrap and replace the piping system? The piping system will need to meet all the requirements of a Canadian registered piping system – acceptable quality control program, acceptable materials, CRNs on all the fittings, calculation set, a drawing with identified code materials. We have been involved in imported machines with piping systems not built to Canadian standards but requiring registration. The process can be very long and expensive (think more than 1 year). It is often easier to start from scratch.

Fitting Classification

Fittings are broken down into categories for registration. A manufacturer must apply separately with different statutory declarations for each category that their registered product line covers. PRINT EXPAND SHRINK LINK

Fitting Classification

Fittings are broken down into categories for registration. A manufacturer must apply separately with different statutory declarations for each category that their registered product line covers. This unfortunately increases the registration costs but has allowed BC and Manitoba to declare categories A, B, C exempt from registration provided they are designed to standards listed in Table 126.1 (B31.1), Table 326.1 (B31.3), Table 526.1 (B31.5) or Table 926.1 (B31.9). Category G is also exempt from registration if designed to ASME or National Board. Saskatchewan has an outright registration exemption for fittings in category A, B, C, and G. They no longer provide CRNs in these categories, and they no longer require them on registered vessels or piping systems. Other provinces still require these items to be registered.  (Also, Quebec has future plans where category A, B and C will not require registration – contact RBQ for more information on your project.)

CSA B51-14 Table 1: Categories of Fittings
Category Type of Fitting
A Pipe fittings, including couplings, tees, elbows, wyes, plugs, unions, pipe caps, and reducers
B All flanges
C All line valves
D All types of expansion joints, flexible connections, and hose assemblies
E Strainers, filters, separators, and steam traps
F Measuring devices, including pressure gauges, level gauges, sight glasses, levels, and pressure transmitters
G Certified capacity-rated pressure relief devices acceptable as primary overpressure protection on boilers, pressure vessels and pressure piping, and fusible plugs
H Pressure-retaining components that do not fall into Categories A to G
(1) These categories do not take into account size, materials, end connections, ratings, schedules, and methods of fabrication.
(2) Category H can include
2(a) small pressure vessels registered and inspected as specified in Figures 1(a), (b), or (c). Such pressure vessels shall be designed and constructed in accordance with Clause 7, except that items that fall under Figures 1(a) and (b) may be designed and constructed to Clause 8, provided that the pressure vessel
2(a)(i) does not require full radiography in accordance with the ASME Code;
2(a)(ii) does not have a quick-actuating closure;
2(a)(iii) is not in cyclic service; and
2(a)(iv) is 4 NPS or smaller;
2(b) an assembly of components (including piping components), provided that the diameter of any component does not exceed 152 mm (6 in) and the total volume of the assembly does not exceed 42.5 L (1.5 ft3). Such an assembly is considered a single Category H fitting for the purposes of fitting registration; and
2(c) condenser coils and evaporator coils as defined in CSA B52 and air heater coils, provided that the diameter of any component does not exceed 152 mm (6 in) and the design pressure does not exceed 4.14 MPa (600 psig).

Refer to the CSA B51 Graphs (Fig 1a, 1b, 1c) to determine if you have a vessel or a category H fitting. The above dimension limitations only apply to category H fittings. Category A-E fittings can be any size and remain a fitting.

Do I Have A Vessel or a Category H Fitting?

Category H fittings often look like miniature vessels. Determining if you have a vessel or fitting only applies to items that look like large or small pressure vessels.  PRINT EXPAND SHRINK LINK

Do I Have A Vessel or a Category H Fitting?

Determining if you have a vessel or fitting only applies to items that look like large or small pressure vessels. Determining if you have a vessel or fitting only applies to Category H, the items that do not fit into other categories. These Category H fittings often look like miniature vessels.


This accumulator (which has a lot in common with a vessel) is either a Vessel, a Category H Fitting, or does not need registration – see the charts below…

These charts are from the Canadian B51-14 standard and include more items as pressure vessels than the definition found in ASME VIII div 1 section U-1.

Service Categories

There is a grey area when it comes to determining if vessel contents are more hazardous than water. For assistance in deciding which chart to use, it is useful to have Material Safety Data Sheets (MSDS). The MSDS sheets will not specifically tell you which chart to use, but a review of the “Toxicity” and “Health Effects and First Aid” on the MSDS can help you decide. The jurisdictions are not responsible for classifying service; it is the responsibility of the owner/user to perform this evaluation. Lethal service is defined in the B51-14 code, what is more hazardous than water is not:

Lethal substances — poisonous gases or liquids of such a nature that a very small amount of the gas or of the liquid’s vapor mixed or unmixed with air is dangerous to life when inhaled. For the purposes of Part 1 of this Standard, this definition includes substances of this nature that are stored under pressure or can generate pressure if stored in a closed vessel.

Vessel or Fitting Charts

Important note: These charts are from the Canadian B51 Standard. Each province also has a pressure vessel regulation which modifies these charts. Be sure to check the regulation for the province that your product will be shipped to!

B51 Figure 1(a)

Figure 1(a): Registration and inspection requirements for pressure vessels (and pressure vessels registered as Category H fittings) for liquid service with liquids not more hazardous than water

B51 Figure 1(b)

Figure 1(b): Registration and inspection requirements for pressure vessels (and pressure vessels registered as Category H fittings) containing a non-lethal gas or vapor or a non-lethal liquid not covered by Figure 1(a)

B51 Figure 1(c)

Figure 1(c): Registration and inspection requirements for pressure vessels (and pressure vessels registered as Category H fittings) containing lethal substances

Each chart references Table 1 (above), Clauses 4.1.1 and 4.8.2 below:

CSA B51-14, 4.1.1: The calculations, drawings, and specifications pertaining to the designs of boilers, pressure vessels, fittings as specified in Clause 4.2, fired-heater pressure coils, and piping shall be submitted to the regulatory authority in the province where the item is intended to be used. The submission shall identify the substance for which the item is intended. It shall be the responsibility of the users or an agent they designate to determine whether the substance is lethal. Figures 1(a), (b), and (c) shall be used to determine whether items are to be registered as pressure vessels or Category H fittings (see Table 1). The name of the authorized inspection agency to be employed when a boiler or pressure vessel is to be manufactured outside Canada shall also be submitted when required by the regulatory authority. Acceptance and registration shall be obtained before construction begins. Manufacturers who commence construction prior to receiving design registration shall rectify any design deficiencies that are identified in the design registration process.

CSA B51-14, 4.8.2: Vessels shall be subject to individual shop inspection except as follows: (a) low-pressure steel boilers with 4.5 m2 (50 ft2) or less of wetted heating surface; (b) cast iron and cast aluminum sectional boilers; (c) miniature pressure vessels, as defined in Section VIII, Division 1, of the ASME Code, when the manufacturer has registered its quality control manual with the regulatory authority where the manufacturing shop is located and has completed a manufacturer’s data report for miniature pressure vessels [see Figure D.1(a)]; (d) hot water tanks, hydropneumatic tanks, and cushion tanks not exceeding 762 mm (30 in) in diameter (with no limit on capacity); (e) propane storage tanks for recreational vehicles not exceeding 0.09 m3 (3.2 ft3) in volume and 2153 kPa (312 psi) in design pressure; (f) electric boilers of a capacity up to 60 kW; and (g) small pressure vessels registered as Category H fittings and inspected in accordance with Figures 1(a), (b), and (c).


Every province has exemptions or modifications to the B51 requirements. As an example, TSSA takes complete exemption to charts 1a, 1b and 1c above. Instead they use:

Fitting Fittings as categorized in [B51] Table 1 including those described in NOTE 2 that are not attached to a boiler, pressure vessel, or piping under the Act, are exempt from CSA B51. Additional notes to CAD amendment: The definition for fitting identifies that it is not a fitting unless the fitting is attached to an item such as a boiler, pressure vessel or piping system that is under the regulation and this is consistent with O. Reg. 220/01. That is stand-alone items that are best categorized as fittings are exempt and this includes category H items e.g. pressure vessels with a volume less than 1.5 cubic feet or a small piping system that has an internal diameter less than 6″ and internal volume less than 1.5 cubic feet. [Code Adoption Document (CAD) BPV-13-01, March 11, 2013, 1.3 ii]


Figures 1 a), b) and c) are revoked and replaced with the following: Figures 1 a), b) and c) Items less than 6″ in internal diameter or less than 1.5 cubic feet in internal volume are classified as Category H fittings not pressure vessels. [Code Adoption Document (CAD) BPV-13-01, March 11, 2013, 1.29]

these two definitions of fittings from the code adoption document are not the same, working with the definition from Code Adoption Document section 1.29 we get this chart:

Vessel or Fitting in Ontario

Items that are Always a Fitting

These charts do not apply to all Category A-G fittings listed above.  For example, a valve no matter how large is always a fitting. Not being in Category H, the above charts do not apply.


Not a Category H fitting – always a fitting no matter what size…

Fabrication of Vessels vs Fittings

A Pressure Vessel must be built in a shop with an accredited quality control program, and the finished vessel inspected by an Authorized Inspector (Except UM vessels which are inspected by the shop). A CRN (Canadian Registration Number) is required, and is written on the manufacturers data form. The CRN is also stamped on the vessel nameplate.

For a pressure vessel built outside of Canada, the shop’s National Board and U-stamp authorization would be proof of the quality control program. The fabricator has to CRN register AND National Board register the vessel.

A Fitting that needs to be registered also has to be built to a quality control program, but the inspection will be by the shop that fabricated it, according to the shop’s quality control program, proof of which is included in the registration package.

Does your fitting need registration?  If it’s part of a piping system, the answer is always yes.  If it’s on a vessel, the answer is a little more complicated, but usually no.  If the fitting you are using is built to a specification listed in Table U-3 of Section VIII-1, you can use it on your vessel without a CRN.  If the standard is not listed in Table U-3, you need to use a registered fitting.


The above charts do not include piping, the definition for which can be found in B31.3:

300.2: “piping: assemblies of piping components used to convey, distribute, mix, separate, discharge, mete, control , or snub fluid, flows.”

CSA B51 2009 – 11.4: “a series of components (including piping components) joined together to form a single fitting, provided that the diameter of any component does not exceed 152 mm (6 in) and the total volume of the fitting does not exceed 42.5 L (1.5 ft3).can be registered as Category H fittings.”

The registration of piping can be more restrictive than vessels or fittings, so registering small piping systems as fittings is a considerable convenience. See more about piping at: Piping Registration

CRN Registration at PVEng

We are Canada’s largest independent registrar of fittings, vessels and piping under the CRN program registering for more than a thousand customers. We are experts in the specialized field of pressure equipment design and registration.

  • Integrated design, review and registration services
  • Extensive knowledge of registration requirements, including what needs registering and what is exempt province by province
  • We work to many ASME codes – VIII-1, VIII-2, I, IV, B31.1, B31.3, B31.5 and others
  • Design validation by burst test to many codes

Other Services

ASME Code DesignWe work to many ASME standards to design and validate pressure vessels, boiler, fittings and piping systems.

Finite Element Analysis (FEA)We use FEA to design and validate fittings and vessels that cannot be designed by rule-based codes like VIII-1 or B31.3.

Pipe Stress Analysis Pipe stress analysis is mandatory for British Columbia registration and it is recommended practice for many other systems.

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