CRN Essentials

Generic Designs Revisited

The truth is, fewer CRNs are better in many ways.  

With fewer CRNs, it’s easier to keep track of CRN registration numbers, it’s easier to ensure the right CRN registration number is affixed to the right equipment, and it’s easier if the regulators need not be contacted as much.

It’s usually possible to combine several pressure equipment designs of a particular type into one design.  This is what a generic design is all about.

Generic Pressure Vessels and Boiler Components

For example, pressure vessels or boiler vessels and components with different nozzle locations in heads and shell, different nozzle sizes, and different shell lengths can be combined into one design, i.e. a generic design.  For pressure vessels, nozzle spacing tables showing required nozzle spacing distances in accordance with ASME Section VIII-1 paragraphs UG-36, UG 37, UG-39, UG-40, UG-41, UG-42, UW-14, etc., can be included on the drawing and considered as part of a design.  Similarly for boiler vessels and components, nozzle spacings are governed by paragraphs PG-32 etc.  

Only relative locations of nozzles need to be prescribed; specific locations for each nozzle need not be defined.  In this way, a virtually unlimited number of nozzle combinations and locations can thereby be included with a vessel design, as long as they reasonably represent the product line and market demand.  The idea is not to combine all possible nozzles at all possible locations, at all nozzle offset distances, and at all nozzle inclination angles.  A reasonable set of nozzle locations and sizes is acceptable to the regulators.

Generic vessels must have a fixed:

  • design pressure 
  • max design temperature, 
  • minimum design metal temperature (MDMT), 
  • shell diameter, 
  • corrosion allowances for each vessel component, 
  • weld configuration for each nozzle
  • head type
  • head and shell thicknesses, and
  • materials of construction, with reasonable exceptions.

A drain must be located at a location to permit drainage, if required.  And inspection openings, if required, must be located within a diameter’s distance of the heads’ circumferential seams.

Generic Fittings

Fittings designs are regularly combined into one application for CRN registration, as long as the same fitting category is considered.  For example, a catalogue of category A ASME B16.9 pipe fittings can be registered with one application.  Same thing for various different catalogues with sets of drawings: category B flanges, whether ASME B16.5 or custom in accordance with ASME Section VIII-1 Appendix 2; category C valves fittings in accordance with ASME B16.34, or ASME B31.3, etc.; category D expansion joints or hose assemblies; category E filters, separators, or steam traps; category F measurement instruments like gauge glasses, pressure transmitters, flow meters, etc.; or category G pressure relief valves, rupture disks and fusible plugs.  Such CRN registrations cover a wide range of sizes, pressure ratings, temperature ratings, materials of construction, etc.  In general, requirements for generic fittings are less stringent than for pressure vessels.

An exception to the above is for category H fittings, which typically look like little pressure vessels.  For generic CRN registrations involving category H fittings, it is advised to apply the guidelines for generic vessels  noted above. 

Revisions and Additions to Generic CRNs

After registration is obtained and before it expires, a CRN revision can add new design models or variations to the list of equipment already included with a CRN registration.  With a revision to a CRN, the same CRN number can be used for new models or for design variations, further to what was originally anticipated.

Revisiting Maximum Allowable Working Pressure & Design Pressure

Maximum Allowable Working Pressure (MAWP) and Design Pressure (DP)

Contrary to the articles referenced below, it is a mystery how some seem to believe and even encourage others to think that the true design pressure of any vessel component, as defined in the code, is ever less than the MAWP of the vessel. It would necessarily suggest a potentially perilous situation.

Back in April of 2019, CAMMAR published an article entitled “MAWP is NEVER Greater than ASME Design Pressure,” and it generated lots of attention in the ASME pressure vessel and piping forum group on LinkedIn, with a surprising number of questions and discussion suggesting that the article was wrong.

Addressing those questions and comments is what this article about. It is worth re-emphasizing that the design pressure of vessel components as defined by ASME and per the previous CAMMAR article can never be less than the MAWP of the vessel provided that the vessel has one chamber (as almost all do).

For the Alberta regulator’s perspective on this matter, please see the following link (page 3) for their related publication:

The ABSA article discusses the dangers associated with suggesting that ‘design pressure’ is less than MAWP and that “‘Design pressure’ within the scope of the vessel code (as discussed therein) is thus required to be at least equal to the vessel’s MAWP, …” In order to register a vessel with a CRN number, the design pressure of each vessel component can never be less than the MAWP of the vessel.

Per the original CAMMAR article, MAWP and design pressure are not synonymous and, if mistakenly used interchangeably, the difference can compromise the safety of your equipment. When considered properly in the context of pressure equipment, MAWP is NEVER greater than design pressure.

Questions and misunderstandings of readers, which are apparently still evident, are previously answered and clarified as part of the discussion here, in the ASME pressure vessel and piping forum: via LinkedIn. If you’re not a subscriber to that forum group, we suggest that you subscribe.

Here’s a sample of some of the questions/comments elicited, together with CAMMAR’s responses:

“MAWP is never greater than ASME DP.”

Reader A, P.E. in the USA

“MAWP can be Higher or lower; it depends on each component of our equipment. MAWP is the pressure which the weakest component of your system can handle.”

CAMMAR’s response:

In accordance with our explanations above and, at the risk of belabouring this issue but in the interest of public welfare, we maintain with good reason that MAWP is never greater than ASME DP, in accordance with code requirements, including the definition of DP via ASME Section VIII-1 paragraph UG-21, when considered properly with Appendix 3, and Appendix KK. MAWP is always less than or equal to the design pressure of vessel components. Design pressure (DP) as defined by the code relates to vessel components and is, therefore, a function of component location.

“The language of the code is not subject to preferences.”

Reader B, Engineer in the USA

“I agree with the content of the article. It encourages us to properly understand how MAWP, Design Pressure is defined in code. It cautions about a very specific case where assuming ” MAWP would always be greater than the design pressure” would be risky. I, however, do not agree with the title of the article. It is misleading. Please note the (*) mark against the article and do not accept the title at its face value. There is an interpretation in the code that does not agree with the title of the article ( . It is my experience that sometimes ASME BPVC code rules are read differently in different parts of the world. They are preference based on Industry, past industry experience, local laws. All of those preferences even though different complies with the language of the code.”

CAMMAR’s response:

Referenced articles (including titles) above are consistent with code rules, definitions, and interpretations. Note that the interpretation you mention relates to initial design conditions, not final design conditions. It is a mystery how some seem to believe and even encourage others to think that the true design pressure of any vessel component, as defined in the code, is ever less than the MAWP of the vessel. It would necessarily suggest a potentially very dangerous situation. The language of the code as understood by regulators is not subject to preferences! Definitions of design pressure and MAWP are what they are. There is no law directing the use of any different definitions for design pressure or MAWP in Alberta; they are defined as what the ASME code already requires.

“DP is always greater than or equal to MAWP.”

Reader C, Certifying Engineer in Germany

“Cameron, you are wrong. MAWP can be greater than Design Pressure. Even on one vessel. When the actual wall is thicker than required, you can calculate a MAWP that exceeds the design pressure of the vessel.”

CAMMAR’s response:

Well [name removed to preserve anonymity], it seems that we disagree! But thanks for your response. It’s an important topic, hence my article. MAWP is, of course, the maximum pressure permissible at the top of the vessel. That said, some vessel components might well be overbuilt in relation to others but, in that case, the MAWP will not change. If properly defined, as noted in the article, DP is always greater than or equal to MAWP. Period.

Have questions about getting your CDN? Find out how we can help you register your pressure vessels in Alberta/Canada.

ASME B31.3 is different than API 6A. FInd out how with Cameron Sterling from Cammar.

API 6A Is Not The Same as ASME B31

API 6A and ASME B31.3 Chapter IX High Pressure Piping Components are NOT the Same.

As those in the oil and gas industry venture to where ASME codes prevail, you could find out the hard way that API standards do not govern these component designs. Expensive assumptions about API applicability can be made incorrectly, at great cost to budgets and schedules. In Canada, regulators like ABSA in Alberta and the TSSA in Ontario govern pressure equipment use and CRN registration requirements when related safety regulations apply.

For example, API 6A – Specification for Wellhead and Christmas Tree Equipment, is unacceptable as a code of construction for valves or equipment for any ASME B31.3 service in the jurisdiction of CSA B51. Regardless, many high-pressure valve and equipment suppliers often mistakenly use API 6A as their standard and do not realize that its requirements differ markedly from ASME B31.3 Chapter IX.

Here’s a quick list of some significant requirements associated with ASME B31.3 Chapter IX for you to consider:

User Design Specification:

Per paragraph K300, at their option to use Chapter IX as the code of construction, the owner must designate piping as being in ASME B31.3 Chapter IX high-pressure fluid service and must provide the designer with all system operation information necessary to properly design the equipment. In return, the designer must make a written report to the owner that certifies that calculations and the design have been performed in accordance with the code requirements.

Cyclic Analyses:

Cyclic analysis is necessary per paragraph K304.8 unless the owner designates that the piping system will not undergo cyclic loading, that there will be no pressure or temperature cycles throughout the lifetime of the piping system. If the component is listed and conforms to standards listed Table K326.1, fatigue can be analyzed with either ASME Section VIII-2 or ASME Section VIII-3 methodologies.


For pressures that exceed #2500 class, flanges are to be validated through ASME Section VIII-2 Part 4 calculations, per paragraph K304.5.1(b). Regulators will be reluctant to consider proof tests or FEA justifications.

Unlisted Components:

Valves etc. not conforming in any way to ASME B16.34 per K307.1 and other components unlisted in ASME B31.3 Chapter IX per K304.7, must be validated through an ASME Section VIII-3 finite element analysis (FEA) which inherently includes a VIII-3 fatigue analysis, a proof test, or a combination of both these methods. Even with meticulous records and affidavits, it is exceedingly difficult to adequately document successful service to the satisfaction of the regulator and all stakeholders.

Proof Testing:

Proof test pressure is different in ASME Chapter IX than for ASME B31.3 Chapter VI requirements and is a function of yield strength at ambient and at temperature.

Listed Materials and Allowable Strengths:

Refer to Table K-1 of ASME B31.3, not Table A-1 for pressure boundaries. Refer to ASME Section VIII-2 for bolting materials per paragraph K309 and Section VIII-2. Allowable strengths are a function of yield strength alone, per paragraph K302.3.2.

Pressure Boundary Thicknesses:

Cylinder thickness is calculated based on thick cylinder theory per ASME B31.3 Chapter IX paragraph K304.1.2, and differs from the thin-walled theory approach of ASME B31.3 Chapter II.

Impact Testing:

Impact tests are necessary for base metals and welds in accordance with ASME B31.3 Chapter IX Table K323.3.1 requirements, further to material specifications. Exemptions unrelated to specimen size are unavailable. There are no exemptions associated with material thickness.

Valid Canadian Registration Number (CRN) Database and Directory Information

Valid Canadian Registration Number (CRN) Database and Directory Information

To ensure a strong supply chain, industry often needs to locate manufacturers of CRN registered pressure equipment. Pressure piping, vessels, boilers, and thermal liquid heating systems unexempt from CRN registration need components suitable for CRN registration and, though it can be difficult to find legitimate manufacturers, locating them and the registered pressure equipment they make is necessary.

Is there a legitimate directory available to the public and industry, that lists the tens of thousands of CRN numbers that exist? And is there a published list of all legitimate manufacturers in a jurisdiction with acceptable quality control programs?

Yes! There already are legitimate and valid CRN directories on official regulator and registrar websites, that are publicly available to everyone that wants to look for CRN registration records. Only regulators have access to all legitimate CRN registration and manufacturer information, keep it complete and up to date as much as possible, and publish it as they see fit in accordance with their governing regulations. However, significantly incomplete, substantially limited, and unofficial lists are found elsewhere on the internet.

CRN’s are considered confidential information and many manufacturers do not want their CRN information published by others, as commonly evidenced by non-disclosure agreements and requirements for confidentiality.

Given the relatively high concentration of pressure equipment per capita in Alberta, it is worthwhile knowing that the Alberta regulator (ABSA) has allowed access to its CRN Directory here: And though less populated, the maritime provinces’ CRN Directory can be accessed here, with the assistance of the registrar (ACI Central) and permission of the CRN recipients: The ABSA directory is searchable based on particular CRN numbers, while the ACI Central directory is searchable by CRN and / or manufacturer name. ABSA search results provide the manufacturer name, CRN, drawing number, description, and expiry date. The ACI Central site also provides a more detailed description, including notes associated with the registration.

Using these two CRN Directories, manufacturers with pressure equipment registered in Alberta and / or the maritime provinces can be located and, if the equipment is registered in other jurisdictions too, it’s ordinarily noted.

Fitting CRN registration numbers are categorized per Table 1 of CSA B51, according to the following schedule:

Category Type of Fitting
A pipe fittings, such as elbows, tees, couplings, wyes, caps, unions, etc.
B flanges
C Line valves
D expansion joints, flexible assemblies, hose assemblies etc.
E Strainers, filters, and steam traps etc.
F Measurement devices such as pressure gauges, levels, transducers etc.
G Pressure relief devices
H All other pressure retaining components that don’t fall into categories A through G


Unfortunately, wide searches within a fitting category cannot be manually conducted instantaneously. However, formats of CRN numbers as defined in CSA B51 assists with searching the CRN directories for suitable manufacturers. A fitting category letter is included with all fitting CRN numbers, and so specific searches for manufacturers of fitting categories can be made.

For example, if you want to find a piping fitting manufacturer that initially registered their equipment in Alberta, you can successively conduct a manual search using the 0AXXXXX.2 number format until a manufacturer (or all such manufacturers) are found. Similarly, if you want to find a piping fitting manufacturer that first registered their design in Ontario, then you can successively conduct a manual search using the 0AXXXXX.52 format until a manufacturer (or all such manufacturers) are found.

Spending just a minute or so with the ABSA search template, and starting a search at 0A10000.2, revealed the one of thousands of CRN registrations listed there: 0A10032.2. To the best of ABSA’s knowledge, data published on their site is valid, and includes the manufacturer name, registration details, and the expiry dates of all pressure equipment registered in Alberta. A lengthier search, or a lengthier search within a different fitting category, will yield more lengthy lists of CRN numbers and manufacturers!

For the maritime provinces, similar CRN registration searches can also be conducted with manufacturers’ names, and this can shorten the searching process.

The legality of scraping websites with even a simple VBA software routine, to systematically identify and log all fitting CRNs and manufacturers, is questionable since ABSA has claimed copyright on its website contents. Public access to the CRN registration directory information is freely available to anyone that would like to look for it.

A list of qualified manufacturers is also a good place to start looking for registered fittings that might be of interest to you. ABSA publishes a searchable list of all Alberta companies qualified to manufacturer all categories of pressure fittings here: . Manufacturers with an acceptable quality control program can get CRN registration for fittings, provided that the designs meet code and regulation requirements.

CRN Number

Is The CRN Valid and Legit?

“It’s registered they said.  Here’s the proof they said.”

Really. Ok, so what can you believe?

As an end user of pressure equipment (valves, flanges, fittings, instrumentation, vessels, boilers, thermal liquid heaters, etc), you are responsible for its safe operation in accordance with all applicable ASME codes, standards, and jurisdictional regulations.  This means that you need to ensure it is properly registered with a CRN.  CAMMAR Corp can help you do this.

“But wait a minute.  Aren’t the regulators responsible for registering pressure equipment?”  Nope, they aren’t. They just accept it for registration, but before the equipment is used, sold, distributed or even offered for sale, the responsibility for registering it, and ensuring that it is registered properly, rests with those who have care and control over it.  Regulators don’t own it.

“Ok, but I asked the vendor if it was registered and they said it was.  They even provided ‘proof’ of the registration with the CRN number. And that CRN is valid, so it’s registered, right?”

Uh, not necessarily.

For example, suppose your project needs some ASME B16.34 valves with a CRN number.  You ask your vendor for proof of registration, and they provide you a copy of a stamped Statutory Declaration with CRN included.  But what they neglect to tell you is that the acceptance letter provided by the regulator has a condition included, that goes something like this: “Only valves which comply with all aspects of ASME B16.34 in its entirety are part of this registration.”

So, what does that mean?  

It means that the regulator does not always itemize which of the vendor’s valves or items meet the requirements and which do not.  And with the note above, if pressure parts of any valves are made from any materials not listed in ASME B16.34 and supported by mill test reports, then those valves are not registered.  And if the flanges of those valves are improperly reamed or hollowed out, or chambered, too thin, too short, or whatever, and thereby don’t meet ASME B16.5 or B16.47 dimensions in their entirety, the valves are not registered.  Etc.

So, even though there may be a CRN number, the equipment might well not be registered.  Despite what your vendor might tell you!  

And if you were to use such excluded valves or equipment anyways, it would be like you were using unregistered equipment…!  And you don’t want to go there!

Make sure the pressure equipment you want to use is registered properly with CRNs. We, at Cammar Corporation, can help you deal with the complexities of getting a CRN registration. Call Cammar Corporation right away.

ASME Code Changes

Lookout For Anticipated 2019 ASME Code Changes

As the year progresses and new codes are published, there are a few things to keep a lookout for, particularly with respect to material property requirements.

Two materials are of particular interest, and are reportedly likely to change with the 2019 edition of ASME Section VIII-1. The potential ramifications of these changes on pressure equipment designs and CRNs are quite significant and interesting.

SA-105, Specification for Carbon Steel Forgings

As many Canadians can attest, particularly this year, Canada is not a stranger to cold weather. The thermometer drops below -29C (-20F) with uncomfortable regularity here. As such, impact toughness characteristics and impact test requirements are of primary concern when designing pressure equipment for Canadian use. Nobody wants a pressure boundary to crack and lose containment.

With respect to the SA-105 material specification, somewhat recent brittle fracture incidents at relatively moderate temperatures have been reported, despite adherence to current code rules. As is, ASME Section VIII-1 2017 lists the SA-105 specification as a curve B material per ASME Section VIII-1 Figure UCS-66. We understand that the 2019 Edition of ASME Section VIII-1 will likely change this and instead list SA-105 as a curve A material, thereby requiring impact testing for SA-105 when it wasn’t required before.

We are relatively unsure about whether reclassification of A105 will immediately be reflected by the newest anticipated edition of ASME B31.3 or ASME B31T.

Regardless, the reclassification of SA-105 will be of interest to industry. SA-105 is a common choice for flanges and other forgings for all sorts of pressure piping, and would likely be one of the most, if not the most, prevalent type of carbon steel forging currently used in pressure equipment design.

Since this code change will be more stringent than recent requirements, the onus will be upon end users and manufacturers to ensure that pressure equipment being made, sold and used meets current code requirements. Over the recent past, code changes have instead relaxed requirements in general and so designs with pre-existing CRN were automatically grandfathered by subsequent code changes.

It will also be interesting to see how regulators administer this code change given it makes the code more stringent than what was originally required for pre-existing registered CRNs. Regulators maintain an archive of all registered designs and can compel manufacturers and end users to adapt to more stringent code requirements as needed.

Grade P91 Alloy Steel

This material seems to be a preferred choice for some thermal power plant station designs, given its reported relatively high strength at high temperatures.

However, concerns about P91 material failures and measurements of reduced strength in some circumstances have reportedly led the 2019 Edition of ASME Section I to consider substantial reductions in allowable strength! Minutes from a recent Pressure Equipment Sub-Council meeting report that expected allowable strength reductions are to be in the order of up to 19%!!

As you probably know, permitted pressure is directly proportional to the strength of the material containing that pressure. If code requires that the allowable strength of P91 pressure boundaries to be reduced by 19% then, excluding corrosion allowance if any, the maximum permitted pressure will also be reduced by a proportional amount.

The effect on the existing power plant operation and future designs could be substantial. For reliable and efficient operation, design conditions of power plants are carefully controlled and specified. Needless to say, a prescribed pressure reduction in maximum operating pressure could be, at best, very problematic for the power industry and the public that depends on electricity.

Similar to code changes relating to the SA105 material specifications, it will be interesting to see how regulators administer code changes relating to P91 grade material, given these changes make the code more stringent than what was originally required for pre-existing boiler CRNs. On behalf of the public, regulators must be satisfied that pressure equipment designs are as safe as, or safer than, what current code requires. Regulators maintain an archive of all registered designs and can compel manufacturers and end users to adapt to more stringent code requirements as needed.

Loop of Despair

CRN Number Registration Problems, Pitfalls, and the Dreaded Loop of Despair

From my years worked at ABSA as a Safety Codes Officer, together with my engineering experience in industry and now at Cammar Corporation, I have a very good idea about what the CRN number registration process problems are, including its pitfalls.  I’ve evaluated and pointed out in detail the deficiencies for thousands of designs needing CRN number registrations.  Some designs were good, and some were – well, let’s just say that they needed improvements and more revisions than others.

The CRN Registration Process

The generalized CRN number registration process is sketched below for reference.  Note the loop of despair.

CRN Number Registration Problems, Pitfalls, and the Dreaded Loop of Despair

Regulator’s Role

During a review, the regulator decides whether to accept and register a design in accordance with provincial legislation, with a focus on safety and technical aspects.  They should be satisfied that the design meets the requirements of the legislation and is designed in a manner that protects the public, before it is registered.  The regulator can consider whatever design information it wants to for it to reasonably decide that a design is safe, but what it considers (or doesn’t consider) is up to them.  They do not approve any designs, and instead accept or reject them.  They are not the owners of designs and are not responsible for them.

If a regulator determines that a design application is deficient in some way, is not safe or does not meet the adopted codes etc, the design application can be put on hold awaiting a revision or can be rejected, at the regulator’s discretion.  If put on hold, then it enters what we call the dreaded loop of despair and, unless the required revision is provided, the application will remain there until rejected or withdrawn.

Hopefully regulators will continue to proactively review applications as thoroughly as possible and continue with detailed design evaluations.  But given the somewhat recently published statistics (see below), the temptation and pressure to fast track the process by eliminating proactive independent third party reviews must be high.  Succumbing to that pressure and temptation would be, in Cammar’s opinion, a mistake and a race downhill that nobody, including the public, would win.


Dreaded Loop of Despair

How many applications enter the dreaded loop of despair? Well, published numbers are scant but ABSA alone reported that in 2014, of the more than the 10000 applications it received that year, more than 50% were deficient (see page 2: ABSA article) and could not be accepted without a resubmission.  This is quite shocking and means that during that year more than 5000 applications either went into the loop of despair and required a revision of some kind, or were rejected or withdrawn.

If a purchase order is cancelled or if production is delayed due to the loop of despair, then associated costs to industry can obviously be large.  But they would potentially be even larger with the use of unsafe or illegal equipment, so it’s good that the bad applications were caught.  Registering applications without detailed third party evaluation and instead conducting audits after registration and sale or installation etc would be, in our opinion, fraught with risks for manufacturers, end users, and the public.  If a deficient product is mistakenly registered and installed, what then?  Recalling a product after installation would certainly cost far more than fixing it on the shop floor before any sale.  And how much reactive auditing after registration would ensure the same level of safety as proactive reviews?


Avoiding the Loop of Despair

Avoiding the loop of despair while maintaining a high level of quality is, in Cammar’s opinion, key to public safety.  Strategies for this will be discussed in the next blog article.  Stay tuned.

Canada Map

Is a CRN Number Required? When and Why.

Well, hopefully this won’t sound repetitive, but CRN registration is required unless an exemption or Variance applies!  Requirements vary by province/territory – some regions have specific exemptions and others have more general ones.  Alberta has an entire regulation devoted to some exemptions.  See this article for more .

And, of course, CRN registration is required before the pressure equipment is operated in Canada.  To follow the legislation and CSA B51 even more carefully, CRN registration is required before the pressure equipment is even built, while still at the finalized design stage.  So as to avoid a whole host of complications, a good rule of thumb to follow is that CRN registration is required before the assembled equipment leaves the manufacturer.

But sometimes, this is not possible.  For example, boilers assembled in the field obviously need to be put together after leaving the manufacturer but nevertheless, the design should have a CRN well before assembly.  As another example, unregistered code stamped vessels can potentially be registered after they leave the manufacturer, but the rule of thumb stated above is the best way to avoid issues.

For those unfamiliar with CRN requirements, the obvious question is why are CRN numbers required?  No other nation beside Canada has them.  One reader recently wrote to ask these questions: Do CRN numbers improve safety, or help Canada to be competitive?  Our answer was that given their indirect reference in public safety legislation, governments in Canada recognize the importance of  crn number canada.  They help to ensure that pressure equipment is designed, built and tested to codes and standards that have, through careful collective deliberation, been written to help ensure public safety by using adequate safety margins and other considerations.  In Canada, designs that meet code and legislated requirements are competitive.

Canadian Registration Numbers (CRN numbers) are used by provincial governments to record,  document, and ascribe responsibility for pressure equipment designs in Canada that are non-exempt from registration.  The exemptions associated with each province should be considered carefully for each type of design to ascertain the differences between each jurisdiction.  If a Canada wide CRN number is required then the jurisdiction that has, on balance, the most stringent requirements with the fewest exemptions should be identified and applied to first  – pursuant to harmonization and efficiency.

Similarly, revisions or additions to a CRN number must be registered in related regions following a particular sequence to avoid issues. Permission from the province that first issued the CRN is needed before the revisions in another region can be registered.  And this can cause problems and delays if this requirement is not known.

For example, suppose a category H fitting or a vessel design was registered in Ontario first and then registration was subsequently sought in Alberta.  Further suppose that Alberta (ABSA) requirements exceed those in Ontario for the design in question.  In that case Ontario will need to consider the revised design before ABSA will consider registering it with the same CRN number.

CRNs follow a format as specified in CSA B51 and are first issued by the region identified by the digit following the decimal point.  Other registration numbers for alternative or special designs are issued numbers with a different format, but they are relatively rare.  CRN numbers are unique for each design.  Referencing specific CRN numbers cannot be done without linking the design owner.  Without owners’ written permission, publication of CRN numbers could cause confidentiality issues.

Alarm Clock

When Should I Apply For a CRN? And Why.

When should a CRN application be made?  This is a common question. After all, knowing when you should apply for a CRN number is important.

Some people only want to know what they ‘must’ do, and they want to know the difference between requirements and suggestions. And though ‘should’ apply for a CRN really means ‘must’ apply for a CRN in normal circumstances, the same people might instead consider ‘should’ to somehow mean a suggestion and will go on endlessly as if there is somehow a misunderstanding as to what is required.  And they also want their ‘musts’ listed in bullet form. Thankfully, there aren’t many of those people around.

But for those people and the rest of you, please be assured that ‘should’ in this instance is really a polite way of saying ‘must’. And at risk of upsetting my web editor for using sterile and unfriendly language, and to appease those who dislike reading too much, here is a bulleted list that inherently includes occasions when a CRN should (must) be applied for and when CRN registration should (must) be obtained:

  • Before operation in Canada

Pretty simple eh?

And it gets more complicated. Believe it or not, legislation and CSA B51 state that CRN registration is required before construction. So this means that an application should (must) also be made and CRN registration should (must) be obtained before the equipment leaves the shop, is shipped, is purchased, or is installed.

The list gets longer with the details. Here is a more detailed bulleted list that includes occasions when a CRN should (must) be applied for and when CRN registration should (must) be obtained:


  • Construction.
  • Shipment.
  • Offer To Sell.
  • Purchase.
  • Installation.
  • Operation in Canada.
  • Alterations to existing pressure equipment commences.

Practically speaking, operation under pressure delineates a line between what modern art and pressure equipment is. Nevertheless, the law refers to CRN registration of designs when the equipment has not even been built yet, and designs are at the finalized stage.  So, why should (must) CRN registration of designs be acquired at such an early stage?

Besides abiding by the law, there are two reasons that come to mind:

    1. Nobody wants to necessarily fix equipment to meet the requirements of a CRN number issued after construction. For example, there is no greater pain than for someone to realize that installed equipment is unregistered and a startup needs to be delayed to fix it. Hence before pressure equipment is even constructed, it should (must) be registered to avoid potentially huge headaches and costs.
    2. Canada does not need or want unregistered and illegal pressure equipment made, shipped, sold, purchased, installed, or operated. It is not worth it.

Obviously not all pressure equipment in the world already has a CRN yet – but we’re working on it!

All this leads to another question, is all unregistered pressure equipment that is already built necessarily unable to be assigned a CRN number?   Hmm…, of course not, though some situations are certainly more challenging than others.

Answer Key

Responsibility for CRN Numbers and Safety

In this space, some questions posed by customers and industry are published in case others have similar questions. Anonymity is preserved. Check back for updates and new correspondence.

Dear Cammar,
If a vessel, fitting, boiler design, or some pressure piping not meeting the legislation requirements and/or that is simply not registered with a CRN number is operated, then so what?
IM Concerned

Dear Concerned,

Safety is a big deal to the public, the engineering profession, and the regulator. Breaking the law is not a good idea.

Unless exemptions apply, operation of pressure equipment (vessels, fittings, boilers, pressure piping systems, etc) that does not meet the legislation, or that is without CRN registration, would be against the law.

Though non-exempt pressure equipment certainly needs to be registered before operation, the equipment also needs to meet the minimum requirements of the adopted codes and standards. In all cases, it needs to be safe.

Committing an offense has potential consequences. For example, in Alberta per Section 68 of the Safety Codes Act, those found guilty are subject to a potential fine of $100000 and imprisonment of 6 months for a first offence, and a fine of $500000 and imprisonment of 12 months for a second or subsequent offence.

So… safety, and responsibility for it, is important.