CRN Essentials

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.

Answer Key

Bleed Ring Design Responsibility Q&A

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,
Does ABSA require that bleed rings be registered or not? I don’t see anything in the pressure equipment safety regulation that exempts bleed rings from having CRN number registration.
I look forward to hearing from you.

IM Concerned

Dear Concerned,
Thanks for your email.
ABSA reportedly does not require CRN number registration for bleed rings – in general. See page 5 of for more information. But each circumstance should be considered on its own merits. For example, a pressurized cylinder sealed with o rings between two ASME B16.5 flanges and held together with threaded bars connecting the flanges, is not a bleed ring. The line between a bleed ring and something else can be blurry and open to interpretation.

What is always necessary is a safe design. Instead of your question, a better question would be: can the device with the pressure port included, safely withstand the proposed pressure? ‘Safely’ means within the factor of safety specified by the code of construction as a minimum. Regardless of whether pressure equipment needs a CRN number or not, the design always needs to meet the minimum requirements of available codes and standards, and the design must thereby provide an acceptable safety margin that the designer, vendor, and end user can responsibly attest to.


How much does a CRN Cost?

The biggest CRN cost might surprise you.  Marketing and operation delays end up costing much more than CRN application and regulator costs. Regulators’ bills aren’t the biggest thing. The regulator will charge as little as about $150CAD or much, much more. Poorly prepared applications for CRN registration will be either rejected, or subjected to a very lengthy iterative review, or both.

Responsibility for registration and application quality rests with the applicant.

Well prepared, professional quality CRN applications will often take a regulator about two to three hours to review on average and this equates to regulator fees of about $500CAD or so or less. But they have many, many applications to review and it might well take a few weeks for an application to reach the top of their pile unless extra expediting fees are paid. Costs are legislated, and registrar’s rates are published (see links here), but regulators’ time can be charged on a half hourly rate if an application is very complex or large. Larger or more calculation intense applications, like a heat exchanger or firetube boiler, will take the regulator a little longer to review but if everything is in order, only a slightly larger fee can be expected for all but the most complex or large applications.

Regulators are NOT responsible for your design.

Poorly prepared CRN applications, that consist basically of a pile of unorganized and unreferenced documents, non-compliant designs, catalogues, drawings, etc., used to be entertained by regulators while the applicant provided corrections. But sorting through such an application would take a regulator longer to evaluate and, as a result, refusals are now a real option. Applicants that rely on the regulator to check their application, to perform the applicant’s quality control, i.e. to do the applicant’s work, are more likely to get a shocking surprise – a bill and no registration! Poor quality applications would result in wasted application and evaluation fees, sometimes higher costs, registration applications that are rejected, and poor relationships with regulators.

Worse yet if a design is mistakenly registered by a regulator, then reactively correcting a mistake once discovered or revealed can obviously be colossally more expensive in terms of reputation than what a proper design application preparation would have been in the first place. Responsibility for registration rests with the owner (end user, seller, distributor, manufacturer, designer, applicant etc.), and recalling or replacing a design that is already distributed and in use can be very expensive. Proper review and checking before an application for CRN registration is submitted should be welcomed, not criticized.

Optimize registration costs by minimizing CRN application delays and mistakes.

Before an application for registration is submitted, ensure that your registration application contains the required information, that the information it contains is correct, that it is well organized with interconnected consistent documents, and that the design meets or exceeds all required regulations, code and standard requirements.

Generic CRN Registration Cammar Corporation

Generic CRN Registration

It makes the most sense to include as many options as possible in a generic CRN registration to minimize the frequency of applications. In general, it is up to the applicant how they want to organize their CRN registration applications in accordance with model numbers, equipment use, markets, etc.

To help optimize the registration process, it is important to consider what a generic design is and if it makes sense to use in your circumstance.
When a design includes options or variations, the design is called generic. In other words, a generic design describes a range of options for the equipment. And if the design is described properly, in many circumstances only one CRN is required for a generic fitting or a generic vessel.

Except for category ‘H’ fittings, any number of model numbers and configurations of the same category can often be included in one generic CRN registration. For example, a bunch of control valves, ball valves, globe valves and butterfly valves are all inline valves and could all be included in a single category ‘C’ CRN registration number. Or a bunch of ASME B16.5 and custom ASME Section VIII-1 Appendix 2 flanges could all be included in a single category ‘B’ registration number. Similar considerations apply for pipe fittings (category ‘A’), expansion joints (category ‘D’), strainers, filters, evaporators and steam traps (category ‘E’), instrumentation including measuring devices like pressure gauges, level gauges, sight glasses, levels, and pressure transmitters (category ‘F’), and certified relief valves and fusible plugs (category ‘G’). Generic category ‘H’ fittings can also be registered but requirements are a bit more restrictive and akin to generic vessel registration.

Generic vessel CRN registration requirements are more restrictive. Authorized inspectors need to quickly ascertain whether a vessel design meets registration requirements or not. So, to avoid generic vessel applications where every conceivable option and geometry is proposed for registration under a single CRN number, some guidelines have been put in place by ABSA. In addition to ordinary design requirements, generic vessels are also to have:

  • fixed maximum allowable working pressure (MAWP)
  • fixed maximum allowable temperature
  • fixed minimum design metal temperature
  • fixed corrosion allowance
  • fixed head geometry and thicknesses
  • fixed diameter(s)
  • all relocatable and optional nozzles, together with their potential locations, identified
  • a nozzle spacing chart for relocatable nozzles meeting requirements of ASME Section VIII-1 paragraph UG-36 for pairs and clusters
  • only one nozzle configuration (neck thickness, internal projection, weld size and reinforcement) for each nozzle size, except for ASME Section VIII- paragraph UW-16(f) fittings

To achieve the maximum amount of spacing variations, nozzles normally exempt from reinforcement per ASME Section VIII-1 paragraph UG-36 should instead be reinforced.

Depending on complexity, generic vessel designs might take slightly longer for the regulator to evaluate and register, but if all possible variations of a vessel are included with one CRN number, it is of benefit to the design owner to register a generic design. Even complex generic designs can be described clearly so that registration is not significantly delayed.

Answer Key

CRN Renewal Q&A

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,
We have a fitting CRN for some equipment in Alberta and a second Canada wide fitting CRN that originated in Ontario for different models of the same equipment category. If we renew the Canada wide CRN, is it advisable or possible to add the equipment registered in Alberta to the Canada wide CRN that was first registered in Ontario?
I M Interested

Dear Interested,
In general:

  • In general, fittings registered with a CRN in one province can be added to a Canada wide registration that has a different CRN, subject to regulator acceptance. It is arguably easier for manufacturers to have one CRN for all of Canada to avoid a very problematic situation where the CRN and province to where the equipment is shipped or stocked do not match. Our advice therefore continues to be that when equipment is to be used in all provinces, Canada wide registration should be sought whenever possible to best avoid any problems associated with not doing so.
  • Some categories of fitting registrations like piping (Category A), flanges (category B), or inline valves (Category C), etc. can include any combination, or number of models if requested by the manufacturer, but at the discretion of the regulators. Category H fittings are less accommodating.
  • Regulators will try to avoid duplicate CRN numbers in their province if they become aware of overlap, to help ensure consistency and avoid confusion. If an overlap is noticed, the applicant might be asked to not renew or merge one CRN in favour of the overlapping Canada wide one.
  • For example, if Ontario adds fittings registered in Alberta to 0******.5**, then if/when Alberta agrees to the addition and if they notice, Alberta might well ask that fittings already registered in Alberta be extracted from 0*****.2 or if the fittings already registered in Alberta comprise all the designs in 0*****.2, they might ask that 0*****.2 be merged with the Ontario based registration number. (Actual CRNs are masked to preserve anonymity)
  • If a fitting CRN has a ‘2’ after the decimal, then additions to the existing CRN must be initiated in Alberta. Additions must be initiated in the province where the CRN was first issued, else the amended CRN would be invalid since the originating province would not know about the addition and a new CRN would need to be issued by an alternate province if it accepts the application for registration.
  • Fitting CRN registration will expire 10 years from the date of the first registration or latest renewal, not 10 years from the date of the last addition.
  • Each province has a ‘final call’ for their region as to whether they want to accept or merge an addition to a CRN or not. Ontario does not have a final call for Alberta. If, for example, Ontario requires X# of FEAs but Alberta later requires more FEAs or other requirements, then despite previous registration in Ontario, Ontario will subsequently need to accede to Alberta’s request and reconsider the application again if the addition is to be considered for registration in Alberta. That is why it is important to first register equipment in the province that has what is perceived to be the most challenging requirements for any particular application. And similarly, Ontario is under no obligation to merge fittings registered in Alberta as an addition to an Ontario based CRN.
Answer Key

Harmonizing CRN Process Benefits Q&A

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,
I read your article about harmonizing the CRN process, in which it is stated that we need CRN’s. I am puzzled about the benefit to the general public safety of this process for fittings, seeing that this is only practiced in Canada. How do we compete with countries that don’t have CRN process? How can we claim to have a higher standard of safety, when the rest of the world manages quite fine without CRNs for fittings? How do we produce a compliant design when equipment is available but without a CRN that the manufacturer does not see the need to apply for and register their product?
I look forward to hearing from you.
Concerned Ontarian

Dear Concerned Ontarian,
Thanks for your email.
Governments in Canada deem the CRN process worthwhile and pursuant to public safety, given that CSA B51 is referred to in Canadian legislation. CSA B51 helps to ensure through third party oversight that pressure equipment is designed, built and tested to codes and referenced standards that have, through careful collective deliberation, been written to help ensure public safety by using adequate safety margins and other considerations.
These codes and standards are adopted by legislation and stipulate minimum requirements. In some foreign locales where CRNs are not required, designs do not always meet minimum code and referenced standard design philosophies. And when they do not, designs are therefore less safe than those that do.
In Canada, pressure equipment designs meeting legislated requirements are competitive and registerable.
Public safety is, I’m sure you would agree, of paramount importance.

Canadian Registration Number

Cammar Corporation Discusses Selected CRN Issues: Part 1

Recently, Cammar Corporation was asked to deliver a presentation to pressure equipment industry professionals in Drayton Valley, Alberta, about Canadian Registration Number (CRN) topics of interest. Check out the video below for a brief introduction to some of the CRN issues that were presented.

If the content of the above video is something that would benefit your business or organization then I invite you to contact Cammar Corporation to schedule a CRN training session/presentation.

About Canadian Registration Number (CRN) Training:

Cammar Corporation can tailor training agendas and schedules to suit your needs.  The recent Canadian Registration Number training session in Drayton Valley was one and a half hours in length and included topics like:

  • Documentation requirements for CRN / pressure piping applications and construction reports
  • Pressure testing requirements and responsibilities relating to components and assemblies
  • Fitting modifications and procedures
  • Issues with intermixing components from different manufacturers
  • Priorities in building a QC program (Quality Control program content was discussed such as quality manuals, quality procedures and quality work products)

The training can be held at your workplace or place of convenience to deliver customized presentations about pressure equipment topics of most interest to you and your colleagues. Ordinarily if the presentation is in a conference room with about 15 people or less, the participants will be asked to introduce themselves so that they can mention any questions that they have on their minds, so they can be addressed during the presentation.

If the presentation is to one company and their representatives alone, then this allows for a detailed questions-answer period where confidential information can be discussed and solutions relating to their particular specific issues can be identified.

About the Facilitator:

Cameron Sterling MSc, PEng, Director, Cammar Corporation
Cameron Sterling is the Director of Cammar Corporation and he’ll be facilitating these learning sessions.

Cameron has been a professional engineer in Canada since 1991 and is registered in Alberta with APEGA (Association of Professional Engineers and Geoscientists of Alberta) and Ontario with PEO (Professional Engineers Ontario).

Cameron provides engineering expertise in relation to pressure equipment design evaluation, compliance, and registration (CRNs). All of these topics are related to helping clientele obtain Canadian registration and to enhancing public safety.

His past working experience at ABSA as a Safety Codes Officer and NB Commissioned Inspector gives additional value and expertise to training sessions provided by Cammar Corporation. With a relatively high per capita concentration of pressure equipment in Alberta, ABSA is a very significant pressure equipment regulator in Canada. Experience and expertise enhanced from working at ABSA is very valuable to industry.

Cammar Corporation has a lot of experience to share about pressure equipment design evaluation and CRN registration. The comments in this presentation series are general in nature, so please bear in mind that specific topics relating to your particular situation deserve greater attention and advice tailored to your particular circumstances.  We would be pleased to speak with you about your particular projects in more detail.

For further information, stay tuned and for Cammar Corporation to tailor a presentation to meet your needs, don’t hesitate to contact us at your convenience.


Cammar Corporation Harmonized CRN Registration and Public Safety

Harmonized CRN Registration and Public Safety

Have you ever tried to sing along with the radio?  Sometimes, harmony just doesn’t happen easily.  Now, consider 13 people trying to sing along to the same tune.  For them to sing in harmony, even with the same music, they would need to work at it quite a bit.  But, I digress.

To get a Canada wide CRN (Canadian Registration Number), applications to 13 separate jurisdictions need to be considered and a comparable number of separate, independent regulatory reviews are required.  Why?  Well, in short, each province or territory in Canada is constitutionally responsible for legislation about public safety within their boundaries.  Hence, time for parallel and separate reviews, then separate and additive fees, and then separate registrations, etc. are currently required.  In this day and age, when ideas can flash around the globe at a key stroke, national CRN registration of designs (i.e. ideas) in Canada seems to be, well, quite awkward and glacial in December.

This is not to say that regulators do a bad job.  On the contrary, they are needed, appreciated, and certainly do contribute to the safety of the populace by helping owners of equipment (users, manufacturers, distributors, etc.) meet safety requirements.  Indeed, regulators are of particular importance at a time of increased public scrutiny in relation to safety, and responsibility.  This series of articles is about the system that pressure equipment regulators currently operate in.

But can there be improvements to the CRN registration system?  Can it be more harmonious, in better tune? Of course.  CRNs are still needed.  But in our opinion, there must be a willingness, and some proper foundation, for change.

Now, imagine a world where getting a CRN registration in Canada is harmonized.  In other words, CRN registration in this world is a one stop process, that includes just one high quality, third party regulatory review.  Safety would be maintained or even enhanced from the status quo, and barriers associated with the time for different reviews and additive costs would be gone.

“Safety would be maintained or even enhanced from the status quo.”

To get to such a new world, what sorts of foundations would properly drive this harmonized change to the CRN registration process?  In our opinion, such a drive would necessarily have at least two foundations for it to truly be in the public interest.

The first foundation would be a drive towards enhanced and maintained levels of public safety.  Owners could be encouraged, nationwide, to meet established and documented requirements prescribed from the collective experience of pressure equipment regulators across the country.  Each ‘port’ of entry to nationwide CRN registration, if you will, would enforce the exact same high requirements based on collective regulatory experience.  Selection of nationwide requirements should never be a race downhill so that in effect, the lowest common denominator, weakened or lessened, requirements would result.   No, the highest topical CRN requirement currently in place should be selected nationwide in each case.

“Barriers associated with the time for different reviews and additive costs would be gone.”

The other foundational driver would surely be economic.  A more efficient and shorter registration process would encourage foreign and domestic manufacturers.  A shorter response time from the manufacturer to the market would obviously have economic and competitive benefits for Canadian industry.  These benefits, though obvious, would be difficult to reliably quantify.  Subject to maintained and enhanced safety, this driving force must be managed well.

With these two drivers, surely there is likely a willingness amongst the public and industry, together with the provincial and federal governments, for change.  But time will tell.

As this year draws to a close, here’s hoping that the future will usher in an era where requirements across Canada are held high for the safety and economic benefit of all.

Details relating to the implementation of any harmonized CRN registration process are important.  As time permits, future Cammar Corp blog articles will explore how the implementation of a harmonization process could, in some cases, be a benefit or a disadvantage to the public interest.  Stay tuned.

British Columba Oil and Gas Facilities Cammar Corporation

British Columbia Oil and Gas Facilities; What is Going On

As of November 7, 2016, BC effected some changes to its safety legislation.  From discussions with a BC Oil and Gas Commission (BCOGC) representative, it’s reported that they are addressing these changes to ensure that no gaps in regulatory oversight occur.  It will be interesting to see how this transpires.

The BCOGC now regulates oil and gas facility pressure piping (and related refrigeration) systems in British Columbia while the British Columbia Safety Authority (BCSA) continues to regulate pressure vessels, boilers, and boiler external piping.  For more details from the BCOGC, please take a look at their Appendix A relating to the changes, the Memorandum of Understanding with the British Columbia Safety Authority (BCSA), and the Liquified Natural Gas Facility Permit Application and Operations Manual.

Governing legislation relating to codes of construction acceptable to the BCOGC for oil and gas facility pressure piping include ASME B31.3 or CSA Z662, per the BC Drilling and Production Regulation (Section 78(3)).  Pressure piping drawings must be professionally authenticated per the Drilling and Production Regulation (Section 78(4)) and the BC LNG Facility Regulation(Section 12). “A facility permit holder must submit to the commission all as-built drawings including piping and instrumentation diagrams, metering schematics and plot plans, signed and sealed by a professional engineer licensed or registered under the Engineers and Geoscientists Act, within 3 months of beginning production or completing permitted modifications, as applicable” (BC Drilling and Production Regulation (Section 78(4))), and  “An LNG facility permit holder must submit to the commission the record drawings, including process flow diagrams, metering schematics and plot diagrams, signed and sealed by a qualified professional, within 9 months after” notice of operation (BC LNG Facility Regulation (Section 12)).

The BC LNG Facility Regulation s 3(1)(f) further requires that the elements of a quality assurance program be presented to the BCOGC before the construction of the pressure piping system, but whether the program needs to (or even can, given the proprietary nature of fitting designs) address fitting design details or quality does not seem to be explicitly addressed.

PIDs and Process Flow Diagrams do not usually contain the information used to evaluate mechanical qualities of a design.

Details relating to mechanical design such as codes or standards of construction, calculations, identification markings, thicknesses and other dimensions, design pressures, design temperatures, minimum design metal temperatures, material specifications, impact testing, heat treatment, test pressures and mediums etc are ordinarily excluded from PID’s, Process Flow Diagrams, Metering Schematics and Site Plot Diagrams.

In combination, these regulations indicate that P&IDs, Process Flow Diagrams, Metering Schematics, and Site Plot Diagrams need to be professionally authenticated by a professional engineer registered in BC, within a limited time frame after completion of construction or operation of the pressure piping systems.  So, in effect, the BC Drilling and Production Regulation (Section 78(4)) and the BC LNG Facility Regulation (Section 12) do not seem to require that details relating to fitting design be provided to the BCOGC before the pressure piping can be operated.

The above approach seems to be a departure and relaxation from what was required to use fittings in British Columbia prior to November 7, 2016, when registration of all non-exempt fittings within a pressure piping system required registration before operation.

Without a requirement to follow CSA B51, there would be no requirement to register oil and gas facility fittings with CRNs.

The previous CRN registration process for non-exempt fittings in BC required a third party accreditation of the fitting manufacturer’s quality control and capability, a statutory declaration attested to by the manufacturer that stated their products complied with all requirements of the selected adopted codes and referenced standards, detailed design drawings with enough detail to permit manufacture, and other technical information from the manufacturer to justify their design.  After supplying the above proprietary information to the satisfaction of BCSA, and with BCSA’s assurance of confidentiality relating to design details, the fitting would be registered in BC.

Added to all of the above, CSA B51-2014 (The Canadian Boiler, Pressure Vessel, and Pressure Piping Code) is referred to in safety legislation across Canada and, from extensive and thoughtful deliberations, has requirements that extend beyond ASME B31.3-2014 and CSA Z662-2015 requirements.  CSA B51 is about much more than just CRNs.  So, CSA B51 includes more requirements than the codes referred to by the BC Drilling and Production Regulation.  Similarly, CSA Z662 and ASME B31.3 make no reference to CSA B52-2013, the Canadian Mechanical Refrigeration Code.

It will be interesting to see how the BC Oil and Gas Commission, together with the BC provincial government, manages the BC legislative changes that are now in effect to ensure that the safety of British Columbians is not reduced.  British Columbians, like all other Canadians, deserve nothing less.

Comparing CRN regulations is like comparing apples to oranges.

ASME B31.3 vs ASME B31.1: Are CRN Registration Requirements the Same?

Cammar Corp was recently asked, “If a fitting has a CRN registration with ASME B31.3 as the code of construction, it’s likely ok to use it as a ASME B31.1 design, and vice versa, right?”

The short answer is a qualified “no”.

Now for the long answer, with our explanation and point of view with some background.  For even more detail and elaboration, please check with the code texts.

In General

Some would say that “if a fitting has a CRN registration, what does it matter if it’s registered to a different code of construction than another?  After all, a CRN registration is a registration is a registration.”  This response would seem to be in line with the idea that, when considered in their entirety, both codes are equal.  But when considering CRN (Canadian Registration Number) requirements, this idea is incorrect in many ways.

For a fitting to be registered at all, a manufacturer must attest on a witnessed Statutory Declaration, that the fitting it manufactures completely conforms to either a referenced North American standard, code of construction, or equivalent.  This means that the fitting must meet all requirements of that standard or code of construction.  If only some rules of one code are used together with some rules of the other, then besides not meeting either code, the resulting mix will likely not be safe, and will likely not be registerable.  Cherry picking requirements from various codes is not permitted.

CRN registrations are tied to codes of construction, referenced standards, etc.

And the specific requirements of B31.3 and B31.1 differ significantly from one another.  Table 1 compares a selection of some of the most commonly encountered differences, described here.


ASME B31.3 and ASME B31.1 are the most applicable ASME codes of construction for many pressure piping and fitting CRN designs in Canada.  However, their scopes are different in at least one major respect.

ASME B31.1 covers the requirements of boiler external piping, and ASME B31.3 does not.  So, whereas some ASME B31.1 fittings can be used as part of a boiler external piping design, ASME B31.3 fittings cannot be.

For example, if some boiler external piping systems needs a valve replacement, the replacement valve must be registerable to ASME B31.1, and the material must be suitable for boiler external piping.  An ASME B31.3 valve would not be acceptable.

Allowable Strengths

ASME B31.3 generally permits higher allowable strengths in many cases and thereby somewhat thinner pressure boundary thicknesses.  For example, in ASME B31.3-2014 the allowable strength at 100F of A106B is 20 ksig and in ASME B31.1-2014 it is 17.1 ksig.  Check the allowable stress tables and methods of determining allowable strengths in each code carefully.

So as a result, some equipment with a CRN that meets the thickness requirements of ASME B31.3 would be too thin to meet ASME B31.1 requirements and therefore would not be a suitable candidate for a B31.1 based CRN.

Material Specifications

The available selection of materials in ASME B31.3 and ASME B31.1 has overlap, but is not the same.  Check to ensure that the proposed material is listed in the code that you want to use with your CRN application.

Unlisted materials are defined and treated differently by B31.3 and B31.1.  ASME B31.3 states that unlisted materials can be used provided that they are described in a suitable published specification (see ASME B31.3-2014 para 323.1.2), and in addition to this ASME B31.1 states that their use must be approved, in writing, by the end user (see ASME B31.1-2014 paragraph 123.1.2(D)).

So, for example, suppose a site glass is to be made with unlisted material conforming to the requirements of an acceptable published specification.  If the use of the unlisted material is not accepted by the end-user in writing in every instance, then code does not permit the equipment to be used as a B31.1 fitting.

Pressure Testing

Regardless of design temperature, all non-service hydro-static pressure testing for ASME B31.1-2014 designs is conducted at 1.5 times the design pressure.  But for ASME B31.3-2014 designs, all non-service hydro-static pressure testing is conducted as a function of design temperature, to account for any decrease in allowable strengths as temperature increases during operation, per paragraph 345.

So, a fitting that is shop hydro tested to only meet ASME B31.1 will quite possibly not meet ASME B31.3 requirements if the allowable strength of the construction material decreases at design temperature.

Only with the regulator’s acceptance and at the owner’s option are service tests at design pressures permitted for ASME B31.3 Category D fluid (see para 300.2) pressure piping systems.  But ASME B31.1 has no limitation in relation to fluid category for this, and with the regulator’s acceptance, pressure piping can be service tested “when specified by the owner, when other types of tests are not practical or when leak tightness is demonstrable due to the nature of the service”, per ASME B31.1 para 137.7.1.

Notwithstanding what ASME B31.1 allows for here, service testing should be avoided whenever possible, especially when high energy piping systems are concerned.

Pneumatic testing is permitted by both ASME B31.3 and B31.1, but only with the regulator’s acceptance, together with proper justifications, procedures, and safeguards.  For ASME B31.3-2014, the pneumatic test pressure would be between 1.1Pdesign and 1.33Pdesign, and for ASME B31.1-2014 it would be between 1.2Pdesign and 1.5Pdesign.  For details, refer to ASME B31.3 paragraph 345.5 and ASME B31.1 paragraph 137.5.  Pneumatic testing is obviously inherently dangerous compared to hydrostatic testing due to stored energy.

Equipment should not leave the manufacturer’s shop without being pressure tested.  It is difficult to imagine a situation where pressure tests are impractical in the shop unless, due to size, assembly in the field is required.  And, even then, field testing will likely be required.

Alternatives to Pressure Testing

With the regulator’s acceptance, proper justification and procedures, closure welds are permitted on ASME B31.3 pressure piping systems.  An ABSA document, AB-519, provides good background in relation to the type of information that is required for justification and documentation.  Weld tolerances and allowable imperfections before, during, and after joining should be specified, together with the proposed weld locations and identification on a numbered list and isometric drawing, with post weld heat treatment if any, non-destructive testing techniques, etc.  All of this information should be documented for each weld.

ASME B31.1 does not permit closure welds.

Radiography and Ultrasonic Examination

All ASME B31.3 pressure equipment designs require at least 5% acceptable random radiography (RT) or ultrasonic examination (UT) of all circumferential butt and miter groove welds per B31.3-2014 paragraph 341.4.1(b).  Depending on the category of the service, more volumetric examination might well be required.

For ASME B31.1, the level of radiography or ultrasonic examination depends on the design temperature, pressure, and size of the piping per ASME B31.1-2014 paragraph 136.4.  So, though in some instances the RT and UT requirements of B31.1 could be met in the absence of any radiography or ultrasonic testing, equipment with circumferential welds would likely not meet the requirements of B31.3 unless some RT or UT was specified

Minimum Design Metal Temperature

As part of the design conditions, ASME B31.3 designs require that the minimum design metal temperature (MDMT) be specified.  It indicates the lowest temperature at which the equipment is designed to operate at.

ASME B31.1 does not list minimum design metal temperatures even though some material specifications listed in B31.1 do have metal transition temperatures below which brittle behavior becomes evident with ambient conditions in Canada.

Instead, B31.1 somewhat indirectly includes requirements associated with low temperature design via a reference to B31T in paragraph 124.1.2.  Even though ASME B31.1 designs do not ordinarily require explicit specification of the MDMT in the application, good engineering judgement requires that the MDMT be properly considered.  B31.1 designs without a specified MDMT would not meet ASME B31.3 requirements.

Impact Testing

To ensure that materials can withstand the wear and tear required at cold, potentially embrittling temperatures, ASME B31.3 requires impact testing to help ensure safety.  Please refer to ASME B31.3 paras 323.2 and 323.3 for some more details.

As noted above, ASME B31.1 does not include an MDMT as a design condition beyond a reference to ASME B31T and in paragraph 124.1.2.

Table 1:

Summary of Some Differences Between ASME B31.3 and ASME B31.1
(See text above for more information, and codes for full details)

Difference ASME B31.1 ASME B31.3
Scope includes boiler external piping systems see above
Allowable Strengths generally less than B31.3, so wall thicknesses are greater generally greater than B31.1, so wall thicknesses are thinner
Unlisted Material Specifications written, end-user approval is required, see above see above
Non-Service Hydro Pressure Testing Ptest = 1.5Pdesign


Ptest = 1.5Pdesign*Stest/Sdesign
Pneumatic Pressure Testing 1.2Pdesign<=Ptest<=1.5Pdesign

and see above


and see above

Service Testing see above category D fluids only, see above
Alternatives to Pressure Testing no closure welds permitted
see above
closure welds permitted, subject to conditions
see above
Radiography and Ultrasonic Testing dependent on size, pressure and temperature minimum 5% random testing for circumferential and miter groove welds
MDMT needs to be considered per B31T, and paragraph 124.1.2 is a design condition that needs to be specified
Impact Testing needs to be considered per paragraph 124.1.2 is a design parameter that needs to be specified


It is possible to design equipment that meets both codes of construction, where all ASME B31.1 and B31.3 requirements are met.

Registering equipment to meet the requirements of more than one code of construction can be done.  And some manufacturers do this, so that their brand can be sold to a wider range of clientele.

An adequate design and properly prepared CRN application can assist with the CRN registration process.