BCSA Identifies PRV Servicing & Inspection Intervals

British Columbia - BCSAOn September 12, 2016, the British Columbia Safety Authority (BCSA) issued Directive D-BP-2016-01 named “Propane Storage Tank Pressure Relief Valve Servicing and Inspection Intervals.”

The directive, issued by the Provincial Safety Manager, Boilers and Pressure Vessels, clarifies the timelines for required servicing and inspection intervals as specified in the CSA B51-14 Boiler, pressure vessel and pressure piping code.  Due to the number of propane tanks subject to these requirements, the Directive also outlines the dates by which owners must be in compliance.

PRV Servicing Intervals

Servicing of the PRV generally refers to the replacement of the valve.  The required servicing interval is determined by the size of the storage tank and whether or not the PRV is of the internal or external spring type.

  • ASME propane storage tanks greater than 2,500 USWG must be serviced every 10 years.  Owners of these propane tanks will have until January 1, 2024, to ensure the tank is in compliance.
  • ASME propane storage tanks 2,500 USWG or less with external spring PRVs must be serviced every 10 years.  Owners of these propane tanks will have until January 1, 2024, to ensure the tank is in compliance.
  • ASME propane storage tanks 2,500 USWG or less with internal spring PRVs must be serviced every 25 years.  Owners of these propane tanks will have until January 1, 2027, to ensure the tank is in compliance.

Visual PRV Inspection

Checked - LowRes - shutterstock_242884063The visual inspection of the PRV generally refers to conducting a formal inspection of the valve while it’s in service.  The visual inspection is conducted without removing or servicing the valve to identify signs of malfunction and to determine if the valve requires immediate servicing.  A formal, documented visual inspection is required every five years.  Owners of affected ASME propane storage tanks must be in compliance with the visual inspection requirements by no later than January 1, 2022.

Training Requirements

The directive outlines the training requirements for individuals who service PRVs or conduct in-service visual PRV inspections.

  • Servicing and recertification is to be completed by the PRV’s original manufacturer, a holder of a valid “VR” stamp Certificate of Accreditation, or by an organization holding a BCSA contractor licence, class “SRV” for PRV service.
  • Individuals conducting in-service inspections must be trained and competent in the duties for which they are responsible.

The Fuels Learning Centre offers two courses designed to train individuals on how to conduct visual tank and PRV inspections.  Our primary version of “Visual Tank and PRV Inspection (SO02) is designed for a variety of propane industry personnel.  For propane tank truck operators our “Loading and Unloading Propane Tank Trucks Including Visual Tank & PRV Inspection (TO04)” covers both how to operate the bulk delivery vehicle AND conduct visual tank and PRV inspections.

To read and download a copy of the directive, click on the “Read More” button below.


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Alberta Municipal Affairs, Safety Services Issues Safety Tip Related to Servicing Intervals for PRV’s on Tanks of 2,500 USWG and Less

Alberta LogoThis Safety Tip confirms the requirement that propane tanks of up to 2,500 USWG in capacity must have the PRV replaced every 25 years and that a periodic visual inspection must be conducted every 5 years. Industry is required to have a compliance plan in place by December 31, 2015 and that ALL tanks must be in compliance by no later than May 31, 2024.

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PRV Change Out Challenges

This article, regarding PRV change out challenges, first appeared in the 2015 May/June edition of Propane Canada Magazine.

As a consultant, I often get asked by clients to look at the risk associated with performing certain tasks and to advise on what is the best way to complete those tasks. I was recently asked to look at the processes and training skills required for a company to successfully meet their regulatory obligation with respect to the replacement of pressure relief valves (PRVs) in consumer propane tanks.

My review of this subject has led me to the conclusion that this is most likely going to be the most challenging regulatory requirement the propane industry has faced in its history.  This single requirement will put a tremendous strain on the industry’s resources, people, equipment, and finances.

Now that the regulatory requirement is in place to change out the PRV, it is time for serious discussion on how this is actually going to be accomplished.

Three Basic Steps for PRV Replacement

When one talks about the replacement of a PRV in a propane tank, there are three basic steps:

  1. Disconnection of the propane system to which the tank is connected;
  2. Removal of all liquid and vapour propane so that the tank’s internal pressure is 0 psig; and
  3. Removal and replacement of the PRV.

These three steps sound fairly straight forward until one gets into the details of how this is going to occur.

Removing liquid propane from the tank is much easier said than done

The majority of consumer propane tanks are not equipped with an easy method of removing the propane liquid from the tank.  A limited number of tanks are equipped with a liquid withdrawal excess flow valve (Chek-Lok) mounted on top of the tank with a dip tube, or directly into the bottom of the tank that can be used to remove the liquid propane from the tank.  If the Chek-Lok does not work properly, then you are back to the situation of how to remove the liquid from the propane tank.

Using a Flare Stack

Flaring of PropaneOne method is to use a flare stack to burn off the propane within the tank.  Depending upon the quantity of liquid propane in the tank, this is quite a time-consuming process that does not lend itself to being conducted at the customer’s location.  Can you imagine flaring off a propane tank in the customer’s backyard?  The flare stack creates a large flame and a lot of noise; not the type of situation that would make the public feel safe in their own homes.  Also, you would have to notify the local fire department, who may want to attend, which is not a good scenario overall.

Using Tank Rollers

Another option for evacuating the tank, which has been brought to my attention is the use of tank rollers to roll the tank so that the vapour space now becomes the liquid space.  There is an adapter that can be connected to the fill valve to ex-tract the liquid propane by gravity from the tank to a pump to fill the new tank. This method requires the tank to be elevated so that the necessary fittings and connections can be completed.  Unfortunately, this practice also puts the PRV in the liquid space, so if the PRV does activate for any reason, the liquid will be released to the atmosphere creating a rather dangerous scenario.

TDG Requirements

1075 PlacardOne of the major hurdles is the Transportation of Dangerous Goods requirement which only allows consumer propane tanks to be transported with a maximum liquid volume of 5%.  This means that to transport a propane tank from a customer’s location to a location where the tank can be evacuated prior to PRV replacement, its volume must be less than 5%.  Update:  In 2016, Transport Canada issued an Equivalency Permit allowing members of the Canadian Propane Association to move tanks up to 500 USWG with more than 5% directly back to the propane bulk plant for evacuation under a number of conditions.  While helpful, the permit creates other issues related to the transport of the tank since it will have to be secured on proper cradles to prevent movement of the tank and damage to the feet.  Tanks larger than 500 USWG will still have to have the contents reduced to 5% or less of maximum capacity.

It’s also important to note that Alberta Transportation once had a permit which allowed movement of ASME tanks to be moved with more than 5% capacity within the oil-patch.  This permit was ultimately revoked due to flagrant misuse of the permit.  Incidents involving misuse of this permit may result in revocation of the Equivalency Permit.

One option is to allow the customer to use the propane in the tank so that the liquid level is below 5%. This approach is not a feasible way of reducing the pro-pane liquid volume to a point where the tank can be transported since the scheduling of the tank’s replacement will have to be carefully orchestrated so the customer does not run out of propane.  Trying to schedule 30,000 propane tank replacements on an annual basis under this process seems to me to be quite a daunting task.

Really, when one considers the options available: PRV replacement at the customer’s location or transportation of the tank to a central point, such as a bulk plant, replacement at the customer site does not seem feasible.  So in essence, the only logical option is to exchange the customer’s tank and transport the old tank back to a central location where the PRV can be replaced in a controlled environment.

The Magnitude of Meeting this Regulatory Obligation

Bulk Storage TanksThere are approximately 750,000 propane tanks in Canada, which means the industry will have to exchange 30,000 propane tanks on an annual basis.  Given that at best, one can expect to conduct this type of work during the 6 to 7 month period of April to October, this will require 4,285 tank exchanges per month.

These numbers are based on every PRV having a 25-year change out as required by regulation.  Unfortunately, the industry is faced with the problem of replacing PRVs which have currently been in service for 25 years or more, and playing catch-up to get to a position whereby the 4,285 tank exchanges per month can be completed.  I don’t think anyone has a handle on exactly how many propane tank exchanges will have to take place on an annual basis for the industry to become current with this regulatory requirement.  Every company will have a different schedule based on the age of tanks in operation.

The CSA B51-14 Boilers, Pressure Vessels and Pressure Piping Code requirement for the replacement of PRVs does not provide for a phase-in period to allow the industry to deal with the existing PRVs that are currently in service longer than the stipulated change out times.  This means that industry members will have to go to each provincial jurisdiction to work out a schedule of replacement so that PRVs in service beyond the change out times can be left in service until such time the industry can deal with them.  If some type of change out schedule is not put into place, then the moment that the CSA B51 code is adopted in the province any PRVs that are in service beyond the time limits specified in the code would be considered non-compliant.  The fuel supplier cannot supply propane to a non-compliant installation.

Training Requirements

In looking at the certification and Records of Training (ROTs) required to change out a PRV in a propane tank, one must consider working with both liquid and vapour propane, which can require separate training certification.  The specific level of Propane Fitters Certificate required will be dependent upon the provincial requirements.  Provinces have different descriptions for the levels of Propane Fitters Certificates and what the certif-cate holder may do.  However, when handling liquid propane, a certified pro-pane fitter must also have a liquid propane (LP) endorsement attached to the certificate.

The training and certification required to replace a PRV will be dependent upon how the propane is to be removed from the tank.  There are two ways that the propane liquid and vapour can be re-moved from the tank:

  1. Allow the customer to use up as much propane liquid as possible so there is only a small percentage of liquid propane left in the tank;
  2. Transfer the propane into a new tank brought to the site for the purpose, then transport the customer’s old tank back to a central location for PRV replacement.

Remember, you cannot legally release propane to the atmosphere unless it is done as part of the transfer process i.e. through the fixed liquid level gauge.

If the customer’s propane tank is to be brought down to 5% or less liquid volume to permit it to be transported back to a central location and a replacement tank installed, it will require the person(s) to have the following certificates and ROTs:

  • Transportation of Dangerous Goods (TDG) training in order to transport propane tanks to and from the customer’s location;
  • ROT for the operation of a boom or crane truck for loading and unloading the tanks;
  • A Propane Fitters Certificate to shut down the propane vapour system and appliances, disconnect the pro-pane tank from the system; reconnect and reactivate at the end of the propane transfer process.
  • A Propane Fitters Certificate with a Liquid Propane endorsement to transfer liquid propane from the existing customer’s tank to the new tank; and
  • If the liquid propane is transferred from the customer’s tank directly to a propane tank truck then a person with an ROT to operate the tank truck and conduct the liquid pro-pane transfer would also be required.

Once the customer’s propane tank is back at a central location for the PRV to be replaced it will require the removal of the remaining liquid and vapour propane in the tank so that the tank’s interior pressure is 0 psig.  Again in most jurisdictions, this will require the services of a certified propane fitter with an LP endorsement.  Some jurisdictions will permit a person holding an ROT for the operation of a propane plant to transfer the liquid and vapour propane out of the tank.

Update on Training

Since this article was first published in Propane Canada magazine, the Fuels Learning Centre has developed a comprehensive training course covering all the aspects of evacuating propane from the tank and how to operate the equipment required to conduct the evacuation.  Regardless of where the evacuation occurs (customer site or at the propane bulk plant), our Evacuating Propane From Consumer Storage Tanks (SO03) course provides all the necessary instruction for employees involved in the process.

Purging the Propane Tank

Another issue for discussion is that by removing the PRV from a propane tank you are exposing the interior of that tank to the atmosphere.  The regulations currently in place stipulate that if the interior of a propane container is exposed to the atmosphere, then it must be purged.  The regulations do not stipulate any period of time, so in essence, once the PRV is replaced, the tank should be purged.

To address this issue, testing is required to determine that if air does enter the tank during the PRV replacement, will the limited quantity have any effect on the operation of appliances connected to the tank.

Achieving Compliance Will be a Strain on Resources

In addition to staffing being a major concern, I also see challenges regarding the acquisition of equipment required to simply change out a PRV.  This includes the purchase of replacement PRVs and careful scheduling of crane trucks, tank trucks, tank moving equipment, compressors, pumps and flare stacks.

In conclusion, this single regulatory requirement has a tremendous mushrooming effect in that there will be mandated up to 30,000 more propane transfers and approximately 60,000 more propane tank transports down our highways on an annual basis.  The industry’s actual experience of PRV failure is nonexistent, with only one reused PRV failure in 25 years as we discussed in our Knowledge Base article entitled “History of PRV Service in Canada“.  One must question the increased risk of additional transfers and transports versus actual experience.

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Inspection of PRVs in Propane Service


This article, regarding the inspection of PRVs in propane service first appeared in the March/April 2015 edition of Propane Canada magazine.

PRV 01The publishing of the mandatory Annex H of the CSA B51-14 Boilers, Pressure Vessel and Pressure Piping Code, that requires the replacement of Pressure Relief Valves (PRVs) in propane tank service has brought the issue of PRV inspection to the attention of provincial Authorities Having Jurisdiction (AHJ).

Mandated Inspection Cycles

The staff at the Fuels Learning Centre were recently contacted by a provincial AHJ to see if we could assist them in researching the history of the use and failures with PRVs in propane tank service and propane tanks. The AHJ is looking at possibly mandating a PRV and propane tank inspection program on a yet-to-be-determined cycle.

We provided a document representing a consolidation of information gained over the years. The document provided points to be considered by the AHJ in making a decision as to the mandating of PRV and tank inspections.

The rationale for putting a mandated documented inspection cycle in place is to ensure that PRVs with a potential for failure are identified and removed from service prior to a failure. We consider a pressure relief valve failure to be when the pressure relief valve fails to activate in an over pressure situation, or opened or partially opened in a non-over-pressure situation. The mechanical components of the valve failed to operate as designed.

Pressure relief valves are required to function under widely varying conditions. Corrosion, aging of the resilient seat disk, and friction all proceed at different rates depending upon the nature of the specific environment and application.

Predicting the safe useful life of pressure relief valves is obviously not an exact science. The conditions to which the valve is subjected will vary widely and will determine its useful life.

We are aware of only one incident, in the past 25 years in which a used external spring type PRV was reinstalled in a propane tank and subsequently failed as per the criteria for a PRV failure.

There are approximately 750, 000 pro-pane tanks in Canada. All of these pro-pane tanks, regardless of size, are equipped with one or more PRV.  The majority of the propane tanks are located at residences, farms, and commercial establishments.

An industry standard practice is that the PRVs in propane service are visually looked at for any factors that could impair the operation of the PRV each time the container is filled.  This prefill examination is not documented.

Ontario is the only province that currently mandates a documented Inspection of PRVs in propane tank service and the propane tank on a three-year cycle. The person conducting the inspection must hold a valid Record of Training that permits the person to complete the documented visual inspection. The owner of the propane tank must maintain a record of the most current PRV inspection.

If all provinces and territories followed Ontario’s lead and mandated a three-year cycle for PRV and tank inspection it would mean that approximately 750,000/3 = 250,000 PRVs would have to be inspected on an annual basis.  The one saving grace in all of this is that the majority of propane tanks are visited at least once annually for refilling and the tank truck operator can be trained to perform the visual PRV and tank inspection while at the site.

If tank truck operators are excluded from being able to perform the documented visual inspection and tank owners are forced to rely on certified propane technicians to conduct the inspection, an impractical situation for compliance will be created.  There just are not enough certified propane technicians available to meet the demand for 250,000 annual inspections.

The other issues to be considered include document creation and retention as well as training costs.  There will be 250,000 documents to be created and retained per year. While one cannot put a cost on safety, the financial impact of training people to complete the inspection must also be considered for training sufficient staff to meet the demand for inspection.

Inspection Checklist

PRV Inspection ChecklistA properly sequenced checklist inspection document, supported by training, can assist the person completing the inspection to obtain all of the information required in a consistent manner.  It is also an opportunity to develop a database on the age of PRVs in service to assist in establishing a replacement schedule to meet the requirements of the CSA B51-14 Code.


We are currently aware of only one AHJ seriously looking at implementing a mandated inspection cycle; however, from a national perspective, it could be a daunting issue that will require a consolidated common national approach by the propane industry to ensure that the industry can meet the regulatory compliance.

History has shown that specific provincial requirements have a tendency at some point to become a national requirement.  If this occurs with PRV and tank inspections it will indeed create a potentially burdensome situation.

Available Training

To meet your training needs, the Fuels Learning Centre offers a version of its Tank Truck Operators training course which includes PRV and tank inspection embedded within the curriculum.  This means the tank truck operator needs to take only one training program – Loading and Unloading Propane Tank Trucks Including Visual Tank & PRV Inspections (TO04), reducing training time and costs.  We also offer a stand-alone inspection course for other personnel who need to learn these skills – Visual Tank & PRV Inspections (SO02).


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History of PRV Service in Canada

This article is a consolidation of information and experience gained over the years. It is provided to assist the reader in having an understanding of the propane industry’s experience with pressure relief valves (PRVs) in propane tank service.

Current Regulations Impacting PRVs

The updated Annex H of the CAN/CSA B51-14 Boiler, Pressure Vessel, and Pressure Piping Code states that for:

  • Propane tanks over 2,500 USWG, the maximum PRV service interval is to be 10 years.
  • Propane tanks 2,500 USWG or less, the maximum PRV service interval is to be 25 years.

In Ontario, a formal inspection of the PRV is conducted on a “maximum” of a three-year frequency with a record of the inspection being maintained by the propane distributor.  At bulk plants and propane dispensing facilities, inspections including the PRVs are conducted annually.

As each province adopts the 2014 version of the B51 code into regulation, an implementation plan will be prescribed in order to provide tank owners appropriate time to come into compliance with the new requirements.

Types of Pressure Relief Valves in Propane Service

There are two types of pressure relief valves in propane service:

  1. External spring type where the “spring” is located “outside” of the tank.
  2. Internal spring type where the “spring” is located “inside” the tank.

Approximately 95% of the propane tanks in service are equipped with a single internal spring type pressure relief valve.

Larger capacity tanks (10,000 USWG and larger) are normally equipped with single or multiple external spring type pressure relief valves. Tanks equipped with multiple external spring type pressure relief valves do not have to be taken out of service to replace the PRVs.

PRV Operation

Propane is known as a “sweet gas”, having no corrosive or other deleterious effect on the metal of the containers or PRVs.

PRVs used in propane service are constructed of corrosion-resistant materials and are installed so as to be protected against the weather.  The variations of temperature and pressure due to atmospheric conditions are not sufficient to cause any permanent set in the valve springs.

PRVs are visually inspected each time a propane tank is filled as part of the filler’s responsibility to ensure the tank and all of the visibly attached components are in acceptable condition.  PRV inspection programs ensure that the pressure relief valves found in unacceptable condition due to damage, corrosion or weeping are replaced so as not to create a potential safety hazard.

Persons conducting the inspection of pressure relief valves on propane tanks are trained on how to inspect PRVs and tanks. The Fuels Learning Centre offers a training program to instruct bulk truck drivers, service technicians, and plant operators how to inspect PRVs and tanks – Visual Tank & PRV Inspection (SO02).

As previously stated the majority 95% of the PRVs in domestic service are PRVs with “internal springs” sitting within the propane vapour space, and are, therefore, not subject to corrosion or contamination.  The external components are protected from the elements by the use of protective caps, designed to keep moisture and debris out of the valve.  The protective cap is an item that a delivery driver checks to ensure it is in place and in good condition each time a delivery is made.  Missing or damaged caps are replaced by the delivery driver.

Current State

There are approximately 750, 000 propane tanks in Canada.  All of these propane tanks, regardless of size, are equipped with one or more PRVs.  The majority of the propane tanks are located at residences, farms, and commercial establishments.  Tanks are either owned by the propane consumer or leased from the propane company supplying the fuel.

Pressure Relief Valve Failure Statistics

We classify a pressure relief valve failure to be when the pressure relief valve failed to activate in an over-pressure situation or opened or partially opened in a non-overpressure situation.  The mechanical components of the valve failed to operate as designed.

Industry experience in Canada and the United States is an indicator that PRVs in propane service have experienced very minimal failure rates and should not be grouped or treated legislatively with PRVs in service with gases or fluids that may have an adverse effect and documented life expectancy on the PRV.

The propane industry is aware of only one reported failure on a stationary propane tank in which a used “external spring” pressure relief valve was reinstalled in a 2,000 USWG propane tank at a plant north of Kingston, Ontario in the mid-1990s.  The pressure relief valve partially opened when the propane tank was being filled.  This is one incident, in 25 years, that involved a type of PRV designed with an external spring, which represents approximately 5% of the PRVs currently in use.

As a result of this failure, a Directors Order was issued by the Technical Standards and Safety Authority (TSSA) instructing all propane marketers to inspect and replace as required pressure relief valves equipped with “external springs”.

Information received from the Ontario Fire Marshal’s Office (OFM) indicated the OFM was not aware of any specific cases involving propane PRVs.  Fire Marshall Office (FMO) statistics are gathered through fire and explosion reports received from the fire services and FMO investigators.  A propane release without fire would not be reported to the FMO.

The National Propane Gas Association (NPGA) in the United States has no statistics on PRV failures in stationary propane tanks.  NPGA staff are not aware of any incidents of this nature.  The National Board of Boilers and Pressure Vessel Inspectors in Columbus, Ohio was also not aware of any incidents involving the failure of PRVs in propane service.

The NPGA did, however, commission a study examining relief valve performance in cylinders.  These valves are smaller and more susceptible to damage.  Cylinders, unlike tanks, are meant to be portable and readily transported by the general public.  The study found there was broad scatter and inconsistency in relief valve performance regardless of valve age, manufacturer or source location.

PRV Manufacturers

There are three manufacturers of pressure relief valves currently used in Canada; Engineered Controls (Rego), Fisher Controls and Sherwood.  A review of the literature published by the three manufacturers shows that Fisher recommends a 15-year replacement cycle, while Rego and Sherwood recommend a 10-year replacement cycle.

Of the three manufacturers of pressure relief valves, one of them currently provides replacement parts for servicing PRVs in propane service.  Replacement of the pressure relief valve’s components still requires removal of the pressure relief valve from the tank so the components are accessible and can be replaced in a facility equipped with the proper tools and trained personnel.

The safe, useful life of a pressure relief valve can vary greatly depending on the environment in which it lives.

Pressure relief valves are required to function under widely varying conditions. Corrosion, aging of the resilient seat disk, and friction, all proceed at different rates depending upon the nature of the specific environment and application.

Predicting the safe useful life of pressure relief valves is obviously not an exact science. The conditions to which the valve is subjected will vary widely and will determine its useful life.

Rego states in their literature “The LP-Gas dealer must observe and determine the safe useful life of relief valves in his territory”.

Summary of PRV Failure in Canada

  • The majority (95%) of the PRVs in domestic propane service are PRVs with internal springs situated within the vapour space and not subject to corrosion, contamination, or dam-age.
  • There are no industry statistics (from Canada or the USA ) confirming that failure of PRV’s in propane service are a safety issue – only one documented incident in Ontario in the last 25 years.

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