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  1. A boiler utilized in conjunction with a hot liquid heating system that allows unrestricted flow between the boiler and an expansion tank, which is openly vented to the atmosphere.

  2. A boiler with a heating surface area of 10 square feet (0.93 square meters) or smaller.

  3. A low-pressure boiler that either has a wetted heating surface area of 30 square feet (2.79 square meters) or less, or a power rating of 30 kW or lower.

MPI inspection, or Magnetic Particle Inspection, is a non-destructive testing method used to detect surface and near-surface defects in ferromagnetic materials. It works by magnetizing the material, applying magnetic particles to its surface, and observing the accumulation of particles around defects, forming visible indications that highlight the presence and shape of flaws. Trained inspectors interpret these indications to determine the nature and severity of the defects. MPI inspection is effective, cost-efficient, and widely used in various industries.

Contact us for your next MPI inspection whether reperformed during manufacturing for quality control, as part of regular maintenance and inspection programs, for failure investigation, or as part of in-service inspections to ensure safety and reliability.

For a summarized version of this information along with related links, please visit the our website and check TSSA - Regulations of Ontario for a summary of how TSSA enforce these regulations anda list of organized useful links that give you a quick overview without the hassle of searching for the information you need.Visit our Pressure Vessel Engineering and TSSA Certification services for more information. Contact us for your next boiler and pressure vessels project and ensure compliance with the regulations set by the TSSA in Ontario.

Check the Procedure to Request Name Change on BPV Certificateson ASME website here.

The Certificate Holder needs to inform the ASME Conformity Assessment Department at of the address change due to postal re-designation including any changes to the building number, street name, zip code, etc. ASME will issue a revised ASME Certificate of Authorization provided the Certificate Holder'/s Authorized Inspection Agency (AIA) of record provides documentation to ASME to support the Certificate Holder'/s request. Where there is no AIA involved in the Certificate Holder'/s code activities, documentation from the postal authority and/or the jurisdictional authorities where the shop is located will be needed to support the request. There is no charge to revise ASME Certificates of Authorization due to postal re-designation.

Reference: ASME website

The most common design of pressure vessel is the cylindrical shape with spherical or dished ends, known as a cylindrical pressure vessel with hemispherical or ellipsoidal heads. This design is widely used in various industries, such as oil and gas, chemical, petrochemical, power generation, and many others.

Cylindrical pressure vessels are relatively simple to manufacture, provide good structural integrity, and are capable of withstanding high pressures. The hemispherical or ellipsoidal heads are commonly used as they distribute the pressure evenly, reducing stress concentrations and promoting uniform material deformation under pressure. This design also allows for easy inspection, maintenance, and cleaning of the vessel.

However, it's important to note that pressure vessel designs can vary depending on specific application requirements, operating conditions, and regulatory standards. Other common designs include spherical vessels, torispherical vessels (which have a shallow knuckle radius), and conical vessels, among others. The choice of pressure vessel design depends on factors such as the type of fluid being stored or processed, operating pressure and temperature, material properties, fabrication techniques, and applicable codes and standards.

  1. Material: Failure resulting from improper material selection or defects in the material used.
  2. Design: Failure caused by incorrect design data, inaccurate or incorrect design methods,or inadequate shop testing,
  3. Fabrication: Failure due to poor quality control, improper or insufficient fabrication procedures including welding, heat treatment, or forming methods.
  4. Service: Failure resulting from changes in service conditions by the user, inexperienced operations or maintenance personnel, or upset conditions. Some types of service that require special attention in terms of material selection, design details, and fabrication methods include lethal service, fatigue (cyclic) service, brittle (low temperature) service, high-temperature service, and high shock or vibration service. Additionally, vessel contents such as hydrogen, ammonia, compressed air, caustic, chlorides, and hydrocarbons can also pose challenges in pressure vessel design.
  5. Standard requirements: Failure due to non-compliance to standard requirements such as ASME Section IX.

The ASME Codes for Pressure Vessel Design are utilized for pressurized equipment, such as vessels, piping, and fittings, in various regions around the world, including North America. These codes encompass the design, construction, maintenance, and modification of pressurized equipment. The commonly used ASME codes include:


  • VIII-1 for vessels, towers, and exchangers
  • I and IV for hot water heaters and boilers
  • B31.1, B31.3, and B31.5 for piping systems
  • B31.3 is often applied to various fittings

These codes rely on rule-based design and offer formulaic approaches that are effective when the design is within the limits of the code's scope.

The qualified welding procedure is owned by the company and not the welder who conducted the qualification tests. Therefore, departure of the welder will not affect the status of the qualified welding procedure and no requalifications are required.
A pressure vessel, fitting or piping that contains liquids not more hazardous than water and that operate at a temperature of 150°F (65°C) or less and at a maximum allowable working pressure of 250 psi (1,717 kPa) or less is exempt from TSSA boiler and pressure vessel regulations.
Professional inspections of boilers should occur on an annual basis, although there are various types of inspections that an inspector can conduct. To ensure safety and compliance, regulatory bodies and insurance companies typically advise that power boilers undergo both internal and external inspections annually, while they are not pressurized. Additionally, an external inspection of the boiler while it is under pressure is recommended halfway between the annual inspections.