CODE FOR THE FIELD APPROVAL OF FUEL-
BURNING APPLIANCES      AND EQUIPMENT
               CSA-B149.3:25

CSA
CODEB149.3:25
     FOR THE FIELD APPROVAL OF FUEL-
BURNING APPLIANCES AND EQUIPMENT



2026             Saskatchewan Interpretations

                              Eﬀective April 1, 2026
TSASK CSA B149.3:25 Interpretations
Compliance is mandatory. This document addresses circumstances where inconsistent
interpretation has been identiﬁed throughout industry and addresses past failures.

Contents
4 Pressure regulators .................................................................................................. 1
   4.6 Pressures greater than 0.5 psig (3.5 kPa) ........................................................... 1
      4.6.1 Gas to a combustor ...................................................................................... 1
7 Pilot safety shut-off valves and burner ...................................................................... 1
   7.1.2 Inputs equal to or less than 20 000 Btu/h (6kW) .............................................. 1
      7.1.2.1 Oilﬁeld installations ................................................................................... 1
8 Main safety shut-off valves, input ﬂow control systems, and main burners ............... 2
   8.1.4 For single burner input up to and including 400 000 Btu/h (120 kW) ................ 2
      8.1.4.1 Gas to a combustor ................................................................................... 2
   8.1.5 For single burner input in excess of 400 000 Btu/h (120 kW) and up to 5
   MMBtu/h (1500 kW) ................................................................................................. 2
      8.1.5.1 Gas to a combustor ................................................................................... 2
   8.1.6 For single burner input in excess of 5 MMBtu/h (1500 kW) and less than 12.5
   MMBtu/h (3660 kW) ................................................................................................. 2
      8.1.6.1 Gas to a combustor ................................................................................... 2
   8.1.24 Safety shut-off valves for combustors ........................................................... 2
10 Applications ............................................................................................................ 3
   10.4.4 Overpressure protection alternatives ............................................................. 3
      10.4.4.1 Unmanned oilﬁeld .................................................................................... 3
   10.6.10 Isolation of a vent line or an overpressure relief device ................................ 3
      10.6.10.1 Constantly operating burners ................................................................. 3
      10.6.10.2 Common ﬂare header............................................................................. 3
12 Safety Controls ....................................................................................................... 4
   12.3 Low ﬁre start .................................................................................................... 4
      12.3.1 Valve train components .............................................................................. 4
  12.4.1 Safety limit controls ...................................................................................... 4
     12.4.1.1 Oilﬁeld installations.................................................................................. 4
  12.5.1 High gas pressure safety limit control............................................................ 4
     12.5.1.1 Oilﬁeld installations.................................................................................. 4
  12.5.2 Low gas pressure safety limit control ............................................................ 5
     12.5.2.1 Oilﬁeld installations.................................................................................. 5
  12.5.3 Pilot gas pressure safety limit ....................................................................... 5
     12.5.3.1.1 Oilﬁeld installations ............................................................................... 5
     12.5.3.3 Gas to a combustor ................................................................................. 5
Annex J - Mobile outdoor food service unit .................................................................. 6
  J.1.1 General ............................................................................................................ 6
4 Pressure regulators
4.6 Pressures greater than 0.5 psig (3.5 kPa)
4.6.1 Gas to a combustor
A waste gas stream and pilot gas stream to a combustor

   a) of 5 psig and over shall be controlled with a regulator per clause 4.1 and
   b) below 5 psig shall be either
      i) controlled with a regulator per clause 4.1, or
      ii) ﬂash back protected by an in-line ﬂame arrestor, and overpressure protected
          by a relief valve.

       Note: A pressure vessel relief valve may be used for combustor burner
       overpressure protection.

Rationale: The intent of 4.6.1 is to provide clariﬁcation and options for waste and pilot gas
streams based on inlet pressure.




7 Pilot safety shut-off valves and burner
7.1.2 Inputs equal to or less than 20 000 Btu/h (6kW)
7.1.2.1 Oilﬁeld installations
All oilﬁeld appliances approved under the Saskatchewan Field Approvals Program
having a pilot train with an input up to and including 20 000 Btu/h (6 kW) shall either

   a) be part of a circuit controlled by a combination control in accordance with clause
      7.1.3 (b); or
   b) be equipped with safety shut-off valves in accordance with clause 7.1.4.

Rationale: The intent of 7.1.2.1 is to provide detail for pilot burner requirements on ﬁeld
approved oilﬁeld appliances.




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8 Main safety shut-off valves, input ﬂow control
systems, and main burners
8.1.4 For single burner input up to and including 400 000 Btu/h
(120 kW)
8.1.4.1 Gas to a combustor
A waste gas stream to a combustor up to and including 400 000 Btu/h (120 kW) shall
be controlled with two CSA B6.5 safety shut-off valves or one valve certiﬁed to CSA 6.5
C/I.



8.1.5 For single burner input in excess of 400 000 Btu/h (120
kW) and up to 5 MMBtu/h (1500 kW)
8.1.5.1 Gas to a combustor
A waste gas stream to a combustor over 400 000 Btu/h (120 kW) shall be controlled
with a CSA 6.5 C/I safety shut-off valve, up to and including 5 MMBtu/h (1500 kW). No
proof-of-closure (POC) is required.



8.1.6 For single burner input in excess of 5 MMBtu/h (1500 kW)
and less than 12.5 MMBtu/h (3660 kW)
8.1.6.1 Gas to a combustor
A waste gas stream to a combustor over 5 MMBtu/h (1500 kW) shall be controlled with
at least two CSA 6.5 C/I safety shut-off valves. No proof-of-closure (POC) is required.



8.1.24 Safety shut-off valves for combustors
A waste gas stream to a combustor does not require safety shut-off valves to be
equipped with proof-of-closure (POC), temperature control valves, automatic vent valves
(double block and bleed), nor a valve proving system (VPS).

Rationale: The intent of 8.1.4.1, 8.1.5.1, 8.1.6.1, and 8.1.24 is to provide detail for
acceptable safety shut-off valve (SSOV) requirements on a waste gas stream.



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10 Applications
10.4.4 Overpressure protection alternatives
10.4.4.1 Unmanned oilﬁeld
Overpressure protection on an unmanned oilﬁeld installation shall be provided by any
one of the following:

   a) pressure relief valve per clause 10.4.5; or
   b) overpressure shut-off device.

Rationale: The intent of 10.4.4.1 is to provide acceptable means of overpressure
protection on unmanned oilﬁeld installations.



10.6.10 Isolation of a vent line or an overpressure relief device
10.6.10.1 Constantly operating burners
Where burners are required to operate constantly, then a locked-open, or sealed-open,
manual valve to isolate a safety limit control may be installed for servicing, maintenance
or testing purposes. This valve may only be unlocked, or unsealed, and then closed, if
the gas-ﬁred equipment under the protection of the safety limit control has constant
manual supervision while the safety limit control is out of service. A documented work
procedure submitted and acceptable to Gas Inspections shall be followed during use of
each such isolation valve. Under no circumstances are input lines to relief valves to be
isolated, or have isolation valves installed, except as speciﬁed in clause 10.6.10.2.



10.6.10.2 Common ﬂare header
In a plant environment, where a relief valve terminates into a common ﬂare header, a
locked-open, or sealed-open, full port manual valve may be used to isolate the
operational ﬂare header from a relief valve discharge for maintenance purposes of the
equipment under the protection of the relief valve. In this situation, the TSASK Pressure
Relief Path (PRP) Stop Valve Control Program may be utilized. The requirements for
application and the PRP Stop Valve Control program manual are available from TSASK
BPV Inspection Services.

Rationale: The intent of 10.6.10.1 and 10.6.10.2 is to identify acceptable service and work
procedures for constant operating burners.



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12 Safety Controls
12.3 Low ﬁre start
12.3.1 Valve train components
Where the low ﬁre start required in clause 12.3 is accomplished by means of a separate
low ﬁre valve train, the low ﬁre valve train shall meet the requirements for a pilot valve
train.

Rationale: The intent of 12.3.1 is to align the component requirements for a low ﬁre valve
train and a pilot valve train.



12.4.1 Safety limit controls
12.4.1.1 Oilﬁeld installations
In oilﬁeld facility applications, tank heaters that are mounted in tanks which are not
equipped with a visual tank level indicator, shall be controlled with an operational low
liquid safety device, the function of which is to shut off the fuel supply upon low level
and automatically enable the fuel supply when the level is regained. This operational low
liquid safety device shall be installed at a level above the low liquid level safety device
required in 12.4.1(a) which requires a manual-reset before resuming operation.

Rationale: The intent of 12.4.1.1 is to provide acceptable means that ensure tank heaters
are not permitted to operate in a low-level condition.



12.5.1 High gas pressure safety limit control
12.5.1.1 Oilﬁeld installations
In oilﬁeld applications, where all components on the manifold are rated above the
working gas pressure, tank heaters rated up to 1 million Btu/h, at remote single
wellhead battery sites only, a high gas pressure safety device is not required.




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12.5.2 Low gas pressure safety limit control
12.5.2.1 Oilﬁeld installations
In oilﬁeld applications, once conﬁrmed through a combustion analysis that the burner
design at full turndown does not result in the formation of carbon, tank heaters rated up
to 1 million Btu/h, at remote single wellhead battery sites only, do not require a low gas
pressure safety device.



12.5.3 Pilot gas pressure safety limit
12.5.3.1.1 Oilﬁeld installations
In oilﬁeld applications, tank heaters rated up to 1 million Btu/h, at remote single
wellhead battery sites only, which do not require a low gas pressure safety device on the
main burner per TSASK CSA B149.3:25 Interpretations Clause 12.5.2.1, do not require a
low gas pressure safety device on a multi-fuel pilot.



12.5.3.3 Gas to a combustor
A waste gas stream and pilot stream to a combustor

   a) of 5 psig and over shall be controlled with high pressure (HP) and low pressure
      (LP) safety devices as per clause 12.5; and
   b) below 5 psig shall be either:
      i) controlled with high pressure (HP) and low pressure (LP) safety devices per
          clause 12.5; or
      ii) ﬂash back protected by an in-line ﬂame arrestor, and overpressure protected
          by a relief valve.

       Note: A pressure vessel relief valve may be used for combustor burner
       overpressure protection.

Rationale: The intent of 12.5.1.1, 12.5.2.1, 12.5.3.1, and 12.5.3.3 is to provide detail on
high and low gas pressure device requirements in oilﬁeld applications.




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Annex J - Mobile outdoor food service unit
J.1.1 General
Annex J of CSA B149.3-25 is adopted in Saskatchewan as mandatory for inspections of
mobile outdoor food service units.

Rationale: The intent of J.1.1 is to align the requirements of other related codes governing
mobile outdoor food service units in the province.




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