The CSA B149.1 and CSA B149.3 Codes require use of "certified" components. What does this mean?
When it comes to manual valves there are specific references in the code to 4 valves in the fuel train (for a single burner / single fuel configuration):
- certified main fuel inlet valve (the upstream valves which is used to shut ALL fuel off)
- certified pilot fuel takeoff valve (at the split of pilot fuel from the main line)
- certified pilot burner test valve (also called pilot firing cock), and
- certified main burner test valve (also called main burner firing cock)
There is a definition in the Codes of what certified means, which is basically tested by a recognized certification organization (such as CSA, UL, Intertek, FM) to published standards. There are specific testing standards for manual fuel shutoff valves, for example CSA 3.16 standard for ball valves or CSA 3.11 standard for quarter-turn lubricated plug valves used for this aplication.
In addition, Codes require that these valves be quarter-turn, that the handle must be non removable and must be parallel to the flow of fuel when valve is open, and that these valves are easily accessible to the operator. Until about 15 years ago the only valves which could be used legally for this service in Canada were the quarter-turn lubricated metal-to-metal plug cocks. Then gradually ball valves with elastomeric seats were added to the approved list.
The intent behind all of this is that an operator must be able to easily see if the valve is open, closed or partially open, and must be able to quickly close the valve in emergency. Plug or gate valves do not meet this safety requirement and this is why they will never be considered suitable/certified for this application.
There is no question that a good quality plug valve will hold the fuel pressure which is not very high to start with, but the standards are written around the operational availability, access for quick shutoff and indication of valve position visible from a distance.
With plug valves, or even worse with needle valve, one cannot easily tell just by looking at them if valve is fully open or closed and it takes "long" time (30 seconds versus 1 second with ball valve) to close these valves.
There are a number of companies making certified valves for fuel shutoff. At the end the issue of using certified versus non-certified manual valves for fuel shutoff is not much different from using certified versus non-certified disconnect switches for electrical equipment.
A separate issue is that of manual valves on pressure switches. To start, codes prohibit ANY valves on pressures switches or transmitters used as safety permissives. There is simply too much risk in closing the valve "by mistake" or intentionally thus disabling the permissive. This is similar to trying to use manual valves on PSV lines from pressure vessels. We have been getting away with using valves under pressure switches for calibration purposes under a variance issued by AMA. However the valves must be quarter turn and locked and taged in open position. So it is obvious just by looking at them that they are important for safety. You cannot get that with barstock needle valves for example or non lockable ball valves from China.
Finally, for aproval of SAFETY SYSTEMS we need to evaluate all components for their suitability for service. And for that we need some proof that the valves were pressure tested, have CRN number in Canada, and that materials of construction are suitable for the service which in some cases involves higher pressures and wet and sour gas.
Brass valves and components used for this corrosive environment are questionable. 316L valves such as Swagelok are probably more costly but better quality than NEO valves. The easiest and most economical way to get a field approval is to use NEO 2500 series ball valves which come with right paperwork and are well proven in this application and readily available.
We work in a heavy resource industry which has high safety requirements and expectation of ruggedness and reliability. Our industry is all about certifications and testing and "proper paperwork". We as engineers are obliged to uphold these requirements. Trying to make things cheaper and without ANY testing and PAPERWORK can be only considered to be poor workmanship and negligence.
Evaluation costs time and money and in some cases is difficult to do. To reduce costs in the long run you are better off to to do it right at the beginning.
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