RobsVette
Mechanical
- Apr 15, 2009
- 94
Hey guys, I'm looking for some help in understanding the proper classification to be used with different pieces of equipment and why the different classifications are used.
First, I will explain the situation we are working with and then give my understanding of how this should be done.
Our company has been given a project to take two existing boilers that share a common economizer and install two new economizers, one for each boiler. The boilers are old B&W water tubes producing 120,000 #/hr of 150 psig saturated steam.
The company we are purchasing the economizers from is saying that they can build and certify the economizers to Sec VIII as opposed to Sec I. The point of doing this, is that Sec VIII allows the use of compression style tube connections and section I does not. They are stating that as long as the economizer is placed outside the Sec. I boundary everything is fine. Access to the area where the boilers are is the driving force here. We will be purchasing the economizers in Knock Down configuration and assembling on site, since there is no access to rig them in.
In principle, I disagree with this, however we have seen some weird exceptions to this rule in the past.
The reason for my disagreement with this, is that since an economizer is a device for heating water that is fueled by flue gasses from a burner, it should be constructed to the rules of Sec I. This would be consistent with most of the installations we have seen. Our company has assembled many large 3 pressure HRSGs and all of the economizers on these boilers fall into Sec. I, the same goes for small cogen units that produce 150 psi saturated steam. We have also done some High Temp Water heater installations and again all these items are fired with a burner and are constructed to the rules of Sec I.
The exception to this is that we have done some small fire tube boilers that produce 150 psi steam and are operated using waste heat from a recip engine (really no different than using waste heat from a gas turbine,) and these are classified as Sec VIII vessels with a form U-1 data report.
Can someone please explain the intention of when you should classifiy a water heater / boiler to each section of the code and if there is any intuitive reason as to why, please state that. (example would be for B31.1 the requirements are intended for high pressure, high temp systems as opposed to B31.3 where you could have high pressure mod temp or B31.9 which would be just water at low temp and low press)
If any other information is needed please let me know and I will provide it.
Thanks,
Rob
First, I will explain the situation we are working with and then give my understanding of how this should be done.
Our company has been given a project to take two existing boilers that share a common economizer and install two new economizers, one for each boiler. The boilers are old B&W water tubes producing 120,000 #/hr of 150 psig saturated steam.
The company we are purchasing the economizers from is saying that they can build and certify the economizers to Sec VIII as opposed to Sec I. The point of doing this, is that Sec VIII allows the use of compression style tube connections and section I does not. They are stating that as long as the economizer is placed outside the Sec. I boundary everything is fine. Access to the area where the boilers are is the driving force here. We will be purchasing the economizers in Knock Down configuration and assembling on site, since there is no access to rig them in.
In principle, I disagree with this, however we have seen some weird exceptions to this rule in the past.
The reason for my disagreement with this, is that since an economizer is a device for heating water that is fueled by flue gasses from a burner, it should be constructed to the rules of Sec I. This would be consistent with most of the installations we have seen. Our company has assembled many large 3 pressure HRSGs and all of the economizers on these boilers fall into Sec. I, the same goes for small cogen units that produce 150 psi saturated steam. We have also done some High Temp Water heater installations and again all these items are fired with a burner and are constructed to the rules of Sec I.
The exception to this is that we have done some small fire tube boilers that produce 150 psi steam and are operated using waste heat from a recip engine (really no different than using waste heat from a gas turbine,) and these are classified as Sec VIII vessels with a form U-1 data report.
Can someone please explain the intention of when you should classifiy a water heater / boiler to each section of the code and if there is any intuitive reason as to why, please state that. (example would be for B31.1 the requirements are intended for high pressure, high temp systems as opposed to B31.3 where you could have high pressure mod temp or B31.9 which would be just water at low temp and low press)
If any other information is needed please let me know and I will provide it.
Thanks,
Rob