Airmandunkel
Mechanical
- Dec 17, 2013
- 1
I am currently Reviwing NFPA-497 and trying to come up with a design standard. I'm having difficulty in a few areas listed below
[ul]
[li]NFPA-497 section 5.4.1 (1) states, Locations that have adequate ventilation, where combustible materials are contained within suitable, well maintained, closed piping systems do not need to be classified. Outdoor areas have adequate ventilation, therefore, natural gas and hydrogen piping are not classified at flanges and valves. However, lighter-than-air gas Figures 5.9.8 and 5.9.9 show outdoor storage and compressors as classified.
Question: Is the intent to classify the storage unit or compressor and connecting flanges.
Question: Is outdoor miscellaneous equipment with small natural gas or hydrogen tubing expected to be classified?
[/li]
[li]When classifying a piece of equipment at what point of that system does the classification end.[/li]
Example – A flange on a natural gas pipe connected to a combustion turbine generator is classified. Are the flanges upstream from that connection point to be classified as well? Such as a flanged elbow prior to the pipe routing below grade.
[/li]
[li]NFPA-497 does not appear to address vents on lighter-than-air gas such as hydrogen and natural gas storage and equipment. Venting is an abnormal condition, how should vents of this nature be classified? Is it class 1, div 1 for a certain distance? Is class 1, div 2 extended 15 ft or 25 ft?[/li]
[li]Section 1.1.4 states that NFPA-497 does not apply to catastrophic events. What is the design case for these classified areas? Is there a typical size leak that is assumed?[/li]
[li]We are seeing an increasing number of clients enforcing API-500 for power plants. From my understanding API is strictly for Petroleum facilities. Do you know of any documentation or background information that can be referenced to verify NFPA-497 is the governing document for hazardous classified areas in power plants?[/li]
[/ul]
Sorry for the length I'm reaching out to some committee members as well I thought maybe a few on here could help.
[ul]
[li]NFPA-497 section 5.4.1 (1) states, Locations that have adequate ventilation, where combustible materials are contained within suitable, well maintained, closed piping systems do not need to be classified. Outdoor areas have adequate ventilation, therefore, natural gas and hydrogen piping are not classified at flanges and valves. However, lighter-than-air gas Figures 5.9.8 and 5.9.9 show outdoor storage and compressors as classified.
Question: Is the intent to classify the storage unit or compressor and connecting flanges.
Question: Is outdoor miscellaneous equipment with small natural gas or hydrogen tubing expected to be classified?
[/li]
[li]When classifying a piece of equipment at what point of that system does the classification end.[/li]
Example – A flange on a natural gas pipe connected to a combustion turbine generator is classified. Are the flanges upstream from that connection point to be classified as well? Such as a flanged elbow prior to the pipe routing below grade.
[/li]
[li]NFPA-497 does not appear to address vents on lighter-than-air gas such as hydrogen and natural gas storage and equipment. Venting is an abnormal condition, how should vents of this nature be classified? Is it class 1, div 1 for a certain distance? Is class 1, div 2 extended 15 ft or 25 ft?[/li]
[li]Section 1.1.4 states that NFPA-497 does not apply to catastrophic events. What is the design case for these classified areas? Is there a typical size leak that is assumed?[/li]
[li]We are seeing an increasing number of clients enforcing API-500 for power plants. From my understanding API is strictly for Petroleum facilities. Do you know of any documentation or background information that can be referenced to verify NFPA-497 is the governing document for hazardous classified areas in power plants?[/li]
[/ul]
Sorry for the length I'm reaching out to some committee members as well I thought maybe a few on here could help.