P 113
J3 Deluge Arrangement RO introduction
The necessity and introduction of restriction orifice in deluge discharge arrangement is chicken-egg story! I was surprised to understand that most of the DEC engineers- be it piping design specialist or process system engineers are not able to distinguish the difference between a flow orifice with that of RO! Over&above, they were not able to comprehensively understand what is the difference between MVWS & HVWS and which one to be utilized where and why. So it came as my responsibility to take classes to each of the consultants in their engineering office.
As the NFPA code recommend that the MVWS nozzle tip to be at a distance of 600 mm from the target body surface of the equipment to be protected and in throw pattern of water, there should be overlap of throw so that there is no intermediate dry spot, NFPA have come out with parallel rings to
cater to tall column spray protection.
Why 600 mm and a circular ring ?
When a hydrocarbon containing equipment catches fire, it is expected to release 3.4KW-Hr/M2 of heat and it has to be cooled by MVWS spray@10.2lpm/M2 of water spray to control the fire intensity. Through research and practical experience , the code have come out with the gap of the nozzle tip to be 600mm with a maximum of discharge pressure of 2.5Kg/Cm2g as recommendation.
Now the question arise :- how to ensure the uniform gap of 600mm as well as limiting the discharge pressure within 2.5 kg/cm2g, when a deluge valve has inlet pressure of about 8 kg/cm2g? (its maximum can be as high as 10.5kg/cm2g being the fire water pump setting).
Here only, the circular ring importance arise; with that configuration only, one can ensure to have the uniform gap between the nozzle tip in a ring to that of vessel body. But invariably the piping engineer move for octogen/hexagon/pentagon shape ring arrangement because of AutuCad software limitation. I as customer has to impose my authority and take the deviation to come out of AutoCad and ensure perfect ring arrangement. For this I took hell of time convincing the DEC engineers but finally ensured that all of them fall in line.
Coming to limiting the discharge pressure to 2.5 kg/Cm2g at each of the ring at different elevations in a process column , only the restriction orifice introduction in that circular ring can serve our end objective. In some cases, that ring piping diameter can be as low as 1" !
In general,for standardization of design , we state d/D to be equal to /more than 0.5. d being the bore diameter of restriction orifice. Here comes the catch ! The design engineers do not look into the aspect of foreign debris in fire water choking the RO boreholes and restricting the water throw during fire emergency. They argue that the strainers and Y caps are supposed to take care of the issue and there is no possibility of external debris choking the RO and the MVWS nozzles.
They overlook the special aspect that this deluge protection is life line saving grace in hydrocarbon industry.
Even within Reliance, the discipline engineers in design are not able to visualize its importance and they criticize me as if I am over-stretching its importance.
There is another issue: Choosing area protection with combination of MVWS/HVWS @10.2lpm/M2 in compressor shelter as an alternative to using only 20.4lpm/M2 MVWS strapped arrangement on compressor body. Considering operation & maintenance access provision,I have opted for the former in each of J3 compressor shelter. Some people are not agreeing with me and still there are discussions going on.
Key Aspects :- Conviction, Critical challenge,Initiative, Proactive approach, Responsible, Technical issue, Training
J3 Deluge Arrangement RO introduction
The necessity and introduction of restriction orifice in deluge discharge arrangement is chicken-egg story! I was surprised to understand that most of the DEC engineers- be it piping design specialist or process system engineers are not able to distinguish the difference between a flow orifice with that of RO! Over&above, they were not able to comprehensively understand what is the difference between MVWS & HVWS and which one to be utilized where and why. So it came as my responsibility to take classes to each of the consultants in their engineering office.
As the NFPA code recommend that the MVWS nozzle tip to be at a distance of 600 mm from the target body surface of the equipment to be protected and in throw pattern of water, there should be overlap of throw so that there is no intermediate dry spot, NFPA have come out with parallel rings to
cater to tall column spray protection.
Why 600 mm and a circular ring ?
When a hydrocarbon containing equipment catches fire, it is expected to release 3.4KW-Hr/M2 of heat and it has to be cooled by MVWS spray@10.2lpm/M2 of water spray to control the fire intensity. Through research and practical experience , the code have come out with the gap of the nozzle tip to be 600mm with a maximum of discharge pressure of 2.5Kg/Cm2g as recommendation.
Now the question arise :- how to ensure the uniform gap of 600mm as well as limiting the discharge pressure within 2.5 kg/cm2g, when a deluge valve has inlet pressure of about 8 kg/cm2g? (its maximum can be as high as 10.5kg/cm2g being the fire water pump setting).
Here only, the circular ring importance arise; with that configuration only, one can ensure to have the uniform gap between the nozzle tip in a ring to that of vessel body. But invariably the piping engineer move for octogen/hexagon/pentagon shape ring arrangement because of AutuCad software limitation. I as customer has to impose my authority and take the deviation to come out of AutoCad and ensure perfect ring arrangement. For this I took hell of time convincing the DEC engineers but finally ensured that all of them fall in line.
Coming to limiting the discharge pressure to 2.5 kg/Cm2g at each of the ring at different elevations in a process column , only the restriction orifice introduction in that circular ring can serve our end objective. In some cases, that ring piping diameter can be as low as 1" !
In general,for standardization of design , we state d/D to be equal to /more than 0.5. d being the bore diameter of restriction orifice. Here comes the catch ! The design engineers do not look into the aspect of foreign debris in fire water choking the RO boreholes and restricting the water throw during fire emergency. They argue that the strainers and Y caps are supposed to take care of the issue and there is no possibility of external debris choking the RO and the MVWS nozzles.
They overlook the special aspect that this deluge protection is life line saving grace in hydrocarbon industry.
Even within Reliance, the discipline engineers in design are not able to visualize its importance and they criticize me as if I am over-stretching its importance.
There is another issue: Choosing area protection with combination of MVWS/HVWS @10.2lpm/M2 in compressor shelter as an alternative to using only 20.4lpm/M2 MVWS strapped arrangement on compressor body. Considering operation & maintenance access provision,I have opted for the former in each of J3 compressor shelter. Some people are not agreeing with me and still there are discussions going on.
Key Aspects :- Conviction, Critical challenge,Initiative, Proactive approach, Responsible, Technical issue, Training
