Important discussion - tank cooling rings for atmospheric storage tanks

[adamjin]

Hi to everyone,

I was wondering which standards are used in other Oil Tank Farms about Tank Cooling Water Spray Application Rates.

1) For API RP 2030 (2005)

7.3.13 Atmospheric Storage Tanks:
In general , It suggests an application rate 4.1 lpm/m2 for storage tanks

"When reviewing an atmospheric storage tank’s protection from an external fire the design personnel should recognize that cooling water is of potential benefit only for the exposed portions of the roof and for those portions of the shell that are not in contact with the liquid contents. Those portions of the tank most likely not to be in contact with liquid include the roof of cone roofed and covered floating roof tanks and the upper portion of the shell on all tanks. If spray is used, typically only the upper 12 to 24 ft (3.7 to 7.4 m) of shell is sprayed; up to 12 ft (3.7 m) of rundown is allowed on inclined and vertical surfaces. If there are wind girders at the top of the tank, spray nozzles should be placed below each girder ring."

"Where water spray protection is used the system should be designed to provide an application rate of 0.10 gpm/ft2 (4.1 lpm/m2) of protected surface"

2) NFPA 15 - "Standard for Water Spray Fixed Systems for Fire Protection"

Section 7.4.2.1: Water spray shall be applied to vessel surfaces (including top and bottom surfaces of vertical vessels) at a net rate of not less than 0.25 gpm / ft2 [10.2 (L/min) /m2] of exposed surface.

As per API RP 2030 a rundown of 3.7m is allowed.

MY QUESTIONS ARE:

1. WHICH WATER APPLICATION RATE IS GENERALLY USED IN THE OIL INDUSTRY. NFPA 15 IS A STANDARD WHILE API 2030 IS A RECOMMENDED PRACTICE (10.2LPM/M2 OR 4.1LPM/M2)

2.IF A RUNDOWN OF 3.7M IS ALLOWED MEANING AFTER 3.7M WE HAVE A SECOND RING FOR THE NEXT 3.7M TO A MAXIMUM OF 7.4M (I.E ANY TANK HEIGHT ABOVE 7.4M WOULD REQUIRE 2 RINGS AS PER BOTH API RP 2030 AND NFPA 15. HOW COME GENERALLY WE ONLY FIND ONE TANK COOLING RING IN OIL FACILITIES?????

3. THIRDLY, CAN SOMEONE PROVIDE AN EXCEL SHEET FOR TANK COOLING WORKOUT BASED ON APPLICATION RATES, NO OF NOZZLES AND K FACTORS

4. IF THERE IS A FIRE IN ADJACENT TANK, WHAT IS THE RECOMMENDED PRACTICE FOR COOLING TANKS NEARBY BASED ON DISTANCE BETWEEN ADJACENT TANKS,WIND ETC., WHAT ARE THE APPLICATION RATES???

I WOULD LOVE FOR EVERYONE TO CONTRIBUTE AS IT IS CRITICAL FOR TANK FARM SAFETY.

REGARDS

[adamjin]

To add to the above, I cannot see anywhere in API RP 2030 or even API RP 2001 (which is cross referenced in the 2030) where it stipulates the period of coverage for tanks and the surface area to be considered when designing the fire fighting. For example if you have 10 tanks in a bund area and you are designing the water requirements do you need to allow for the surface area of all 10 tanks to be covered at the same time and what period of time do the tanks require coverage for?

Anybody with experience in design of tank cooling and firefighting systems

[adamjin]

To add to the above, I cannot see anywhere in API RP 2030 or even API RP 2001 (which is cross referenced in the 2030) where it stipulates the period of coverage for tanks and the surface area to be considered when designing the fire fighting. For example if you have 10 tanks in a bund area and you are designing the water requirements do you need to allow for the surface area of all 10 tanks to be covered at the same time and what period of time do the tanks require coverage for?

Anybody with experience in design of tank cooling and firefighting systems

[adamjin]

Anyone who can provide advise on this please