Foam fused ports on atmospheric storage tanks seals 1

[MACARTHUR]

Could anyone advise me whether there is any standard and/or code for specifying a foam port that can let the fire fighting foam go between the floating roof seals in case of fire..?? I heard about NFPA regulations every 3 meters along the secondary seal but what about the size of it and fusing material spec.?

Thank you

 

[IFRs]

These are typically round holes punched in the seal support plates with urethane fabric trapped between clamp rings. The fabric burns away alowing foam to allow move from the foam dam area to the seal area. The fabric needs to be resistant to the product vapors yet flammable. Typically I see 4", 6" or 8" holes. I'm not sure if there are any specs.

 

[MACARTHUR]

Thank you for tips...

I found out the NFPA rules which seem very minimum though.. and the European EN 14 015 2004 standard mentionning this..

I must add that these foam traps are being a real safety issue as in case of fire and /or late foam delivery, these could be an additional source of oxygen feeding the fire..

I believe delivering foam right from the center of tank and distributed directly through these holes with correct piping just in the middle of the flotating rook seals is a much safer and quicker solution...

See for information what I got from elsewhere and many thanks again

EN 14015:2004 (E)


E.5.6 Compression plate secondary seals

Depending on the maximum expected rim space, a minimum compression plate height shall be

provided for satisfactory operation.

NOTE 1 The compression plates should incorporate foam ports to allow fire fighting foam to enter the rim

space.

NOTE 2 Compression plate secondary seals have good centering forces and protect the sealing curtain

against sun light and weathering.

NOTE 3 The height of the required foam wall and the maximum lifting height of the floating roof are

determined by the maximum contact point between the secondary seal and the tank wall.

 

[IFRs]

I always thought that if your foam dam was 2" higher than the compression plate seal, you did not need burn-out panels.

If you pipe through the compression plate seal you need some kind of flexible connection so the seal can accomodate tank out of roundness and floater movement.

If you use burn out panels, they should be sized to pass the flow rate of foam needed to flood the seal area behind it in the time required.