Engineering Standard

Document Responsibility Loss Prevention Standards Committee
SAES-B-018 Publish Date 13 February 2020 Next Revision 13 February 2025 Foam Systems Saudi Aramco 2020. All rights reserved
Page 6 of 14 Saudi Aramco Company General Use
7
Open-Top Floating Roof Tanks
7.1 For tanks less than 38 min diameter, foam chambers are not required. All tanks with open-top floating roofs, regardless of diameter, shall have a foam dam installed around the rim seal on the roof. The foam dam height shall be not less than 600 mm (24 in. The foam dam shall extend at least 150 mm (6 in) above the seal's weather shield. See Figure
1 7.2 Where a wind girder and a wind girder access stairway is provided and no foam chambers are provided, schedule 40 or equivalent standpipe riser (minimum 75 mm or 3- inch NPS) meeting SAES-L-132 requirements shall be installed. The riser shall befitted with two inch gated male hose connection that are listed for fire service at the top and a 125 mm (inch) Storz gated hose connection at the riser bottom. See Figure 4
Note: The purpose of the riser is to aid the Fire Protection Department in extinguishing a rim seal
fire on smaller tanks. The inch hose connections provide a location for FrPD personnel to
connect hoses that run along the wind girder. The riser avoids having to run a hose up the
winding stairway. The gated valve at the top of the riser should be located at the top stairway
platform, if provided. The Fire Protection Department's tactical plan allows deployment of attack
lines fora maximum of 150 feet along the wind girder. For other tank access information, see
SAES-B-054.
7.2.1 The top stair platform shall be located on the upwind side of the tank.
7.2.2 Prevailing wind direction shall be based on the wind rose diagram for the area via the Environmental Protection Department.
7.3 All hose connections shall be listed per NFPA 1963. Dust caps shall be provided for the couplings. The dust caps shall have a 3 mm (inch) diameter vent hole.
7.4 Tanks 38 m (125 ft) and over in diameter shall have multiple fixed foam chambers and deflectors located at intervals not to exceed 24.4 m (80 ft, equally spaced around entire tank shell (see Figure and NFPA 11). Foam chamber supply piping is shown in Figure
3
. Wind girder access shall be provided and shall meet SAES-B-054.
Note: For existing open-top floating roof tanks, retrofit of chambers or risers shall be done at the
next tank turnaround.
7.5 Riser, lateral, and distribution piping (minimum 75 mm or inch NPS- schedule 40 or equivalent piping) shall meet SAES-L-132 requirements. Foam riser and lateral piping shall be located a minimum of 7.5 m away from main inlet/outlet piping connections) to the tank.
Exception: For existing tanks, the modification shall be made only during major upgrades/T&I,
while ensuring the below performance requirement.
The capacity of the foam system shall be based on 0.34 L/s/m² (0.5 gpm/ft²) of foam solution per area between the foam dam and tank shell . The minimum pressure at each foam maker shall be 485 kPa (70 psig) based on system inlet pressure of approximately
1,035 kPa gauge (150 psig). Hydraulic calculations shall be performed to size the riser, lateral, and distribution piping using latest version of computer software specialized for firewater system design that is certified to meet NFPA 13 and SAES-B-017 section 5.13.1 to assure that the design will meet flow-rate and residual pressure requirements. Drawings and the supporting hydraulic design study calculations of all fire protection systems shall be submitted for review following the company procedures and guidelines.

Document Responsibility Loss Prevention Standards Committee
SAES-B-018 Publish Date 13 February 2020 Next Revision 13 February 2025 Foam Systems Saudi Aramco 2020. All rights reserved
Page 7 of 14 Saudi Aramco Company General Use
7.6 Fixed foam discharge outlets (type II discharge device listed per UL 162 and in accordance with NFPA 11) shall be designed to deliver fully aspirated foam to the annular seal area of open top floating roof storage tanks for fire protection. All foam making equipment shall be listed per UL 162 or otherwise qualified per 8.1.
7.6.1 A mesh screen with 12 mm openings shall be installed over foam maker and deflector openings to prevent birds from nesting in the deflectors or foam chambers.
7.6.2 Foam makers shall be designed for flow-testing such that foam entry into the protected tank is avoided (e.g., foam chambers able to be rotated on a swivel.
7.7 Laterals shall run independently from each tank and terminate at a road on or outside the dike for the tank involved.
7.7.1 Lateral terminals shall beat a predominately upwind or crosswind location. Prevailing wind direction shall be based on a wind rose diagram via the Environmental Protection Department. These terminal locations should beat the corner of the diked area between tanks. The terminal distance from the tank shell shall be not less than one tank diameter.
7.7.2 Lateral terminals shall be located on the roadside of all pipelines and drainage ditches, with a maximum distance of 23 m (75 ft) from terminal to hydrant. Lateral terminals shall befitted with signs to identify which tank and tank section they serve.
7.7.3 Two 125 mm (inch) Storz hose connections shall be provided on each lateral terminal, each connection provided with an independent listed gate valve spaced to allow maximum speed of opening.
7.7.4 The Storz hose connections shall be standard fire hose couplings per
NFPA 1963. Dust caps shall be provided for the couplings. Hose connections to put foam solution into the system shall have check valves to prevent back-flow. A manual block valve shall be installed on each lateral terminal connection. A inch drain valve shall be installed between the Storz and the check valve.
7.7.5 Laterals shall be installed above ground to slope continuously with a slope of 1 in 100 towards the dike, without crossing through other tank dike areas. If practical, the lateral should slope directly to outside the dike, terminating at a minimum height of 300 mm above grade. If continuous slope to the terminal connection is impractical due to grading, a carbon steel inch drain valve shall be installed at the low points.
7.7.6 Any foam system piping that runs underground or passes through a dike wall shall be protected against external corrosion in accordance with the requirements of SAES-H-002.

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