Title: Internal Floating Roof Leg Vent Setting

Agenda Item 650-706

Title: Internal Floating Roof Leg Vent Setting

Date: 04/18/2012

Contact: Kah-Kan Chan

TCI Services, Inc.

918-583-3968

Purpose: Eliminate an arbitrary level range over which internal floating roof leg or cable activated vents must remain open.

Source: Request from Larry Foster, Marathon Petroleum Company. This agenda was originally handled by Karen L. Kennedy, ConocoPhillips Transportation.

Revision: 2

Impact: Maximizes the tank working inventory by allowing an evaluation of the opening / closing height of internal floating roof vents to be made by the tank owner and the manufacturer.

Rationale: There is no accurate basis for requiring the leg / cable vents to be open at least 6” before its low (operating) and high (maintenance) levels. The set point of vent opening is depends on construction imperfections and future differential settlement of tank bottom. Modify H.5.2.1.4 to allow owner and manufacturer to design a different set point for vent opening.

Proposal:

Revision 2 - New Proposal

·  H.5.2.1.4 Unless agreed otherwise by the Purchaser and roof Manufacturer, Lleg or cable activated vents shall be designed to open automatically when the roof lowers to 150 mm (6 in.) above its support levels lowest operating position and to close automatically when the roof raises more than 150 mm (6 in.) above its lowest operating position these levels.The set point of vent opening should be based on potential construction imperfections, future differential settlement of the tank, floating depth of the floating roof, and deformation of the tank roof. Float-activated vents shall be designed to remain closed while the roof is floating. Pressure-vacuum activated vents shall be designed to open and achieve required flow rates within the design capacities of the floating roof and floating roof support system as described in H.5.2.1.1.

(Note: Deleted last sentence of H.5.2.1.4 due to duplication of H.5.2.1.1 requirements)

Revision 1 - As Balloted in spring, 2012

H.5.2.1.4 Leg or cable activated vents shall be designed to open automatically when the roof lowers to 150 mm (6 in.) above its support levels lowest operating position and to close automatically when the roof raises more than 150 mm (6 in.) above its lowest positionthese levels or at a distance agreed upon by the purchaser and manufacturer. The set point of vent opening shall be based on potential construction imperfections and future differential settlement of tank bottom. Float-activated vents shall be designed to remain closed while the roof is floating. Pressure-vacuum activated vents shall be designed to open and achieve required flow rates within the design capacities of the floating roof and floating roof support system as described in H.5.2.1.1.

Revision 0 - As Balloted in spring, 2011

H.5.2.1.4 Leg or cable activated vents shall be designed to open at a point agreed upon by the owner and manufacturer. automatically when the roof lowers to 150 mm (6 in.) above its lowest operating position and to close automatically when the roof raises more than 150 mm (6 in.) above its lowest position. Float-activated vents shall be designed to remain closed while the roof is floating. Pressure-vacuum activated vents shall be designed to open and achieve required flow rates within the design capacities of the floating roof and floating roof support system as described in H.5.2.1.1.