Layout Consideration for Heaters, Columns, Tanks

  Layout Consideration for Fired Heaters:

• Fired heaters should be located at least 15m away from other equipment that could be a source of liquid spillage or gas leakage.
• To avoid accumulation of flammable liquids, no pits or trenches should be permitted to extend under furnaces or any fired equipment, and if possible, they are to avoided in furnace areas.
• Ensure sample room at the firing front of the fired heater for operation and removal of the burners and for the burners and for the burner control panel, if required.
• Bottom floor fired furnaces require adequate headroom underneath the furnace. Wall fired furnaces require an adequate platforms width with escape routes at each end of the furnace.
• Apart from adequate platform and access to firing front, other structural attachments and platforms around furnace should be kept minimum. Access by means of stepladder is sufficient.
• Arrange fired heaters on a common line, whenever possible.
• Provide unobstructed space for withdrawal.
• Operation and maintenance platforms should be wide enough to permit a 1m clear walkway.
• Escape ladders should be provided on large heaters.
• Vertical heaters usually are supplied with stub supporting feet; ensure drawings show adequate supports elevated to the required height.
• Headroom elevation from the floor level to the underside of heater should be 2.3m to provide good firing control operations.

 Layout Consideration for Columns:

• Columns usually are self-supporting with no external structures.
• Circular or segmented platforms with ladders are supported from the shell.
• The maximum allowable straight run of a ladder before a break platform should not exceed 9m.
• The factors influencing column elevation are the provision of a gravity flow system & installation of thermosyphon reboilers.
• Depending on the plant arrangement, columns may have to be elevated to a height in excess of the normal requirements to allow for headroom clearance from lower-level piping off-takes.
• The skirt height of all columns or vessels providing suction to pumps, particularly if handling hot or boiling liquids should be adequate for the pump NPSH requirements.
• Access platforms should be provided on columns for all 3'' and above instrument controller and transmitter, relief valves, manholes and blinds or spades, and other components that require periodic attention.
• Platform for access to level gauges and controllers should not be provided if underside of supporting steelwork is less than normal headroom clearance from grade.
• Adjacent columns should be checked, so that platforms do not overlap. for layout 2.0-2.5 m between shells, depending on insulation, should suffice.
• Allow a 900 mm minimum clearance between column foundation and the adjacent plinth.
• Provide clearance for the removal of internal parts and attachments and for davits at the top of columns, if relevant.
• The center line of manholes should be 900mm above any platform.
• Horizontal vessels should be located at grade, with the longitudinal axis at a right angle to the pipe way, if possible.
• Consider saving plot space by changing vessels from the horizontal to the vertical, if possible and combining vessels together with a internal head (subject to project or process approval).
• The size and number of access platforms on horizontal vessels should be kept to a minimum and are not to be provided on horizontal vessels or drums when the top of the vessel is 2.5m or less from the grade.
• The channel end of vessels provided with internal tubular heaters should face towards an open space. The withdrawal area must be indicated on studies, general arrangement (GAs), and plot plans.
• Internal agitators or mixers are to be provided with adequate clearance for removal. Removal area must be indicated on studies, GAs and plot plans.

 Layout Consideration for Tanks:

•  The layout of tanks, as distinct from their spacing should always take into consideration the accessibility needed for firefighting and the potential value of a storage tank in providing a buffer area between process plant for example, public roads and houses, for safety and environmental reasons.
• The locations of tank relative to process units must be such as to ensure maximum safety from possible incidents.