Exchangers, Reboiler (Kettle Reboiler)
Locate kettle reboilers at grade and as close as possible to the vessel they serve. This type of reboiler is identifiable by its unique shape. It has one end much like a normal Shell and Tube exchanger then a very large eccentric, bottom flat transition to what looks like a normal horizontal vessel. You could also call it a “Fat” exchanger. The flow characteristics on the process side of a kettle reboiler are the reason for the requirement for the close relationship to the related vessel.
Reboilers normally have a removable tube bundle and should have maintenance clearance equal to the bundle length plus 5 feet (1.5m) measured from the tube sheet.
Exchangers, Shell and Tube
Shell and tube exchangers should be grouped together wherever possible. Stacked shell and tube exchangers should be limited to four shells high in similar service; however, the top exchanger should not exceed a centerline elevation of 18 feet (5.5m) above high point of finished surface, unless mounted in a structure. Keep channel end and shell covers clear of obstructions such as piping and structural members to allow unbolting of exchanger flanges, and removal of heads and tube bundles.
Exchangers with removable tube bundles should have maintenance clearance equal to the bundle length plus 5 feet (1.5m) measured from the tube sheet to allow for the tube bundle and the tube puller.
Maintenance space between flanges of exchangers or other equipment arranged in pairs should be 1′- 6″ (0.5m) (min.). Exchanger maintenance space from a structural member or pipe should not be less than 1′- 0″ (300mm) (min.).
Furnaces (Fired Equipment)
Locate fired equipment, if practical, so that flammable gases from hydrocarbon and other processing areas cannot be blown into the open flames by prevailing winds.
Horizontal clearance from hydrocarbon equipment (shell to shell) 50′- 0″ (15m) Exception: Reactors or equipment in alloy systems should be located for economical piping arrangement.
Provide sufficient access and clearance at fired equipment for removal of tubes, soot blowers, air preheater baskets, burners, fans, and other related serviceable equipment.
Clearance from edge of roads to shell 10′- 0″(3m)
Pressure relief doors and tube access doors should be free from obstructions. Orient pressure relief doors so as not to blow into adjacent equipment.
The elevation of the bottom of the heater above the high point of the finished surface should allow free passage for operation and maintenance.
Furnace Piping
Locate snuffing steam manifolds and fuel gas shutoff valves a minimum of 50 feet (15m) horizontally from the heaters they protect.
Burner Valving for a Floor Fired Furnaces: Combination oil and gas firing valves should be operable from burner observation door platform. For those fired by gas only, the valves should be near the burner and should be operable from grade.
Burner Valving for a Side Fired Furnaces: Locate firing valves so they can be operated while the flame is viewed from the observation door.
Flare Stacks
Locate the flare stack upwind of process units, with a minimum distance of 200 feet (60m) from process equipment, tanks, and cooling towers. If the stack height is less than 75 feet (25m), increase this distance to a minimum of 300 feet (90m). These minimum distances should be verified by Company Process Engineering.
Future Provisions
Space for future equipment, pipe, or units should not be provided unless required by the client or for specific process considerations. When applicable this requirement should be indicated on the plot plan and P&IDs.
Insulation Shoes and Cradles
Locate Insulation shoes anywhere a line crosses a support for hot insulated piping when the piping is 3 inch (80mm) and larger carbon and alloy steel lines with design temperatures over 650 degrees F (350C).
Large diameter lines (20 inches (500mm) and over), stainless steel lines where galvanic corrosion may exist, lines with wall thickness less than standard weight, and vacuum lines should be analyzed to determine if shoes or wear plates are needed.
Provide cradles at supports for insulated lines in cold service and for acoustical applications.
Ladders & Cages
Maximum height of a ladder without a cage should not exceed 15′-0″ (4.5m)
Maximum vertical distance between platforms 30′- 0″ (9m)
Cages on ladders over 15′-0″ (4.5m) high shall start at 8′-0″ (2.5m) above grade.
Minimum toe clearance behind a ladder 0′- 7″ (200mm)
Minimum handrail clearance 0′- 3″ (80mm)
Level Instruments
Locate liquid level controllers and level glasses so as to be accessible from grade, platform, or permanent ladder. The level glass should be readable from grade wherever practical.
Wherever possible, orient level instruments on the side toward the operating aisle.
Loading Racks
Locate loading and unloading facilities that handle flammable commodities a minimum of 200 feet (60m) from away from process equipment, and 250 feet (75m) from tankage.
Maintenance Aisles (at grade)
Equipment maintenance aisle for hydraulic crane (12T capacity) should have a horizontal clearance width of 10′- 0″ (3m) (min.) and a vertical clearance of 12′- 0″ (3.5m) (min.). Where a fork lift and similar equipment (5000 lbs / 230kg capability) is to be used the horizontal clearance should be 6′- 0″ (2m) (min.) and the vertical clearance should be 8′- 0″ (2.5m) (min.).
Where maintenance by portable manual equipment (A-frames, hand trucks, dollies, portable ladders or similar equipment) is required the horizontal clearance should be 3′- 0″ (1m) (min.) and the vertical clearance 8′- 0″ (2.5m) (min.).
Operating Aisle (at grade)
Minimum width 2′- 6″ (800mm)
Headroom 7′- 0″ (2.1m)
Orifice Runs and Flanges
Locate Orifice runs in the horizontal. Vertical orifice runs may only be used with the approval of Company Control Systems Engineering. Orifice flanges with a centerline elevation over 15 feet (4.5m) above the high point of finished surface, except in pipeways, should be accessible from a platform or permanent ladder.
Locate orifice taps as follows:
Air and Gas
-Top vertical centerline (preferred)
-45 degrees above horizontal centerline (alternate)]
Liquid and Steam
-Horizontal centerline (preferred)
-45 degrees below horizontal centerline (alternate]
(Note: The piping isometrics should show the required tap orientations)
Personnel Protection
Locate eye wash and emergency showers in all areas where operating personnel are subject to hazardous sprays or spills, such as acid.
Personnel protection should be provided at uninsulated lines and for equipment operating above 140 degrees F (60 C) when they constitute a hazard to the operators during the normal operating routine. Lines that are infrequently used, such as snuffing steam and relief valve discharges, may not require protective shields or coverings.