Vertical Vessal Foundation
Vertical Vessal Foundation
Vertical Vessal Foundation
AGENDA
1/21/2020
TYPES OF VERTICAL VESSELS
SUPPORTS
VESSEL
SKIRT SUPPORTED SUPPORTED ON SIDE SUPPORTED VERTICAL VESSEL
VERTICAL VESSELS LEGS LUGS WITH REBOILERS
1/21/2020
Vertical vessel supported on skirts
1/21/2020
Vessel supported on unbraced legs
1/21/2020
Vessel supported on braced legs
1/21/2020
Typical Scheme of lug
1/21/2020
Side supported lugs
Side legs are provided
1/21/2020
Cantilevered Reboilers attached to Vessel
1/21/2020
DESIGN LOAD CLASSIFICATION
FITTING &
EMPTY OPERATING FIXTURE SNOW & ICE PIPING WEIGHT
LOAD (DE) LOAD (DO) WEIGHT LOAD (if significant)
1/21/2020
DESIGN LOAD CONSIDERATIONS: VERTICAL LOADS
DEAD LOADS
• Structure load (Ds) - Weight of the foundation and weight of the soil above the foundation that
are resisting uplift.
• Pedestal load (Dp) is a part of Ds representing the weight of the pedestal used in the calculation
of tension in pedestal dowels.
• Erection load (Df) - Fabricated weight of the vessel generally taken from the certified vessel
drawing.
• Empty load (De) - Empty weight of the vessel, including all attachments, trays, internals,
insulation, fireproofing, agitators, piping, ladders, platforms, etc..
• Operating load (Do) - Empty dead load of the vessel plus the maximum weight of contents
(including packing/catalyst) during normal operation. Increase 15% of operating load for piping,
platforms etc.
• Test load (Dt) - Empty dead load of the vessel plus the weight of test medium contained in the
system. The test medium should be as specified in the contract documents or as specified by the
owner. The test medium should have specific gravity of not less than 1.0. It should be specified if
the cleaning fluid used is heavier than test fluid.
1/21/2020
LIVE LOADS
Definition:
Live loads, or imposed loads, are temporary, moving and of short duration.
In context of Vertical Vessels, Live loads are usually taken on the Access platforms.
1/21/2020
DESIGN LOAD CONSIDERATIONS: HORIZONTAL LOADS
Following horizontal loads are considered while designing the horizontal vessel:
• Wind load,
• Thermal load.
1/21/2020
WIND LOAD
• Wind load is the load which is applied on a structure due to the blowing winds.
• Effect of wind on the cross wind direction (i.e. Vortex Shedding) should be considered.
• Some of the provisions for wind load calculation are listed below:
Wind Loads for Petrochemical Facilities: Add 5 feet (1.52m) to the diameter of the
vessel as the projected width, or add 3 feet (0.91m) plus diameter of the largest pipe to the
diameter of the vessel, which ever is greater.
- The vessel height should be increased by one times vessel diameter to account for a large
diameter pipe and platforms attached above the top tangent.
- The increase in vessel height or diameter to account for wind on appurtenances should not
be used in calculating the h/D ratio for force coefficients or flexibility.
1/21/2020
WIND LOAD
- Wind load on equipment shall include an allowance for piping and platforms. The design
diameter shall be greater than the actual diameter D, as follows:
• Seismic Response Modification Factor (R) from ASCE 7-05 for Vertical Vessel Types:
1/21/2020
SEISMIC LOADS
1/21/2020
LOAD COMBINATIONS SYMBOLS & NOTATIONS
• W- Wind Load
• R- Rain Load
PEDESTAL SIZING AND DESIGN
PEDESTAL SIZING CONSIDERATIONS:
• On the basis of standard available forms for the project, the pedestal size is ascertained. When
form information is not available, octagon pedestal dimensions should be sized with pedestal faces
in 2-inch increments to allow use of standard manufactured forms.
where:
BC = bolt circle, inches
BD = bolt diameter, inches
SD = sleeve diameter, inches
1/21/2020
• Pedestals 6 ft and larger should be octagonal. The pedestals smaller than 6 ft should be square, or
round if forms are available.
• It is normally desirable to make the pedestal deep enough to contain the anchor bolts and to keep
them out of the footing.
1/21/2020
PEDESTAL REINFORCEMENT
• The pedestal should be tied to the footing with sufficient dowels around the pedestal perimeter to
prevent separation of the pedestal and footing. Development of reinforcing steel should be checked.
• Dowels should be sized by computing the maximum tension existing at the pedestal perimeter
attributable to overturning moments.
• Top reinforcement - A mat of reinforcing steel with minimum steel should be #4 bars at
12-inch maximum spacing across the flats in two directions only.
1/21/2020
FOOTING SIZING
• Footing acts as the base of a foundation and transmit the superimposed load to the soil.
• Footings may be rested directly over the soil or on piles depending upon the bearing capacity
of soil and the superimposed load.
• Footings for vertical vessels may be octagonal or square and sized based on standard
available form sizes.
• When form information is not available, footing dimensions should be sized with footing
faces in 2-inch increments to allow use of standard manufactured forms.
• If extended to the recommended depth specified in the geotechnical report, the pedestal may
be adequate without a footing.
1/21/2020
GENERAL CONSIDERATIONS
• The footing thickness should also be checked for top tension without top reinforcement in
accordance with ACI 318.
• Increasing the footing thickness is typically more cost effective for construction than adding a
top mat of reinforcing steel except where seismic effects create tensile stresses requiring top
reinforcement.
• Footings shall be proportioned to resist the factored loads and induced reactions.
• Base area of footing or number and arrangement of piles shall be determined from unfactored
forces and moments transmitted by footing to soil or piles and permissible soil pressure or
permissible pile capacity determined through principles of soil mechanics.
1/21/2020
THANK YOU
1/21/2020