A Comprehensive Guide to Atmospheric Storage Tanks
Tanks:
built to store equipment subject to fluid pressure atimosférica.Pressão 0 to 0.5 kg / cm ²
contructon solder rivets bolts, a cylindrical vertical position. Regulamentoda by API 650 in Brazil NBR7821.
nature of the roof types:
Fixed roof fixed roof:
directly on the upper side freestanding APOAII the periphery of the side supported by an internal struct profiles metallic forms the roof, conical, curved panels, regular polygon.
Ceiling mobile lifting roof:
you move outside to the side, movement due to vapor pressure safety device to prevent excess internal pressure and external sealing system between cosat and ceiling to prevent loss by evaporation may be seal liquid or drought.
diaphragm flexible roof diaphragm: the change in vapor volume due to change in pressure. Functions as a flexible membrane to allow variation of the vapor space as is made of neoprene nylon plastic material etc., must resist the product stored.
Floating roof floating roof:
directly supported on the liquid acompqanha moving fluid, minimizes evaporation losses pro, need for sealing, there are 3 types floating simple:
the most simple + cheap buoyancy precarious> evaporative loss trasnmite incident solar energy.
With float:
it has a central disk and a float on the edge of the roof has better buoyancy less evaporative loss greater cost.
Floating double:
sheets of plate connected internally by a metal structure forming watertight structure robuista excellent buoyancy.
Containment basin:
Purpose of security in storage, contain stored in case of leakage from the tank or piping failure or operação.Diques built with successive layers and uniform thickness ñ> 30 cm compression surface of the earth must be protegiata copmtra erosion with planting of grass or paving the ground are + barartos put higher cost of maintenance should have a ladder to access and storm drainage.
Foundations can cause excessive repression, strains and stresses in high-risk equipment integrity, high efforts in the nozzles and connections, errors in measurement of level, malfunctioning components appendix b api 650 makes recommendations for the construction of bases.
build 30 cm above the bottom of the basin directly to the foundation ring of concrete being treated on the surface of the coating is waterproof q be deep, Piling under concrete slab supporting the bottom plates and side
measurement racalque: N 1807 fixes the p measurement hydrostatic test, using pin d Ereference leaded 10 cm below the top of the foundation directly CFOM landfill compact set in welded steel angles on the side tank D <30m 4 pin / D 30 <50m 6 pin / D> 50 8 pins.
Repression: are measured during the test stage hydrostatic filling 0,25,50,75 and 100%
repression repression permissible N270 absolutely no point edge 300mm repression differential periphery 2 points 38 mm 9000 mm measured along the perimeter
API 650 Welded Steel Tanks for Oil Storage
It includes specifications on
stuff,
design,
manufacturing
assembly
tests
Tank
‘Vertical
‘Cylindrical
‘Not buried
»Top open or closed,
‘Welded construction,
‘Steel,
‘Various dimensions and capacities,
‘To service refrigerated and internal pressure approximately
pollution (no more than 2.5 psig)
NBR 7821 (ABNT)
practically the same conditions of API 650
BS 2654
Specifies requirements for materials, design, fabrication, assembly
and testing of steel tanks, non-refrigerated, soldiers,
cylindrical and vertical. High design pressure of 56 mbar and
minimum design temperature of -10 o C
API 620
Design and construction of large tanks of low pressure
soldiers, assembled in the field for oil and oil products
maximum pressure of 15 psig steam in space.
API 2000
standard requirements and plans for tanks not buried,
Oil and oil or refrigerated tank, buried
or not for oil.
API Specification 12A
requirements for materials, design, manufacture, assembly and testing
for steel tanks, vertical and cylindrical riveted, capacity
Rated 240 bbl to 250,000 bbl (standard sizes).
Widely used in production fields
API Specification 12B
Specifies requirements for materials, design, fabrication, assembly
and testing of steel tanks, not buried, bolted,
cylindrical and vertical. Rated capacity of 100 bbl to 10,000
bbl (standard sizes). Widely used in fields
production
API Specification 12D
Specifies requirements for materials, design, fabrication, assembly
and testing of steel tanks, not buried, soldiers in the work.
Rated capacity of 500 bbl to 10,000 bbl (sizes
standard). Widely used in production fields.API Specification 12E
requirements for materials, design, fabrication, assembly
wooden tanks, vertical and cylindrical, not buried,
nominal capacity of 130 bbl bbl in 1500 (sizes
standard). Widely used in production fields API Specification 12F
Specifies requirements for materials, design, fabrication, assembly
and testing of steel tanks, not buried, soldiers
workshop, cylindrical and vertical. Rated capacity of 90 bbl of
750 bbl, maximum diameter 15.5 ft (standard size). Very
used in production fields N-270
Sets requirements for mechanical design of tanks, surface
carbon steel, welded fabrication, vertical and cylindrical, without
ceiling with ceiling fixed or floating oil storage
and derivatives. Maximum temperature of 260 C
N-271
Specifies requirements for assembly of steel tanks, soldiers,
cylindrical, vertical, operating at atmospheric pressure and
temperature of -6 to 150 o C and pressure up to 1 kg / cm 2 and
temperature of -50 to 95 C
N-1888
Fixed conditions for manufacturing workshop, and the
atmospheric transport tanks Fund should be tapered with a slope of less than 1:120
center to the periphery
Outline the bottom of the tank should be done with the plates
willing
Background
Butt joints commonly used in welding plates
ring (chamfered V or simple – with copper-gasket)
Lap joints commonly used in sheet
plants. Solders only in the upper fillet with total
Welding of the bottom plates with the first ring of the side are
made with continuous welding angle, the two sides with
size limits as below
Not exceed ½
Not less than the thickness of the plate thinner
Not less than the value of the table
Annular plate up to ½ adopts the following table
2 passes at least for material belonging to the side
groups IV, IVA, V or VI by API 650
Strengthening the bottom is used in the support structure
support the fixed roof supported (19 mm thick) in
regions support the floating roof (6.3 mm thick) and region
accessories
In regions of mixers is used plates with 2 mm
thickness most cost
Nominal thickness of plates
not be less than a minimum structural
set normally
based on assembly requirements
So it needs to increase the thickness of corrosion in this
minimum. See comparison table Backing
Arrangement of plates of sides:
symmetrical, most recommended, but almost fitting
impossible
outside surface esthetics, easy assembly and better
finish
the inner most usual in practice. Easy mounting and
regular finish. More common in floating roof
Vertical joints of adjacent rings must be out of phase by
least 1 / 3 the length of each plate
It is permissible for a minimum plate closing ring 5 times
nominal thickness of the ring thicker rings considered
There should be no accumulation of vertical joints in the same region of
side of the tank
Ceiling
api 650 as all ceilings and support structures must be designed to support your carf static, weight plates, own roof and support structures masi a live load including snow iferior to 120 kg / cm of projected area.
The amount of overhead required varies according to the standard
Material used is structural carbon steel (A-283 Gr B, Gr-570
33). Use plate superimposed
Minimum thickness is 3 / 16
Greater thicknesses may be required to ceilings
freestanding
Profiles support in A-36
Minimum slope of 1:16 bracing rings
Every tank must have to keep open circularity
when subjected to wind loads
Constructed from welded continuous weld profile. Sections
welded top. The ring can be circular or polygonal.
Intermediate rings may be necessary to maintain
circularity of the side when subjected to loads
Simultaneous wind and vacuum storage materials
Calendered sheets should be stored on cradles
suitable timber and at least 20 cm above the ground
Small parts such as flanges, screws, nuts,
washers should be stored in boxes and in dry
Surfaces machined parts should be protected
corrosion grease, anti-corrosive substances
The flange faces should be covered with wooden disc mount fund
Welds between the bottom and sides should be conducted after
welding of vertical joints of the first ring
(preferably after the second ring) and before welding
kernels of the fund with the peripheral plates.
Sequence traditionally adopted:
1. Implementation of the internal weld
2. Inspection of the internal weld
3. Implementation of the external solder
Inspection operation
Check the physical condition of the tank and its
components, internal and external
Determine the corrosion rate and evaluate the life of
tank
Assess the causes of deterioration and / or damage
Standard N-2318 lays down the requirements and practices
recommended for inspection of tanks in operation
carbon steel tanks for oil and derivatives
water, alcohol.