Storage Tanks

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Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer) July 29, 2010Petrofac Saudi Arabia Ltd.Introduction to Storage Tanks July 29, 2010Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)To Give Basic Information on Storage Tanks used for Oil & Gas industryOBJECTIVES 2July 29, 2010 Tanks have been around since the beginning of hydrocarbon production. Tanks vary considerably, in the type and size, based on the type of products to be stored and the volume involved.The failure of a tank can have several undesirable effects such as endangering personnel, affecting the environment and interrupting the Operators business. Companies therefore, require a consistent approach for assessing tank integrity and maintaining compliance with industry and regulatory standards, (that is community requirements). Such an approach must;Ensure tanks are not leaking and will not leak before next inspectionReduce the potential for releasesMaintain tanks in safe operating conditions, andMake repairs and determine when replacement is necessary.

1. BackgroundStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)3 The primary function of a storage tank is to store liquid substance. This liquid substance may be:a) Water b) Feedstockc )Finished products prior to shipping out to customersd) and Unfinished petroleum components awaiting for further - processing - blending While in the storage tanks, these products may settle out undesirable substances such as; Water, Emulsions, Dirt etc. These undesirable substances can then be removed through draw-off devices. Products may also be mixed, blended and treated in storage tanks effectively, using the large capacity available in these tanks.

2. Functions of TankStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 20104Broadly, the storage tanks can be divided based on internal pressure:

Atmospheric Tanks:

Atmospheric storage is a term applied to tanks operating at or near atmospheric pressure. Although they are called atmospheric, they are operated at internal pressure slightly above atmospheric pressure ( pressure varies from atmospheric up to 0.5 psi above atmospheric.

Low Pressure Tanks:Within the context of the tanks, low pressure means that tanks which are designed for a pressure higher than atmospheric tanks. This means that these tanks are relatively high pressure tanks. These tanks are designed to operate from atmospheric up to 15 psig Note: Above types of tanks are used to hold liquid which will not vaporize at ambient temperature. Tanks used in this category are primarily the open top, fixed roof (cone & dome) and floating roof. These tanks are most commonly used

3. Classification of TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 20105

Pressurized storage :

Pressurized storage applies to those vessels (mounded bullets) which are designed to withstand pressure sufficient to keep the liquid stored, from vaporizing. High vapor pressure hydrocarbons such as propane, butane, iC5 are the types of products requiring pressurized storage vessels (Mounded Bullets).

Note: We will basically focus on aboveground vertical storage tanks of various types.

3. Classification of TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 20106 Above & below-ground tanks: There are many ways to classify the storage tanks. Most fundamental classifications based on whether they are above ground or below ground tank.Above ground tankThe above ground tanks have almost all their structure exposed. The bottom part of these tanks is placed directly above solid or concrete foundation.Advantages of these tanks are that they r easy to construct and can be built in for large capacities and cost less than underground tanksBelow ground tankThese tanks have less capacity than above ground tanks and are usually limited to between 20k liters (20 cum) to 75k liters (75cum)Can store fuel as well as variety of chemicalsThey are subjected to severe corrosion

Note: We will mainly focus on aboveground, vertical storage tanks of various types

4. Types of TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 20107 Open Top tank: This type of tank has no roof and shall be used for storing city water, fire water and cooling water

4. Types of Vertical TankStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 20108Based on Type of Roof

Fixed Roof Tanks: These tanks can be divided into cone and dome roof types and each can further subdivided into non pressure, low pressure, high pressure & very high pressure fixed roof tanks.

Non pressure Fixed roof tanks are suitable at atmospheric pressure and are therefore provided with open vents. The design pressure/vacuum is 10/ 5 mbar (g)Low pressure Fixed roof tanks are designed to work at low internal pressure or vacuum. The design pressure/vacuum is 25/ 8.5 mbar (g). They are provided with pressure/vacuum breather valves ser to be fully open at design pressure. High pressure Fixed roof tanks are designed to work at higher internal pressure or vacuum and are also fitted with pressure/vacuum breather valves set to be fully open at design pressures. The design pressure/vacuum is 60/ 8.5 mbar (g). Very High pressure Fixed roof tanks are designed to work at higher internal pressure or vacuum and are also fitted with pressure/vacuum breather valves set to be fully open at design pressures. The design pressure/vacuum is 500 / 20 mbar (g).

Can be used to store hydrocarbons as per product classification as given for example in the IP code.

4. Types of Vertical TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 20109 Fixed Roof TanksA1 Cone Roof :These tanks have vertical sides and is equipped with a fixed cone shaped roof that is welded on the sides of the tank.Bottom is usually flat & the top is made in the form of shallow cone. They are economical to built ,These are the most widely used tanks for storage of relatively large quantities of fluid.

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4. Types of Vertical TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201010 Fixed Roof Tanks :(A1) Cone Roof :Self Supported Cone roof:

As per API 650, the slope angle of these tanks should be 37 (slope 9:12) , 9 (slope 2:12) These are relatively smaller sizes of tank

4. Types of Vertical TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201011 Fixed Roof Tanks :A1. Cone Roof : Supported Cone Roof As per API 650 Slope of supported cone Roof is 19mm in 300mm or greater approx 4 Support can be in the form of Truss, Column . For large diameter fixed roof tanks single or multi column supported roof are used.

4. Types of Vertical TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201012 Fixed Roof Tanks :(A1) Cone Roof :Single Column Supported Cone Roof ( construction of Roof)

4. Types of Vertical Tanks

Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201013 Fixed Roof tanks:A1 Cone Roof :Multi Column Supported Cone Roof


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201014 Fixed Roof tanksA2 Dome Roof :Dome approximates a spherical surface. These tanks are self supported


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201015 Fixed Roof tanksA3 With Internal Floating Cover (IFRT) In fixed roof tanks internal floating roof (IFC) can be installed to give a further reduction of vapor losses . These tanks can be designed as non, low & high pressure tanks. For safety & environmental reasons, internal floating covers shall be of full contact type.In addition to cone roof the tanks has an internal floating roof pan is provided that floats directly on fuel surfece.


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201016 Fixed Roof tanksA3 With Internal Floating Cover (IFRT) : Internal ViewsThese types of tanks can easily be identified with open vents in the tank side walls just beneath the roof joint

4. Types of Vertical TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201017 Fixed Roof tanks A3 With Internal Floating Cover (IFRT) (Pictorial views)


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201018Internal view of an internal floating roof tank


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201019EXTERNAL FLOATING ROOF TANKS (EFRT)Recommended for diameters of 15 m & above however can be used for small diameters in special circumstancesThese types of tanks are designed to work at atmospheric pressureDiameters Common Types of Floating Roof Tanks are::

Pontoon Single Deck Floating Roof:A pontoon single deck type of roof consists of an outer pontoon ring divided by bulk heads into liquid tight compartments with an inner section of ordinary steel plates acting as single deck membrane. This type of roof is recommended for tanks diameters up to 48m.

Double deck Floating Roof: A double deck floating roof consist of an upper and lower deck extending over entire area of liquid surface. The lower deck is separated from upper deck by circumferential rim plates and radial bulk heads to form a liquid tight compartments.

4. Types of Vertical TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201020EXTERNAL FLOATING ROOF TANKS (EFRT) (site view)


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201021EXTERNAL FLOATING ROOF TANKS (EFRT)


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201022EXTERNAL FLOATING ROOF TANKS (EFRT) Diagrammatic View


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201023EXTERNAL FLOATING ROOF TANKS (EFRT)Details of Flexible Seal employed for Floating Roof TankThe floating roof has mechanical seal attached to its full perimeter . The rim seal covers the space between the floating roof and the tank shell (side wall)


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201024EXTERNAL FLOATING ROOF TANKS (EFRT) Pictorial view


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201025EXTERNAL FLOATING ROOF TANKS (EFRT) Pictures from site

The purpose of using floating roof (internal/external) is that they minimize evaporation by covering the liquid surface


Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201026 COMMON INTERNATION ALSTANDARDS:

API 650 : (American Standard)Covers design fabrication, erection and testing requirements of vertical, above ground, closed & open top welded steel storage tanks fro various sizes & capacities .For internal pressure approximating atmospheric, but higher internal pressure is permitted when addition requirements are met and Appendix F is followed.

ii.API 620: (American Standard)Covers large field assembled storage tanks that contain petroleum intermediates (gas or vapour) and finished products.The standard covers design & construction of large welded low pressure carbon steel above ground storage tanks.

iii.API 579: (American Standard) is fitness for service standard and was developed to evaluate flaws & damage associated with in service operation.

5. Design Codes/Standards used for TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201027a.COMMON INTERNATIONAL STANDARDS:

iv.BS EN 14015 ( British Standard)Specification covers the design manufacturing of site built, vertical, cylindrical flat bottomed, above f ground, welded steel tanks for storage of liquids at ambient temperature & above.

Shell DEP ( 34.51.01.31-Gen) Covers the design requirement of shop assembled and site built, vertical, cylindrical flat bottomed, above ground, welded steel tanks Shell DEP ( 64.51.01.31-Gen) This is extension of above DEP & covers the Erection & Testing of vertical tanks

UL 142 ( Underwriter laboratory)Covers design & construction requirement of above ground storage tanks

UL 52 ( Underwriter laboratory)Covers design & construction requirement of below ground storage tanks

5. Design Codes/Standards used for TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201028b.COMPANY STANDARDS:

32-SAMSS-005 ( Manufacturing of Atmospheric Tanks)

32-SAMSS-030 ( Manufacturing of Small Tanks)

5. Design Codes/Standards used for TanksStorage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 201029

6.Question/ Queries?Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 2010

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Storage Tanks ( basic info) Prepared by: M.SIRAJUDIN (Sr. Static Equipment Engineer)July 29, 2010

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Storage Tanks