API 620 Appendix R Tanks for Storage of Refrigerated Product

TECHNICAL SPECIFICATION API 620 APPENDIX R TANKS FOR STORAGE OF REFRIGERATED PRODUCTS (FIELD ERECTED) DATE: 01 MAY 2003

ENGINEERING SERVICES BY KBR TECHNICAL SERVICES, INC.

MF40-3F PAGE 1 OF 16

TABLE OF CONTENTS Section 1. 1.1 1.2 1.3 1.4 1.5 1.6 2. 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 3. 3.1 4. 4.1 5. 5.1 5.2 5.3 5.4 5.5 5.6 5.7 6. 6.1 6.2 6.3 6.4 6.5 7. 7.1 7.2 7.3 8. 8.1 8.2 8.3 8.4 8.5 8.6 9. 10. 10.1 10.2 10.3 10.4 11.

Title Page No. GENERAL ......................................................................................................................................2 Scope..............................................................................................................................................2 Units of Measurement.....................................................................................................................2 KBR Documents, Codes, and Industry Standards .........................................................................2 Design Drawings and Data .............................................................................................................3 Technical Data to be Furnished with the Tank Manufacturer's Proposal .......................................3 Documentation and Records ..........................................................................................................4 DESIGN ..........................................................................................................................................4 General ...........................................................................................................................................4 Tank Shells .....................................................................................................................................5 Tank Bottoms..................................................................................................................................5 Tank Roofs......................................................................................................................................5 Corrosion Allowances .....................................................................................................................5 Nozzles and Connections ...............................................................................................................6 Anchor Bolting.................................................................................................................................6 Structural Steel ...............................................................................................................................7 TANK APPURTENANCES AND ACCESSORIES ........................................................................7 General ...........................................................................................................................................7 TANK INSULATION.......................................................................................................................8 General ...........................................................................................................................................8 FOUNDATION HEATING SYSTEM.............................................................................................10 General .........................................................................................................................................10 Design Requirements ...................................................................................................................10 Foundation Heating System Type ................................................................................................10 Method of Heat Distribution ..........................................................................................................10 Control and Monitoring .................................................................................................................11 Installation.....................................................................................................................................11 Spare Parts ...................................................................................................................................12 MATERIALS .................................................................................................................................12 General .........................................................................................................................................12 Filler Materials...............................................................................................................................12 Bolting ...........................................................................................................................................12 Gaskets.........................................................................................................................................12 Supplementary Materials ..............................................................................................................12 FABRICATION .............................................................................................................................12 General .........................................................................................................................................12 Welding .........................................................................................................................................13 Tolerances ....................................................................................................................................13 INSPECTION, REJECTION, EXAMINATION, REPAIRS, AND TESTING .................................13 Purchaser's Inspection..................................................................................................................13 Third Party Inspection...................................................................................................................13 Rejection .......................................................................................................................................13 Examinations ................................................................................................................................13 Repairs..........................................................................................................................................14 Testing ..........................................................................................................................................14 PURGE AND COOL-DOWN ........................................................................................................14 MARKING, PAINTING, AND SHIPPING .....................................................................................15 Marking .........................................................................................................................................15 Painting .........................................................................................................................................15 Preparation for Shipping ...............................................................................................................15 Shipping ........................................................................................................................................15 MANUFACTURER'S DATA REPORTS ......................................................................................15




1. GENERAL 1.1 Scope This specification defines mandatory technical requirements for the design, materials, fabrication, shipping, erection, inspecting, and testing of API 620 Appendix R Tanks for the storage of refrigerated products. Tanks supplied to this specification shall be limited to flat bottom, single or double wall cylindrical shell, dome or umbrella roof tanks. 1.2 Units of Measurement US Customary units or metric units of measurement shall be used by the manufacturer for drawings and calculations consistent with the units of measurement shown on Purchaser's drawings or data sheets. 1.3 KBR Documents, Codes, and Industry Standards The following documents are referenced herein and form part of the Order. Additional KBR documents, when applicable, will be listed on the Requisition. The issue dates of KBR documents shall be as specified in the Requisition. Current editions of the industry standards including all mandatory addenda in effect at the time of the Order shall apply unless otherwise indicated. (Note: KBR will be referred to as the Purchaser.) KBR DOCUMENTS 4-7TS, "General Welding Requirements" MF40-1PS, "General Purchasing Requirements for API Storage Tanks" P18-1D, "Selection of Gasket Materials" SDR-1MDMF, "Supplier Drawing and Data Requirements For Pressure Vessels, API Tanks, Vessel Trays and Internals" AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) ASME B1.20.1, "Pipe Threads, General Purpose (Inch)" ASME B16.5, "Pipe Flanges and Flanged Fittings NPS 1/2 through NPS 24" ASME B16.11, "Forged Steel Fittings, Socket-Welding and Threaded" ASME B16.47, "Large Diameter Steel Flanges NPS 26 through NPS 60" AMERICAN PETROLEUM INSTITUTE (API) API 620, "Design and Construction of Large, Welded, Low-Pressure Storage Tanks" API 650, "Welded Steel Tanks for Oil Storage" API 2000, "Venting Atmospheric and Low-Pressure Storage Tanks-Nonrefrigerated and Refrigerated" AMERICAN INSTITUTE OF STEEL CONSTRUCTION (AISC) AISC, "Manual of Steel Construction, Allowable Stress Design" AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) ASTM A537, "Pressure Vessel Plates, Heat Treated, Carbon-Manganese-Silicon Steel" ASTM C549, "Perlite Loose Fill Insulation" PERLITE INSTITUTE (PI) PI-201, "Compacted Density"




1.4 Design Drawings and Data 1.4.1 The Purchaser will furnish the manufacturer with drawings or data sheets specifying the tank configuration, dimensions, capacity, generic material requirements, design pressures and temperatures, allowable heat leak, heat gain or percent boil-off, product specific gravity, corrosion allowance, insulation and painting requirements, wind, earthquake, and snow load design criteria, certain construction details and engineering data as required by the manufacturer to mechanically design and construct the tank. 1.4.2 When the Purchaser requests the manufacturer to furnish a tank conforming to the manufacturer's proprietary design, the materials of construction and other construction details shall be selected by the manufacturer based on the design conditions specified by the Purchaser. 1.4.3 Acceptance of Vendor drawings and data with details, which deviate from those shown on Purchaser's drawings, data sheets, or specifications, does not constitute acceptance of the deviations. Manufacturer shall obtain separate written approval from Purchaser for all such deviations, prior to submission of drawings and data, for Purchaser's review and acceptance. 1.5 Technical Data to be furnished with the Tank Manufacturer's Proposal The following technical information shall be included as a part of the proposal: a.

The proposed plate thickness and material specifications for the roof, shell, bottom, annular plates, and compression rings.

b.

The proposed type of roof, roof radius, and type of welded roof joints.

c.

The proposed insulation type and thickness.

d.

The "K" values for each insulation component (e.g., roof, shell, and bottom insulation).

e.

The size, quantity and length of anchor bolts or straps (if design and construction of the tank foundation is excluded from tank manufacturer’s proposal).

f.

The tank dimensions and liquid height when the manufacturer is responsible for sizing the tank for a specified design capacity.

g.

Foundation design loads for Purchaser's use in designing tank foundations. The required loads are as follows (when foundation design is by Purchaser): Load shell dead load roof dead load (applied to shell) insulation dead load (applied to shell) roof live load (applied to shell) roof partial vacuum load (applied to shell) wind moment and shear at tank bottom earthquake moment and shear at tank bottom (tank full of liquid) 8. product and design pressure loads on tank bottom 9. test water and test pressure loads on tank bottom 10. tank bottom insulation load 11. maximum uplift on each anchor bolt or strap

1. 2. 3. 4. 5. 6. 7.

Units lb/ft (N/m) of circumference lb/ft (N/m) of circumference lb/ft (N/m) of circumference lb/ft (N/m) of circumference lb/ft (N/m) of circumference ft-lb (N·m) and lb (N) ft-lb (N·m) and lb (N) lb/ft2 (Pa) lb/ft2 (Pa) lb/ft2 (Pa) lb (N)




The earthquake moments transmitted to the Purchaser must include both the overturning moment at the bottom of the tank shell and the overturning moment applied to the tank foundation. The moment applied to the tank foundation shall be calculated in accordance with the paper titled "BASIS OF SEISMIC DESIGN PROVISIONS FOR WELDED STEEL OIL STORAGE TANKS" by R.S. Wozniak and W.W. Mitchel published in API Proceedings 1978, 43rd Midyear Meeting. h.

Calculated liquid slosh heights (under design earthquake conditions).

i.

Catalog information on crushing strength of load bearing insulation.

j.

Calculated boil-off rate based on the proposed insulation system.

k.

For tanks on elevated pile cap, the minimum air gap below the pile cap for air circulation.

l.

Size, quantity and catalog information for the pressure and vacuum relief valves including for spare valves.

m. Catalog information on proposed level gauge, level alarms and transmitters. n.

The maximum differential settlement that the proposed tank can be allowed to tolerate without affecting its structural integrity.

1.6 Documentation and Records The Seller shall submit drawings and data of the type and quantity as specified on Purchasing Standards MF40-1PS and SDR-2MF. Instructions and requirements for Vendor's drawings and data are contained in Purchasing Standard SDR-1MDMF. 2. DESIGN 2.1 General 2.1.1 Design pressures, temperatures, product specific gravity, corrosion allowance, generic material specifications, insulation and painting requirements, wind, earthquake, and snow load design criteria, and storage capacity will be specified on the Purchaser's drawings or data sheets. 2.1.2 Normal and emergency vents shall be provided based on the venting capacity determined in accordance with API 2000. 2.1.3 Manufacturer shall check the acceptability of loads on the shell openings in accordance with API 650, Appendix P, when requested by Purchaser. 2.1.4 For design of piping system connecting to tank nozzles, manufacturer shall calculate and furnish to Purchaser, the maximum radial and vertical movements for each nozzle due to contraction of tank. 2.1.5 Figure 2 shows tanks resting on elevated pile cap foundation and the Figure 3 shows the tanks resting on ring wall foundation. There are following three tank types shown in Figures 2 and 3. Type A: Single wall single integrity tank using impact tested materials per API-620, Appendix R. Type B: Double wall single integrity tank using impact tested materials for inner tank per API-620, Appendix R. The inner tank is designed to hold product and the outer tank is designed as a container for insulation in the annulus between the inner and outer tank shells, and as a container for the product vapor. Only the inner tank is required to be hydrostatically tested.




Type C: Double wall double integrity tank using impact tested materials for both inner and outer tanks per API-620, Appendix R. The shell and bottom insulation are applied on the outside of the outer tank only. The inner and outer tanks are both designed to hold the product and are both required to be hydrostatically tested. The required tank type will be specified on the drawings or data sheets. 2.2 Tank Shells 2.2.1 Shell seams shall be located to clear openings and weld joints in compression ring to the maximum extent possible in accordance with Paragraph R 7.4 of API 620. 2.2.2 The maximum thickness of shell plates shall be 1 1/2 inch (38mm). 2.2.3 The outer shell of double wall tanks shall be of buttwelded construction. 2.3 Tank Bottoms 2.3.1 Butt-welded annular bottom plates shall be furnished under liquid-containing shells. 2.3.2 Bottom plates inside the annular plates may be lap-welded with full fillet welds with the lap toward the direction of drainage. Buttwelded bottom plates shall be furnished when specified on the design drawings or data sheets. 2.3.3 The minimum thickness of bottom plates for single wall tanks or the inner tank of double wall tanks shall be 1/4 inch (6.35 mm) exclusive of corrosion allowance in accordance with API 620, Paragraph 5.9.4.2. 2.4 Tank Roofs 2.4.1 Tank roofs shall generally be of a dome configuration with a minimum roof radius of 0.8 x D and maximum roof radius of 1.2 x D, where D is the normal diameter of the tank. Unless otherwise specified, tank roofs shall be designed for a minimum load of 25 lb/ft2 (1.2 kPa). 2.4.2 Roof plates may be lap-welded. Buttwelded roof plates shall be furnished when specified on the design drawings or data sheets. 2.4.3 All components of dome or stiffened umbrella roofs shall be designed to resist specified loads and pressures. Consideration shall be given to bending moments induced in undished roof plates of umbrella roof such that the intent of API 620, Paragraph 5.1.1 is met. 2.4.4 Tank roof design shall be such that the vapor space volume above the design high liquid level, upon which the nominal capacity is based, is not be less than 2% of the total liquid volume. 2.5 Corrosion Allowances 2.5.1 The full specified corrosion allowance shall be added to the calculated thicknesses of shell, roof and to the minimum shell thickness required by API 620, Paragraph 5.10.4.1 (a), and to the minimum thickness of bottom plate specified in Paragraph 2.3.3 above. 2.5.2 One half of the specified corrosion allowance shall be added to each surface of internal members.




2.6 Nozzles and Connections 2.6.1 Flange bolt hole orientation shall be as follows: a.

When the flange is in a horizontal plane, the bolt holes shall straddle the north-south centerlines indicated on the design drawings.

b.

When the flange is in a vertical plane, the bolt holes shall straddle the vertical centerline of the flange.

c.

Bolt hole orientation of flanges not specified above will be shown on the design drawings, or per Figure 1.

FIGURE 1 - BOLT HOLE ORIENTATION 2.6.2 Raised face and flat face flanges shall be furnished with a stock gasket surface finish. 2.6.3 Flanges for external nozzles NPS 24 and smaller shall be in accordance with ASME B16.5 for the rating and type of facing specified. Flanges for external nozzles NPS 26 through NPS 60 shall be in accordance with ASME B16.47, Series B. For sizes over NPS 60, flange dimensions will be shown on the drawings or data sheets. Manways or other access openings may be designed in accordance with API 620, Paragraph 5.20. 2.6.4 Each reinforcing pad or segment, if more than one piece is used, shall be furnished with two NPS 1/4 NPT threaded holes. Welds in segmented two-piece reinforcing pads on shell shall be in the circumferential direction. The outside edge of reinforcing pads shall be ground smooth before welding to tank. 2.6.5 Threaded connections shall be Class 6000 couplings in accordance with ASME B16.11. 2.6.6 All threaded connections shall have NPT threads in accordance with ASME B1.20.1. 2.7 Anchor Bolting Anchorage shall be designed in accordance with API 620, Paragraph 5.11.2.3. When Purchaser designs the tank foundation, tank Manufacturer shall furnish complete design and details of the anchors to Purchaser and shall also furnish any anchors that are not anchor bolts.




2.8 Structural Steel 2.8.1 Ladders, stairways, platforms, and handrails shall be furnished as follows: a.

An independent stair tower shall be furnished for single wall tanks and double wall tanks with external shell insulation.

b.

Double wall tanks with internal shell insulation 20 feet (6 meters) or less in height shall be furnished with a ladder without a cage and those greater than 20 feet (6 meters) in height shall be furnished with a spiral stairway or stair tower unless specified otherwise on tank drawing. The spiral stairway shall be furnished with an inside stringer; the treads shall not be welded directly to the shell.

c.

The ladder or stairway or stair tower, platforms and handrails may be of the tank manufacturer's standard design and shall comply with the requirements of Tables 3-17 and 3-18 of API 650 and AISC.

2.8.2 A landing platform shall be furnished at the top of the ladder or stairway. A walkway shall be furnished from the independent stair tower to a landing platform on the roof of the tank. Wing rails extending 6 feet (2 m) from the edge of the landing platform (on two sides along the circumference of the tank) shall be furnished. 2.8.3 Walkways shall be furnished extending from the landing platform to the center of the roof or to other platforms for access to and maintenance of roof-mounted accessories. 2.8.4 All walkways, stairways, and platforms shall be furnished with handrails on open or exposed sides. 2.8.5 Platforms shall be designed for a uniform live load of 75 lb/ft2 (3.6 kPa). 2.8.6 Unless specified on tank drawings or data sheets, the platform and stairway flooring shall be galvanized rectangular welded grating, 1 inch x 3/16 inch (25 x 5 mm) bearing bars on 1 3/16 in. (30 mm) centers and cross bars on 4 inch (100 mm) centers. If checker plate is specified, it shall be 1/4 in. (6 mm) thick. 3. TANK APPURTENANCES AND ACCESSORIES 3.1 General Tanks shall be furnished with the following: a.

A minimum of one 24 inch (610 mm) outside diameter roof manhole and one 24 inch (610 mm) outside diameter shell manhole.

b.

One ground-reading automatic level indicator gauge with digital readout, float, float guide wire assembly, and tape block valve.

c.

Pressure/vacuum vent valves (including an installed spare to permit maintenance on any one valve) equipped with car seal open block valves on the tank side.

d.

Four grounding (earthing) lugs.

e.

A scaffold cable support for tanks over 18 feet (5.5 m) diameter.

f.

A purge system for the annular insulated space of double wall tanks.

g.

Cool down spray rings or spargers for refrigerated product tanks.

TECHNICAL SPECIFICATION API 620 APPENDIX R TANKS FOR STORAGE OF REFRIGERATED PRODUCTS (FIELD ERECTED) DATE: 01 MAY 2003 h.



Temperature recording devices (RTD's) on tank parts to indicate the temperature profile during operation and cool-down located as follows: One set of four RTD's located around the outside of the primary shell, equally spaced, at shell to bottom junction and four more sets of RTD's equally spaced vertically up the primary shell and on same vertical line as the RTD's of bottom set. Starting at the same cardinal points as per the above RTD's, two circles of four RTD's spaced equally across the suspended deck. The RTD leads shall be terminated in a junction box near the bottom of the tank.

i.

Insulation fill nozzles on double wall tanks.

j.

Level alarms and level transmitters when specified.

4. TANK INSULATION 4.1 General 4.1.1 The insulation system shall generally consist of: a.

Cellular glass, perlite concrete, or other load bearing insulation approved by the Purchaser for the tank bottom

b.

Perlite and resilient blankets between the shells of double wall single integrity tanks

c.

Cellular glass, foamed-in-place polyurethane, or other systems for the shell and roof of single wall tanks and double wall double integrity tanks

d.

Alternatively, an internal suspended insulation deck in lieu of external roof insulation can be provided.

4.1.2 The insulation system shall be designed to limit the heat leak, heat gain or percent boil off to the specified amount. 4.1.3 External roof and shell insulation of single wall tank shall be covered with an aluminum vapor barrier unless otherwise specified in the Order. 4.1.4 Tank bottom insulation shall generally be installed as shown in Figures 2 and 3. Any alternate details shall be submitted with quotation for acceptance. 4.1.5 Allowable compressive stress of cellular glass bottom insulation shall be set using a safety factor of 3 at the full operating liquid load with design internal pressure applied to the manufacturer's published compressive stress. This safety factor may be decreased for temporary and seismic loads subject to approval by the Purchaser. 4.1.6 Expanded perlite shall meet the requirements of ASTM C549. Installed perlite shall have a compacted density between 3 and 4.5 lb/ft3 (50 and 70 kg/m3) as determined by Perlite Institute PI-201. 4.1.7 The width of the annular insulation space on double wall tanks shall be determined by the tank manufacturer for construction clearances, but as a minimum, sufficient width shall be provided to prevent surface condensation on the outer tank at 80% relative humidity and ambient design temperature.




VAPOR BARRIER

LOAD BEARING RING

VAPOR BARRIER

LOAD BEARING RING

SHELL INSULATION

SHELL INSULATION SAND CUSHION INSULATION

VAPOR BARRIER

SAND CUSHION

SAND CUSHION INSULATION

VAPOR BARRIER RING WALL

SAND CUSHION HEATING COILS

GRADE AIR CIRCULATION SPACE

GRADE

TYPE - A SINGLE WALL TANK

TYPE - A SINGLE WALL TANK

INNER TANK WALL

OUTER TANK WALL SHELL INSULATION

OUTER TANK WALL

LOAD BEARING RING SAND CUSHION INSULATION SAND CUSHION

SHELL INSULATION

INNER TANK WALL LOAD BEARING RING SAND CUSHION INSULATION

RING WALL

SAND CUSHION HEATING COILS

GRADE GRADE

AIR CIRCULATION SPACE

TYPE - B DOUBLE WALL TANK (SINGLE INTEGRITY)

OUTER TANK WALL

VAPOR BARRIER

TYPE - B DOUBLE WALL TANK (SINGLE INTEGRITY)

OUTER TANK WALL

VAPOR BARRIER

LOAD BEARING RING

LOAD BEARING RING SHELL INSULATION VAPOR BARRIER

INNER TANK WALL CONCRETE PAD SAND CUSHION INSULATION SAND CUSHION

INNER TANK WALL

SHELL INSULATION

CONCRETE PAD SAND CUSHION INSULATION

VAPOR BARRIER RING WALL

SAND CUSHION

GRADE GRADE

HEATING COILS

AIR CIRCULATION SPACE

TYPE - C DOUBLE WALL TANK (DOUBLE INTEGRITY)

DOUBLE WALL TANK (DOUBLE INTEGRITY)

TYPE - C

FIGURE 2 TANKS ON ELEVATED PIPE CAPS TYPICAL BOTTOM INSULATION DETAILS

FIGURE 3 TANKS ON RING WALL TYPICAL BOTTOM INSULATION DETAILS




5. FOUNDATION HEATING SYSTEM 5.1 General 5.1.1 A foundation heating system is required for all "cold" service tanks supported directly on soil foundations when the calculated soil temperature during normal or upset conditions is below 37oF (3oC). Unless specified otherwise, the electrical foundation heating system is to be designed and furnished by the tank manufacturer and the parts of the heating system to be embedded in or beneath the foundation shall be furnished by the tank manufacturer for installation by the Purchaser or the tank foundation contractor. 5.1.2 The Purchaser shall furnish the following information to the tank manufacturer for use in designing the foundation heating system: a.

Minimum stored-product temperature.

b.

Subsoil type (i.e., foundation description).

c.

Required heating system duty cycle (normally between 55% minimum and 80% maximum).

d.

Available power supply (voltage, cycles, phase).

e.

Area electrical classification.

f.

Meteorological data for design basis.

5.2 Design Requirements 5.2.1 The total heat requirement shall be calculated using accepted heat transfer calculations for heat migration from the subsoil through the foundation and the load-bearing insulation beneath the product storage tank. The calculations shall be made using stored product minimum temperature and a subsoil minimum design temperature of 37oF (3oC). 5.2.2 The foundation heating system shall be capable of supplying to the subsoil the total heat requirement from Paragraph 5.2.1 above, with a duty cycle of 55% minimum and 80% maximum. 5.2.3 The tank manufacturer shall state clearly in his foundation heating system design report, the time after any heating cable fails during service before the calculated subsoil temperature at any point beneath the tank will drop below 32oF (0oC). In no case shall the calculated time for the foundation subsoil to reach 32oF (0oC) be less than 7 days (168 hours). 5.3 Foundation Heating System Type The foundation heating system may be self-limiting or constant wattage parallel resistance type cables. 5.4 Method of Heat Distribution 5.4.1 The heating cables shall be installed in heavy wall rigid metal conduits, or approved equal, arranged in a physically-parallel pattern. The conduit shall have an appropriate corrosion resistant coating when so noted on the Purchaser's drawings. 5.4.2 The conduit may range from 1/2 inch (13 mm) trade size to 1 inch (25 mm) trade size. The conduit system shall be designed so that all heating cables are replaceable, if required, with the tank in service.




5.4.3 The conduit spacing shall be designed to minimize the number of conduits required, but the design shall ensure that there will be no cold spots beneath the foundation. Conduit spacing of 2 ft to 4 ft (600 to 1200 mm) are normally acceptable. Spacings outside this range require advance approval of the Purchaser. The system design shall be such that the required heat input to the subsoil will be provided by one conduit containing one heating cable at each design location. The tank manufacturer shall advise the Purchaser in his written foundation heating system design proposal of the maximum watt density used in design in watts per foot (watts per meter). 5.4.4 Heating cables shall be sufficiently flexible for initial installation and subsequent replacement in the conduit system provided. The cables shall provide the watt density required by the conduit spacing design to maintain the minimum design-basis subsoil temperature. The tank manufacturer shall specify to the Purchaser the electrical power requirements, such as transformer sizes required, as a part of his heating system design. The Purchaser will supply all electric cable and electrical system components from the first junction box outside the tank foundation to the power supply. Heating cable splices shall be avoided when possible; no heating cable splices are allowed beneath the tank foundation. The entire system shall be approved for the area electrical classification of the tank. 5.5 Control and Monitoring 5.5.1 The foundation heating system shall be provided with temperature measuring and controlling systems as follows: a.

Each tank shall be subdivided into zones. Each zone shall be controlled by an indicating temperature controller with RTD or thermocouple input. The RTDs or thermocouples shall be installed in rigid metal conduit midway between two heating conduits and at the same elevation as the heating conduits. The temperature controller shall energize a contactor to switch the electrical heating load. The RTD's shall be located as described in Paragraph 3.1.h.

b.

Each temperature controller shall be provided with a low temperature alarm contact for remote alarm annunciation.

c.

Unless otherwise noted, power supply will be 120 V AC 60 Hz. The Purchaser will provide and install all control system components remote from the tank area (power to controller, alarms, etc.). The tank manufacturer shall supply and install control system components from the tank foundation to and from the controller.

5.6 Installation 5.6.1 All heating cable and temperature measuring conduits shall be installed as shown on the tank manufacturer's drawings within ±1 inch (±25 mm) in any horizontal or vertical direction. Conduit splices shall be made by using threaded joints and couplings, with a spot weld on each threaded conduit splice joint to ensure tightness. 5.6.2 All conduits shall be installed free of dirt, sand, water, or other foreign substances. Each end of the conduit protruding from the foundation shall terminate in a threaded connection for installation of conduit caps or junction boxes. 5.6.3 The heating cable shall be installed according to the cable manufacturer's instructions. Each cable shall be tested for power output and insulation resistance after installation and before tank commissioning. Any defective cable shall be replaced prior to tank commissioning. Cable terminations shall be made according to the cable manufacturer's termination instructions. Heating cables with metallic braid shall have the braid securely grounded in the junction box. 5.6.4 The installation, calibration, and operation of the control system shall be according to the control system manufacture's instructions. All temperature controllers shall be calibrated, tested, and operated in a test run prior to tank commissioning.




5.7 Spare Parts The tank manufacturer shall provide spare parts (e.g., six spare heating cables of sufficient length to replace the longest cable segment beneath the tank without a splice being required, any special tools required to replace a failed heating element, RTDs or thermocouples, temperature controllers, etc.) for on-site warehouse storage. The quantity shall be sufficient for replacement of any failed heating system component without requiring parts to be ordered or delivered to the job site in the event of a failure. For multiple tanks installed at the same location with identical foundation heating systems, the tank manufacturer shall make an overall spare parts recommendation. 6. MATERIALS 6.1 General 6.1.1 All materials shall be new and as specified in the Order. 6.1.2 Material shall be impact tested as required by API 620 except that the impact test temperature for ASTM A537 material shall not be higher than -50oF (-45.5 oC). 6.2 Filler Materials Welding rods, electrodes, and wires shall be selected in accordance with Purchaser's Technical Standard 4-7TS. 6.3 Bolting 6.3.1 Bolt heads and nuts shall be heavy hex. 6.3.2 Stud bolts shall be threaded their full length. 6.4 Gaskets Gaskets shall be 1/16 inch (1.5 mm) minimum thickness non-asbestos fiber sheet compatible with the stored product or as specified on drawing or data sheet and shall comply with Purchaser's Design Specification P18-1D, unless specified otherwise on drawings and data sheets. 6.5 Supplementary Materials The tank manufacturer shall furnish blind flanges, manhole covers, bolts, and gaskets including one spare gasket for all manholes and all other nozzles specified to be furnished with blinds. 7. FABRICATION 7.1 General 7.1.1 Holes shall not be cut into the shell for erection purposes. 7.1.2 Plate misalignment shall not be corrected by grinding off plate thickness to reduce offset. 7.1.3 Arc strikes on the tank shall be avoided. When they occur, the surface shall be conditioned to eliminate surface stress raisers and shall be examined by the magnetic particle or liquid penetrant method.




7.2 Welding 7.2.1 Welding shall be in accordance with the applicable construction code and Purchaser's Technical Standard 4-7TS. 7.2.2 Fabrication involving welding shall not be sublet to others without the prior approval of the Purchaser. 7.3 Tolerances Tank nozzles shall be installed within the following tolerances: a.

Projection from the inside of the tank to the face of flange ±1/8 inch (±3.5 mm).

b.

Elevation or orientation ±1/4 inch (±6.5 mm).

c.

Flange tilt in any plane ±1/2 degree but not to exceed 3/16 inch (5.0 mm).

d.

For hillside nozzles, from face of flange to centerline of tank and from centerline of tank to centerline of nozzle ±1/4 inch (±6.5 mm).

e.

Flange bolt hole orientation ±1/16 inch (±1.5 mm).

8. INSPECTION, REJECTION, EXAMINATION, REPAIRS, AND TESTING 8.1 Purchaser's Inspection All materials and fabrication work shall be subject to inspection (shop and site) by the Purchaser. The manufacturer's drawings shall be made available to the Purchaser's inspector at the time of inspection. 8.2 Third Party Inspection The tank shall be subject to inspection by Purchaser’s qualified inspectors or by an approved third party inspection agency in the shop and in the field during fabrication, erection, and testing. The qualification of the inspector shall satisfy the requirement of API 620, Paragraph 7.2.1. 8.3 Rejection 8.3.1 Completed tanks, parts of tanks, or materials containing defects originating with the manufacturer's design, materials, or workmanship and that are not in complete compliance with the requirements of the Order will be rejected. 8.3.2 Discovery of such conditions after inspection and acceptance of the tank or tank components by the Purchaser does not relieve the manufacturer of his responsibility to comply with the requirements of the Order. 8.4 Examinations In addition to the construction code requirements, the finished surfaces of the tank bottom welds in contact with the stored liquid product shall be examined by the magnetic particle or liquid penetrant method.




8.5 Repairs 8.5.1 Welds with defective areas shall have: a. b. c. d.

The defect removed. Confirmation of defect removal by magnetic particle or liquid penetrant examination. Repair welding using qualified welding procedures. Re-postweld heat treatment if originally required.

8.5.2 The finished weld-repair shall be radiographed if originally required and the surface shall be re-examined by magnetic particle or liquid penetrant examination. If the repair involves serious alterations, the approval of the Purchaser shall be obtained before proceeding with the repair. 8.6 Testing 8.6.1 Testing shall be in accordance with the construction code. 8.6.2 Prior to the hydrotest, the inside of the tank shall be cleaned by sweeping, vacuuming, or other methods so that the tank will be "broom clean" and free of all trash, dirt, welding rod stubs, and other construction debris. 8.6.3 The tank manufacturer shall be responsible for conducting the tank hydrostatic-pneumatic test. Any limitations on filling rates or stage filling requirements for foundation consolidation will be specified by the Purchaser. 8.6.4 The tank manufacturer shall prepare a hydrostatic-pneumatic test procedure which shall state the maximum filling rate based on the total available venting-out capacity, taking into consideration all the pressure vents and the pressure/vacuum combination vents that are provided for normal and emergency venting per API 2000. This procedure shall also state the maximum emptying rate based on the total available venting-in capacity, taking into consideration all the vacuum vents and the pressure/vacuum combination vents that are provided for normal venting only per API 2000. Such filling and emptying rates shall not be exceeded during hydrotest at any time. The tank manufacturer may take into consideration the venting capacity of the roof manway or other roof connection in the calculation of emptying and filling rate, but the hydrotest procedure must clearly state that these openings must be open during filling and empting the tank. 8.6.5 The hydrotest shall be conducted with all accessories and appurtenances installed. 8.6.6 After completion of the hydrotest, the tank manufacturer shall drain the tank and open the tank for inspection. Final cleaning of the tank will be by the Purchaser. 9. PURGE AND COOL-DOWN 9.1 The tank fabricator shall conduct purge and provide an experienced advisor for cool-down of the tank. The tank fabricator shall provide all piping accessories, and a written procedure for tank dry-out, purging and cool-down which shall specify the tank cool-down rates, the method of introduction and distribution of cool-down fluid in the tank, the total quantity of cool-down fluid required, the vapor disposal method, nitrogen purge gas quantity with flow rate, and pressure used to maintain inert atmosphere in the tank until cool-down. 9.2 The tank fabricator shall be responsible for the safety and integrity of the tanks throughout testing, cool-down and the initial loading operation. 9.3 A special cool-down line, including a spray header, shall be provided under the center of the suspended deck to ensure gradual cool-down.




10. MARKING, PAINTING, AND SHIPPING 10.1 Marking 10.1.1 Stamping on all impact tested materials shall be with "low stress" steel stamps having round or "U" shaped cross sections or with "interrupted dot" die stamps. 10.1.2 Tank shall be provided with nameplate, in accordance with API 620, Paragraph 8.1.1. 10.2 Painting Surface preparation and painting shall be as specified on the tank drawings or data sheets. 10.3 Preparation for Shipping 10.3.1 All machined and threaded surfaces of carbon steel materials shall be coated with one of the following rust preventatives or equal approved by the Purchaser: E. F. Houghton Co. Rust-Veto Exxon Chemical Co. Rust-Ban

No. 342 No. 326

10.3.2 Weld bevels of carbon steel materials shall be coated with a weldable corrosion inhibitor such as one of the following rust preventatives or equal approved by the Purchaser: “Deoxaluminite” manufactured by:

AACCO 5220 N 125th Street Butler, Wisconsin 53007, USA Phone: (414) 781-7160 Fax: (414) 781-3558

“Aluminized Bloxide” manufactured by:

Tempil Inc. 2901 Hamilton Blvd. South Plainfield, New Jersey 07080, USA Phone: (908) 757-8300 Fax: (908) 757-9273

10.4 Shipping Requirements and responsibilities for transporting material to the construction site shall be as specified in the Order. 11. MANUFACTURER'S DATA REPORTS A Manufacturer's Data Report with certificate of compliance as shown on the next page shall be completed for each tank in accordance with API 620, Paragraph 8.3 and submitted to the Purchaser upon completion of all fabrication and testing. A separate Manufacturer's Data Report is required for each tank in a group of identical tanks.




MANUFACTURER'S DATA REPORT FOR LOW-PRESSURE STORAGE TANK Built to API Standard 620 Appendix R 1.

Job No __________________________ Purchase Order No.____________________________________ Tank No._________________________ Supplier Order No. ____________________________________

2.

Manufactured by ________________________For ___________________________________________

3.

Manufacturer's Tank Serial No. ______________Year of Completion _____________________________

4.

Fluid to be stored ________________Minimum Design Temperature _____________________________

5.

Type of Tank _________________________________________________________________________

6.

Inner Shell: Diameter __________Height ___________Nominal Capacity _____________________ bbls

7.

List Manufacturer's reference drawings giving details for tanks, material specification, connection, etc: ____________________________________________________________________________________ ____________________________________________________________________________________

8.

Design Pressure for Gas or Vapor Space at Top of Tank _______________________________________

9.

Maximum Permissible Specific Gravity of Liquid Contents to be Stored ____________________________________________________________________________________

10. Maximum Elevation to which Tank may be filled with Liquid of design specific gravity, with Full Design Pressure above surface_ ________________________________________________________________________ 11. Maximum Elevation to which Tank may be filled with Water for Test Purposes: ______________________ 12. Pressure and Vacuum Relieving Devices ___________________________________________________ We certify that the statements made in this report are correct and that the design, materials, construction, and workmanship on this low-pressure tank conform to the requirements of API Standard 620, Appendix R "Recommended Rules for Design and Construction of Large Welded, Low-Pressure Storage Tanks" and applicable supplementary requirements of this Purchaser's Specification. Date ____________Signed ________________________By ________________________(Manufacturer) CERTIFICATE OF INSPECTION: have I, the undersigned, having the required inspection qualifications and being employed by inspected the tank described in this Manufacturer's Data Report in accordance with the standards listed, and state that to the best of my knowledge and belief, the Manufacturer has constructed this tank in accordance with the applicable sections of the listed standards. By signing this certificate, neither the inspector nor his employer makes any warranty, expressed or implied, concerning the tank described in the Manufacturer's data report. Furthermore, neither the inspector nor his employer shall be liable in any manner for any personal injury or property damage or loss of any kind arising from or connected with this inspection. Date _________________

_____________________________________________________ (Inspector's Signature)

API 620 Appendix R Tanks for Storage of Refrigerated Product

Recommend Documents