Section 6 — Rotating Equipment

Centrifugal Fans in General Refinery Service

IPE Engineering Practice IPE-EP-6-6-1

Document number: IPE-EP-6-6-1 · Section: 6 — Rotating Equipment

SCOPE

• This Practice covers the minimum requirements for centrifugal fans in General Refinery Services. For special purpose fans requiring special consideration due to the gas handled and/or are unspared units necessary for uninterrupted, critical services, API 673 shall be applied.
• Additional requirements and detail design data shall be specified in the attached centrifugal fan Data Sheets, per EP 6-6-1DS.
• The vendor may offer alternative designs for consideration if they are cost effective while meeting the technical requirements.
• All conflicts between the requirements of this Practice and the purchase order or Data Sheets shall be referred to the Purchaser for clarification and/or approval before proceeding with the manufacture of the affected parts.
• Any deviation from this Practice must be approved by the procedure described in EP 1-1-3.
• All exceptions taken to this Practice and EP 6-6-1 DS shall be clearly stated in the vendor proposal.
• Table 4 records the vendor drawing and data requirements.
• A revision bar indicates all changes made to this Revision.

REFERENCES

• The latest edition of the following standards and publications are referred to herein.

STANDARDS AND PUBLICATIONS

STANDARDS AND PUBLICATIONS (CONTINUED)

• The vendor and the Owner shall mutually determine the measures that must be taken to comply with any federal, state or local codes, regulations, ordinances, or rules that are applicable to the equipment.

DEFINITIONS

• Evase - A diffuser or a diverging discharge transition piece.
• Fan Rated Point - Defined as (1) the highest speed necessary to meet any specified operating condition and (2) the rated capacity required by fan designs to meet all operating points.
• Fan Rotor - The assembly of the fan impeller and the shaft.
• Fan Wheel - The assembly including the blades, centerplate (or back plate), shrouds and wear plates, if used.
• Forced Draft Fans - Usually have ambient inlet conditions and are in air service.

• Heat Slinger (heat shaft) or Shaft Cooler - A fan mounted on the shaft between the seal and bearings that reduces heat transfer from the fan housing to the bearings.
• Induced Draft Fans - Usually have suction conditions that are not ambient and can be found in various gas applications.
• Inlet Cubic Feet per minute (ICFM) - Refers to the flow rate determined at the conditions of pressure, temperature, compressibility and gas composition at the inlet flange.
• Inspector - A Refining Company appointed engineer or inspector.
• Manufacturer - The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a Manufacturer by a Contractor or the Owner. An indirect order is one issued to a Manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.
• Maximum Allowable Speed (revolutions per minute) - The highest speed at which the Manufacturer's design will permit continuous operation.
• Maximum Allowable Temperature - The maximum continuous temperature for which the Manufacturer has designed the equipment (or any part to which the term is referred) when handling the specified fluid at the specified temperature.
• Maximum Continuous Speed (revolutions per minute) - The speed at least equal to the product of 105 percent and the highest speed required by any of the specified operating conditions.
• Minimum Allowable Speed (revolutions per minute) - The lowest speed at which the Manufacturer's design will permit continuous operation.
• Normal Operating Point - the point at which usual operation is expected and optimum efficiency is desired. Unless otherwise specified, fan performance shall be guaranteed at this point.
• Owner - Refining Company.
• Owner's Engineer - A Refining Company appointed engineer.
• Purchaser - The party placing a direct purchase order. The Purchaser is the Owner's designated representative.
• Sound Trunk - The silencer(s) plus transition piece(s) between silencer(s) and fan.
• Standard Cubic Feet Per Minute (SCFM) - Refers to capacity at a pressure of 14.7 pounds per square inch absolute (1.01 bar) and a temperature of 60°F.

• Trip speed (revolutions per minute) - The speed at which the independent emergency overspeed device operates to shut down a prime mover.

4.0 BASIC DESIGN

4.1

4.1.1

4.1.2

4.1.3

4.1.4

4.1.5

4.1.6

4.1.7

4.1.8

4.1.9

4.1.10

4.1.11

General

Coordination

• The fan vendor shall coordinate, expedite and resolve any problems with his subvendors. The vendor shall also be responsible for the design and satisfactory performance and operation of the complete unit, i.e., fan, gear, coupling, driver(s), instrumentation and all auxiliary equipment.
• If the drive is purchased separately, the fan vendor shall provide all necessary fan data that enable the drive vendor to size and design the fan drive, i.e., WR2 of the rotor assembly, critical speeds, shaft dimension, key-way details, etc.

The equipment, including auxiliaries, shall be suitable for the specified operating conditions.

The fan shall be designed and constructed to operate satisfactorily at all specified operating conditions, maximum continuous speed, and to the trip speed setting of the driver.

The vendor shall assume responsibility for the engineering coordination of the equipment and all auxiliary systems included in the scope of the order.

The fan unit and its auxiliaries shall be suitable for operation under the conditions of location and site data specified on the Data Sheets. The vendor shall list in the proposal any special protective measures required or recommended.

The arrangement of the equipment, including ducting and auxiliaries, shall be developed jointly by the vendor and the Owner. The arrangement shall provide adequate clearance areas and easy access for operation and maintenance.

The arrangement of the equipment, including ducting and auxiliaries, shall be developed jointly by the vendor and the Owner. The arrangement shall provide adequate clearance areas and easy access for operation and maintenance.

Fan performance shall be based on the static pressure differential across the fan inlet and outlet flange. Silencer and inlet damper losses, including control system losses, shall be added by the fan vendor to the pressure differential given on the fan Data Sheets.

Performance curves shall have a continuous rising pressure characteristic from the rated point, as specified, to 50 percent or less of the rated flow. The vendor shall provide the lowest flow at which the fan can operate stably without exceeding the noise and vibration limits imposed by this Practice.

Performance curves, corrected for the specified conditions, shall be based on performance tests of actual or prototype equipment, including evase, if any, and inlet box(es). For variable speed drives, the vendor shall furnish a set of performance curves at various speeds specified on the data sheets.

Fans used in applications where the inlet gas temperature is above ambient temperature shall be mechanically designed for operation at least 150°F above the maximum specified inlet gas temperature. The maximum allowable rate of change in temperature shall be provided.

• The fan, components, and accessories shall be designed to withstand all loads and stresses during rapid load changes such as across-the-line starting of motor drivers, failure of damper operator, and sudden opening of dampers.
• The fan shall be of "stiff shaft" design with the first lateral critical speed at least 25 percent above the maximum continuous speed. Fans with rated speed exceeding 1200 revolutions per minute shall require prior approval by the Owner's Engineer.
• Unless otherwise specified, for forced draft fans, the entire inlet stack arrangement, including rain hood, trash screen, silencer(s), transition piece(s), inlet damper or guide vanes, inlet box(es) shall be provided by the fan vendor. The entire stack shall be self-supporting on the fan housing. All components shall be flanged for easy removal/reassembly. The stack shall be designed to withstand the specified windload. The minimum plate thickness for the above components shall be 1/4 inch. Unless otherwise specified, the air intake shall be at least (10) feet above the shaft center line.
• All equipment shall be designed to permit rapid and economical maintenance.
• Unless otherwise specified on the Data Sheets, the fan arrangement and bearing support shall be in accordance with AMCA Standard 99-2404-78, arrangement 3, with the fan wheel located between bearings, the bearing mounted on independently supported pedestal, and the bearings protected from the air or gas stream when any of the following conditions exists:
• Impeller diameter greater than 50 inches for forced draft service and 30 inches for induced draft service.
• Driver rated power of 100 Horsepower or greater.
• Speed of 1200 RPM or greater.
• Toxic, flammable, or other hazardous service.
• 300°F or greater design temperature.
• Corrosive or erosive service.
• Service subject to fouling deposits that could cause rotor unbalance.
• Unless otherwise specified, the sound level of all equipment furnished by the vendor shall comply with the requirements of the Owner's Recommended Environmental Guidelines. If a silencer is required, detailed drawings and an instruction manual on the silencer(s) shall also be provided with the proposal.
• The vendor shall furnish, as part of the initial supply of the fan, any special tools and fixtures required to assemble, disassemble, or maintain the units.
• Fan Housing
• Unless otherwise specified, the fan housing shall be a minimum plate thickness of 1/4 inch, with flanged outlet and flanged inlet boxes. Induced draft fan housings used in erosive and/or corrosive service shall have a minimum plate thickness of 3/8 inch.
• The fan housing shall be of continuously welded plate construction with scroll housing(s). For arrangement 3 fans, the housing and inlet box(es) shall be split at a bolted, flanged and gasketed connection to permit easy removal of the assembled rotor without disturbing duct connections and rotor alignment. Other arrangements shall have a similar split where the rotor diameter exceeds 40 inches. Stiffeners shall be provided to form a rigid housing free of structural resonances, and to limit noise and vibration. If specified on the Data Sheet, the housing shall be furnished with insulation studs that shall be welded in place before painting.
• The inlet cone(s) shall be constructed such that it does not impede rotor removal or installation. The cone must be split, separately removable as a whole, or removable in assembly with the rotor.

• Flanged, bolted and gasketed access doors, minimum size 24 inches X 24 inches shall be provided in the scroll and the inlet box(es) for access to the fan internals for inspection and service. If fan size and construction will not permit 24 inch X 24 inch access doors, the largest possible access openings shall be provided in the scroll and inlet boxes.
• Fan Housing Connections
• Inlet and discharge connections shall be flanged and bolted. Unless otherwise specified, gaskets and bolting of the inlet and discharge connections shall be specified and provided by the vendor of readily available commercial material. Gaskets shall not be made of asbestos containing materials.
• Connections welded to the fan housing shall meet the housing material requirement including impact values.
• Fan housing openings for pipe connections shall be at least 3/4 inch nominal pipe size and shall be flanged or machined and studded. Where flanged or machined and studded openings are impractical, threaded openings in pipe sizes of 1-1/2 inch and smaller are permissible.
• Accessible drain connections, 2 inch minimum size, shall be provided at the lowest possible points of the housing and inlet boxes. Solid, round-head stainless steel plugs shall be furnished for threaded connections.
• All of the Purchaser's connections shall be accessible for disassembly without moving the equipment.
• For forced draft fans, an accessible tapped opening, 2 inch minimum size, with plug shall be furnished at the transition piece between silencer(s) and inlet box(es) for field testing purposes.
• The vendor shall provide expansion joint information and recommendations, if joints are required for thermal expansion and/or vibration isolation.
• Rotating Elements
• Materials selection shall be by joint agreement between the vendor and Purchaser. The vendor shall provide material thicknesses, and construction details for each rotor assembly as requested on the Data Sheets.
• Unless otherwise specified, backward inclined blade designs shall be selected. In forced draft services, with low turn-down capacity required, air-foil blade designs can be considered. In dirty, abrasive gas and/or high pressure applications, radial tipped designs shall be used.
• Welded construction of the fan wheel is required.
• Impellers shall have solid hubs, be keyed to the shaft and be secured with an interference fit. The impeller hub to shaft fit design shall preclude axial movement of the hub along the shaft caused by gross changes in temperature. Fan wheels bolted to the hub require special approval by the Owner.
• Shafts shall be of one piece, heat treated, forged steel, suitably ground. Shafts 6 inch in diameter and smaller may be machined from hot rolled steel. Welding on the shaft is not permitted. Hollow shaft designs are not acceptable.
• Shaft Sealing of Fans
• Shaft seal clearances and materials shall be based on the operating temperature as specified. High temperature excursions shall also be considered in the design.
• Shaft seals shall be easily accessible for replacement from the outside of inlet boxes without disturbing the shaft and/or bearings.

• Critical Speeds
• Resonances of support systems within the vendor's scope of supply shall not occur within the specified operating speed range or specified separation margins, unless the resonances are critically damped.
• Unless otherwise specified, the separation margin of encroachment from all lateral (including rigid and bending) modes shall be at least 25 percent above the maximum continuous speed.
• Torsional modes of the complete fan-driver unit shall be at least 10 percent removed from any possible excitation frequency within the specified operating speed range (from minimum to maximum continuous speed).
• Balancing
• Unless otherwise specified, each rotating assembly shall be dynamically balanced in accordance with 4.7.1.1 through 4.7.1.6 listed below:
• The shaft and wheel shall be weighed individually before balancing. The actual weight shall be recorded on the inspection report.
• Prior to rotor assembly, the shaft shall be inspected for mechanical runout and concentricity at the wheel mounting surface seat and bearing journals. Shaft runout is the total indicator reading in a radial direction when the shaft is rotated in V-blocks. Runout shall not exceed the total indicator reading shown in Table 1.
• A runout recheck shall be made after rotor assembly and prior to balancing. Also, face runout on the thrust collar shall be checked.
• The balancing machine shall be calibrated before the rotor balance.
• Balance weights, if required, shall not exceed 1/4 inch in thickness or exceed the thickness of the member to which the weight is attached and shall be continuously welded onto the wheel in two or three defined balancing planes. Those balance weights required in the gas passage shall be ground to the impeller surface at a fillet angle not exceeding 20 degrees.
• The residual unbalance shall not exceed the value given in Figure 1 taken from the International Organization for Standardization (or ANSI S 2.19) balance grade of G.6.3, or balance grade G.2.5 for high temperature services where the gas temperature is over

300°F and/or fans with a 300 HP drive or larger. The Owner shall specify the balance grade on the Data Sheets.

• A witnessed critical frequency test (impact test) shall be performed on the rotor assembly after balancing for fans with variable speed drive (above 50 HP) and /or having a driver of 200 HP and greater.
• Bearings and Bearing Housings
• Purchaser may specify dry-sump oil mist for rolling element bearings. Unless otherwise specified, each fan rated at greater than 200 HP shall have horizontally split, self-aligning sleeve bearings supported on rigid independent pedestals and sole plates outside the fan housing. Provisions for air or water cooling shall be provided if the gas temperature exceeds 200°F.
• When the use of anti-friction bearings is approved or specified by the Owner, they shall be self aligning and the selection shall be based on the following ratings:
• ON factor less than 200,000 (the ON factor is the product of bearing size (bore) in millimeters and the rated speed in revolutions per minute).
• L-10 life factor (see AFBMA Standard 9 or Standard 11) of 100,000 hours or greater.
• Load factor less than 2,700,000 (Load factor is the product of rated horsepower and rated speed in revolutions per minute).
• The use of filling slot type anti-friction bearings is prohibited for any service, including drivers.

• Ball type thrust bearings shall be dual single row, 40 degree, light pre-load, angular contact type (7,000 series) installed back-to-back, mounted on shafts with close-tolerance interference fits not exceeding 0.0002 inches (0.005 mm). Alternatively, double-row bearings with single outer ring and two inner rings (Series 5300UPG, with 40 degree angular contact), mounted with manufacturer's recommended fits are acceptable.
• Thrust collars for hydrodynamic bearings shall be integral or installed with a substantial shrink fit to prevent fretting and positively locked to prevent axial movement. Integral collars shall be provided with a minimum of 1/8 inch additional material on each thrust face for remachining should the collar be damaged. The maximum total indicated face runout shall be 0.0005 inch. The use of a split thrust collar (squeezed fit and screw on) shall require prior approval by the Owner.
• Shaft bearings shall be easily accessible for maintenance without dismantling the duct work or the fan housing. Overhung impeller designs shall have provisions for supporting the rotor during bearing maintenance.
• Bearing housings for oil lubricated bearings shall be provided with tapped and plugged fill and drain openings at least 1/2 inch NPT in size. The housing shall be equipped with constant level sight-feed oilers at least 16 ounces in size, with a positive level positioner, glass container, and protective wire cages. A permanent indicator of proper oil level shall be accurately located and clearly marked for high, low and normal levels. The constant level sight-feed oiler shall be the pressure-balanced type (i.e. incorporating an O-ring so as to exclude ambient air and having a balance line connect the surge chamber to a location at or near the top of the bearing housing). TRIGO Model No. 30510 is preferred.
• Bearing housings shall be equipped with rotating labyrinth, double contact, or face-type end seals where the shaft passes through the housing; lip type seals shall not be used.

• All induced draft fans or process fans handling gas above 150°F shall be furnished with a shaft mounted heat slinger complete with rigid safety guards located between the fan housing and/ or inlet box(es) and the adjacent bearing(s). The design of the heat slingers and the shaft mounting arrangement shall be described in the vendor's proposal.
• Bearing housings shall be drilled with pilot holes for use in final dowelling.

4.9 Materials

4.9.1 General

• Materials of construction shall be the Manufacturer's standard for the specified operating conditions, except as specified on the Data Sheets.
• Materials shall be identified in the proposal with their applicable ASTM, AISI, ASME or SAE numbers, including the material grade.
• Any corrosive and/or abrasive agents present in the process gas and in the environment shall be stated clearly on the Data Sheets.

4.9.2 Welding

• All welding, including weld repairs, shall be performed by welders, welder operators, and procedures qualified in accordance with the specifications of American Welding Society (AWS) D14.6 "Specification for Welding of Rotating Elements of Equipment".
• The vendor shall be responsible for review of all welding, including weld repair, to ensure that the requirements of AWS D14.6 section 7 Inspection and Quality have been satisfied.
• Repair of Welding defects shall be performed in accordance with AWS D14.6 section 8

"Modification and Repair".

• All butt welds shall be continuous full fusion, full penetration welds.

4.10 Nameplates

4.10.1 Nameplates and rotation arrows shall be of AlSI Standard type 300 stainless steel or monel, securely fastened by pins of similar material, and located at an easily accessible point.

4.10.2 The rated conditions and other data below, as a minimum, shall be clearly stamped on the nameplate:

• Vendor
• Model Number
• Serial Number
• Size
• Type
• Volume (inlet cubic feet per minute)
• Static pressure differential (inches H2O)
• Temperature, inlet (°F)
• RPM, rated
• RPM, maximum allowable (@ maximum allowable temperature)
• First critical speed
• BHP, rated
• WK2 , rated
• Rotor weight, actual (pounds)

ACCESSORIES

The Purchaser shall specify the accessories to be supplied by the fan vendor on the Data Sheets.

• Drivers
• General
• The type of driver will be specified by the Owner. The driver shall be suitable for satisfactory operation under the site and utility conditions specified in the Data Sheets.
• On forced draft fans, motor drivers shall be sized for undampered fan operation at the minimum specified ambient temperature. On induced draft fans, consideration should be given to possible variations in operating temperature and gas density which may affect driver size.
• The driver's starting-torque capabilities shall exceed the speed-torque requirements of the driven equipment at start up at the combination of lowest suction temperature and lowest steam supply or drive motor voltage conditions.
• Motors
• Electric motors shall comply with EP 13-3-1 or EP 13-3-2, depending on their type and size.
• Unless otherwise specified, motor driven fans shall be direct connected. V-belt connections shall require prior approval by the Owner's Engineer.
• Where operating conditions have wide variations, two speed or variable speed motors should be considered for energy conservation and operation flexibility.
• As a minimum, motors shall have horsepower nameplate ratings sufficient to drive the fans throughout their static pressure-capacity curve without overloading with the wheel diameter furnished. If this unnecessarily oversizes the motor, an alternate quote shall be provided in compliance with the table listed below. In any case, minimum motor rating, including service factor, shall not be less than the percentage of fan rated brake horsepower shown in Table 2.

• Steam Turbines
• Unless otherwise specified, steam turbine drivers shall conform to EP 6-3-1.
• Turbine horsepower rating shall be greater than the fan rated brake horsepower (including gear losses) by at least 10 HP or 10%, whichever is greater.
• Gears
• Gears rated at 500 Horsepower and higher shall conform to API Standard 613.
• Unless otherwise specified, gears rated below 500 Horsepower shall comply with AGMA 420 and 421.
• Couplings and Guards
• Flexible couplings and guards between drivers and driven equipment shall be supplied by the fan vendor, unless otherwise specified on the Data Sheets.
• Unless otherwise specified or approved by the Owner, couplings shall be dry, flexible, of spacer type with the minimum spacer length of 6 inches. The flexible discs shall be stainless steel.
• Each coupling shall have an OSHA approved coupling guard that sufficiently encloses the coupling and shafts. The guard shall be readily removable for inspection and maintenance of the coupling without disturbing the coupled equipment.
• Limited end float couplings shall be used with sleeve bearing motors to prevent the motor rotor from rubbing the ends of either bearing.
• Unless otherwise specified, a service factor of 2.0 shall be applied to all flexible element couplings.
• All spacer type couplings shall be of a design in which the spacer is positively constrained from flying out in the event of failure of the flexible elements
• Mounting Plates
• Fan driver equipment shall be furnished with sole plates or a base plate, as specified on the Data Sheets. When a base plate is specified, it shall be extended (length and width) for the fan, driver, and all accessories without overhang, except that motor driver conduit boxes may extend beyond the baseplate.
• In the following paragraphs, the term mounting plate refers to both baseplates and sole plates.
• The upper and lower surfaces of bearing pedestals and mounting plates shall be machined parallel.
• When epoxy grout is specified on the data sheets, the vendor shall pre-coat all grouting surfaces of the mounting plates with a catalyzed epoxy primer applied to degreased white metal.
• Fasteners for attaching the components to the mounting plates and jack screws for leveling the pedestal sole plates shall be supplied by the vendor.
• Stainless steel shims with a total thickness of 1/16 inch shall be supplied by the fan vendor between the fan and its supports, and at least 1/16 inch, but not more than 1/8 inch between the driver train and its supports. All mounting pads shall be fully machined flat and parallel to receive the equipment. Corresponding surfaces shall be in the same plane within 0.001 inch per foot of distance between pads.
• Controls and Instrumentation
• General

Unless otherwise specified, controls and instrumentation shall be suitable for outdoor installation.

• Control Systems
• The fan may be controlled on the basis of inlet pressure, discharge pressure, flow, or some combination of these parameters. This may be accomplished by suction throttling, variable inlet dampers or guide vanes, speed variation, or a discharge blowoff (when a constant speed driver is used).
• For a constant speed drive, the control signal shall actuate an operator that positions an inlet and/or outlet damper, adjustable inlet guide vanes or discharge blowoff.
• For a variable speed drive, the control signal shall act to adjust the set point of the driver's speed control system.
• The full range of specified control signal shall correspond to the required operating range of the driven equipment. Unless otherwise specified, the maximum control signal shall correspond to the maximum continuous speed or the maximum flow.
• Unless otherwise specified, facilities shall be provided to automatically open or close (as specified) the dampers or guide vanes on loss of control signal and to automatically lock or brake the dampers or vanes in the last position on loss of motive force (air supply, electric power, etc.).
• Dampers or Inlet Guide Vanes
• Frames for inlet dampers and outlet dampers shall be flanged and drilled airtight with a tight fit to the fan or ductwork, or silencers. Damper blades shall be supported continuously by the shafts. Damper shafts shall be sealed or packed to limit leakage, except for atmospheric air inlet dampers. No stub shafts are allowed.
• Unless otherwise specified, the damper or guide vane mechanisms shall be interconnected to a single operator. The operating mechanism shall be designed so that the dampers or guide vanes can be manually secured in any position.
• When provided, inlet variable guide vane operating mechanisms shall be located outside the flowing gas stream. The mechanism shall be readily accessible for in-place inspection and maintenance, and be of bolted attachment construction to permit removal, if necessary. Provisions shall be furnished for lubrication of the mechanism during operation.
• Appurtenances
• Unless otherwise specified, the vendor shall furnish inlet trash screen(s) for forced draft fans to prevent entry of debris. The screen shall be fabricated from 0.135 inch minimum diameter wire, with a mesh of 1-1/2 inch maximum opening. The screen shall be sufficiently supported by galvanized carbon steel cross members. The trash screen shall be of 300 series stainless steel.
• For forced draft fans with vertical inlets, the vendor shall furnish rainhood(s), unless otherwise specified.
• Silencers
• The pressure drop through each silencer shall not exceed 0.5 inches water gauge.
• Full details of the proposed silencer including drawing shall be submitted with the proposal for approval.
• Carbon steel construction of silencers shall be of 3/16" minimum thickness plate. Corrosion allowance and alternate material, if required, shall be indicated on the Data Sheets.
• Silencers shall not interfere with the movement of damper blades.
• Unless otherwise approved by the Owner's Engineer, silencers shall be designed, fabricated, inspected and tested in accordance with EP 7-1-2.

• Coatings and Insulation
• Coatings
• Unless otherwise specified, when constructed of carbon steel or cast iron, the following areas shall be sand blasted to SSPC-SP10 near white and painted with a coat of inorganic zinc.
• Internal surfaces of forced draft fan intake ducts and accessories, fan housing, and internals.
• Internal surfaces of induced draft fan housing, inlet box(es), discharge connections, and accessories.
• External non-machined surfaces of all bearing pedestals and bearing housing.
• Unless otherwise specified, fans and accessories shall be externally coated as follows:
• Uninsulated fans shall be supplied as a minimum one coat of manufacturer's standard primer over an SSPC-SP6 sandblasted surface.
• Fans to be insulated shall receive, as a minimum, one coat of manufacturer's standard primer over an SSPC-SP2 surface preparation with solvent wipe.
• Any additional coating requirements shall comply with EP 10-3-1.
• Insulation
• Insulation clips or studs shall be welded on fan housings, inlet boxes and discharge connections for fans having normal operating gas temperature higher than 180°F and/or requiring acoustic insulation. Unless otherwise specified, the clips or studs shall be designed and installed for a 2-inch minimum insulation thickness. Insulation supports shall comply with the requirements of EP 11-3-3.
• Insulation shall not interfere with damper or other operating mechanism(s).
• Insulation thickness shall be approved by the Owner's Engineer.

INSPECTION AND TESTING AND PREPARATION FOR SHIPMENT

• General
• After advance notification to the vendor, the Owner's representative shall have entry to all vendor and sub-vendor plants where manufacturing, testing, or inspection of the equipment is in progress.
• The vendor shall give a five-working day in advance notice to the Owner before any inspection or test is to be witnessed or observed, unless otherwise established by mutual consent of the Owner and the vendor.
• The Purchaser will indicate on the Data Sheets the extent of the Owner's participation in the inspection and testing.
• Witnessed means that a hold shall be applied to the production schedule and that the inspection or test shall be carried out with the Purchaser's inspector in attendance.
• Observed means that the Purchaser shall be notified of the timing of the inspection or test; however, the work shall be performed as scheduled, and if the Purchaser's inspector is not present, the vendor shall proceed to the next step.
• Equipment for the specified inspection and tests shall be provided by the vendor. The vendor shall provide details of his test facilities. The vendor shall submit test procedures for Purchaser's review and approval, complete with acceptance criteria.
• Unless otherwise specified on the Data Sheet, a witnessed critical frequency test (impact test) shall be done on fan units whose drives are 200 HP and larger or fans with variable speed driven (above 50 HP). The test shall be performed on the rotor assembly after balancing. The rotor shall be re-balanced should addition or removal of weight becomes necessary to correct potential excitation source(s). Critical resonances shall be kept ± 20% away from the rotational

and blade passing frequencies. The vendor shall provide calibration certificates for all instruments used in testing of the equipment.

• The vendor shall furnish the Owner with data and calculation of the 1st lateral critical frequency, maximum continuous speed and maximum shaft deflection.
• Acceptance of shop tests does not constitute a waiver of requirements to meet field performance under specified operating condition, nor does inspection relieve the vendor's responsibility.
• Inspection
• Parts shall not be coated until the specified inspection of the parts is completed.
• The vendor shall provide the Purchaser's inspector with data on final assembly maintenance, running clearances, runouts and results of documented tests and rotor balance.
• Painting
• In the proposal, the vendor shall include its standard painting procedure.
• Painting requirements shall comply with section 5.6 of this Practice.
• Preparation For Shipment
• Equipment shall be suitably prepared for the type of shipment specified, including blocking the rotor when necessary. The preparation shall make the equipment suitable for 6 months of outdoor storage from the time of shipment, with no disassembly required before operation, except for inspection of bearings and seals.
• The equipment shall be prepared for shipment after all testing is completed and the equipment has been approved by the Purchaser. The preparations shall include as a minimum those items listed below:
• All machined surfaces shall be coated with a suitable rust preventive.
• The rotor shall be treated with a rust preventative if the fan is to be field assembled. It shall be suitably crated for the specified shipment, the rotor shall not be supported at the shaft journals.
• Inlet and discharge duct connections on fans shipped as an assembly shall be provided with wood or metal covers to prevent entrance of foreign materials and damage to the duct connection. The vendor's proposal shall state how the duct connections are to be protected.
• Threaded openings shall be provided with steel caps or solid shank steel plugs. In no case shall nonmetallic (such as plastic) plugs or caps be used.
• All flanged auxiliary piping connections shall be provided with metal closures of 3/16 inch minimum thickness, with rubber gaskets and at least four full diameter bolts.
• The center of gravity, the lifting points and the lifting lugs shall be clearly identified on both the vendor's drawings and on the units.

VENDOR'S DATA

• Proposals

The vendor's proposal shall include the following items as a minimum requirement:

• A specific statement that the proposed system and all its components are in strict accordance with this standard. The vendor shall clearly state all exceptions to this standard and include a specific list that details and explains each deviation.
• Copies of the Owner's Data Sheets with complete vendor's information entered thereon.
• Complete performance curves to fully define the envelope of operations and the point at which the Manufacturer has rated the fan. Any special inlet or outlet duct design required to

meet performance shall be fully described.

• Utility requirements (such as steam, water electricity, air and gas) plus driver ratings and net loads. Approximate data shall be defined clearly as such. This information shall be entered on the Data Sheets where applicable.
• Preliminary outline and arrangement drawings and schematic diagrams.
• Net and maximum operating weights, maximum shipping and erection weights with identification of the item, the maximum normal maintenance weights and identification of the item. These data shall be entered on the Data Sheets, where applicable.
• Details and drawings of shaft seals and inlet silencers, if furnished.
• A list, including price and delivery, of spare parts recommended for start up and normal maintenance purposes.
• An itemized list of the special tools included in the offering. The vendor shall list any metric items included in the offering.
• Contract Data
• Coordination Meeting: When specified, a coordination meeting shall be held within 2-4 weeks after the purchase commitment. An agenda shall be prepared for this meeting and should include the following items:
• The purchase order, scope of supply, and subvendor items.
• The Data Sheets.
• Schedules for transmittal of drawing, production, and testing.
• Inspection, expediting and testing.
• The physical orientation of the equipment, piping and auxiliary system.
• Schematics of lube oil and cooling systems, if applicable.
• A review of applicable specifications and previously agreed-upon exceptions to specifications.
• Schedule for drawing review and communication channel
• Progress report.
• Drawings
• The Purchaser shall state in the inquiry and in the order whether manufacturing is to proceed without advance review of the drawings.
• The Purchaser will promptly review the vendor's drawing when received; however this review shall not constitute permission to deviate from any requirements in the order, unless specifically agreed upon in writing. After the drawings have been reviewed, the vendor shall furnish certified copies in the quantity specified. Drawings shall be clearly legible and in accordance with ANSI Y14.2M.
• The following information shall be provided on the drawings (typical drawings are not acceptable).
• The Purchaser's order number.
• The Purchaser's equipment item number.
• The vendor's shop order and/or serial number.
• The weight of each assembly, of the heaviest piece of equipment that must be handled for erection, and of any significant item to be handled for maintenance.
• Principal dimensions, including those required for piping design, maintenance clearances, and dismantling clearances.
• The direction of rotation.
• The size, type, rating, location and identification of all the Purchaser's connections, including vents, drains, lubricating oil, conduits, and instruments.
• Manufacturer, size and type of the shaft coupling and the style of the coupling guard.
• Complete information to permit adequate foundation design by the Purchaser. This shall

include but not be limited to the following:

• Grouting details.
• The size and location of foundation bolts.
• The weight distribution for each bolt/sub-soleplate location.
• Details of damper linkage and control systems, including torque requirements.
• Curves
• The vendor shall provide complete performance curves to encompass the map of operations, with any limitations indicated thereon. The vendor shall provide, as a minimum, fan static pressure/capacity and horsepower/capacity curves for 100, 50 and 20 percent damper control settings and a capacity/efficiency curve. Where gas temperature varies, separate curves shall be provided for each specified temperature.
• The curves for dampered systems shall illustrate the degree of damper control necessary to attain each operating point and shall correspond to the geometry of equipment as installed.
• For variable speed fan systems, the performance curves shall illustrate the degree of speed control necessary to attain rated, normal and minimum flows.
• Efficiency vs. speed curves for variable speed fan systems (including fan and drivers), within the vendor's scope of supply, shall be provided.
• Data
• The vendor shall provide full information to permit completion of the Data Sheet, first for "as purchased" and then "as built". This should be done by correcting and filling out the Data Sheets and submitting copies.
• The vendor shall make available to the Owner the following information:
• Completed as-built data sheets.
• A certified log sheet of the shaft runout check and balancing.
• A critical frequency test report.
• The critical speed analysis report.
• The vendor's physical and chemical data from mill report (or certification).
• The vendor shall provide AS-BUILT thrust bearing, radial bearing, and seal running clearances.
• Unless otherwise specified, the vendor shall provide fan and drive WR2. For each motor driven fan under full voltage across-the-line starting conditions, the vendor shall provide the following information, if the motor is furnished by the fan vendor:
• Full load and starting currents.
• Curves for motor speed vs. torque, motor speed vs. current, and speed vs. power factor.
• Allowable number of cold starts and/or hot restarts per hour and any at-rest period required.
• System acceleration time vs. current curve.
• Progress Report

When specified, the vendor shall submit progress reports to the Purchaser at the specified frequency. The reports shall include engineering and manufacturing information on all major components

GUARANTEE AND WARRANTY

• Mechanical

Unless exception is recorded in the vendor's proposal, it shall be understood that the vendor agrees to the guarantees and warranties specified in Items 1 and 2 below:

• All equipment and component parts shall be warranted by the vendor against defective materials, design, and/or workmanship for 1 year after being placed in service (but not more than 18 months after date of shipment).
• If any mal-performance or defects occur during the guarantee and warranty period, the vendor shall make all necessary alterations, repairs, and replacements free of charge, free on board factory. Field labor charges, it any, shall be negotiated between the vendor and the Purchaser.
• Performance

The equipment shall be guaranteed for satisfactory performance at all operating conditions specified on the Data Sheets.

9.0 TABLES

TABLE 1 SHAFT RUNOUT

TABLE 2 MINIMUM MOTOR RATINGS

TABLE 3 DRIVER TRIP SPEEDS

TABLE 4

DOCUMENTATION REQUIREMENTS

FOR CENTRIFUGAL FANS IN GENERAL REFINERY SERVICES PER EP 6-6-1

TABLE 4 (CONT.)

DOCUMENTATION REQUIREMENTS

FOR CENTRIFUGAL FANS IN GENERAL REFINERY SERVICES

PER EP 6-6-1

NOTE:

(1) If the document cannot be provided in the format as indicated, the Manufacturer shall consult with the Owner's Engineer for an acceptable alternative.

10.0 FIGURES

FIGURE 1

MAXIMUM RESIDUAL SPECIFIC UNBALANCE CORRESPONDING TO

BALANCE QUALITY GRADES G 2.5 & G 6.3

0.1

0.05

0.01

0.005

0.001

0.0005

0.0001

0.000050

0.000010

0.000004

30 50

100 500

RPM

1000 5000 10000 50000 100000

.5 1

5 10 …………

50 100

500

1000

2000 Hz

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