Section 6 — Rotating Equipment

Centrifugal Pumps

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

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

The following paragraph numbers refer to API 610, 8th Edition, August 1995, titled, "Centrifugal Pumps for Petroleum, Heavy Duty Chemical, and Gas Industry Services," which is part of this Engineering Practice.

INTRODUCTION

Table 1 records the vendor drawing and data requirements.

GENERAL

• Scope

• a. (Exception) This standard covers the mandatory requirements for heavy duty centrifugal pumps. Any deviation from this standard must be approved by the Purchaser in accordance with the procedures specified in EP 1-1-3.

• All requirements specified in this standard are additions to those of API Standard 610, unless specifically noted as exceptions. Paragraph numbers in this standard which do not appear in API Standard 610 are new paragraphs. Paragraph numbers may not be consecutive and all API 610 paragraphs not mentioned herein shall be considered to be verbatim requirements of this specification.

• The Purchaser's requirements for all paragraphs in API 610 which require a Purchaser's decision (bulleted paragraphs) are indicated on the Data Sheets or in this specification. An asterisk (*) indicates that a decision by the Owner's Engineer is required or that additional information is furnished by the Owner's Engineer.

• Vendor qualification. Pumps shall be supplied by Vendors qualified by experience to manufacture the units proposed. To qualify, Vendor must have at least two pumps of comparable rating and design performing satisfactorily in a similar service. Special attention to Vendor qualification should be given for pumps rated over 500 HP, pumps handling cold liquids at -50 oF or lower, or pumps with a suction specific speed (NSS) that exceeds 12,000.

• Alternative Designs

• (*) a. Where the Vendor qualification of Paragraph 1.1.1d prevents the application of the latest technology, the Vendor shall submit to the Purchaser an alternative proposal incorporating such features for review and approval by the Owner's Engineer. The proposal shall specifically identify the undemonstrated features and state their advantages.

• (*) b. Proposals to furnish pumps that do not meet all requirements of this standard, based on specific nonflammable, non-toxic service conditions, shall be submitted to the Purchaser for approval by the Owner's Engineer.

• Definition of Terms

The following additional terms are used in this standard.

• Bubble point temperature is the temperature at which the first bubbles appear in a liquid when heated at constant pressure.

• Product temperature margin (PTM) is the difference between the bubble point temperature and the actual temperature of the liquid at a given pressure.

• Inspector - A Refining Co. appointed engineer or inspector.

• Owner - The Refining Co...

• Owner's Engineer - A Refining Co. appointed engineer.

• Purchaser - The party placing a direct purchase order. The Purchaser is the Owner's designated representative.

1.5 Referenced Publications

1.5.4 The referenced Engineering Practices, and any other attached to the requisition shall apply to the extent referenced herein or on the Data Sheets. The Data Sheets and Inspection Checklists from API 610 shall be used in conjunction with this document.

STANDARDS AND PUBLICATIONS

BASIC DESIGN

• General

• Pumps with constant-speed drivers shall be capable of at least a 5-percent head increase or decrease at rated conditions, either by trimming impeller(s) or with different impeller(s).

• (*) NPSHR shall be less than (NPSHA - 3 feet) unless approved by the Owner's Engineer.

2.1.9 (*) Pump suction specific speed (NSS) shall not exceed 12,000 (calculated using rotative speed in rev/min, flow in GPM, and NPSH In feet) without written approval of the Owner's Engineer. See paragraph 1.4.49.

2.1.11 (*) a. The head curve for the pump shall be continuously rising from the specified capacity point to the shutoff point. The pump head at shutoff shall be between 110 and 120 percent of the head at the specified capacity point. Pumps whose shutoff head exceeds 120 percent of the head at the specified capacity point may be submitted for approval by the Owner's Engineer. Written approval by the Owner's Engineer is required to apply a discharge orifice as a means of providing a continuous rise to shutoff.

b. Pumps for parallel operation shall have equal head rise to shutoff.

(*) c. Low capacity, high-head pumps may be exempt from the requirements of 2.1.11.a and

2.1.11.b with the approval of the Owner's Engineer.

2.1.14 The maximum allowable sound pressure level is 85 dBA measured at 3 feet from any equipment surface. Test data on similar pumps shall be made available upon request.

2.1.17 Pumps shall be designed to operate continuously without the use of cooling water.

•  Unless otherwise specified, the pump and auxiliaries shall be suitable for unsheltered outdoor installation at the refinery.

• Diffuser or double volute pumps are required for pumps with discharge nozzle sizes of 4 inch NPS or larger. Impellers with an even number of vanes are not acceptable on double volute pumps.

2.2 Pressure Casings

2.2.4 Areas of vertically suspended, double-case and horizontal multistage pumps which are normally subjected to suction pressure shall be designed to the same pressure as discharge areas of the pump.

2.2.14 (*) Vertical turbine pumps shall have columns and bowls of the bolted design. Screwed bowl sections may be supplied only if specifically approved by the Owner.

2.3 Nozzles and Pressure Casing Connections

2.3.2 Suction and Discharge Nozzles

2.3.2.1 (Exception) All pumps shall have suction and discharge flanges of equal rating. The ANSI permissible hydrostatic test pressure of suction flanges shall be equal to, or greater than, the pump casing hydrostatic test pressure.

• Pressure Casing Connections

• (Exception) All pipe nipples shall be schedule 160.

• (Exception) Plugged openings that are not required shall be seal welded except in mechanical seal gland plates.

2.3.3.10 a. All vents and drains shall be valved, either flanged or socket welded.

2.3.3.12 a. Valved vent and drain connections shall comply with the requirements of EP 5-5-1.

b. Valves for vents, drains, and clean-out connections shall be as follows:

• Either a Smith, Vogt, or Newco class 800 extended body valve, compact body valve with a schedule 160 nipple, or flanged valve per EP 5-3-6 shall be used.
• For alloy pump cases, the valve and connection material shall be the same as that of the pump case.
• All piping between the valve and the pressure casing shall be socket welded or butt- welded. Butt-welds are required for design pressures above 1000 psi.
• The socket weld at the connection of extended body valves to fittings or the pump case shall have a complete bridge weld from fitting or casing to the body of the valve.
• Hydrotesting of the valved connections shall be made by hydrotesting the pump casing at the specified pressure with the valve(s) fully attached and completed. The hydrotest certification should note the inclusion of the valve(s) in the test.
• Rotors

• (Exception) Colleted impellers are not required.

• (Exception) Solid hub impellers are required.

2.5.7 (Exception) The shaft stiffness for all pumps shall limit the total shaft deflection under the most severe conditions over the complete head-capacity curve to .002 inch at the face of the stuffing box or seal chamber and to less than one-half the minimum diametrical clearance at all bushings and wear rings. The shaft shall be designed to transmit momentarily at least four times the rated torque of the pump driver.

• Wear Rings and Running Clearances

• Circumferential grooves, 0.03 inches deep by 0.06 inches wide shall be machined into the rotating wear ring periphery.

• Dupont "Vespel" or equivalent high-perfromance polymers are preferred as wear ring materials

• Cast iron shall not be used as an impeller wear ring material.

2.8 Dynamics

2.8.1.1 Full rotordynamic (lateral and Torsional) analysis are required for pumps exceeding 4000 RPM (except OHG) or 1000 HP.

• Torsional Analysis

• (Exception) A torsional vibration analysis is required when the train includes a gear.

• No torsional natural frequency shall be closer than 5 percent to twice any shaft speed.

2.8.2.6 If a torsional analysis is required per paragraph 2.8.2.1, a detailed report shall be furnished.

2.8.3 Vibration

2.8.3.10 The Vendor shall demonstrate that the pump can operate at any capacity from 120 percent of the rated capacity to the quoted minimum continuous stable flow without exceeding the vibration limits given in paragraph 2.8.3.7.

2.9 Bearings and Bearing Housings

2.9.1 Bearings

2.9.1.5 a. Ball-type thrust bearings shall have machined brass cages. The vendor shall verify the adequacy of duplex, single-row, 40 degree (0.7 radian) angular-contact type (7000-series) bearings, installed back-to-back. This verification shall include selection of proper axial and radial (shaft interference fit-related) preload values to prevent skidding of the unloaded bearing over the entire operating range of the pump.

• If (a), above, points out inadequacies or potential problems, the vendor shall offer suitably preloaded sets of ball-type thrust bearings with dissimilat contact angles (e.g. 40 degrees/15 degrees).

• Sets of properly preloaded, back-to-back mounted 15 or 29 degree angular contact bearings are acceptable for pumps with double-flow impellers located between two bearing housings.

2.9.2 Bearing Housings

2.9.2.2 The constant-level lubricators shall be Trico Optimatic, or Owner-approved equivalent fully balanced type, and installed with the stainless steel balance line entering the bearing housing at the former vent connection, i.e. at the top of the bearing housing (Note that there shall be

no bearing housing vent). The lubricator shall be at the "up arrow" side of the bearing housing, as recommended by TRICO Mfg. Company

2.9.2.6 The vendor shall provide INPRO style VBX bearing isolators at all bearing housings.

• Lubrication

•  Unless otherwise specified, pumps with rolling element bearings shall be designed for future on-line conversion to pure oil mist lubrication using ISO grade 100 synthetic (PAO or Diester) lubricants.

• Provide API 610 pressurized lube-oil systems on pump trains over 500 HP. Provide API 614 lube-oil systems on pmup trains over 1000 HP and on all unspared critical trains.

• Materials

• General

2.11.1.1 Twelve percent chrome castings shall be per ASTM A487, Grade CA6NM.

Austenitic stainless steel shall be per ASTM A351 with liquid penetrant examination to S.6. Monel Castings shall be per ASTM A494 grade M-30C with weldability test S.2. and liquid penetrant examination S.5.

• Castings

2.11.2.2 Chaplets in casings other than cast iron that are not completely fused into pressure castings or other defects shall be replaced by weld metal equivalent to the casing composition. No other repair method is permitted. Casings shall be heat treated following any major repairs.

• Welding

2.11.3.5.5 PWHT is required for all carbon and ferritic alloy steel pressure-containing components that are welded and/or weld repaired, when the weldment is exposed to a process containing wet H2S. The PWHT procedure outlined in ASME Code Section VIII, paragraphs UW40, UW49, UHA32, and UCS56 shall be followed, except that the notes in Tables UHA32 and UCS56 do not apply. All welds, regardless of type or size, that are exposed to wet H2S shall be PWHT at a minimum temperature of 1150 oF. External attachments or seal welded threaded connections on P-1 Group 1 and 2 materials do not require PWHT.

• Low Temperature

(Exception) Pressure casing components, either cast, forged, or welded, shall meet the following impact requirements:

• In the notation 15/12, the first number is the minimum average energy of the three specimens while the second number is the minimum for any one specimen in the impact determination.

• The minimum CET for any part of a casing shall apply to the entire casing.

• No impact tests are required for a particular pressure containing component if the maximum casing working pressure generates a stress less than 25 percent of the minimum specified yield stress for the material as determined by the Manufacturer.

(*) c. All impact test details shall be approved by the Owner's Engineer.

ACCESSORIES

• Drivers

3.1.1  Unless otherwise specified, drivers shall be induction motors designed per EP 13-3-1, if 500 HP or smaller, and per EP 13-3-2, if larger than 500 HP. Synchronous Motors shall be in accordance with EP 13-3-3.

• Motors shall not be overloaded at the end of the pump curve.

• The motor shall be designed in accordance with the following:

• Electrical characteristics - 3 phase/60 cycle with 460 volts for motors less than 100 HP and 2400 volts for 100 HP and larger

• Starting conditions - 70% of rated voltage

• c. Type of enclosure -Totally enclosed fan cooled (TEFG), unless otherwise specified

• Sound pressure level - 85 dBA at 3 feet

• Area classification - Class I, Group D, Division 2 unless specified otherwise

• Type of insulation - Class F V PI with a Class B temperature rise

• Rotor material 400 HP and larger - copper bars

300 HP and 350 HP - copper bars if intermittent duty 350 HP and smaller - cast aluminum

• h. Service factor - 1.0 unless specified otherwise

• Ambient temperature - Design 40°C, actual 45 to 105°F

• Elevation -Sea level

• Temperature detectors -Two 100 ohm Platinum RTD's per phase for motors 125 HP and larger, 1 RTD per bearing when sleeve bearings are used

• Vibration sensors - 2 Bently-Nevada proximity probes per bearing for motors 1000 HP and larger with sleeve bearings

• Reduced voltage at starting shall be 70% of rated voltage.

3.1.9  Steam turbines shall conform to EP 6-3-1, unless otherwise specified.

3.1.13 For vertical pumps, the Vendor shall assemble, align and dowel the motor or gear to the pump in its shop to assure proper unit fit-up and shaft mating.

3.2 Couplings and Guards

3.2.2  When the coupling type is not specified by the Owner, a Rexnord Thomas Series 71 nonlubricated disc type coupling with stainless steel disc packs shall be supplied by the pump Vendor.

• (Exception) Couplings shall be mounted on the shaft with a keyed straight cylindrical fit having a 0.0005- 0.001 inch interference between the hub and the shaft.

• The coupling to shaft juncture shall be capable of withstanding a momentary torque four times the rated torque without yielding.

3.2.8.1 API 671 applies to applications over 750 HP and for unspared critical machines.

3.2.12 Coupling guards for horizontal pumps shall be fabricated from aluminum or molded from rigid OSHA-approved orange-color polyurethane. Guards shall be provided with a hinged door for inspection of coupling flexible elements.

• Baseplates

• (Clarification) Baseplates shall be filled with epoxy before pads are machined. Only approved surface preparation procedures shall be used. All mounting pads shall be machined flat and parallel. Centers of mounting pads shall be at the correct relative elevation within 0.0005 inch per foot of separation between pads (i.e., two pads three feet apart shall deviate no more than 0.0015 inch from the correct elevation). Additionally, each pad shall be level in all directions within 0.001 inch per foot. Space shall be provided at each pad for a precision level for two- plane leveling of the baseplate with the rotating equipment mounted. These requirements shall be met in a relaxed (non-clamped) state.

• All shims shall straddle hold down bolts.

3.3.14 Alignment positioning jackscrews shall be provided for all equipment feet, regardless of equipment weight.

3.3.21 Mounting plates for vertical pumps shall be per the following:

3.3.21.1 Double-casing vertical pumps shall have a steel mounting plate that completely surrounds the outer casing and is attached to it by a continuous weld. The steel mounting plate shall have a 3/4 inch (22 mm) pipe connection to vent the space between the outer barrel and the foundation. The plate shall be rectangular with radiused corners. Foundation bolts shall not be used to secure the flanged pressure-casing joint.

• A rabbetted fit, with excess clearance shall be provided for the mounting flanges between the pump and direct mounted driver. Driver/pump allignments shall be achieved via dowels per pargraph 3.1.13.

• All vertical pumps shall have sufficient anchor bolting to withstand nozzle reaction forces due to start-up conditions.

• Instrumentation

3.4.3 Provide vibration probes per paragraph 3.4.3.1 and bearing RTDs per paragraph 3.4.3.2 on pump trains exceeding 1000 HP and/or 4000 RPM, and on all unspared critical trains.

• Piping and Appurtenances

3.5.1 General

3.5.1.4 Barrier/buffer fluid reservoirs shall be designed for mounting off the pump baseplate and shall be supplied by the Purchaser along w\ith connecting tubing and instrumentation.

• h. Piping shall be designed to facilitate disassembly and reassembly of the equipment.

• Vendor's piping shall terminate with a flanged connection of a line rating at least equal to the design pressure and design temperature rating of the equipment.

• Piping design, materials, joint fabrication, and inspection shall be in accordance with ASME B31.3 and the additional requirements of EP 5-6-2.

3.5.1.9 Threaded or slip on flanges are not acceptable.

3.5.1.15 Threaded connections shall be made up without the use of PTFE tape.

3.5.2 Auxiliary Process Fluid Piping

3.5.2.7 All orifice plates shall be installed in flanged connections and have a tab, marked with the orifice size, extending from the flange where they are installed to indicate their location.

3.5.2.10.1 Flanges are required.

3.5.2.11 (*) Mechanical seal flush lines in Flammable or Hazardous service shall be piped unless tubing is approved by the Owner's Engineer.

3.7 (New Section) Pressure Vessels and Heat Exchangers

(*) Unless otherwise approved by the Owner's Engineer, pressure vessels and heat exchangers associated with rotating equipment shall be designed, fabricated, inspected and tested in accordance with EP 7-1-2 and EP 8-1-2.

INSPECTION, TESTING, AND PREPARATION FOR SHIPMENT

• General

• The term Inspector, as used in this standard, refers to the Owner's Representative.

• Inspection

• General

4.2.1.3  As a minimum, inspection shall include: verification of the equipment dimensions, compliance with baseplate machining tolerances, examination of test data and checking preparation for shipment. For services with pumping temperatures 500oF or higher, the Inspector shall verify that the internal clearances conform to 2.6.4.2.

4.2.2.1 Pressure boundary components of pumps in flammable or toxic service shall be inspected per the requirements of paragraph 4.2.2.4 (magnetic particle inspection) or paragraph 4.2.2.2 (radiography).

• Testing

• General

•  As a minimum, inspection and testing of all pumps shall be conducted according to the completed Inspection Checklist from API STD 610 and the following:

NOTES:

• Hydrostatic tests will be witnessed for monel casings.

• Witnessed performance test shall be specified if the pump is high capacity over 1000 HP, over 4000 RPM, and/or for critical service.

(*) (3) If the NPSH required for the pump differs from the specified available NPSH by 6 feet or less, an NPSH suppression and performance test is required. For pumps requiring NPSH testing, the test of one pump in each service shall be witnessed by the Inspector. For the balance of identical pumps, witness is not required; however, certification of test results is required.

• (4) If specified by the Owner's Engineer.

(*) (5) Each sleeve bearing pump receiving a witnessed performance test shall have a witnessed bearing inspection by the Inspector following the final performance test.

• Hydrostatic Test

• a. (Exception) Suction sections of multistage horizontal and double-case pumps shall have a hydrostatic test pressure equal to the maximum casing discharge pressure. Vertical pumps shall be tested at the full hydrostatic test pressure from the suction flange to the discharge flange.

c. Mechanical seal flushing liquid coolers shall be hydrostatically tested to at least the same pressure as the pump casing.

• Performance Test

4.3.3.2.1 All pumps shall be operated for at least one hour at rated speed and capacity. One of the data points shall be the rated point.

(*) When specified by the Owner's Engineer, the seal chamber pressure shall be measured at each point during the performance test. The Vendor shall ensure that the measured seal chamber pressures, when corrected for rated suction pressure and specific gravity, are consistent with those assumed in designing the mechanical seal (see 2.7.1.12). Corrective steps needed to improve the seal design or seal chamber conditions shall be mutually agreed upon by the Vendor and Owner's Engineer.

4.3.3.3.3 (*) (Exception) In no case shall the minus tolerance allowance for shutoff head exceed two percent. The shutoff head with the positive tolerance allowance included shall not exceed 120 percent of the head at the rated capacity, unless previously approved by the Owner's Engineer.

4.4 Preparation for Shipment

4.4.3.4  (Exception) Unless otherwise specified, the rust preventive applied to unpainted exterior machined surfaces shall be of a type: (1) to provide protection during outdoor storage for a period of 12 months exposed to a normal industrial environment, and (2) to be removable with mineral spirits or any Stoddard solvent.

5.0 SPECIFIC PUMP TYPES

5.2.6 Lubrication

5.2.6.2 b. Materials of construction for coolers in salt water cooling service shall be as follows:

5.2.6.4 Lube oil pumps shall be IMO screw-type. Pumps enclosed in the lube-oil reservoir shall have stell or ductile iron cases.

• Non shaft driven horizontal pumps shall have positive suction heads and suction lines sloped to vent to the reservoir.

• (*) Motor drives for lube oil pumps shall be specified by the Owner's Engineer.

5.3 Vertically Suspended Pumps

5.3.7.3.5 A separate sole plate is required. The underside shall be prepared for epoxy grout.

6.0 VENDOR'S DATA

• Proposals

• Technical Data

• Wear ring clearances and diameters for proposed pumps for pumping temperature 500oF or higher.

• Design details of all coolers.

• Minimum case thickness and amount of corrosion allowance.

• For pumps rated over 500 HP, pumps handling cold liquids at -50 oF or lower, or pumps with suction specific speed over 12,000, include proof of compliance with 1.1.1.d.

• Vendor's proposals for spare parts shall include proposed method of protection from corrosion during shipment and subsequent storage.

• Vendor's proposals shall specify the maximum dynamic and static pressure ratings of the mechanical seal.

• Vendor's proposal shall state the minimum flow rate recommended for sustained operation (more than 1,000 hours per year) on the specified fluid.

• Alternative Vendor proposal provided per paragraph 1.2a shall identify undemonstrated features and their advantages.

• Curves

Quoted efficiency and power shall take into account the increased clearance required for hot pumps.

• Contract Data

6.3.2 Drawings

Cross-sectional dimensioned drawings of the stuffing box, seal, gland, shaft sleeve, and proposed flushing arrangement for the mechanical seal shall be provided.

GUARANTEE AND WARRANTY

• Mechanical

Unless exception is recorded by the Vendor in his 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 workmanship for one year after being placed in service (but not more than 18 months after date of shipment).

• If any malperformance 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, if any, shall be subject to negotiation between the Vendor and the Purchaser.

• Performance

The equipment shall be guaranteed for satisfactory performance at all operating conditions specified on the data sheet. Field checks on performance, when made by the Purchaser, shall be made within 60 days of initial operation

8.0 TABLES

TABLE 1 DOCUMENTATION REQUIREMENTS FOR CENTRIFUGAL PUMPS PER EP 6-1-1

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.

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