Pump installation “To do” lists

A process engineer has selected a pump, chosen a vendor, and placed the equipment on order (Fig. 1). The project engineer begins managing the installation details. As he contemplates the remaining items required, he realizes that a variety of design activities lie ahead and a “To Do” list must be prepared.

Primary “To Do” list

U Provide utilities

Design foundation

Provide access

Determine piping configuration

Select suction strainer

Analyze piping stresses

Select valving

Select instrumentation

Inspect equipment

Provide spare parts

Utilities

Coordination with plant personnel ensures that required utilities are available in sufficient quantity. Often utility requirements are submitted by the pump supplier with their approval documents.

If the required plant utilities do not exist in sufficient quantities, consider stand-alone or dedicated utility subsystems, such as an API-614 lube system, seal water system, and a chiller package for cooling capability.

Be certain utility piping is cleaned prior to connecting the newly installed process pump skid.

Utilities frequently required

Bearing lubricating oil

Cooling fluid

Seal water

Steam

Electricity

Foundation

One initial concern is the equipment footprint or pump skid outline drawing. After this document is received from the supplier, locate the equipment within the plant and begin the foundation design.

The dimensions of the foundation should be

4—6-in. greater than the equipment footprint. Depending on soil conditions, the foundation height, h, can be determined based on the total weight of the equipment skid.

h = (M 3 F)/(d 3 l 3 w)

Where:

h = foundation height, ft

M = equipment skid weight, lb

F = vibration factor, dimensionless

d = concrete density, lb/cu ft

l = foundation length, ft

w = foundation width, ft

Vibration factor guide

Installed equipment Vibration factor, F

Pumps 50—100 hp 1.5

Pumps 100—250 hp 2.5

Pumps 250 hp & above 5.0

Concrete is relatively inexpensive, but extremely difficult to add after equipment is installed. Therefore, size the foundation generously (Fig. 2).

Foundation design considerations

Determine foundation size based not only on equipment weight but also equipment elevation for maintenance of seals, couplings, and instrumentation.

Consider equipment elevation compared to nearby potential tank leakage and general housekeeping.

Make provisions to add shims beneath the baseplate to compensate not only for flatness/leveling, but piping interface connections and sloping drain lines. The baseplate should be 1—2-in. above the foundation when properly shimmed. Remember, raising equipment with shims is convenient; reducing the height of the foundation is difficult.

Leveling bolts are an option with the pump base and provide a convenient means of setting the base height.

Use stainless steel anchor bolts and nuts if the atmosphere is potentially corrosive. Add an extra 1—2 in. to the anchor bolt length to account for future design changes. They are easily shortened, if required.

Grout the equipment skid only after the baseplate has been shimmed level, anchor bolts tightened, alignment initially verified, and suction and discharge piping connections made and checked for pipe spring.

Access

The best place to begin the assessment of access and operability is with the equipment general arrangement drawing. Review this document with key maintenance and operations personnel to resolve key points about access.

Access considerations

What lifting equipment will be required to pull major components for repair (drivers, rotating assemblies, and bearing housings)? What are the maximum anticipated weights?

How will the lifting equipment access these components? Will an aisle be provided?

How frequently will the lifting equipment be used? Should the equipment be installed permanently?

What obstructions might prevent equipment removal (existing piping, conduit, instrumentation, tanks, insulation, etc.)?

Is there convenient access to start/stop buttons, instruments requiring frequent readings, seal pots, and valves?

As the design of the installation progresses, continue to review the general arrangement with maintenance and operations personnel. Since equipment and piping tend to increase in size/complexity rather than decrease, all engineering changes should be reviewed for impact on the general arrangement.

Piping

As the plant design progresses, space becomes a premium, particularly in front of the pump suction flange. Be certain the suction pipe is straight into the pump flange for a distance of 5—10 pipe diameters. Eccentric reducers may be necessary to adapt to the optimum suction line size

Suction pipe velocity should conform to the recommended velocity range for the particular fluid conveyed. A minimum velocity must be maintained to prevent particulate settlement and to maintain proper mixing. The maximum velocity should not be exceeded to prevent pipe erosion or pump suction cavitation. The optimum suction pipe diameter is the next pipe size larger than the pump suction flange.

Recommended fluid velocities

Applicationft/sec

Boiler feed water 8—15

Pump suction and drain lines 4—7

General service 5—10

Determine that the suction piping flange temperature/pressure rating are compatible with the process design and the pump flange size.

Similar recommendations apply to discharge piping, particularly regarding pipe flange ratings. The discharge pipe diameter is typically one size larger than the pump discharge flange to result in reasonable fluid velocities and to minimize pipe erosion.

Suction strainer

A meeting with operations and maintenance personnel should determine whether permanent or temporary suction strainers are preferred.

Temporary or startup strainers should only be considered when protecting the pump from particle damage occurring from construction debris and not continuous, long-term operation. Typically, strainers should be a minimum of 60 mesh and have a net open area of three times the suction pipe flow area.

A permanent, basket-type strainer is recommended where long-term particulate flow is anticipated and maintenance personnel are available for regular monitoring and service. For severe applications, where maintenance is infrequent, consider an automatic backflushing strainer. Be certain there are allowances in the hydraulic calculations to account for strainer pressure to avoid starving the pump suction.

Piping stress

System piping stress analysis is frequently performed as a reaction to resolving a flange leakage, pipe failure, or pump vibration problem. However, most of these problems can be circumvented when the analysis is performed concurrent with the piping design effort.

When a formal analysis is advisable

If the operating temperature is below 20 F or above 250 F

If the operating pressure is greater than 150 psi

If the pipe diameter is greater than 3 in.

If the fluid characteristics are flammable, toxic, or hazardous

If the pump operation is highly cyclical

When the analysis is performed, start with a simple design, and add supports, loops, expansion joints, and flexible connectors only where necessary (Fig. 3). Review the preliminary results with operating, maintenance, and structural design personnel to ensure that piping and supports are placed in optimum locations. A field walkdown with the project team may reveal the most logical support points.

Request the pump supplier to submit allowable pump flange loads or use API or ANSI pump standards as a guide. Use commercially available expansion joints or flexible hoses to connect the pump to the system piping only if the analysis requires them. Often both can be avoided simply by reconfiguring the piping or applying piping support devices. When using pipe anchors, coordinate with the structural design group to be certain the pipe anchor is affixed to a truly rigid member, not subjected to operation or thermal movement.

Valving

Valve categories to consider

Discharge control

Isolation and bypass

Discharge check

Vents and drains

Warm-up

Instrumentation

Upon completion of the valve list, the project engineer should establish valve lead times for compatibility with the overall project schedule.

Key valve questions

Will the pump operating point be established by a manually or automatically positioned control valve?

Should the automatic control valve include a manual bypass loop?

Will there be simultaneous, multiple pump operation? If so, how long?

Should isolation valves be installed on the pump suction and discharge for maintenance?

Will warm-up piping and valves be required to maintain or ramp the idle pump up to temperature?

Should a recirculation line be installed at the pump discharge, with an isolation valve, for startup or troubleshooting?

Should manual vent and drain valves be installed on the pump suction and discharge for startup and maintenance?

Instrumentation

At one extreme, a basic instrumentation package should include suction and discharge pressure gauges. If pumpage is aggressive, diaphragm seals may be required for gauge isolation (Fig. 4).

Optimum instrumentation package

Suction and discharge pressure indicating/transmitter

Flow indicating/transmitter

Pumpage temperature indicating/transmitter

Bearing race or lube oil temperature indicating/ transmitter

Shaft displacement or bearing housing acceleration indicating/transmitter

Motor amperage indicating/transmitter

Pump criticality dictates whether a 100% installed spare will be provided if the primary pump is down. If so, perhaps only basic instrumentation need be installed and supplemented with periodic handheld vibration measurement.

Inspection

For continuity, the mechanical engineer is the most appropriate project team member to visit the equipment supplier and verify acceptability of the equipment for the project.

Visit the supplier when there is substantial complexity to the purchase order; i.e., API kits, special coatings, inspections, and/or test requirements.

Objectives of inspection

Verify that the equipment supplier is using the latest revision of approved documents for the manufacture of the equipment

Verify that all change orders have been incorporated

Verify that all critical dimensions are in compliance with the design documents

Verify that all inspection and test procedures have been followed

Verify that the proper materials have been used

Become familiar with the operation and performance of the equipment, providing a smooth transition at the site startup

Establish factory contacts in the event field installation questions arise

Gain a first hand knowledge of special equipment loading, unloading, installation, and adjustment procedures

Verify that the supplier will provide all outstanding documents necessary to satisfy the requirements of the purchase order

Common problems at final inspection

Supplier not using the most recent approval drawings for construction

Improper materials of construction for valves, fittings, and instrumentation

Incorrect size, location, or quantity of baseplate mounting holes

Incorrect piping interface location dimensions

Excessive horsepower consumption based on performance test data

Missing or improper nameplate data

Incomplete I.O.&M. manual for supplied equipment/instruments

Inadequate structural support and accessibility for ancillary components (instrumentation, valves, and electrical components)

Inadequate preparation for shipment

Spare parts

The pump supplier should be requested to furnish a price list of these parts early in the design phase of the project.

Examples of commissioning spare parts

Sleeve bearings

Impeller wear rings

Gaskets and O-rings

Mechanical seals

Thrust washers

-Edited by Joseph L. Foszcz, Senior Editor,

630-320-7135, jfoszcz@cahners.com

&HEADLINE>Key concepts&/HEADLINE>

More than one list is required for a successful pump installation.

Ample access ensures proper maintenance and monitoring.

Careful piping considerations reduce pump stresses, provide adequate flow, and eliminate contaminants.

&HEADLINE>More info&/HEADLINE>

The author is available to answer questions about pump installation. He can be reached at 804-717-2514.

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