1.2 Installation of pumps and pipes
Installation of pumps and pipes
Installation of pumps and pipes is generally undertaken by suppliers and contractors in accordance with special programmes and drawings. This section is not intended as a guide for these specialists, but deals only with those aspects which may be considered of interest in connection with the planning of pump installations and the checking of their implementation.
Site for the pump
The space allocated for the pump must be sufficient to permit erection, dismantling, care and maintenance. Transport routes and hoisting facilities must be available, also drainage facilities for leakage, tapping, liquid used for flushing sealing devices, water used for operating valves, etc. The risks of flooding the pump unit in addition to the electrical and control systems (which can be very expensive in the event of break-downs) must also be taken into account.
The pump should be sited as Iow as possible in relation to the level on the suction side and in a place permitting the shortest possible suction pipe With the minimum number of bends. The ventilation of the pump site should be further studied. The electric motor of the pump must receive the necessary cooling; and if dangerous substances (harmful to the environment or highly inflammable) are to be pumped, special ventilation requirements must be observed. The electrical and automatic devices belonging to the pump must also be protected against damage. It should be noted here that the heat generated by the pump’s electric motor can be considerable.
Consideration must also be given to the noise caused by the pump, its motor and couplings. More and more attention is being devoted to noise from pump units and their pipe systems, and special measures may have to be taken in this respect. In order to reduce vibration noise, which may be further conveyed through thebuilding structure, it may therefore be necessary for the pump foundation and parts of the pipe system to rest on rubber or similar flexible mountings. Installation of pumps and pipes may also require sound absorbing panels to be erected around the pump unit.
Permissible noise levels are often controlled by legal, safety and environmental requirements, at places of work. In the case of noise exceeding 75-85 dB (decibels) measures must usually be taken, at least if the pump is to be erected on working premises.
Pump installation check list
Many faults and unnecessary costs can be avoided if the following check lists are used. Although more than one hundred check items are included under more than ten main categories, they can not be regarded as entirely exhaustive, because in certain special fields, attention must be paid to some additional factors. Above all, check lists should be used when planning and purchasing pump equipment and during pumping installations, especially for unusual or difficult liquids. For normal applications in a particular branch of industry, e.g. a dairy or for a certain type of pump (e.g. submersible sewage pumps) a special check list or specification can easily be drawn up. Before installation of pumps and pipes make sure to check the following:
Pump capacity
Volume flow rate
- min.
- mean
- max.
Volume flow — duration (and constancy)
Delivery head at different rates of flow min. max. (require a system curve from the supplier of the system)
Delivery head for filling of pipe system with respect to possible siphon effects.
Delivery head affected by possible starting resistance of liquid.
Pump characteristics (e.g. differences between centrifugal and displacement pumps).
Inlet pressure (pressure rating) / NPSH available
Suction factors
Evacuation
Evacuation time
Regulation of pump capacity
- throttling, on-off
- adjustable blades, pre-rotation
- speed regulation
Pump capacity for high viscosity, silting up and gas content.
Changes in temperature and pressure on the inlet side (important when operating close to NPSH)
Dry running capabilities in general and during evacuation
Overheating at zero discharge (Q=0)
Pump, mechanical requirements
- Rigidity of shaft
- Shaft deflection at seals
- Service life of bearings
- Strength. Pressure class (rating)
- Pressure tightness
- Pressure testing
- Anticipated reliability of operation
- Anticipated service life
- Permissible number of starts per hour
- Permissible number of starts per year
- Permissible loads from pipes
- Amount of internal clearance. Risk of galling
- Changes in efficiency resulting from clearance variations
- Dismantling method for maintenance purposes
- Need of access hatches (for cleaning etc.), if any
- Abnormal running in connection with reversed flow
- Abnormal running in connection with wrong direction of rotation
Pipes and pipe connections
- Pressure class (rating)
- Type of flange for pump
- Attachment points for fixing and supporting the pipeline
- Forces and moments between pipe and pump
- Inlet pipe routing
- Location of pump connection joints
- Stop valves (shut-off)
- Check (non-return) valves
- Safety (relief) valve (displacement pumps)
- Rigid, floating or non-basal (free) installation of pump
- Tapping points for measuring e.g. pressure and temperature
- Water hammer for normal stop
- Water hammer in the event of power failure
- Water hammer for initial filling of system
- Short pipe sections for facilitating dismantling of pump
- Minimum flow and sedimentation in pipelines
- Insulation against heat and cold
Pump drive
- Electric motor:
- voltage
- frequency
- method of starting
- form of protection
- cooling system
- Power requirement normal
- Power requirement for excessive or for too iow volume flow
- Space, if any, for future larger motor
- Transmissions:
- gearbox
- belt drive
- Shaft coupling (see also Chapter 6)
- type
- flexibility
- spacer sections for dismantling
- Speed (r/min)
- Direction of rotation (especially steam turbines and combustion engines)
- Starting torque for pumps which can be blocked by deposits and objects
- Starting torque for displacement pumps
- Sizes of transformers for starting large units
- Size of electric fuses
- Disturbance elimination (radio)
- Disturbance elimination (frequency inverters)
- Automation equipment
Environment
- Industrial safety standards
- Noise level
- Vibration level
- Leakage in the form of liquid
- Leakage in the form of vapour
- Safety with respect to explosions
- Radiation of heat
- External condensation on cold surfaces, possible formation of ice (frost) on pump and in pipes
- Permissible gas content in premises (ppm) and necessary ventilation
Erection and installation
- Horizontal, vertical shaft
- Space and transport routes for erection and maintenance
- Lifting devices
- Foundation
- Effect of existing environment on pump and driving
- Space, if any, for changeover to larger pumps in the future
- Draining of sealing leakage
- Draining in connection with emptying the pump
- Draining of lubricants and cooling liquid
Maintenance
- Lubrication
- Maintenance instructions
- Lists of spare parts
Spare parts:- wearing parts
- replacement parts
- standard components
- Drawings of spare parts
- Pump curves
- Special tools
- Data concerning permissible measurements for wear and maximum clearances
- Tapping points/measurement sockets for preventive maintenance (vibration, temperature, electric current, etc.)
- Hours-run meter
- Staff training
- Possibilities of modifying pump for other functions (e.g. replacement of impeller exchange of material)
Purchase
- Standardisation level of product
- Guarantee for product
- Guarantee of function
- Delivery time
- Price
- General terms of delivery
- Measurement drawings
- Weights
- Type and scope of test
- Classification and checking in accordance with legal regulations
- Erection and putting into operation with assistance of supplier’s personnel
- Follow-up as provided for by supplier
- Final inspection
Section 3.7 Standards deals with the criteria and standards which are of prime importance in connection with purchase, especially when certain certifications are required. These are amongst other things, guarantees of performance and quality of the product (pump) but does not serve as a guarantee for service life and reliability in that specific application.
In processing industry and especially at refineries, API 610 is usually applied as a requirement criterion for centrifugal pumps, API 674 and 676 for positive displacement pumps, as it specifies in detail how a pump should be designed, manufactured and tested. Reference may made where applicable to API 610 for pumps to meet these requirements.
The purchase documents should contain references to legislative regulations and requirements affecting design, to the properties of the liquid as well as to operating conditions and function of the pump in order that the manufacturer may able to determine the necessary material and design of the pump.
Properties of Liquids, see Section 7