This is the start of a series of articles on the correct installation of a pump set and its associated pipework which is important for the ongoing operation of the pump system to ensure a long a trouble-free working life.
To complete the installation of a pump set the following safety equipment should be available and used where and when appropriate:
- Work overalls
- Hard hat
- Work gloves
- Eye protection
- Face mask
- Hearing protection
Note, the use of the some or all of the above safety equipment will also be required when commissioning a pump set as outlined in the next series of articles.
Some or all off the above will be required for the following operations which are described in this chapter:
- Mixing grout
- Drilling and cleaning holding down bolt holes
- Grouting
- Installation of pipework
- Coupling alignment
Foundations
The pump set should be supported on a firm foundation or plinth preferably a rectangular concrete block with a mass equivalent to the weight of the complete pump set. The concrete plinth commonly has a height of 150 mm above floor level and is generally about 300mm greater in length and width than the pump base.
A framework for the concrete block should be built and reinforcing steel used to make the block structurally strong. The framework should allow for the appropriate number of holes for the foundation bolts required to hold down the baseplate. These holes should be 4 times the foundation bolt diameter to allow for final positioning before grouting.
Grout allowance – set the top of the foundation 20 to 40mm below the bottom of the base level and the top surface of the block should be rough to provide a key for the grout. Note, before grouting the foundation block must be clean and wet to prevent excessive moisture loss from the grout face.
Allow the foundation to cure until it has adequate strength, before mounting the pump set on the foundation.
Figure 1
Erection
When pumps and their drivers are mounted on baseplates at the suppliers works, they are correctly aligned, i.e., the couplings are concentric and the faces are parallel in both axis, care should be taken to minimise misalignment. It is absolutely essential that this alignment be checked and corrected after installation at site and prior to starting the pump set.
Care should be taken in the erection process to minimise any possibility of misaligning the pump set.
Insert steel wedges or packers and shims between the top of the foundation block and the bottom of the baseplate adjacent to and on each side of the foundation bolts. If the baseplate is supplied with jacking bolts these can be used to level the baseplate instead of wedges or packers and shims. It is necessary, however, to maintain the horizontal centreline or horizontal flange face, whichever is applicable, at the correct RL.
When the pump or pump set is lifted into position it must be lifted with the appropriate lifting tackle and correctly slung by a qualified rigger.
Levelling
The pump set can now be levelled on the foundations using a straight edge and spirit level.
If the baseplate is installed separately without the pump and driver, an engineers’ level must be used to ensure both the pump and motor mounting pads are level in both directions. Again, the correct RL must be maintained.
For baseplates with machined pump and motor pads, the pump and motor pads must be parallel to each other in both the length and width directions.
If the pump set has been subject to maltreatment during transport, it may be necessary to adjust the position of the driver or the pump or both on the baseplate which will require the coupling alignment be checked at the end of the installation process.
A degree of level of 0.1mm per 1,000mm of length of baseplate is generally acceptable. It should be noted that the accuracy of level can vary according to the preference of the end user or contractor. This accuracy can vary between 0.05 to 1.5 mm/meter, however, the pump bearing type and its lubrication should be considered as these have a major impact on the level of accuracy required. Oil lubricated sleeve bearings on pump and/or motor (common in the oil industry) will require the highest degree of accuracy.
For the majority of pump sets which do not have machined pads a level accuracy of 1.5 mm/meter will be acceptable.
To obtain the levels outlined above it will be necessary to adjust the packers or levelling screws under or on the baseplate.
Remember when an adjustment is made the level in another direction will change.
During the grouting in of the pump set and its final alignment it is necessary that the pump set level be rechecked.
Grouting
If the unit is to be installed between fixed limits of suction and discharge piping, it is advisable to temporarily connect the piping to the pump before the pump set is grouted in. The pump set can then, if necessary, be moved slightly to suit the layout of the piping.
Grouting is carried out in two stages:
- Grout and fix the foundation bolts before the pump set is installed on the plinth
- The baseplate is grouted in after the pump set has been installed, levelled and the pipes connected
Figure 2
Traditionally, grout is made from one part Portland cement and two parts sand (no aggregate). Mix with as little water as possible to minimise shrinkage. This grout can be used for both the grouting the foundation bolts and the baseplate.
Alternatively, a commercial non shrink grout material can be used, mixed and used according to the makers’ instructions.
Grout foundation bolts
Traditional method
For this method we use the holes for the foundation bolts cast in the plinth.
- Mix the cement grout or commercial grout
- With the bolts in place in each hole, fill with grout to within 25mm of the top to allow a key for final grouting
Modern method
For this method it is not necessary to cast holes in the plinth with epoxy adhesive being used instead of grout mix.
The following is a general description on how this is done, however when fixing with epoxy adhesive refer to the manufacturers’ instructions for the adhesive being used:
Step 1 – Measure and mark the position of the foundation bolts on the concrete block. For some baseplate designs it is possible to locate the pump set on the foundation and drill directly through the baseplate mounting lugs.
Step 2 – Drill a hole to take the foundation bolt which should typically be no larger than 6mm wider than the bolt diameter. For good quality concrete, the depth of the hole should be generally 10-15 times the bolt diameter, see Figure 3.
Figure 3
Step 3 – Scrub the hole with a stiff bristle brush to remove all drilling debris that will inhibit bonding, see Figure 4.
Figure 4
Step 4 – Blow hole clean with oil free compressed air, brush and blow clean again. All holes should be clean and sound, see Figure 5.
Figure 5
Step 5 – Prepare the epoxy mix in accordance with manufacturers’ instructions ready to fix in the foundation bolt.
Step 6 – Fill the prepared hole with the mix to approximately half the hole depth, see Figure 6.
Fig 6
Step 7 – Insert the foundation bolt slowly in a twisting motion into the hole forcing it to the bottom until the adhesive flows to the top. Twist the bolt to ensure firm contact and a bond is established, see Figure 7.
Figure 7
For both above methods of grouting and fixing the foundation bolts, the grout and adhesive should be allowed to cure. For the grout, 72 hours, for the adhesive as recommended by the manufacturer.
Grouting the baseplate
Why grout a baseplate? Grouting makes up for any discrepancy in the elevation and flatness of the concrete, it also fills any voids to provide a precise and level bearing for the baseplate.
When the foundation bolts are set, recheck the levels of the machined pads on the baseplate with a straight edge and spirit level.
To obtain these levels, it may be necessary to adjust the packing under the baseplate and tighten certain foundation bolt nuts to pull the baseplate down at certain points. It is for this reason that foundation bolts are grouted in first. It should be remembered that when an adjustment is made the level in another direction will change.
When levelling is completed and all foundation bolts are pulled down tightly, the preparation for grouting the baseplate can take place.
Figure 8
A dam should be erected around the baseplate just above the lower flange of the channel as shown in Figure 8.
The grout should be from Portland cement and sand as discussed in the grout section above.
The grout should be well rammed under the baseplate with a wooden stick.
As an alternative to the above, a commercial non shrink grouting material can be bought, mixed and used strictly in accordance with the manufacturers’ directions.
Note: it is important that the grout fills all the cavities between the lower flanges and the foundation and must not shrink after curing.
When the baseplate has a drip tray with air vents the grout must be filled to the top of all the air vents and fully penetrate every corner under the drip tray leaving no voids under the tray, because of the nature of this type of baseplate the grout is a critical part of the baseplate integrity and voids can lead to higher vibration when the pump is running.
When the grout is set (normally after 48 hours) the dam should be removed, and a smooth finish given to the grout and foundation surfaces. Uniformly re-tighten all foundation bolts and check the pump set alignment.
The next step is to align the driver with the pump if the driver has been supplied separately. It is important to note that the flexible coupling permits axial movement of both pump and driver shafts and compensates for thermal expansion. It is to be emphasised that since pin and bush type couplings are designed to reduce the transmission of shock to the bearings etc., and do not compensate for misalignment, they must be aligned to the same accuracy a rigid coupling.
Coupling alignment is fully explained in a later part of this series.
Summary
This article outlines the essential steps for correctly installing a pumpset to the point where the associated pipework is installed including the occupational and safety requirements. Future articles will cover the remainder of the installation process including pipe installation coupling alignment and installing belt driven pumps.