BOILER FEED PUMP
OPERATING INSTRUCTIONS 1. INTRODUCTION
3. MAINTENANCE PROCEDURES
WARNING : IT IS ESSENTIAL THAT THE PLANT SAFETY RULES AND REGULATIONS ARE OBSERVED AT ALL TIMES DURING MAINTENANCE PROCEDURES.
Note : The FK4E36 Boiler feed pump is an integral part of the tandem Boiler feed pump set. The following instructions should, therefore, be read in conjunction with those for the Booster pump in Part 1.
3.1 Preparation for Maintenance
Before commencing any maintenance procedures, the pump must be isolated as follows :-
(1) Isolate the electrical power supplies to the pump driving motor and the lubricating oil system.
(2) Isolate the electrical power supplies to all instruments.
(3) Check that the pump set suction, discharge and leak-off isolating valves are shut.
(4) Check that the Mechanical seal lines have been isolated.
(5) Open the drain and vent connections, and drain the pump casing.
WARNING: BEFORE PROCEEDING WITH ANY MAINTENANCE ON THE PUMP, BE SURE THAT THERE IS NO PRESSURE WITHIN THE PUMP CASING.
3.2 Examining the drive end (DE) journal bearing.
(1) Disconnect and remove any instruments which could interfere with the dismantling procedures.
CAUTION : The top half bearing housing is located on the bottom half bearing housing by two fitted bolts. Care must be taken to avoid damage to the bolts or the holes in the top and bottom half housing.
(2) Withdraw the two fitted bolts and remove the cap screws securing the top half bearing housing to the bottom half bearing housing. Also remove the cap screws securing the top half bearing housing to the suction guide.
(4) Use two jacking screws in the top half bearing housing to separate it from the bottom half.
(6) Lift the top half bearing housing complete with the top halves of the oil guards away. Remove the top half journal bearing from the shaft with the assistance of applying jacking screws to the bearing keep.
(7) Take the weight of the pump shaft and rotate the bottom halves of the journal bearing and oil guards around the shaft and lift them away.
(8) Examine the journal bearing and shaft journal for signs of damage, scoring of deterioration and examine the journal bearing and the oil guards for wear. Reference should be made to the sectional arrangement drawings, for the clearances of the journal bearing and oil guards.
Note: Lightly smear the shaft and journal bearing surfaces with oil before final assembly.
(9) Rotate the bottom halves of the journal bearing and oil guards around the shaft and into position in the bottom half bearing housing. Release the weight of the pump shaft.
(10) Locate the top half journal bearing in position on the pump shaft. Locate the bearing keep on the dowels and secure it with the cap screws.
(11) Lift the top half bearing housing complete with the top halves of the oil guards onto the bottom half bearing housing.
(12) Locate the top half bearing housing to the bottom half housing with the fitted bolts, then secure to the bottom half and the suction guide with the cap screw.
(13) Replace the instruments and the turbo coupling/pump drive coupling guard.
3.3 Examing the Non-drive End (NDE) Journal and Thrust Bearing
(1) Disconnect and remove any instruments which could interfere with the dismantling procedure.
(2) Remove the fluid coupling/pump drive coupling guard.
(3) Remove the fluid coupling/pump drive coupling spacer and element assemblies.
(4) Remove the set screws securing the bearing housing end cover to the top half bearing housing.
CAUTION : The top half bearing housing is located on the bottom half bearing housing by two fitted bolts. Care must be taken to avoid damage to the bolts or the holes in the top and bottom half housing.
(5) Withdraw the fitted bolts and remove the cap screws securing the top half bearing housing to the bottom half bearing housing and the gland housing.
(6) Use four jacking screws in the top half bearing housing to separate it from the bottom half.
(7) Lift the top half bearing housing complete with the top half oil guard away.
Remove the top half journal bearing from the shaft.
CAUTION : The thrust cover is located on the bottom half bearing housing by four dowel pins. Care must be taken to avoid damage to the dowels or the locating holes.
(8) Remove the cap screws securing the thrust cover to the bottom half bearing housing. Use four jacking screws to separate to the thrust cover from the bottom half bearing housing and lift it way.
(9) Lift the top halves of the floating seal carriers away, then take the weight of the pump shaft and rotate the bottom halves of the journal baring, oil guard and floating seal carries around the shaft and lift them away.
(10) Unclip the springs and remove the split floating oil seals from the bearing housing.
Note : The thrust carrier ring split line is at 90° to the bearing housing horizontal surface.
(11) Remove each thrust carrier ring in turn as a complete unit as follows :- Rotate the complete carrier around the shaft until the half ring with the stop pin can be removed, then rotate the other half ring around the shaft until it can be lifted clear of the shaft. Repeat with the second carrier ring on the other side of the thrust collar.
(12) Examine the journal bearing, shaft journal, thrust pads, thrust collar, split oil seal and oil guard for damage or deterioration. Under normal operating conditions it is not expected that any measurable wear will take place on the thrust pads other than a dulling of the white metal surfaces. It is recommended that when this dulling has spread to more than half the surface area of the pads, they should be renewed.
Refer to the sectional arrangement drawing for the clearances and renew the journal bearing and oil guard if necessary.
Note : Lightly smear the shaft, thrust collar faces and baring surfaces with oil before final assembly.
(13) Install each split floating oil seal on the pump shaft with the spring.
(14) Take the weight of the pump shaft and rotate the bottom halves of the journal bearing, oil guard and floating seal carriers around the shaft and into position in the bottom half baring housing. Release the weight of the pump shaft.
(15) Install each thrust carrier ring in turn as a complete unit as follows:-
Take the half carrier ring without the stop pin and place it over the shaft with the pad faces touching the thrust collar and rotate it into the bottom half bearing housing, then place the other half carrier ring with the stop pin upon the first and rotate the complete carrier ring until the stop pin locates on the horizontal face of the bottom half bearing housing. Repeat with the second carrier ring on the other side of the thrust collar.
Note: The thrust carrier ring split line is at 90° to the bearing housing horizontal surface at the stop pin locates in a slot in the top half bearing housing.
CAUTION : Do not insert feeler gauges between the thrust collar and the thrust pads; this may give an inaccurate reading and cause damage to the white metal and surface.
(16) Check the axial clearance by moving the pump shaft towards the drive end so that the thrust collar is hard against the inner thrust pads, then using feeler gauges between the outer thrust bearing spacer and the thrust housing inner wall check the clearance. Refer to the Sectional
Arrangement Drawing for the original total axial clearance. Any measurable variation should be investigation.
(17) Lift the thrust cover onto the bottom half bearing housing ensuring that the dowel pin for each floating seal carrier are properly located. Locate the thrust cover to the bottom half bearing housing with the dowel pins, then secure the thrust cover with the cap screws.
(18) Locate the top half journal bearing in position on the pump shaft.
(19) Lift the top half bearing housing complete with the top half oil guard onto the bottom half bearing housing, ensuring that the oil guard and stop pin are properly located.
(20) Locate the top half bearing housing to the bottom half housing with the fitted bolts, then secure to the bottom half and gland housing with the appropriate cap screw.
(21) Fit a new joint and secure the bearing housing cover to the top half housing with the set screws.
(22) Install the coupling/pump drive coupling spacer and element assemblies.
(23) Replace the instruments and the coupling pump drive coupling guard.
3.4 Checking the Axial Running Position and Thrust Bearing clearance
Note: This operation is to be carried out during the assembly of the drive end and non-drive and bearing housings.
(1) The drive end bearing housing should be assembled without the following components in place.
(a) Top half bearing housing and top half journal bearing.
(b) Oil guard and oil throwers.
(2) The non-drive end bearing housing should be assembled without the following components in place.
(a) Top half bearing housing, top half journal bearing and thrust cover.
(b) Thrust bearing carrier ring assemblies.
(c) Oil guard and oil thrower.
(3) Check the axial running position of the rotating assembly as follows:- (a) Move the rotating assembly as far as possible towards the drive end
of the pump and, using the outer face of the thrust collar as a datum,
scribe a line on the horizontal surface of the bottom half bearing housing.
(b) Move the rotating assembly as far as possible towards the non-drive end of the pump and, using the same datum, scribe a second line on the bottom half bearing housing. Measure the distance between the two lines; this should be approximately 8 mm.
CAUTION : The minimum acceptance total axial travel is 6 mm.
(c) Position the inner halves of the thrust bearing carrier rings and spacers in this bottom half housing and move the rotating assembly as far as possible towards the drive end of the pump. Scribe a third line on the surface of the bottom half bearing housing. Using the same datum as before: this line should be offer 0.50 mm towards the non-drive and from midway between the other two lines.
CAUTION : Do not insert feeler gauges between the thrust collar and the thrust pads; this may give an inaccurate reading and cause damage to the white metal pad surface.
(4) Check the thrust bearing axial clearance as follows :
(a) Position the outer halves of the thrust bearing carrier rings and spacers in the bottom half housing.
(b) Check the axial clearance by moving the pump shaft as before and carefully measuring the difference: alternatively, move the pump shaft so that the thrust collar is hard against one set of thrust pads and use feeler gauges between the opposite thrust bearing spacer and the bearing housing. The total axial clearance was Originally as shown on Drawing Nos. measurable variation should be investigated.
(5) If spare thrust bearing assemblies are fitted, proceed as follows:
(a) With the rotating assembly in the axial running position, accurately measure the distance between the bottom half bearing housing wall and the inner thrust collar face and record the reading. Repeat the procedure between the outer thrust collar face and the bearing wall and record the reading.
(b) The spacers should now be removed form the inner and outer thrust carrier ring halves and machined accurately to give the correct thickness as follows:-
(i) Inner thrust ring spacer thickness – Measured distance between housing wall and inner collar face minus thrust ring thickness.
(ii) Outer thrust ring spacer thickness – Measured distance between housing wall and outer collar face minus (thrust ring thickness + axial bearing clearance).
(c) Secure the spacers to the thrust carrier ring halves and repeat step as previously described.
4. OVERHAUL
WARNING : IT IS ESSENTIAL THAT PLANT SAFETY AND REGULATIONS ARE OBSERVED AT ALL TIMES DURING MAINTENANCE PROCEDURES.
The following instructions apply when the pump cartridge is to be removed and dismantled for a complete overhaul.
Note: If a replacement cartridge is available, this should be prepared and installed as described in Section 4.6 before proceeding to dismantle and repair the worn cartridge as described in Section 4.3. Reference numbers on components should be re-marked as necessary to facilitate assembling.
4.1 Preparation for Overhaul
(1) Prepare the pump for maintenance as described in Section 1.1 (2) Disconnect and remove the following pipes and fittings :-
(a) The lubricating oil pipe work to and from the pump bearings.
(b) The mechanical seal pipe work.
(c) The balance chamber return pipe work from the discharge cover.
(d) The gland well drain pipe work from the suction guide and the housing.
(e) Remove the interstage spool piece and interstage tube.
(f) Remove air vents from the drive end bearing housing and the suction guide.
(3) Disconnect and remove any instruments which could interfere with the dismantling procedures.
(4) Remove the fluid coupling/pump drive coupling guard.
(5) Remove the fluid coupling/pump drive coupling spacer and element assemblies.
(7) Check that all lifting equipment and special tools are in good condition.
4.2 Withdrawing the Pump Cartridge
(1) Remove the set screws securing the split pull-up ring to the pump casing.
The ring can now be removed, the upper half being located by two dowel pins.
(2) Secure the first extension sleeve (5) to the drive end bearing housing with screws (12) and (24).
(3) Enter the cartridge tensioning screw (10) through the hold on the end plate of the first extension sleeve and screw it into the tapped hole in the end of the pump shaft. Run the nut (11) on to the end of the tensioning screw and tighten it until all cartridge movement is taken up.
Note : The cartridge axial movement between the last stage diffuser and the outer guide is approximately 2.5 mm.
(4) Locate the suction and support jack (7) on the base plate pad. Centralise the roller using the slots provided on the jack base. Jack up the roller until good contact is made with the first extension sleeve (5). Tighten the screws to secure the support jack to the base plate.
CAUTION : The support jack (7) is intended to take the weight of the drive end of the pump cartridge and so facilitate removal of the cartridge. Due to the fine diametrical clearance which exists between the suction guide and the pump casing, extreme caution must be observed when adjusting the height of the support jack roller to avoid over tightening, which may lead to damage to the suction guide or pump casing when withdrawal is attempted.
(5) Remove and retain the stud caps.
(6) Remove the pump casing/discharge cover nuts, using the hydraulic stud tensioning equipment as follows:-
(a) Locate the jacking ring and load cell assembly over two pairs of diametrically opposite casing studs and nuts as shown.
(b) Screw the load cell onto the stud until it abuts the jacking ring.
(c) Connect the load cells to the hydraulic pump by means of the manifold and pipe work.
(d) Operate the pump and prime the system with oil, then raise the pressure in the system specified by the supplier of the hydraulic tensioning equipment, to relieve the pre-loading on the studs.
(e) Slacken back the casing nuts using a tommy-bar in the holes in the nuts.