Overhauling Procedure For Single Stage, Multi stage Pumps And Steam Turbines

OVERHAULING PROCEDURE SINGLE STAGE CENTRIFUGAL PUMP

• Remove coupling guards after getting clearance of safety aspects like electrical isolation, process lines drainage etc.

• Remove coupling spacer and loose the casing bolts connects the stuffing box frame after removing and draining oil level glass and lube oil from bearing housing.

• Pullouts back the pump from casing with care of casing gasket.

• Dismantle all parts from the pump unit as impeller, mechanical seal assembly, shaft sleeve, coupling, and bearings respectively with high care.

•  The following factors should be checked and recorded for future to estimate the performance condition of the pump, are wear ring clearance, seal compression, shaft deflection, thrust, trueness etc while or after dismantle.

• Proper tracing of parts need to any vision able damage like crack, score, break etc.

• Best is changing new one comparing reconditioning of parts.

• Assembly is the reversing procedure of dismantle as before seen.

• Before coupled alignment should be checked and corrected

OVERHAULING PROCEDURE FOE MULTISTAGE CENTRIFUGAL PUMP

BASIC PROCEDURE:

• First we have take the permit, Prepared the tools and as per permit requirement.
• Inspect the mechanical and Electrical isolation.
• Inspect the blinding location as per P&ID (PERMIT IDENTIFICATION)
• Inspect pressure gauge zero and opening drain valve

OVERHAULING PROCEDURE:

• Remove Coupling hub with use of the puller
• Remove bearing housing top covers of both inboard and outboard sides.
• take out journal and thrust bearing in the outboard side and journal bearing in the inboard side
• Dismantle the bottom bearing split housing of outboard side
• Remove thrust collar from shaft
• Remove all seal parts from head on both sides.
• Cover the shaft on the bearing seated surface finished area on the tape
• Loosen and remove the head bolts connected with barrel of pump to let the rotor free to remove after taking out the head from position by the jack blots provided on the head. care should be taken about the gaskets. inner and outer and the removal of discharge diffuser case.
• fix the fixture to guide the rotor assembly.
• pullout the rotor assembly including inlet guide vane case, intermediate stage housing with care
• check the keyway of barrel.
• transfer the rotor assembly to workshop for the next step of action.
• Remove tie rods, which connects of all cases and key on the cases.
• Remove balancing piston by loosing locknut.
• Dismantle diffuser, stage bush, impeller, impeller keys, inlet guide vanes with diffuser of all stages respectively.
• Now dismantle of all parts completed.
• proper tracing of parts need to any vision able damage like crack, score, break, etc., while dismantling.
• The following measurement should be measured and recorded for analyzing the performance like wear ring clearances, stage bush clearances of all stages, bearing diametric clearance, thrust allowance, shaft trueness, seal setting compression, etc., while after dismantling.
• Care should be taken about all allowable factors with in design limits.
• Changing new parts is better than re conditioning.
• Assembling is reversal procedure for dismantling before seen. proper tightening torque should be followed is carry over.
• Before coupled with drive alignment should be checked and corrected to retain within limit.

OVERHAULING PROCEDURE FOR STEAM TURBINES

• Isolate steam inlet, remove coupling guard and coupling spacer to disconnect from driven.

• Dismantle governor and linkages with governor valve.

• Loose the bolts connecting top half split casing with bottom casing and take out.

• Remove bearing covers on both side inboard and inboard.

• Remove leak-off lines of carbon ring housings.

• Take out rotor with stuffing box and transfer to workshop to carry further overhaul.

• Dismantle stuffing box case and carbon rings and journal bearings.

• Remove governor  drive coupling, trip collar,  ball bearing, steam bunters on outboard side.

• Remove coupling hub and steam bunters on inboard side.

• Loosen wheel lock nuts with noting proper position of wheel and remove the wheel from the shaft with the use of arbor press.

• Perfect inspection should be carried on each and every parts incase of any damage, score, brake.

• Assembly is the reverse procedures of dismantle. Use proper sealing compound in-between casing split and bearing housing cover.

• The following factors should be considered while and after assembling are, shaft run out, nozzle and reversing chamber condition, governor valve and trip functioning, journal bearing radial clearance and crush, carbon ring clearance, governor function, free rotation, alignment, etc.

• Trip check should be checked before coupled with driven.