Maintenance of GSB series ​ horizontal high-speed pumps

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These pumps in this series are high-speed centrifugal pumps with a single stage, single suction, cantilever design, gearbox-driven speed increase, and horizontal configuration. It is mainly composed of overcurrent components, mechanical seals, a speed increase gearbox, a lubrication system, a motor, etc. The motor and the low-speed shaft of the gearbox are connected using a diaphragm coupling. In terms of the rotation direction of the pump, when viewed from the pump’s inlet side, the high-speed shaft rotates counterclockwise, and the low-speed shaft also rotates counterclockwise. 1. The flow-through part of the pump is mainly composed of the impeller, pump casing, etc. 1) Impeller: A radial straight-blade open impeller is used ； 2) Use an annular flow channel that matches the impeller. 2. Mechanical Seal: This pump’s mechanical seal is of the single-face or double-face type, with a small spring balance design. 3. Disassembly of horizontal high-speed centrifugal pumps: ① Remove the coupling guard and coupling ； ②Remove the auxiliary pipelines and make proper markings ； ③Remove the pump foot bolts and pump casing bolts ； ④Lift the pump out using a jack and place it on the ground ； 1) Remove the induction wheel and impeller, then place them properly ； 2) Make proper markings, loosen the hex bolts, and remove the rear end cover of the impeller ； 3) Remove the mechanical seal: loosen the bolts, take off the gland, rotating ring, and shaft sleeve, and place them neatly ； 4) Remove the fastening bolts on the split surface of the gearbox as well as the bolts on the oil seal cover, and take out the positioning pin ； 5) Tap the upper cover to loosen it, then lift it down and place it properly ； 6) Place the high-speed shaft and low-speed shaft horizontally, clean them thoroughly and then arrange them ； 7) Pull out the backrest wheel using a puller ； 4. Inspection of components: ① Check the wear condition of the bearings; examine whether there are pitting on the rolling elements, any damage to the raceways, and ensure that the bearing clearance does not exceed 3um ； ②Decide whether to replace the bearing based on operational conditions ； ③Check the gear for wear, looking for cracks, pitting, etc ； The contact area of the gear should be no less than 40% along the tooth height and no less than 55% along the tooth width, and it should be evenly distributed around the pitch circle. The side clearance between meshing gears is 0.08~0.10 mm ； ④The oil seal is of the labyrinth type; check whether the set screw for the oil retaining ring functions properly, and ensure that the oil seal shows no signs of aging or cracks ； ⑤Inspect the mechanical seal, and perform grinding or replacement ； ⑥Check the erosion and wear of the impeller, and measure the clearance at the impeller’s mouth ring; it should be within the range of 0.4–0.6 mm. If it reaches 1.2 mm, the impeller needs to be replaced ； ⑦Clean the gearbox and all its components thoroughly, and check whether there are any high points on the partition surfaces inside the gearbox as well as on the sealing surfaces of the oil seals ； ⑧Check the wear and erosion of the volute, and see if the volute gaskets need to be replaced ； 5. Assembly: ⑨ Begin installation after cleaning all components; fit the two shafts in place and rotate the shaft to check it ； ⑩Apply a thin layer of sealant to the mid-surface, attach the cover, and gently tap the positioning pin into its hole ； ⑪Install all the mid-plane fastening bolts, tighten them evenly in a symmetrical manner, and turn the shaft again ； ⑫Measure the gland clearance at each bearing and keep it within the range of 0.08–0.12 mm, adjusting this value by changing the thickness of the gland shims ； ⑬Install each gland, align it with the oil return hole, apply a small amount of sealant, and tighten it evenly. Then install the oil baffle, making sure to leave a gap of 0.15±0.05 mm between the oil baffle and the gland to prevent friction-induced heating ； ⑭Mark the appropriate position, install the rear end cover of the impeller, apply grease to the O-rings, and tighten the hex bolts ； ⑮Install the mechanical seal; it must be cleaned thoroughly before installation, and the sealing surfaces must not contain any dirt or damage ； The required compression amount can be adjusted by changing the length of the shaft sleeve; for this type of mechanical seal, 2/3 of the total compression amount of the two static rings is sufficient ； ⑯After the mechanical seal is assembled, check whether the turning gear operates smoothly ； ⑰After verification, install the key, impeller, and inducer, then lock down the anti-loosening gasket ； ⑱By adjusting the thickness of the pump head gasket, the axial clearance between the impeller and the volute, as well as between the impeller collar and the casing collar, is adjusted to 0.7–1 mm. ⑲Lift the bearing housing to the base, reinstall it, tighten the pump head, and then tighten the foot bolts ； ⑳Align the coupling such that both the radial and axial deviations do not exceed 0.1 mm ； After alignment is completed, install the coupling, guard, and associated piping, fill it with lubricating oil, clean the site, and the repair is complete.