- Case Study Summaries
- Worthington Descaling Pump
- Ingersoll Rand Descaling Pump
- Wilson Snyder Descaling Pump
- Worthington Central Hydraulics Pump
- Union Reciprocating Plunger Pump
- Flowserve Caustic Sump Pump
Proven Experience. Practical Solutions.
Many of the multi-stage pumps in critical steel mill applications were designed and built 30 or more years ago. Since that time, there have been engineering design improvements that both solve earlier design issues and increase the efficiency and reliability of these pumps.
Since 1969, Hydro has provided the steel industry with engineered pump repair solutions that not only ensure many more years of useful pump life, but support your efforts to obtain significant cost saving benefits.
"I’ve been supporting the steel industry throughout my 29 year career in pumps. Before joining HydroAire in Chicago, I worked for a pump OEM and also for a pump distributor representing a large OEM. The interesting difference in working for Hydro is that I don’t represent any single point of view. I can look at each situation objectively and work with my customer and my team to develop the best, most cost effective solution. This customer-focused, solution-driven approach means a lot to me."
Ken Babusiak, Manager Industrial Sales, HydroAire, Inc.
Application: Descaling for Plate Mill
Pump Details: Worthington 6WC135 5-Stage
Pump Type: Barrel
A steel mill experienced consistent maintenance problems with their descaling pump and asked Hydro to implement upgrades and modifications to increase pump reliability.
Running clearances were reduced and concentricities were returned to 0.001" T.I.R. which allows the pump to be rebuilt with tighter fits. Specially heat-treated material was used so residual stresses would not cause bowing during or after the machining process.
The metallurgy of the wear rings, impellers, stage pieces, and twin volutes was upgraded and a special gall-resistant composite material was used for the wear rings. Hydro also upgraded the stationary wear components from "saw tooth" design by furnishing Lomakin grooves to reduce wear.
The rotor was centralized to reduce turbulent flow and the impellers and rotor were dynamically balanced to a stringent standard of 1 W/N where W represents one half the weight of the component being balanced and N represents the operating speed. Hydro performed A and B Gap Modifications in addition to converting the impellers from 7 to 5 vanes, which substantially reduces vibration at vane pass frequency.
As a result of Hydro's upgrades, the life cycle of the pump was extended from approximately 8 to 60 months and provided significant cost savings to the mill. In 48 months, the mill's estimated savings was $1,702,500.
Ingersoll Rand Descaling
Application: Descaling for a Hot Mill
Pump Details: Ingersoll Rand 6x11 DAH
Pump Type: Multi-Stage Horizontal Split Case
After a recent repair, a hot mill's descaling pump failed just 12 hours into operation. The hardness of the wear ring, greater than that of the impeller, caused the wear ring to act as a cutting tool - slicing into the impeller shrouds and causing the impellers to break apart. This catastrophic failure caused severe damage throughout the pump.
The mill sent the 10-stage pump to the OEM for evaluation, then contacted Hydro for a second opinion. Hydro's inspection revealed several details of the failure, including excessive damage to the shroud contact, casing, and shaft. The back hub impeller rings on most of the impellers were destroyed and missing.
Hydro eliminated the wear rings on the impellers by welding the impeller shrouds and machining them to make up the dimensional difference the wear rings would otherwise provide. This design upgrade will increase the pump's run life and reduce the time and costs associated with maintenance required to replace the wear rings.
The pump was repaired and ready for shipment back to the mill after only 8 weeks in Hydro's shop. The pump was started up over a month ago and is running very well.
Wilson Snyder Descaling
Application: Descale for Flat Products Rolling Mill
Pump Details: Wilson Snyder MBD 6-Stage
Pump Type: Multi-Stage Horizontal Split Case
A mill's descaling pump was cycling from full to low flow several times per hour depending on the mill rolling rate. When the vibration became excessive, the pump experienced thrust bearing failure.
Inspection revealed several problems. Due to improper material hardness, the bores had galled from contact with the impeller hub rings. The hub rings had also separated from the impeller hubs and were seized inside the case bushings. The bore ID appeared to have a hard coating, but there was galling on the surface. Hydro found that the coating could be machined, which would suggest softness unlike usual hard coated surfaces.
Hydro replaced the existing impeller rings with new heat treated rings made with greater hardness. The IDs of the impellers were chrome plated to eliminate any galling tendencies. To provide a better fit between the element and casing, the casing bore was welded and re-machined.
Before Hydro’s engineered repair, the pump was being sent out for repair every two years. A lesson learned from this engineered repair is that use of proper material is a key factor in quality repair practices.
Worthington Central Hydraulics
Application: Central Hydraulics for Hot Strip Mill
Pump Details: Worthington Type 3-WT-810
Pump Type: Multi-Stage Split Case Diffuser
A Hot Strip Mill experienced repeated failures of two 10-stage split case diffuser style pumps, which were designed to produce up to 1,400 PSI fluid pressure. Unable to consistently run the two pumps, production was drastically reduced and the mill suffered a high scrap rate.
Hydro was asked to evaluate the pump and propose a repair plan that addressed the underlying issues. After a thorough evaluation, Hydro found that a previous repair shop had manufactured the shaft from incorrect material and had not used accepted manufacturing techniques. This caused stress risers to occur in the threaded areas, leading to shaft failure. In addition, a review of their system revealed deterioration of the pump’s base plate and leaks through the piping system, which contributed to the overall instability of the pump while in operation.
Hydro manufactured a new shaft, impellers, and diffusers from upgraded material and made modifications to reduce turbulence in the pump and increase rotor stability. Rotor centralization, a process of centering the impellers within the stationary hydraulic components, was also performed. These pumps have run for over five years, saving the mill over $500,000 in lost production and maintenance costs.
Union Reciprocating Plunger
Application: Central Hydraulics
Pump Details: Union TX Models 50 & 70
Pump Type: Reciprocating Plunger
A steel mill had been experiencing complications in their operations due to consistent problems with their plunger pumps. Excessive leakage made it difficult to maintain the hydraulic system, and unscheduled periods of down-time were proving costly.
After being told by four different repair shops that their plunger pumps could not be repaired, the mill turned to Hydro for a solution. Hydro assessed the pumps and determined that they could be rebuilt and at a cost less than a new unit.
Hydro reverse engineered and manufactured the fluid head, provided and installed new valves, and rebuilt the pumps to their original standards. These pumps have been running well for over two years now. The plant has realized substantial savings over cost of replacement units, lost production and unscheduled down-time.
In a years time, the mill estimated cost savings of over $70,000.
Flowserve Caustic Sump
Application: Caustic Service for Steel Galvanizing
Pump Details: Flowserve 4x4x12 Model 4565
Pump Type: Single-Stage Vertical Sump
A steel galvanizing plant experienced decreased production when three vertical sump pumps in caustic service suffered consecutive failures. To meet production requirements, the plant was forced to rent submersible pumps until the vertical pumps could be repaired.
Hydro’s inspection revealed bearing failure, impeller vane wear, and damage to the shafts and columns. These failure modes had been caused by a lack of lubrication, which resulted in the shaft eating through the bearing into the column of the pump.
Many new parts were required to rebuild the pumps. Parts that were not readily available, including the shaft and columns, were reverse engineered and manufactured quickly to ensure a quick turnaround. An impeller with severe vane wear needed to be replaced, and OEM delivery was 8 weeks. Hydro repaired the impeller by manufacturing new vanes which were mechanically attached to the impeller.
The pumps were completed in just 4 weeks, and the rest were installed at the plant shortly thereafter. Hydro’s response to this plant’s emergency reduced costly down-time.