Non-OEM Pump ReBuild Shops Part IV.: Case Studies

Author:

Heinz P. Bloch, P.E., Process Machinery Consulting, Jim Steiger, HydroAire Inc., Robert Bluse, Pump Services Consulting

Publisher:

Maintenance Technology

Date Published:

March, 2008

 

How competent is competent? More importantly, how much might it actually cost your operations if you were to entrust your pumps to the wrong shop?

This article is the last installment in a four-part series based on a presentation delivered at the 2007 NPRA Reliability & Maintenance Conference in Houston, TX. As in the previous installments, (which ran in the July and September 2007 and February 2008), the authors discuss how to distinguish competent pump repair operations.

In this fourth and concluding part in our series on non-OEM pump repair facilities, we discuss two actual case studies. As you read on, please recall that we coined the acronym “CPRS” to convey the term Competent Pump Repair Shop.

 

 

Repair case study #1:

Two IR Type J4x 15 lean amine pumps The first of our two case studies concerns the repair of two IR Type J4 x 15 radially split, double suction, betweenbearing pumps purchased in 1982 for lean amine service. Figs. 1 through 3 provide specifics.

The pumps were to be repaired using new 316 stainless steel casings and heads furnished to a CPRS by the refinery client. The client had bought these parts from the “current” OEM—a successor company to the initial OEM. While one pump was being repaired, the other pump remained in service, operating without a spare. However, the new casings and heads required considerable rework before they could be used. This rework included:

1. Sleeving and re-machining an oversize stuffing box bore;

2. Re-machining the two spiral wound gasket faces;

3. Weld-repairing a sand inclusion on a stuffing box face;

4. Re-facing the stuffing box faces to remove steps caused by the milling operation;

5. Re-machining two stuffing box bores that had been damaged so that the seal gland pilot would not engage. Continue reading

Aftermarket Report

Author:

George Harris, Hydro Inc.

Publisher:

Pumps & Systems

Date Published:

February, 2008

 

Aftermarket Business in 2007 and 2008

In general, Hydro enjoyed a strong year, and we are projecting continued growth in 2008. We believe that our mission to provide equipment quality and reliability is resonating with our clients and potential clients more so today than ever before.

 

Critical Issues

A critical issue facing end users is the tremendous worldwide demand for new pumps. This exceptional demand has shifted the industry focus to a new unit supply with the result that aftermarket support may have declined in some areas. On the other hand, this creates an opportunity for our company since our focus is the aftermarket.

Key issues for the pump industry are the continued shortage of skilled labor as well as long lead times for cast parts. These are likely to remain concerns for the foreseeable future and will need to be addressed in innovative ways by each company.

 

Current Trends

As the industries served continue to consolidate, management is increasingly giving more attention to “best in class” equipment performance as a way to realize reliability and profit improvements.

 

 

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Non-OEM Pump ReBuild Shops Part III – Assessment Criteria

Author:

Heinz P. Bloch, P.E., Process Machinery Consulting, Jim Steiger, HydroAire Inc. and Robert Bluse, Pump Services Consulting

Publisher:

Maintenance Technology

Date Published:

February, 2008

 

Use this assessment tool to evaluate any pump repair shop with which your operations are currently working, or any that you are considering for future work.

This article is the third in a series based on a presentation delivered at the 2007 NPRA Reliability & Maintenance Conference in Houston, TX. Here, as with the previous installments (which ran in the July 2007 and September 2007 issues of Maintenance Technology), the authors discuss how to distinguish competent pump repair operations.

Part II of this series, published in September 2007, concluded by promising specific assessment criteria for those considering entrusting their pumps to a non-OEM pump rebuilder. Referring to competent pump rebuild shops, we coined the term “CPRS.”

 

CPRS assessment tool and matrix

The following information can be used as an assessment tool for any shop that you, as a pump user/owner, are considering for future work—as well as for those with whom you might presently be doing business.

Mergers and consolidations over the past decade or so have had a significant impact on both pump users and pump manufacturers. Given the consolidations in the pump industry and changing landscapes in terms of qualified workers/associates to effect a competent repair, it is strongly suggested that a pump user/owner use this tool and survey all the shops it is working with and/or considering working with, at least once a year. A lot of things can change—people come and go, improvements can be made or lost and financial performance pressures persist. These factors all have a direct impact on the capability of your outside repair shop.

Although this assessment tool is by no means complete, it can be the basis for assessing one’s in-house pump repair shops and those of your OEM, as well as any non-OEM facilities. Routine assessments of repair shops can avoid unwanted surprises and the ensuing aftermath of a poor repair on a critical piece of equipment.

 

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Building a Better Boiler Feed Pump

Author:

Robert Aronen, Dennis Plaizier and Dave Sinclair, Hydro Scotford Inc.

Publisher:

Pumps & Systems

Date Published:

November, 2007

 

Say goodbye to concerns about pump seizure: By properly applying composite materials to a troublesome boiler feed water pump, this large process facility in Alberta can now run one pump during full-rate operation with very low vibration and higher efficiency.

The reliability and efficiency impacts of close-clearance wear components – wear rings, inter-stage bushings, throat bushings, and pressure-reducing bushings – have been well documented.

In 1985, Bloch and Geitner cited the following potential problems associated with excessive wear ring clearance: efficiency losses, loss of rotor stability, shaft breakage, driver overloading, bearing overheating or failure, unequal load sharing in parallel pump operation, noise and damage typically associated with cavitation, and possible total pump destruction (p. 31-36).

One application for which the wear components are particularly important is boiler feed water. In the typical process plant, the boiler feed water pump is a multistage, horizontally-split, between-bearings design that is heavily dependant upon the wear components for rotor stability. Material selection is very important to ensure long-term reliability in this service.

The value of proper application and installation of modern composites is demonstrated by the results from a 9-stage boiler feed water pump from a large process facility in Central Alberta.

Why Wear Components are Important

The close clearance wear components in a centrifugal pump perform similar functions. They separate high pressure areas within the pump from lower pressure areas via a minimal clearance between a rotating and stationary member.

Due to the differential pressure across these components, there is substantial flow from the high pressure to lower pressure regions of the pump – recirculation flow. If inadequate clearance lies between two metal components, the rotating and stationary elements could possibly seize and lead to substantial pump damage (Bloch, 1988).

Conversely, as the clearance between rotating and stationary components increases, the recirculation flow within the pump increases and efficiency drops (Bloch and Geitner, 1985). Over time, this will become evident to the pump operators as recirculation flow increases to the point where the pump can no longer operate at design capacity.

What the operators may not notice is that the wear components also contribute substantially to rotor stability (Lobanoff and Ross, 1992, p. 440-451). Increased clearance at the wear components can lead to higher vibration, shorter bearing life, and the potential for high-energy failure modes such as shaft breakage.

Furthermore, recirculation flow at the first-stage impeller eye increases the effective inlet fluid temperature, possibly leading to cavitation damage (Lobanoff and Ross, p. 90-97). The net result is that a pump with increased clearance at the wear components is not as reliable or efficient as a pump with reduced clearance.

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Reduce Consumption of Seal Water

Author:

Fluid Sealing Association

Publisher:

Pumps & Systems

Date Published:

October, 2007

 

Two imperatives for many of today’s industrial plants are to reduce the cost of operations through the enhancement of rotating equipment reliability and enhanced energy efficiency of pumping systems.

One place to look for a significant, yet relatively easy “quick win,” is the seal flush water going to packing, single, and double seals. In many industrial plants water is being used to provide lubrication, cooling and/or as a means to exclude a harmful process fluid from the stuffing box or seal chamber.

The means for providing an external water flush or quench are generally described as API/ISO piping plans 32 (ANSI 7332), 54 (ANSI 7354) or 62 (ANSI 7362).

 

 

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