Using Latest Technology to Refurbish a 50-year-old Pump Element

Power pump performance improved with redesign of the first-stage, double-suction impeller and twin volute. 

This project has been divided into two articles. The first, published in the June 2017 Pumps & Systems; the second, published in September 2017 Pumps & Systems.

Written by: Dave Allard & Dr. Gary Dyson
Published by: Pumps & Systems

In the aftermarket business, part replication is not enough. Precision engineering combined with the latest technology are essential for manufacturing high-quality parts. A main boiler feed pump at a Midwestern United States power plant was built in 1967 using sand casting and wooden patterns, now considered outdated technology. Even though the pumps received refurbishment every six to eight years, the pumps continued to have low performance as well as vibration issues.

Using all its resources—including casting simulations, 3-D models, up-to-date foundry casting techniques and considerable engineering data—Hydro fully manufactured a complete element, performed sophisticated testing in the Pumps Test Lab Approved Program (PTLA) certified test lab, and returned the pump to operation within just 12 weeks.

This project involved the manufacture of a complete first stage twin volute and a description of the latent defects.

The pump suffered from ongoing vibration issues which were caused by pressure pulsations at vane frequency. To improve the vibration levels, hydraulic analysis and redesign were required to develop a new, improved design.

This project has been divided into two articles. The first is the manufacturing of the twin volute and the second is the design of a new impeller.

Twin volute stage piece

Image 1. A received bundle showing failure in the twin volute stage piece. Hydro received the internal element and casing (pump bundle, or element) of the pump. (Images and graphics courtesy of Hydro, Inc.)

The first-stage twin volute is a complicated casting, which failed during operation as a result of poor design.

Hydro re-engineered the casting by using sophisticated engineering and 3-D modeling, along with simulation software and 3-D sand printing.

In addition, Hydro identified the opportunity to improve the performance of the pump by redesigning the first-stage double-suction impeller. To improve vane passing frequency, the first-stage double suction impeller was redesigned with staggered and split vanes.

Hydro’s aftermarket services capability provided a completely new replacement element for this high-energy boiler feed pump and also redesigned the castings to eliminate the original latent defect in the casting design.

Hydro provided sophisticated hydraulic engineering improvements to increase the mean time between repairs (MTBR) of the newly manufactured element.

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Emergency Nuclear Pump Rebuild

Faisal Salman and Nick Dagres of Hydro, Inc report how performing new design modifications on two critical safety-related charging pumps have extended their lifespan and reduced maintenance.

Written by: Faisal Salman & Nick Dagres
Published by: World Pumps

Certified Test Lab

Setting up the pump at Hydro’s Hydraulic Institute Certified Test Lab.

A Western European nuclear power plant was having difficulty meeting the necessary hydraulic performance at runout for two centrifugal charging pumps. The system needed 30 ft of Net Positive Suction Head required (NPSHr).

The pumps are safety-related pumps, which pump bore-rated water (water mixed with boric acid) into the reactor to kill nuclear fission. What water is to fire, bore-rated water is to nuclear fission. Bore-rated water kills nuclear reaction.

The two pumps are each about 15 ins in diameter and about 100 ins in length. They were shipped from the Western European site to Hydro, Inc.’s Chicago, IL facility to conduct analysis, redesign, manufacturing, and testing.

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Quality Nuclear Performance Testing in Urgent Conditions

A 5-day emergency testing turnaround for a nuclear pump proved no problem for this world-class testing facility.

Written by: Nick Dagres & Faisal Salman
Published by: Nuclear Plant Journal

When a vertical safety-related residual heat-removal pump failed its required surveillance performance test at a nuclear power plant, it created the need for emergency hydraulic performance and vibration testing. The plant required the pump back in operation within one week, to prevent shutdowns that could cost the facility up to $1 million per day.

The plant contacted Chicago based Hydro, Inc., which has Hydraulic Institute (HI) Pump Test Lab Approval (PTLA) – certified testing facilities and the ability to perform crucial testing on an urgent basis.

Background
During a routine check by the regulator, a safety-related heat removal pump failed its required in-house surveillance pump performance test. With a safe shutdown of the unit, the plant entered an LCO (Limited Conditions of Operation) period. The power station shut down the unit but wanted to avoid a full shutdown of the facility. This created an emergency situation for the plant.

According to the regulator’s strict standards, if performance requirements are not fulfilled immediately, the plant can be shut down completely. The LCO allows the plant to continue to operate as long as the problem is being resolved in a limited time frame. In this case, the time frame was seven days. To allow for shipping to and from the facility, Hydro had only five of those days to complete the project. The plant was concerned that the repair time might exceed the LCO. Other similar pumps remained in operation performing the same function, however the unit was shut down because there were no spare pump store place it while testing was being
performed. The original equipment manufacturer could not schedule the required tests in the abbreviated time span; therefore the Chicago service company was commissioned. Under normal conditions the scope of work would generally take about six to eight weeks to complete.

Pump as received

Pump as received

Identifying the Problem
In such cases, the regulator requires that a third party inspect the equipment to discover whether the issues were with the instrumentation or with the pump itself. As a result, immediate testing was required to determine whether the pump was functional.

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Setting the New Pump Testing Standard

The pump industry faces a challenge in keeping up with changing efficiency regulations. Programs such as the Hydraulic Institute (HI) Pump Test Lab Approval (PTLA) are helping companies adhere to these standards. Here, we see how Hydro, Inc. made history with the first HI PTLA certification.

Written by: Michelle Segrest
Publisher: World Pumps / June 2016

 

With an engineering first approach, Chicago’s Hydro, Inc., proves the impact of redesigned and engineered pumps by testing their real-time hydraulic and mechanical performance at its state-of-the-art Test Lab. It is in the 46,000-square-foot- facility that Hydro develops and implements engineering modifications for improving the performance of critical pumps and then verifies that performance in the lab.

Thanks to high-quality capabilities in testing vertical, horizontal, and submersible pumps, Hydro made history in September 2015 by becoming the first recipient of full certification of the new Hydraulic Institute Pump Test Lab Approval program.

This new industry standard is designed to assist pump OEMs and other pump test laboratories to improve their current laboratory procedures and policies by working with a third-party auditor to develop and maintain accurate, uniform and repeatable pump testing protocols. The program also helps participating organizations adhere to the requirements of the international test laboratory accreditation standard (ISO 17025) concerning test measurement equipment.

“Hydro’s test lab is unique because it was designed to support the aftermarket by having the flexibility to test a wide range and variety of custom engineered pumps,” said George Harris, Hydro CEO and Founder. “Since it is not incorporated in a plant which manufactures new pump production, as is the case with many large OEMs, it is possible to test a customer’s pump in 1-to-3 weeks lead time. This is very important because customers who need a certified test, need the pump tested quickly.”

Since it opened in 2010, Hydro’s 5,000-Horsepower Test Lab has helped to troubleshoot problems with pumps in the field by isolating the pump from its system in a controlled environment to simulate field conditions in a safe manner.

“Hydro remains independent of the constraints that can be imposed by relying on existing hydraulic designs and manufacturers’ predicted performance curves,” said Jeff Johnson, Vice President, Hydro, Inc., a 41-year industry veteran who was instrumental in the design and construction of Hydro’s Test Lab. “All of these efforts ultimately lead to a more reliable and well understood pump performance.”

fig-258

Single-stage horizontal split case (BB1) pump test with customer motor – test loop.

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