05302017Tue
Last updateFri, 26 May 2017 2pm

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The Future of Coal: Efficiency Over Politics?

The Future of Coal: Efficiency Over Politics?

Many changes in the power industry have ...

Valve World Americas Event Set for June 20-21

Valve World Americas Event Set for June 20-21

End users, distributors, EPC/AEC personn...

Water Hammer

Water Hammer

Water hammer is a shock wave transmitted...

Turning the Tables on Valve Corrosion

Turning the Tables on Valve Corrosion

Multiple valve manufacturers and users w...

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Industry Headlines

Emerson Acquires MYNAH Technologies

5 DAYS AGO

Emerson has completed the purchase of MYNAH Technologies, a long-time Emerson alliance partner. The addition of MYNAH will help support Emerson Automation Solutions and its Operational Certainty program. Terms of  the acquisition were not disclosed.

MYNAH software is currently in use at more than ...

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Roger Fix Named Chairman of Flowserve

6 DAYS AGO

In its most recent annual meeting, Flowserve announced that Bill Rusnack and Lynn Elsenhans have retired as members of the board of directors. Flowserve also announced that board member Roger Fix has been elected to replace Rusnack as chairman.

"Bill and Lynn provided years of distinguished service to ...

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Oil-Fired Plants Provide Small Amount of U.S. Electric Capacity, Generation

4 DAYS AGO

According to the U.S. Energy Information Administration , roughly 70% of petroleum-fired electric generating capacity that still exists today was constructed prior to 1980. Utility-scale generators that reported petroleum as their primary fuel comprised only 3% of total electric generating capacity at...

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ExxonMobil, SABIC Agree on Proposed Petrochemical Project

6 DAYS AGO

Affiliates of Exxon Mobil and SABIC (Saudi Basic Industries Corporation) signed an agreement to conduct a detailed study of the proposed Gulf Coast Growth Ventures project in Texas and begin planning for front-end engineering and design work. The agreement was signed during the Saudi-US CEO Forum in R...

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Kansas City Fed Manufacturing Survey Shows Expansion in May

3 DAYS AGO

Tenth District manufacturing activity continued to expand at a moderate pace in May, and expectations for future activity increased strongly. Price indexes were mixed, but recorded little change overall. The month-over-month composite index was 8 in May, up from 7 in April but down from 20 in March.

Ac...

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Business Borrowing for Capital Investment Up 8% in April

4 DAYS AGO

The Equipment Leasing and Finance Association’s (ELFA) Monthly Leasing and Finance Index, which reports economic activity from 25 companies representing a cross section of the $1 trillion equipment finance sector, showed their overall new business volume for April was $7.9 billion, up 8% year-ov...

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Check Valves: Repair or Replace?

In today’s environment of shorter outage windows and shrinking maintenance budgets, the maintenance team should explore all available options when faced with a decision to repair or replace a valve.

As an example, let’s consider the choices when a damaged seat is discovered in a large bore, high-pressure swing check and/or reverse current valve in a typical steam system. Due to the difficulty in making a successful seat repair on this type of valve, the traditional approach has been to “limp” along until a replacement valve is available and an extended outage window is planned to allow the project.

 

The valve replacement approach is typically very costly because:

  • the new valve is expensive and usually has a long lead time
  • removal of the existing valve and installation labor and equipment is costly
  • the replacement process usually requires civil engineering to establish a rigging plan, restraint system and overall safe removal of existing valve and installation of the new one
  • the replacement process will more than likely require quality control management of extensive nondestructive examination and pre/post-weld heat treatment.

An Alternative
Most check valves are designed with a welded, integral seat located in a narrow valve throat and typically set at a 30-degree angle. This design makes repair of the seating surface virtually impossible using “off the shelf” machines and tooling. The lack of equipment to adequately make this repair has in the past left the end-user with one option to restore the integrity of the system—valve removal and replacement.

To remove and replace check valve seats reliably and in a cost-effective manner, the valve repair vendor must utilize custom tooling, procedures and techniques.

Utilizing this special tooling, craft personnel have performed numerous successful seat replacements on check valves, ranging in size from 12-inch NPS to 50-inch NPS. In this repair process personnel typically:

  • document “as-found” condition and dimensions
  • perform liquid penetrant testing (LPT) of the existing seating surface
  • machine-remove the existing alloy 21 hardfacing
  • perform LPT of the base metal (valve body)
  • perform base metal repairs if needed
  • install new alloy 21 hardfacing
  • machine a new seating surface to OEM specifications
  • perform liquid penetrant testing of the new seating surface
  • re-assemble the valve and “blue check” the seating surface to ensure 100% contact
  • document the “as repaired” critical valve dimensions.

These new techniques, along with the traditional valve repair procedures, provide the end-user with a refurbished component, restored to OEM specifications, in this critical application—without the time and expense required for a full valve replacement.

As with all mechanical components, routine maintenance and inspection is critical to keeping these types of valves in proper working order. Most end-users follow a carefully planned maintenance schedule; however, it is worthwhile to recap the elements of a successful program:

  • Schedule routine inspection and documentation of valve condition.
  • Perform non-destructive examination of valve seating surfaces and base metal pressure-containing components.
  • Maintain seating surface condition through a repair process such as the one described in this article.
  • Refurbish or replace worn valve components discovered during the inspection process.

If replacement of these types of valves does become necessary, contact an OEM to assist in the selection of the best valve for the application; make allowances for rigging and restraining the existing piping prior to valve removal; and take the opportunity to make any configuration changes needed to improve valve maintenance accessibility.

TY L. POTTER is Vice President of Operations, Southeast Valve, Inc.  located in Charlotte, NC. Reach the author at 704.588.0973.

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