06222018Fri
Last updateFri, 22 Jun 2018 2pm

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From Cannon Balls to Pressure Seals: Graphite for Sealing

From Cannon Balls to Pressure Seals: Graphite for Sealing

From time to time, we re-publish well-re...

Gaskets Are Not Created Equal

Gaskets Are Not Created Equal

Gaskets are near the bottom of the food ...

Your Valves May Be Weaponized

Your Valves May Be Weaponized

The advent of the Internet of Things (Io...

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Industry Headlines

SVF Flow Controls Joins VMA

Friday, 22 June 2018  |  Chris Guy

This week SVF Flow Controls became a full member of the Valve Manufacturers Association (VMA). This is the fourth new VMA member in 2018 so far.

For over...

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Industry Headlines

SVF Flow Controls Joins VMA

8 HOURS AGO

This week SVF Flow Controls became a full member of the Valve Manufacturers Association (VMA). This is the fourth new VMA member in 2018 so far.

For over 35 years SVF Flow Controls of La Palma, CA has been manufacturing ball valves, actuators and controls for all industrial applications.

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Emerson Wins Global Tank Storage Award

1 DAY AGO

Emerson’s Rosemount 5900S 2-in-1 Radar Level Gauge has won the Outstanding Terminal Safety Technology Award at the 2018 Global Tank Storage Awards. This award is given to a product or technology that adds an additional layer of safety to the terminal and reduces risk to employees and the surroun...

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U.S. Specialty Chemicals Markets Continue to Gain

1 DAY AGO

The American Chemistry Council (ACC) reported that U.S. specialty chemicals market volumes continued to gain during the second quarter, increasing 0.5% in May after an upwardly revised 1% gain in April and a 0.4% gain in March. All changes in the data are reported on a three-month moving average (3M...

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Global LNG Trade Growing, Led by Australia and the U.S.

2 DAYS AGO

Global trade in liquefied natural gas (LNG) reached 38.2 billion cubic feet per day (Bcf/d) in 2017, a 10% (3.5 Bcf/d) increase from 2016 and the largest annual volume increase since 2010, according to the Annual Report on LNG trade by the International Association of Liquefied Natural Gas Importers...

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Optimism an All-Time High in NAM Survey

1 DAY AGO

In the latest Manufacturers’ Outlook Survey from the National Association of Manufacturers (NAM), it’s clear that businesses continue to experience highly elevated levels of activity as a result of policies like tax reform, with optimism once again breaking records —95.1% of responde...

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Texas Economy Continues to Expand at “Solid Pace”

2 DAYS AGO

The Texas economy is expanding at a solid pace. Employment has grown at a 3.6% annualized rate through May, driven by job gains in the goods-producing sector. Unemployment remains near its historical low, and labor markets are tight. The Dallas Fed’s Texas Business Outlook Surveys (TBOS) suggest...

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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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