05272017Sat
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

2 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

3 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

1 DAY 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

3 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

23 HOURS 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

1 DAY 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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The Well-Functioning Steam Trap

vmwnt09 beyond valves 1Ultrasonic instruments are used to test a thermodynamic steam trapSteam traps are the most important link between the steam and condensate system. Malfunctioning steam traps can waste tremendous amounts of money. Here is an example: A single inverted bucket steam trap (with a one-eighth-inch orifice) blowing-thru in a 150 psi, where the steam cost is $11.00 per 1,000 lbs. of steam produced, will waste 62.49 lbs. of steam per hour and cost approximately $6,022 in fuel losses per year.

 

Steam Traps Defined

For those who are not familiar with the steam trap, it is an automatic valve that, when operating properly, opens to purge a steam system of condensate and closes with the presence of steam.

There are three types of steam traps:

  • Density operated, which includes the inverted-bucket (IB) and the float and thermostatic (FT) types
  • Thermostatic (TH), specifically, the balance-pressure thermostatic (BPT) type
  • Thermodynamic (TD), either the disc or impulse type

Trap Characteristics

vmwnt09 beyond valves 2An inverted bucket steam trapFloat and thermostatic traps consist of a ball float and a thermostatic bellows element. As condensate flows through the body, the float rises or falls, opening the valve according to the flow rate. The thermostatic element discharges air from the steam lines. They are good in heavy and light loads and on high and low pressure, but are not recommended where water-hammer is a possibility.

When these traps fail, they usually fail closed. However, the ball float may become damaged and sink down, failing in the open position. The thermostatic element may also fail and cause a fail-open condition.

Thermostatic traps have, as the main operating element, a metallic corrugated bellows that is filled with an alcohol mixture that has a boiling point lower than that of water. The bellows will contract when in contact with condensate and expand when steam is present. Should a heavy condensate load occur, such as in start-up, the bellows will remain in a contracted state, allowing condensate to flow continuously. As steam builds up, the bellows will close. Therefore, there will be moments when this trap will act as a “continuous flow” type while at other times it will act intermittently as it opens and closes to condensate and steam, or it may remain totally closed.

These traps adjust automatically to variations of steam pressure but may be damaged in the presence of water-hammer. They can fail open should the bellows become damaged or due to particulates in the valve hole that will prevent adequate closing. Sometimes the trap becomes plugged and will fail closed.

Inverted bucket traps have a “bucket” that rises or falls as steam and/or condensate enters the trap body. When steam is in the body, the bucket rises, closing a valve. As condensate enters, the bucket sinks down, opening a valve and allowing the condensate to drain.

Inverted bucket traps are ideally suited for water-hammer conditions but may be subject to freezing in low temperature climates if not insulated. When an inverted bucket trap fails, it fails open due to the bucket losing its prime and sinking, or from impurities in the system that may prevent the valve from closing.

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