05242016Tue
Last updateTue, 24 May 2016 3pm

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Industry and Regulatory Changes in Offshore Operations

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Stop Check Valves

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Industry Headlines

MRC Global Expands Service to Chemours in the U.S. Gulf Coast

21 HOURS AGO

MRC Global Inc. announced that its subsidiary, MRC Global (US) Inc., has been awarded an agreement to be the primary provider of pipe, valve, fitting (PVF) products and services to all U.S. locations of The Chemours Company. The five-year agreement added the Gulf Coast region and also includes valve a...

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Sunbelt Supply Opens Shanghai Valve and Automation Center

4 DAYS AGO

Sunbelt Supply celebrated the grand opening of its new Valve and Automation Center with an open house on May 12, 2016 in Shanghai, China. The open house welcomed 80 customers and manufacturers. Attendees toured the newly stocked warehouse and automation center .

Sunbelt Supply Shanghai is a joint ventu...

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Gulf Coast Petrochemical Boom Contributing to Global Plastics Glut

38 MINS AGO

A surge in new plastics chemical capacity coming from low-cost producers in North America (specifically the U.S. Gulf Coast), the Middle East and China is driving the global market for key plastics polyethylene (PE) and polypropylene (PP) to oversupply, which will pressure margins for producers and ...

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U.S. Chemical Production Stalled in April

23 HOURS AGO

According to the American Chemistry Council (ACC), the U.S. Chemical Production Regional Index (U.S. CPRI) was flat in April , following a 0.4% gain in March, and a 0.1% decline in February, as measured on a three-month moving average (3MMA). In April, the Gulf Coast was the only region to post a smal...

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Markit PMI Shows U.S. Manufacturers Stagnating in May

59 MINS AGO

The U.S. manufacturing sector crept closer to stagnation in May, with the seasonally adjusted Markit Flash U.S. Manufacturing Purchasing Managers’ Index (PMI) registering only slightly above the neutral 50.0 mark at 50.5. This was down from 50.8 in April and signaled only a marginal improvement...

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Why Innovation is the Key to U.S. Manufacturing Growth

1 DAY AGO

Manufacturing may be facing some headwinds, but it’s undeniably in the midst of a technological renaissance that is transforming the look, systems and processes of the modern factory. Despite the risks — and despite recent history — industrial manufacturing companies cannot afford ...

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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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