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October 10, 2006 A Prism Business Media Publication Vol. II No. 19

Maintaining Vessels

Electrical Troubleshooting Quiz

Replacing Vessel Instrumentation

NEC at the Facility

OSHA Misperception

Answer to Electrical Troubleshooting Quiz

Visit the 2006 EC&M E-TradeShow, a Year-Long Virtual Business Event

Maryland Facilities Expo


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MRO Insider addresses topics such as:

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  • National Electrical Code® on the production floor
  • Safety procedures and programs
  • Troubleshooting techniques
  • Equipment maintenance and testing tips
  • Managing motors and generators
  • Trends in training and education
  • Managing energy use

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    Maintaining Vessels
    Your facility may use large furnaces, tanks, or other confined entry vessels for various processes. Most of the maintenance work -- cleaning surfaces, checking welds, replacing hooks, liners, or tiles -- belongs to mechanics, not electricians.

    Yet, electricians must provide temporary power, ventilation, and light. The typical practice is to string portable cord along the entry structure (e.g., stairway or ladder), and into the vessel. This creates tripping and (possible) shock hazards, and exposes the cords to being walked on, spilled on, or punctured.

    This approach may seem like the only option, because operating conditions make permanent wiring or additional penetrations for plugs unacceptable. But it isn't. For example, you can:

    • Add brackets along a predetermined path, to hang cords out of the way. Apply covers (e.g., cut tennis balls) when not in use for safety.
    • Install mesh cable tray (removable or permanent) for the cords.
    • Temporarily install surface-mounted raceway.
    Each of these options requires a small investment, but the increased safety and improved productivity usually justify that. Ask your electrical supplier about products that may suit your application.

    Are You a Survivor?
    AutomationDirect's popular mascot, Smiley, is shipwrecked on an uncharted island. You can help Smiley dodge cranky crabs and manic monkeys as he collects tools to repair a shelter and protect himself from the elements. Answer questions on automation topics while building an automation system to make his stay more comfortable. Qualify for prizes. Take the voyage, click on "Smiley's Island."

    Electrical Troubleshooting Quiz
    At the operator console, the graphic for a large tank shows 70% full, then suddenly drops to empty (triggering a process interruption). A second later, it briefly goes to 100% full (triggering high-level alarms), and then goes back to 70%. It stays there for some time, then repeats this erratic operation. What should you do to eliminate this problem?

    The answer to this question appears at the end of this newsletter.

    Replacing Vessel Instrumentation
    Vessels (and similar equipment) often contain components that should be replaced or calibrated whenever the vessel is out of service (e.g., for repair). This work is often incidental to the reason for the downtime, and it must be done on a tight schedule because each hour of downtime means lost revenue and possibly lost customers. Complicating matters, work inside a vessel is typically cramped, hot, and dirty.

    For example, the mechanics must replace tiles in an annealing furnace, after waiting through five days of downtime for the interior air to cool to 150°F. Standing in a fan-blown breeze, they work in 30-minute shifts. When the project is done, the three-day heat-up process will start.

    Your crew has to do more than supply power for fans and lights. Now is the time to replace the dozen process sensors variously located throughout the first and last chambers of the furnace (rather than wait for one to fail three months later). You don't want techs going back and forth for parts and tools, or using up "inside time" to open packaging, strip wires, or tape threads. Nor do you want them crawling in and out to perform the requisite testing.

    Different crews working in the area will slow each other down, yet all work must be concurrent with that of the mechanics. You must work "between the work."

    To succeed, plan the job. Then do a mockup, and rehearse several times. You don't need to duplicate the actual vessel; you just need to identify the steps and what's needed to perform each one. A mockup can consist of a few tables set up in the parking lot.

    Consider having a dedicated support crew (cannot include the vessel attendant) outside the vessel, even if they spend most of their time standing around. Do these practice sessions, and the "low utilization" support crew, seem like excessive uses of labor? Ask your plant manager how much revenue the plant loses every hour that vessel is out of service. The answer may quickly justify any labor cost concerns. But don't throw people at the job; plan the job for fastest execution and staff it accordingly.

    Beware - Arc
    Flash Hazard

    Pin and sleeve plugs & receptacles can be dangerous if operated under load. To prevent accidents install Decontactor Series switch rated plugs and receptacles. They are a UL rated plug, receptacle and disconnect switch in one device. 100 kA short circuit ratings protect users in fault conditions. Inquire about our free trial program.
    Meltric Corporation, call 800-433-7642,

    NEC at the Facility
    When using the ampacity tables (Tables 310.16 -- 21) remember to apply the adjustment factors [310.15(B)2]. These differ from the correction factors that appear at the bottom of Tables 310.16 -- 20 (Table 21 does not have correction factors).

    OSHA Misperception
    A common misperception is that OSHA bases fines only on physical safety violations. Recognizing that most workplace injuries result from unsafe acts (vs. unsafe conditions), OSHA also examines safety training and hazard communication systems. It's better that you examine these before OSHA does. Correcting deficiencies can reduce or eliminate post-incident fines -- or even prevent an incident in the first place.

    SureTest® Circuit Tracer Takes Testing to a New Level The new SureTest® Circuit Tracer provides unparalleled levels of precision and performance. The innovative, super-bright SwivelDisplay rotates the reading for the user. In addition, the exclusive displayed numeric value (0-99) and variable tone/pitch audible maximizes the ease-of-use when identifying breakers, tracing wires and finding opens/shorts. For more information on our circuit tracer kits, click here to download a PDF.

    Quiz Answers
    Answer to Electrical Troubleshooting Quiz
    Erratic indications of process variables may result from loose connections -- so check screw terminals and crimped connections.

    If the problem remains, suspect electromagnetic interference (EMI) or radio frequency interference (RFI). You may be able to capture an RFI event using a recording DMM or power analyzer. Look for any source of RFI -- such as fixed or portable wireless equipment -- especially near the sensor wiring, the I/O rack, or the control console.

    A common source of EMI is a voltage induced from 480V or 120V wiring running parallel to the wiring between the sensor and the transmitter (other likely places are around the I/O rack and around the operator station). The transmitter sees the induced voltage in addition to the mV input from the sensor as though they are one big input signal. The resulting 4 mA to 20 mA output signal is artificially large.

    If specific equipment switches on (or off), coincident to the appearance of the anomaly, wiring for the equipment is probably your EMI source.

    Having trouble finding that EMI source? You may need to lift wires via the "divide and conquer" method. First, determine the timing of the anomalies, so you can plan downtime around when one is likely to occur. Coordinate with the operators to determine how long you'll have.

    Identify the affected transmitter, and verify against the loop diagram. Shortly before an anomaly is due to occur, break the loop at the transmitter and place a recording DMM on each side. Suppose you saw no anomaly on one side, but you saw a spike on the other. Now you know the direction in which to continue troubleshooting.

    Carhartt's flame-resistant Duck Active Jac is quilt-lined for the colder months, with a three-piece hood and Nomex® cuffs, waistband and hood drawstring. The jacket has an APTV of 50.4 and meets hazard risk category four. All Carhartt FR can be home or industrial laundered and is guaranteed to be flame-resistant for the life of the garment.

    Show & Events
    Visit the 2006 EC&M E-TradeShow, a
    Year-Long Virtual Business Event

    Don't miss these scheduled seminars on October 18 in the EC&M e-Tradeshow:
    • "The Basics of Insulation Resistance Testing," by John Olobri, Dir. Sales and Marketing, AEMC Instruments (9:00 am EST and PST, Conference Room A)
    • "Good Project Management, Enhancing the Bottom Line," by John DeDad, Senior Director, Editorial and EC&M Development (11:00 am EST and PST, Conference Room A)
    • "Presenting AEMC's 3-Phase PQ Analyzer," by Ed Cunie, Eastern Regional Manager, AEMC Instruments (10:00 am EST and PST, Conference Room A)
    • "Electrical Market News Update," by Jim Lucy, Chief Editor, Electrical Wholesaling, and Dale Funk, Chief Editor, Electrical Marketing (10:00 am EST and PST, Conference Room B)
    Before attending these events, make sure you visit the 2006 EC&M e-TradeShow, a year-long virtual business event. In addition to attending live activities at conference sessions scheduled throughout the year, you can meet with exhibitors in virtual exhibit halls. You can also access past presentations that are archived in the e-TradeShow. Employing the latest interactive 3D technology, sponsors use online trade-show booths to generate leads on a continuous basis throughout the year, while interacting live with customers and prospects during scheduled events. Free access and all the information you need are available at the event's Web site.

    Maryland Facilities Expo
    Held October 25-26 at The Fairgrounds in Timonium, Md., the Maryland Facilities Expo is a free two-day trade show, offering an exhibition of products and services along with educational seminars for facilities personnel working in all types of industries, including commercial, industrial, educational, government, health care, hotel and resort, distribution, and warehousing.

    A few sessions in the conference track that may be of particular interest to EC&M readers include: "The Top 10 Cited OSHA Standards," presented by Eddie Bell, Chesapeake Region Safety Council and "Standby Power Generators -- What You Need to Know," by Al Grimes, Curtis Engine and Equipment, Inc.

    For more information on this show, visit the event's Web site.

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    Copyright 2006, Prism Business Media. All rights reserved. This article is protected by United States copyright and other intellectual property laws and may not be reproduced, rewritten, distributed, re-disseminated, transmitted, displayed, published or broadcast, directly or indirectly, in any medium without the prior written permission of Prism Business Media.