Many energy conservation
programs start with a steam trap survey because leaking traps can raise a company's
overhead operating expenses by as much as a third. Energy audits and repairs often save
companies hundreds of thousands of dollars.
Experts estimate that in a plant with no
active steam trap testing and repair program, 50% of the traps are blowing steam. With
monthly inspection and prompt repair, this figure can be reduced to under 3%. Example: One
trap with a 3/32" orifice operating at 100 psi can lost almost 30 lbs. of steam per
hour. At $8/1,000 lbs. of steam, that can result in a loss of over $2,000 a year from each
faulty trap of that type.
Ultrasonic testing can quickly reveal the
condition of each steam trap. In fact, the major trap manufacturers recommend regular
testing. An ultrasonic test is a "positive" in that a user can hear what is
happening within a steam system as it is being tested. A contact probe used to localize
the sound coming from the trap will not pick up the other pipe noises since ultrasound
intensity falls off rapidly as it moves away from its source.
Generally speaking, there are two types
of steam traps: intermittent and continuous flow. Intermittent traps normally operate in a
cycle of open-close-open-close. Continuous-flow traps usually modulate according to
condensate load and a failure most often occurs in the closed position. Continuous flow
traps include float, float & thermostatic and thermostatic (bellows). A failure
usually occurs in the open position causing a constant rushing sound. Each trap in this
category has its own particular method of operation and pattern of open-close. Other
intermittent traps include inverted bucket, bucket, thermodynamic (disk), bi-metallic and,
at times, thermostatic. The cessation of typical operating sound signifies trap failure.
Testing services utilize the latest
technology in ultrasonic equipment and the most comprehensive steam trap software
available. Each trap's number, location, application, size, manufacturer and model number
are logged in. After thorough documentation, the trap is ultrasonically tested. Ultrasound
heterodynes the operational sound of the steam trap and actually allows us to hear the
trap's operation. It is the only positive test available which accurately and
instantaneously allows a performance evaluation of the trap to be made. After the
ultrasonic test is completed, infrared temperature readings are taken at the inlet and
outlet of the trap. This data is then documented for later calculation of inlet and outlet
In a system of 1,000 steam traps, it is
assumed that the average orifice size of a blow-through is estimated at 1/16 inch, the
average pressure is 150 psig, and the cost of steam production is $4.00/1,000 lbs. It is
also assumed that the plant steam is in operation 365 days/year, 24 hours/day. Based on
these assumptions, the steam loss per day is 453 lbs. per trap at a cost of $1.81/day/trap
or $662.25/year loss per trap. A conservative assumption that only 10% of the traps are
faulty would result in an annual cost of $66,225 in lost steam within the system.
Leaking Steam Traps Can Cost!
(Here's how you know when you need a survey)