PAGE 34 / NATIONAL CLOTHESLINE / JULY, 2019 WRENCH WORKS BYBRUCEGROSSMAN Stop energy-wasting steam loss T he article for this month will be the first of two dealing with locating two of the largest sources of wasted boiler energy. Visualize a small leak of wa- ter under pressure. It won’t take long for a slight flow of water to fill a five-gallon bucket — let’s say 30 minutes, or another way of calculating the volume would be 10 gal- lons/hour. If this same volume of su- perheated water was leaking from your boiler under 80 PSI, you wold be wasting about 120,400 BTUs/HR, which is approximately 3.5 boiler horse- power dribbled away every hour your boiler is running at pressure. What’s really aggravating about this type of loss is, un- like faulty steam traps, the source of this type of loss is easily found and relatively in- expensive to fix. Ever give any thought as to why elbows in the blowdown lines seem to spring “pin hole” leaks more than the other fit- ting in the blowdown piping? When you observe the faulty elbow it almost seems like that pin hole was drilled because the area is so small and well defined. The cause of this problem is the same process that created the Grand Canyon, erosion. In the case of the boiler piping this erosion takes on the properties of “sandblasting.” When you blow down the boiler, hard particles of scale, rust and other detritus are ex- iting the boiler at high speed and keep moving in a straight line (see Newton’s first law of motion) slamming into the el- bow near the 90 degree bend. This impact blasts away the metal, drilling that well-de- fined hole. Now let’s take a look the valves used in the blowdown piping. In most boiler installa- tions there are at least two ball valves — one sealing the water column the other sealing the bottom of the boiler pressure vessel. On boilers operating above 80 PSI, there should also be a third. This would be a globe- type, slow opening valve mas- ter blowdown valve. Let’s take a careful look at a ball valve, It’s really a marvel of machining and chemical en- gineering. The ball itself is usually pol- ished stainless steel or chrome plated brass rotating inside a Teflon seat. In order for these valves to seal properly, tight tolerances must be maintained between that rotating ball and the Teflon seat. When the valves are being open or closed, the sandblast- ing effect erodes away the sharp edges of the passageway through the ball as well as scouring the Teflon valve seat. As the spacing between the ball and seat increases, small abrasive particles enter, rap- idly adding to the degrading of the ability to contain the wa- ter and steam inside the boiler. Unlike the testing for faulty steam traps, the test for faulty blowdown valves is a slam dunk. Place a one-inch black pipe elbow on the floor of your boiler room away from the burners or other hot spots and give it about 30 minutes to heat up to the ambient (back- ground) temperature of the boiler room. To learn more, see the Index of Advertisers on page 38 or visit www.natclo.com/ads BLOW DOWN VALVE TESTING- Measure the temperature of the pipe right after the blow down valve under test. If this reading is more than 30 degrees F. higher than the temperature of the elbow on the boiler room floor the valve is likely leaking. BALL VALVE GLOBE VALVE BLOW DOWN VALVE TESTING BLOW DOWN VALVE TESTING BOILER PRESSURE VESSEL IF THIS VALVE IS PRESENT OPEN 2 HOURS BEFORE TESTS WATER COLUMN MEASURE HERE Thanks for helping us make a success! Continued from page 35