Tank Cleaning Seminar Shippers Press for Higher Cleaning Quality
Jun 1, 1999 12:00 PM
SHIPPERS are demanding higher and higher levels of cleaning quality. In fact, chemical cleaning has now reached foodgrade levels in many cases.
The demand for higher levels of quality in cargo tank cleaning puts greater emphasis on the equipment used in the operation. Equipment issues were discussed by several speakers at the annual National Tank Truck Carriers Tank Cleaning Council Seminar April 12 and 13 in St Petersburg, Florida.
As part of the drive for a higher level of cleaning, some chemical shippers are demanding pH levels of 7 or better and filter paper that can detect contaminants at parts per billion or even parts per trillion.
That is needed for some of the ultra pure chemicals that are being shipped today.
"These requirements are running up the cost of tank cleaning," said George Lyon, Texo Corp. "We're hearing that wash racks are having difficulties passing along the higher costs. Customers not only resist higher rates for the more detailed cleaning, but they also want a free exterior wash."
Intermediate Bulk Containers For a growing number of wash racks, tank trailers and tank containers aren't the only items being cleaned. Intermediate bulk containers (IBCs) have joined the mix, and the volumes are growing as the containers eclipse drums.
A forklift is needed to handle IBCs, which range in capacity from about 200 to 750 gallons. Cleaning IBCs can be labor-intensive. Often, workers have to remove numerous labels from the IBC exterior, and domelids, valves, and other hardware must be disassembled and then reassembled.
IBCs often contain a substantial heel, two to three inches in many cases. "That's a lot of heel, especially if it is something like paint or a coating that has solidified," Lyon said. "That's one of the factors that makes IBCs difficult to clean. Spinners and filters get clogged."
Hot Water One of the biggest challenges of meeting today's cleaning requirements is ensuring an adequate supply of hot water at the right temperature. Keith Mundt, QuikWater Inc, described the benefits of a direct-contact industrial water heater.
QuikWater recently received certification from the National Sanitation Foundation International's Food Equipment Program. The patented QuikWater design allows complete combustion of the fuel, leaving no combustion byproducts to contaminate the water.
The system is 99% efficient and requires very little maintenance, Mundt said. Hot water is made as needed for lower operating cost, and it is of potable quality.
In contrast, boilers are no better than 80% to 85% efficient. In addition, 10% to 15% of the heat is lost through the exhaust stack, resulting in total efficiency of around 65%.
The QuikWater heating system is a modular design with a stainless steel vessel, brass valves, and cast aluminum or iron burners. The combustion chamber is water jacketed.
The nonpressurized system is safer than a boiler. In addition, the QuikWater unit is not subject to the American Society of Mechanical Engineers (ASME) pressure-vessel code. It does not require a certified operator.
Ample hot water is necessary for thorough cleaning, but it takes a toll on the cleaning equipment, as do the various wash solutions. Hoses in particular are susceptible to damage from prolonged heat and chemical exposure.
Hose Issues Hoses in the wash rack must be matched to the application, according to Kip Hart, Hart Industries Inc. Locking cam fittings should be standard for safety. He cautioned that cam-and-groove and crows foot fittings should never be used with steam hoses.
Moving on to the way hoses are cleaned in wash racks, Hart pointed out that 70% of all product hose failures are due to improper cleaning techniques. High pressure or temperature destroy hose tubes and can cause failures.
"Don't use high-pressure cleaning wands inside hoses because the liner can be sliced," Hart said. "Often, this damage will remain undetected until the hose fails. It's a time bomb just waiting to go off."
Soaking vats are another place where hoses can be damaged. Cleaning solutions should never be kept at temperatures above 145 degrees F, and hoses should not be left to soak for more than 20 minutes.
"Putting a hose in a vat to soak for a short time is a good way to loosen product residue," Hart said. "However, it's important to choose solvents, caustics, or other cleaning solutions that are approved by the hose manufacturer.
"The hose must be flushed out after being soaked. In addition, it must be allowed to cool before a rotating brush is used to clean the interior. Otherwise, the inside wall can be scored."
Pump Cleaning Hoses often are cleaned along with the tank trailer, and this is an acceptable practice. Pumps also are cleaned this way, but it's not enough. Product residue can hide in many places within a pump, and that can lead to contamination in future loads.
"Pump bypass systems used for drumming and other applications also have to be cleaned," Hart said. "Following the cleaning, it's important to activate the pressure valve on the pump to make sure it operates properly."
Hoses, both those used in the cleaning operation and product handling, must be inspected, tested, and maintained properly. Wash racks need comprehensive procedures, and workers must be properly trained.
Hydrostatic testing is the safest process for hoses, according to Hart. The hose should be in a protective chamber during the testing, which requires a pump capable of producing a minimum pressure of 11/2 times the hose pressure rating.
Hoses should never be tested with compressed air or compressed gas. This is extremely hazardous, and major hose and fitting manufacturers strongly recommend against this procedure.
During hose inspections, maintenance personnel need to check the gaskets used with the fittings, as well as the hose itself. Damaged gaskets should be replaced with a comparable product. Hart Industries offers a gasket identification chart to help with that process.
If hose and fitting repairs are called for, the work should be done by trained technicians. Hoses should be tagged, and any repairs should be noted on the tags. A variety of tags are available today, including bar code labels, laminated text, and metal tags attached by bands.
© 2013 Penton Media Inc.