Seminar Sponsored By Dixon-Bayco Covers Topics Involved in Tank Overfill

July 1, 2001
IN ORDER to increase efficiency, more and more petroleum terminals are pumping product at rates up to 900 gallons per minute. Many terminals have plans

IN ORDER to increase efficiency, more and more petroleum terminals are pumping product at rates up to 900 gallons per minute. Many terminals have plans to increase the number of loading arms at the rack in order to fill several trailer compartments simultaneously.

With the speed and volume that product is flowing into the tanks, the entire overfill system is undergoing a muchneeded review. This is one of the areas being updated in the American Petroleum Institute (API) Recommended Practice 1004. Since tankers are loading faster, the overfill system shutdown reaction time is being updated so the equipment, particularly the probes, will respond accordingly.

Pending changes to API RP 1004, bottom-loading specification and troubleshooting techniques were the topic of discussion at a seminar sponsored by the Dixon-Bayco Division of Dixon Valve & Coupling Company April 27 in Houston, Texas. Dan Burke, sales manager of Dixon-Bayco, and Bob Koeninger, president of FloTech, sister company of Dixon-Bayco, directed the seminar for area maintenance personnel.

The seminar focused on maintenance and troubleshooting of overfill systems commonly in use today. New techniques for rapid identification of failed overfill components using FloTech's FT520 Optic System Test Kit were demonstrated. Attendees had the opportunity for hands-on troubleshooting using an optic overfill system training simulator.

“While it's not exactly like the NASA flight simulators, the demo equipment helps us show what's actually going on inside a tanker,” said Bob Koeninger.

The issues of improving reliability of the grounding system and making reliable wire connections also were discussed.

Changes to API 1004 affect the overfill components, tank capacities, and terminal loading controls. Chevron has been a leader in the proposed new overfill safety standards — led by Al Mosser, a former Chevron senior standards engineer and now manager of Chevron's Hawaii terminal operations. Mosser, Burke, Koeninger, and others from the industry are serving on the API committee.

One of the problems with overfill systems will be solved when the new proposed standard goes into effect. “There will be a new thermistor socket design,” said Koeninger. “And a four-J-slot-compatible plug at the rack will be required.”

The two additional J-slots on the thermistor socket will improve the connection and reduce the rocking of the rack cord, which causes many false alarms and loading shutdowns. Tank trailers will be required to have a 60-gallon outage space above the overfill sensor to handle the loading racks shutdown rate of 60 gallons. This will call for longer probes for many tanks, said Koeninger.

“Most petroleum terminals are loading at 450-650 gallons per minute (gpm) with some pushing the 900 gpm rate,” he said. “This requires a more controlled emergency shutdown of the load rate and space in the tank to capture the overage.”

Another equipment adaptation resulting from the new loading procedure will be splash diversion shields installed over emergency valves.

All of these changes will impact both terminal and transportation companies, the most important being a safer loading process, said Koeninger.

At the same time, shippers and carriers will have to adapt to several operational changes that will occur.

“Although the faster loading process expedites truck movement at the rack and provides a safe shutdown should a spill occur, it could mean less product in smaller tank compartments and, subsequently, more trips required for delivery,” said Koeninger.