Diesel corrosion Post by ZMiller ? November 29th, 2020, 6:30 pm Corrosion Prevention
Re: Diesel corrosion
Post by ZMiller ? November 29th, 2020, 6:30 pm
Corrosion Prevention in Sumps Associated - Gasoline Fuel Storage Tanks.Simple steps being suggested may prevent the degree of corrosion effects being seen. Conditions initially may have been seen to be mainly cosmetic. Over time however exposure to constituents in sumps causing oxidization formation on component surfaces, both hard and soft likely has become more problematic as it pertains to leak containment monitoring and integrity.
It is important to understand that today, piping and pump secondary containment sumps have not been designed for the long term containment of saturated hydrocarbon vapors and liquid fuels. It is fair to say that fuel and or saturated hydrocarbon vapors are not supposed to be in sumps in the first place.
It is as well important to understand that while fuel and saturated vapors may be present in a fuel storage tank, the tank(s) associated sump(s) should as designed remain as a completely isolated compartment.
Observations on test sites are clearly indicating that saturated vapors are migrating from primary tank spaces through conduits into associated sumps thought isolated. Realization being, that where a tank sumps exhibits moderate or severe corrosion the tank is leaking.
Without arguing a point that a tank is or is not leaking, on earth we know that saturated hydrocarbon vapors do not leak into a fuel storage tank from the outside.
Where corrosion effects in sumps are typically seen there is or has been (a Leak) fuel and or residual vapor in the sump. Fuel and or saturated hydrocarbon vapors have combined with moisture and oxygen (three legs of the corrosion triangle) to create a low PH atmosphere. A resident low PH atmosphere primes sump penetration fitting and component hard and soft metal surfaces for the formation and attachment of ferrous (rusticles) oxides and microbial activity.
Vapor Migration (paths) Conduits from the Tank into the Sump.
Tank man way gasket integrity failure and or bolts not torqued.
Threaded loose bung plugs and fittings connecting motor and ATG risers to tank.
Pump motor extraction manifold (packer) connection or when re-assembly bolts not properly torqued.
Electrical lead wire compression fitting through riser cap.
Component leak detection vent tubing.
Daisy chained high and low voltage electrical conduits from other associated tanks and sumps on site.
Loose pressurized product piping (weeps, seeps and leaks) connections.
Vapor Migration Cause.
Over pressurization of tank(s) during a Stage 1 “Out of Compliance” fuel delivery. If a bulk fuel delivery driver for whatever reason does not correctly connect or intentionally bypasses vapor recovery Stage 1 the tank storing gasoline will likely become over pressurized. The degree of over pressurization if the Stage 1 is bypassed or multiple tanks manifolded are delivered to at a drop rate exceeding the pressure vacuum valves rated relief rating a dynamic positive back pressure in the tanks ullage will exceed the tanks ability to contain empty space vapors. A vapor release will vent to atmosphere and or into any associated sump where a loose or leaking tank top fitting may exist.
Additionally considered as an over pressurization suspect is a condition created when a bulk fuel delivery driver connects to a tank receiving fuel in an open tank scenario. In a tank scheduled to receive fuel normally operational before delivery there will be negative (vacuum) pressure caused by customers dispensing. If a driver incorrectly connects Stage 1 vapor recovery hose(s) to receiving tank before the tank trailer compartment when delivering in bulk the receiving tank will ingest large volumes of atmosphere (air). The tank(s) receiving fuel in bulk will then be out of dynamic balance and the delivery made in an “Out of Compliance” condition. Large amounts of air ingested not dynamically expected in the design of Stage 1 vapor recovery equipment will create pressure bounce conditions further causing vapors as fugitives to migrate.
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Location: Atlanta/Phoenix/Sacramento
Re: Diesel corrosion
November 29th, 2020, 6:43 pm
And Yes it is common to see Gasoline vapors migrate through low voltage electrical conduits and open product line secondary piping test boot fittings via UDC's to all associated tanks cause issues in other gasoline and diesel sumps associated on sites. The primary vapor migration to diesel is when a customer is dispensing diesel while a gasoline delivery is causing fugitive vapors to vent at the over pressurized PV valve. The gasoline vapors get sucked into the diesel vent pipe with a rain cap sitting right next to the gasoline vent.
Might be a good idea if the diesel vent was a foot or two feet higher than the gas PV valve.
Just saying.
Protocol and procedure development
1 年I see some diesel tank nitrogen VMI inerting systems combating corrosion, fuel quality degradation and fuel column water issues. While most are on commercial fueling and back up generator sites it's maybe just a mater of time for showing up in the retail world.
Guardian Fueling Technologies, Construction Manager
4 年Zane you are a man among men. I remember when all this vapor corrosion in STP equipment started with the introduction of Ethanol. You've been persistent and by golly I know you won't stop until you find a solution. I worked at VP racing fuel distribution center. Almost all of the drivers never hooked up vapor recovery back to the transport vehicle while delivering. They would insert a small wedge to depress the vapor poppett. No way tanks can vent without building pressure unless the delivery driver used the equipment specifically as designed. personally believe the fill and vapor buckets that receives fuel or removes vapor should have it's own sealed containment factory attached to the tank with fiberglass own built in explosion proof junction box I
I fix stuff
4 年Take the ethanol out of gas and put the Sulphur back in diesel.. . Problem will disappear . Overpressuring the equipment during fuel deliveries is the main culprit of gas tank sump corrosion. Diesel needs Sulphur We test pressure decays a 2" w/c but vent caps rated at 2.5-6 w/c..... lots can prevent this . Atg caps , cord grips inside sumps was the worst design ever and the main culprit of vapor migration. Good stuff Zane !
Protocol and procedure development
4 年Protocol and procedure development
4 年Seeing that as the first of the year high throughput gas stations in North America may well become indexed as stationary sources for VOC (green house gas) emissions maybe the problem will be cured by NOV's and revenue generating penalties'. That should put an end to? to bsilly blowers in sumps.??