Article 515.3 - Barge Classification Questions

[kerickson]

I have 2 questions on how NEC 515.3 applies to a specific situation.

First, there's a barge dock where Class I liquids are handled and dispensed during the loading and unloading of barges. As I understand Figure 515.3, the Class I Div 2 area extends from the edge of the barge horizontally 25' inland and 25' above the tank (barge) at its highest elevation. Is this the correct interpretation for this?

Second, farther down the shore there is a tug boat dock. The longest barge that could be at this terminal is 297' long. Because the distance between this tug boat dock and the previously mentioned barge dock is less than 297', the opposite end of the barge will be located in front of this tug boat dock. The handling of Class I liquids is occurring at the other end of the barge, approximately 270' away from the tug boat dock. Does the classification area shown in Figure 515.3 apply to this tug boat dock area also?

The reason I'm questioning this is because article 515.3 states "Table 515.3 shall be applied where Class I liquids are stored, handled or dispensed..." (emphasis mine). Table 515.3 refers me to Figure 515.3 for piers and wharves. Does the classification in Figure 515.3 extend over the length of the barge even though the loading operation (handling or dispensing) is at the other end?

 

[rbalex]

See Figure 515.3, Note 2:

[FONT=A1C88+LOOFIC+Helvetica]

[FONT=A1C88+LOOFIC+Helvetica](2) The berth area adjacent to tanker and barge cargo tanks is to be Division 2 to the following extent:[/FONT]
[FONT=A1C88+LOOFIC+Helvetica](a) 25 ft (7.6 m) horizontally in all directions on the pier side from the portion of the hull containing cargo tanks.[/FONT]
[FONT=A1C88+LOOFIC+Helvetica](b) From the water level to 25 ft (7.6 m) above the cargo tanks at their highest position[/FONT]

[rba note: underline added fro emphasis][/FONT]

 

[kerickson]

Why is the classified area surrounding a barge that serves as a fuel storage tank different than the classified area for a storage tank on land?

According to Figure 515.3, Note 2, the area that is within 25' horizontally in all directions from the portion of the hull of the barge containing cargo tanks is Div 2. Since these barges are nearly 300' long, this creates a huge classified area if it is required over the entire length.

In Table 515.3 for an aboveground tank, the Div 2 area outside the tank extends 10' in all directions from the shell, ends, or roof of the tank, or 10' in all directions from the open end of a vent. See also NFPA-497 Figure 5.9.4(a).

In Table 515.3 for "loading through bottom connections with atmospheric venting," the Div 2 area extends from 3' to 15' from the point of venting in all directions, and also 18" above grade within a horizontal radius of 10' from the point of loading connection. There is no mention of a classified area that extends a certain distance away from all parts of the tank. See also NFPA-497 Figure 5.9.4(d).

Neither of these examples require the classified area to be 25' away from a location where fuel is stored (such as a barge hull). So, why is it that the area 25' in all directions surrounding a barge's storage tank must be classified? This seems inconsistent. What makes a barge different than an above ground storage tank or a tank vehicle?

 

[rbalex]

“Why?” is usually the toughest question to answer. In this case, I can only offer a bit of history. Article 515 is largely extracted from NFPA 30, Flammable and Combustible Liquids Code. (see the FPN after the Article title) NFPA 30 is heavily influenced by the Coast Guard for marine operations. Figure 515.3 is what the Coast Guard wants – “Why?” – I don’t know.

 

[weressl]

?Why?? is usually the toughest question to answer. In this case, I can only offer a bit of history. Article 515 is largely extracted from NFPA 30, Flammable and Combustible Liquids Code. (see the FPN after the Article title) NFPA 30 is heavily influenced by the Coast Guard for marine operations. Figure 515.3 is what the Coast Guard wants ? ?Why?? ? I don?t know.

It is always frustrating to me that there is nor record accessible of the discussions of the CMP's to see how the arrive at their conclusions. I think it would be a barrel of laughs too. (Perhaps thats why no such records exist.)

 

[rbalex]

It is always frustrating to me that there is nor record accessible of the discussions of the CMP's to see how the arrive at their conclusions. I think it would be a barrel of laughs too. (Perhaps thats why no such records exist.)

There is often a fair amount of historic documentation in the various Technical Committee reports on Proposals and Comments. These have always been easy to get; by simply making a Proposal or Comment or the price of a first class stamp and asking for the reports you got the whole load from the most recent report.

NFPA has been making it even easier recently with making the reports downloadable. To get heavy duty stuff, download the minutes of the Standards Council and General meetings. (This is often the REALLY interesting stuff)

Figure 515.3 is ancient history - it's older than I've been in the industry. However, I've had success extracting a lot of old document reports from NFPA. You do have to know what to ask for though, I don't always and if they are really old, you usually have to pay a modest fee.