(Note: I wrote these notes up thinking about the Spectra/Algonquin AIM pipeline, but I've been doing this PIR research for some time -- BH)

I have something to contribute here concerning

the abuses of the

**Potential Impact Radius (PIR)**formula

used by PHMSA.

An a recent conference call, Richard Kuprewicz spoke eloquently

about how the

to help assess the calculation of

**PIR was never intended to be a prediction**

of the Actual Impact Radius(AIR), but was only a tool developedof the Actual Impact Radius

to help assess the calculation of

**High Consequence Areas**(HCA).What I am working on is this:

Since the existing PIR formula is clearly wrong,

What is a better formula for predicting

theWhat is a better formula for predicting

the

*actual impact radius*?I examined 5 major gas pipeline accidents

where I was able to get these metrics:

where I was able to get these metrics:

1) diameter of the pipe

2) Max allowable operating pressure (MAOP)

3) Actual impact radius

In every case the predicted PIR was short of the actual impact radius, sometimes by a long shot. Sometimes by a factor of 2x predicted.

I grabbed this stock diagram plotting the existing (broken) formula's prediction as a function of diameter and pressure:

Here's my version showing what I found in the data. The arrow going up shows the actual radius of impact vs. predicted down on the line.

The longer the arrow, the farther off the actual (measured) was from predicted.

So you can see that

was found to be over the PIR, it was not by much. ~20%.

The longer the arrow, the farther off the actual (measured) was from predicted.

So you can see that

**Carlsbad**and**Sissonville**, while the AIRwas found to be over the PIR, it was not by much. ~20%.

But as you can see,

and

**Appomattox, San Bruno**,and

**Cleburne**were significantly over, by ~200% or more.I'm not sure how to explain this. I'm normally good at curve fitting.

I think there may be 2 missing terms.

I think there may be 2 missing terms.

Bottom Line for the AIM:

Bottom Line for the AIM:

In my opinion, to properly assess the risk of a potential castrophic incident at Indian Point in relation to the new 42" pipeline, we must use an accurate PIR formula tuned to real-world data.

A good estimate for the

**This should be a top priority of PHMSA**.A good estimate for the

**Actual Impact Radius for AIM**, a 42" 800 psig MAOP pipeline in a dense urban area**could easily be 2,500 ft.,**whereas the calcuated PIR would be about 825 ft. using the existing formula.

I say this because I feel the most important factors

are "pipeline diameter" and also "

are "pipeline diameter" and also "

**dense urban area**".This last term is absent in the present PIR formula.

The existing PIR formula is

**0.69 * SQRT(Max Allowable Operating Pressure) * Diameter**

Sometimes they write that to make it look like D is a squared term.

**I think it should be!**

Remember, the area of a circle is

**Pi * R**.

__,__*SQUARED*Where is the squared term for R (or D) in the PIR formula?

Which grows exponentially as the radius of the pipeline grows?

**dense urban area"**. Sissonville and Carlsbad maybe should get demerits (feet deducted) due to terrain issues: speculative--

"

**Dense Urban Area**" should be reflected in the PIR, although I'm not sure I can say how without a larger dataset.

Here is a map I derived from one generate by someone in the SAPE group:

The

The

**inner yellow band**here is the**predicted PIR.**The

**black line**is from**Cleburne TX**(36" vs 42").The

**outer pink**is a**better indication (IMO) for a potential impact radius**.Take it to 2,500 ft in those neighborhoods to the south.

--

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be happy and free from suffering :)

-- ancient Buddhist Prayer (Metta)

Don't forget to sign the

May you, and all beings

be happy and free from suffering :)

-- ancient Buddhist Prayer (Metta)

Don't forget to sign the

**Pledge to Resist**

**the Constitution Pipeline:**

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## 3 comments:

Bill,

I have calculated the number of LNG tanker trucks worth of LNG that would be equivalent to the amount of gas released in a worse-case event here in Northfield, MA. The calculation includes the following factors, amongst others:

1. cross-sectional area of pipe (using r**2, which you have alluded to)

2. length of pipe to nearest Main Line Valves (both upstream and downstream)

I don't know what a good model for AIR or PIR would be, but I would guess that it would involve both of the above factors.

If you are interested, I can send a copy of my handwritten calculations.

Bob Dickerman

Feel free to send it along, but LNG is quite different from gas in pipeline, since it is 600x more dense then methane @ 1 ATM. I've calculated blast potential of LNG tanker ships, but using a different method, i.e., looking at the total joules in that gas volume, then converting to kilotons of TNT.

Feel free to send it along, but LNG is quite different from gas in pipeline, since it is 600x more dense then methane @ 1 ATM. I've calculated blast potential of LNG tanker ships, but using a different method, i.e., looking at the total joules in that gas volume, then converting to kilotons of TNT.

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