To: Honorable Jeffrey D. Wiese, PHMSA,
Associate Administrator for Pipeline Safety
CC: Ravi Chhatre, PE, NTSB,
CC: Member Sumwalt, NTSB.
From: William Huston, NYPA Concerned Citizens for Pipeline Safety
RE: Corrective Action Order, Docket CPF No. 1-2012-1025H, Dec 20, 2012
Dear Administrator Wiese,
I have just reviewed the above captioned order. I have a few questions.
I have numbered each question.
Thickness of Failed Section
1) You write: "Preliminary data from the pipe at the Failure location shows
a general wall thickness of 0.281 inches...."
This is a different number than that reported by NTSB Member Sumwalt, who said
the thickness at the point of rupture was 0.075", which is less than a 1/10th of an inch.
(statement occurs within the first 2:30 of the video)
In the video, NTSB Member Sumwalt says that 0.075" is 30% of the design thickness.
0.075 = .3 * T
0.075 / .3 = T
T = .25
So according the Member Sumwalt, the design thickess was .25".
Is PHMSA saying that at the point of rupture the thickness was 0.28?
This is GREATER than the NTSB stated design thickness, not 30% of it.
I would appreciate some clarity here.
How was MAOP calculated?
Member Sumwalt reported at the time of rupture, SM-80, SM-86, and SM-86 Loop
were all operating at 929 PSI.
Statement is between 10:00 and 10:15:
My questions are:
3) What is the MAOP of these three segments? Where is this recorded?
4) Are any of these segments using the Alternative MAOP?
5) How were these MAOP calculated?
6) For each of the three segments, SM-80 (20"), SM-86 (26"), and SM-86 Loop (30"),
what is the a) pipe thickness, b) material strength, and c) safety factor of these pipes?
In the Required Corrective Action, I(f)(1) Temporary Maximum Allowable
Operating Pressure, the order directs the operator to use "Use the lower of 741
or 80% of the validated Lanham compressor station pressure in Item I.e. above".
7) How was the value 741 determined?
I appreciate your work in making pipelines safer,
and appreciate your time in responding to these questions.
NYPA Concerned Citizens for Pipeline Safety
PO Box 2873
Binghamton NY 13902
May you, and all beings
be happy and free from suffering :)
-- ancient Buddhist Prayer (Metta)