**I'm trying to decypher the federal formula for Class, MAOP, PIR, HCA, etc.**

**These federal regs are really convoluted.**

**Here's one thing I've found so far--**

While PHMSA acknowledges problems with several types of pipe technology:

While PHMSA acknowledges problems with several types of pipe technology:

- http://primis.phmsa.dot.gov/comm/FactSheets/FSPipeManufacturingProcess.htm
- https://opsweb.phmsa.dot.gov/pipelineforum/reports-and-research/seam-weld/
- http://phmsa.dot.gov/pipeline/regs/advisory-bulletin (1988, 1989 bulletins)

**...specifically, Lap, ERW, and EFW welds,**

there is NO HIT in the Safety Factor

under federal regulations for any of these.

there is NO HIT in the Safety Factor

under federal regulations for any of these.

**To explain:**

**Barlow's Formula is used to determine MAOP:**

MAOP=2*S*T * 1/(D*SF)

http://tridentsteel.com/barlows-formula/

MAOP=2*S*T * 1/(D*SF)

**Federal MAOP formula is a variant of Barlow's formula:**

MAOP=2*S*T * (1/D) * F * E * T

http://www.law.cornell.edu/cfr/text/49/192.105

MAOP=2*S*T * (1/D) * F * E * T

Where

F=Design Factor

E=Longitudinal Joint Factor

F=Design Factor

E=Longitudinal Joint Factor

**T=Temperature derating Factor**

**Notice that 1/(F*E*T) = Safety Factor (SF) in Barlow's Formula.**

So if F*E*T = 0.1 in the Federal Formula,

this is equivalent to a Safety Factor of 10 in Barlow's formula.

this is equivalent to a Safety Factor of 10 in Barlow's formula.

So wherever either F, E, or T=1, this is like a SF=1, meaning, no safety factor.

This is solely a function of Class:

- Class 1=0.72 (SF=1.39) Rural
- Class 2=0.6 (SF=1.7)
- Class 3=0.5 (SF=2)
- Class 4=0.4 (SF=2.5) Cities

__49 CFR 192.113 - Longitudinal joint factor ( E ) for steel pipe.____http://www.law.cornell.edu/cfr/text/49/192.113__

Range is from E=1 (SF=1, no safety factor)

to E=0.6 (SF=1.67)

**NOTE that ERW, and EFW are specifically mentioned in the regs,**

however they have an E=1 (no safety factor!!)

however they have an E=1 (no safety factor!!)

**http://www.law.cornell.edu/cfr/text/49/192.115**

__49 CFR 192.115 - Temperature derating factor ( T ) for steel pipe.__Range from T=1.0 for 250'F (no safety factor)

to T=0.867 for 450'F (SF=1.15)

So if we calculate the cumulative

F(min) * E(min) * T(min) = 0.4 * 0.6 * 0.867 =

**0.20808**,**SF=4.8**F(max) * E(max) * T(max) = 0.72 * 1 * 1 =

**0.72**,**SF=1.39**This does not take into account pipelines rated under Alternate MAOP.

More soon...

BH

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