106 Pipeline & Gas Journal / July 2007 / www.pgjonline.com

Emerson Delivers Unique Custody

Transfer Flow Metering Solution

Technical Challenge

Local economies depend on vast amounts

of petroleum transported through pipelines.

Pipelines provide a safe and economical mode

of petroleum transportation. Pipelines transport

crude oil to refineries for processing into the

products people use daily. Once crude has

been refined, pipelines transport liquid products

through an enormous pipeline infrastructure pro-

viding fuel for cars, trucks, planes, and ships.

When fluid is to be traded between two

parties, accurate measurement of the fluid

passing through pipelines is required to make

a fair transaction. This measurement is termed

custody transfer or fiscal flow measurement.

No measurement is 100% accurate, so pipeline

companies strive to reduce inaccuracies to a

minimum agreed upon amount. A meter sta-

tion operating with an inaccuracy of +/- 0.1%

and measuring product worth $1 million a

day stands to lose $1,000 a day, or $365,000 a

year. With such a large financial stake at risk,

pipeline companies do all they can to ensure

measurement is as accurate as possible.

The Emerson Process

Management Solution

In early 2006, Emerson worked closely

with a leading global oil & gas customer.

The customer performed custody transfer

measurement on a pipeline that transports

diesel and gasoline through the state of

Texas. The metering station consisted of

a 12" pipeline that reduced down to an 8"

line where a turbine meter is positioned. The

challenge for Emerson was to install a backup

measurement device in series with the turbine

meter in the 8" line. Emerson, the global

leader in custody transfer solutions, evaluated

the existing measurement technologies and

recommended the new Daniel Model 3804

Liquid Ultrasonic Meter.

A key challenge with the application was

the short length of undisturbed, straight pipe

on either side of the existing turbine meter.

The American Petroleum Institute (API) recom-

mends a minimum of 10 diameters of upstream

pipe using a flow conditioning element and 5

diameters of downstream pipe on either side of

a turbine or ultrasonic meter. This arrangement

was not possible due to the limited amount of

pipe available, existing drains in the system, and

the need to install the turbine meter and the ultra-

sonic meter in the same short section. Without

an ideal piping arrangement Emerson proceeded

with a recommendation for the installation of a

tube bundle approximately 6D ahead of the ultra-

sonic meter next to a 2" drain line. Emerson also

recommended the turbine meter to be installed 5

diameters downstream of the ultrasonic meter,

also a non-ideal meter arrangement.

Results

The customer tracked flow rate data from the

turbine and ultrasonic meter for over a year. Over

that period the two meters showed a difference

of just 50 barrels over the 15+ million barrels

that flowed through them. This is a difference

of only 0.0003%. This is especially noteworthy

since the turbine meter was proved every batch,

and the liquid ultrasonic meter was proved only

periodically with the customer’s onsite 20” ball

prover. Proving results show the ultrasonic’s meter

factor stayed very steady, even as flow alternated

between gasoline

and diesel fluid (See

table 1).

The customer

was impressed with

the long term stabil-

ity of the ultrasonic

meter. The custom-

er commented, “It

impressed me know-

ing that the meter

stayed very much the

same throughout the

whole time period

with only periodic

provings. That will

allow us to prove on

an occasional basis,

reducing wear and

tear and mainte-

nance costs on our

prover.”

With no moving parts to wear or seize,

maintenance of the ultrasonic meter is

minimal. The ultrasonic meter does not

obstruct flow, and therefore, introduces

little pressure loss to the system. The

customer has found the ultrasonic meter

to be easy to use and was impressed

with the amount of information available

with the Daniel CUI (Customer Ultrasonic

Interface) software. The pipeline company

was so impressed with the meter that they

plan to remove the existing turbine meter

to use it elsewhere. Furthermore, the com-

pany is looking for other locations where

they can install other Daniel Model 3804

Liquid Ultrasonic meters. n

Table 1: Meter factor data of 8” Daniel Model 3804 Liquid Ultrasonic Meter

When 0.10% costs you $13.1 million per year*, there is no room for inaccurate measurement.

The Daniel Model 3804 Liquid Ultrasonic Meter assures you accurate measurement with real

time diagnostics and a graphical representation of the ﬂow rate and ﬂow proﬁle. The Daniel

CUI (Customer Ultrasonic Interface) Windows

- based software offers you a comprehensive

remote dashboard, “Playback and Capture” functionality and a maintenance reporting

feature that makes the Daniel Model 3804 Liqiuid Ultrasonic Meter easy to use.

The diagnostics allow you to improve your asset uptime and lower your operating costs.

See how much you can save at EmersonProcess.com/Daniel/3804.htm

You offloaded 2,091,038 barrels of oil from your tanker.

Or did you?

*Calculation based on crude oil at $60 per barrel and assumes two tanker loads per week.

Daniel Industries Inc. Windows is a registered tradmark of Microsoft Corporation in the United States and other countries.