App Note - Oil & Gas Industry

Flow measurement for natural gas distribution
ProblemA municipal gas distribution network company needed tomeasure the flow of natural gas at multiple locations onvarious pipes. Accurate measurements need to be taken
for two reasons. First, to evaluate whether the company will
be able to meet gas demands over the winter months andsecondly, for the company to plan for future expansion.
Knowing the flow rate of gas at various locations helps thecompany prevent costly outages and provides valuable
information when planning to lay new pipe for expansion.
Currently, flow is monitored throughout the network at asmall number of the pressure reducing stations (mostly
main stations and where large demands are required) byturbine and differential pressure meters.
Besides the obvious draw-backs of these types ofmeters (pressure drop, costly maintenance and intrusive
installation), the customer needed to take measurements
in other locations throughout the pipe network.

Solution
Digital Flow CTF878 clamp-on ultrasonic flow meter with C-RL
transducers installed on various pipe using a CFT clamping
fixture. See each location for transducer details.
Location 1: Reducing station

Pipe OD:
3 in (80 mm)
Pipe wall:
0.2 in (5 mm)
Pipe material: Carbon steel
Pressure:
116 psig (9 bar)Temperature: Ambient ~ 50°F (10°C)
Transducers: 	C-RL-304 (500 kHz) with no dampening material

Location 2: Underground carbon steel pipe with PE coating

Pipe OD:
4 in (100 mm)
Pipe wall:
0.16 in (4 mm) steel, 0.08 in (2 mm) PE
Pipe material: 	Carbon steel with 2 mm polyethylene (PE)coating on the outside of the pipe
Pressure:
116 psig (9 bar)Temperature: Ambient ~ 50°F (10°C)
Transducers: 	C-RL-304 (500 kHz) with no dampening material
Location 3: Underground cast iron pipe

Pipe OD:
6 in (150 mm)
Pipe wall:
0.27 in (6.8 mm)
Pipe material: Cast iron
Pressure:
116 psig (9 bar)Temperature: Ambient ~ 50°F (10°C)
Transducers: 	C-RL-304 (500 kHz) with no dampening material
Location 4: Flow to and from reducing station

A. Pipe to Station
Pipe OD:
8 in (200 mm)
Pipe wall:
0.34 in (8.6 mm)
Pipe material: Cast iron
Pressure:
14.5 psig (2 bar)Temperature: Ambient 28°F (-2°C)
Transducers: 	C-RL-304 (500 kHz) with no dampening material
B. Pipe from station
Pipe OD:
12 in (300 mm)
Pipe wall:
0.43 in (11 mm)
Pipe material: Cast iron
Pressure:
1.45 psig (1113 mbar)
Temperature: Ambient 28°F (-2°C)
Transducers: C-RL-306 (200 kHz) with DMP-1 applied

Location 5: PVC pipe from reducing station

Pipe OD:
12 in (300 mm)
Pipe wall:
0.30 in (7.7 mm)
Pipe material: PVC
Pressure:
1.45 psig (1113 mbar)
Temperature: Ambient 36°F (2°C)
Transducers: C-RL-304 (500 kHz) with no dampening material

Location 6: Cement pipe from reducing station

Pipe OD:
12 in (300 mm)
Pipe wall:
0.94 in (24 mm)
Pipe material: Asbestos Cement
Pressure:
1.45 psig (1113 mbar)
Temperature: Ambient 36°F (2°C)
Transducers: C-RL-304 (500 kHz) with no dampening material

Installation
The CTF878 flow meter and transducer was installed temporarily in three locations(see specifications of more details on each site).
Location 1: Reducing station
The equipment was installed in a reducing station on
a carbon steel pipe upstream of a reducing valve withpressure ranging from 116 to 14 psig (9 to 2 bar).
Flow profile was good despite the disturbances upstream.
The noise from the reducing value was not present in thislocation. Good flow profile was attributed to the 3 to 4 in (80to 100 mm) reducing pipe section.

Location 2: Underground carbon steel pipe with
polyethylene (PE) coating
Flow readings and diagnostics at this location wereexcellent. Typically, polyethylene (PE) has interfered withintegrity of the transducer signal; however, it did notpresent a problem here. It is assumed the PE coating had
no effect on the quality of the transducer signal.
If you compare the flow rate graphs from location 1 and 2
you will see similar data. Flow rate was similar because themeasurements were taken on the same pipeline. Location
2 was located 82 ft (25 m) upstream of location 1. The
similarity in flow measurement further proved the accuracyof the meter.

C-RL transducers installed on a 3 in (80 mm)
pipe in a reducing station

C-RL transducers installed on a 4 in (100 mm) carbon steel
pipe with a 0.08 in (2mm) PE coating (outside)

Flow rate measurement at Location 1

Flow rate measurement at Location 2

Location 3: Underground cast iron pipe

Location 4: Flow to and from reducing station

Despite the poor pipe wall conditions, flow readings anddiagnostics were excellent at this location as well.

Transducers were installed on two cast iron pipes
approximately 33 ft (10 m) away from the reducing station.
Measurements were good despite the valve noise present.
DMP-1 was applied to location B.

C-RL transducers installed on a 6 in (150 mm) cast iron pipe

C-RL-304 (A) and 306 (B) transducers installed on pipe
leading to and from the reducing stationFlow rate measurement at Location 3
Flow rate measurement at Location 4(Flow fluctuations shown above were caused by customer
controlling the pressure downstream of the reducing valve.)Location 5: PVC pipe from reducing station

Location 6: Cement pipe from reducing station

Flow measurements were good at this location despite
valve noise. Minimum velocity was approximately 3 to 5 ft/s
(1 to 1.5 m/s) with good straight run.

This measurement location was initially thought to be abad location for two reasons. First, the pipe was very oldand secondly, it had a 0.94 in (24 mm) wall thickness ofpure asbestos cement.
Despite the pipe condition, the C-RL-304 transducers wereinstalled and the CTF878 returned good flow readings.

C-RL-304 transducers installed on a 12 in (300 mm)
asbestos cement pipe downstream of reducing station

C-RL-304 Transducers installed on a 12 in. (300 mm)
PVC pipe downstream of reducing station

Flow rate measurement at Location 5

Flow rate measurement at Location 6(Flow fluctuations shown above were caused by customer
controlling the pressure downstream of the reducing valve.)

Benefit
The CTF878 provided the portability the customer needed.
More importantly, the CTF878 was able to demonstratereliable, accurate measurements over a complete rangeof pipe sizes, materials (including pipes with polyethylene
coating) and pressure ranges with only one set oftransducers.
Additionally, the customer preferred our technology
because of the easy transducer mounting and alignment
with the CTF clamping fixture.

Panametrics, a Baker Hughes business, provides solutions in the toughest
applications and environments for moisture, oxygen, liquid and gas flow
measurement.
Experts in flare management, Panametrics technology also reduces flareemissions and optimizes performance.
With a reach that extends across the globe, Panametrics’ criticalmeasurement solutions and flare emissions management are enablingcustomers to drive efficiency and achieve carbon reduction targets acrosscritical industries including: Oil & Gas; Energy; Healthcare; Water andWastewater; Chemical Processing; Food & Beverage and many others.
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BHCS39249		

(04/2023)

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