Pipeline Fluid Velocities 1

[eliebl]

I have been googling for days and have been unable to find any papers/articles/studies with respect to fluid velocities in pipelines. What I am particularly interested in is the erosion rates in oil pipelines as the fluid velocies increase.

Does anyone have any links or references?

Thanks in advance

EJL

 

[SJones]

Google this one:

UK HSE Research Report 115 Erosion In Elbows In Hydrocarbon Production Systems: Review Document

or start around here:

http://www.hse.gov.uk/research/publish.htm

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[GregLamberson]

The University of Tulsa has a soil erosion study group. Try these.

http://www.ecrc.utulsa.edu/whyj.htm

They seem to be very willing to assist.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[GregLamberson]

eliebl

A follow up note. Using the University of Tulsa Erosion/Corrosion Research Center’s “SPPS Sand Erosion Prediction Program"(I believe available for free???), you can graph the relationship between liquid and gas flow rates with respect to an erosion limiting factor for average production rates in various size pipes. This garph can then be used to select approximate threshold velocities for specified base metal loss in your lines.

Also keep in mind, relying on API-RP-14E C-factor calculations alone is not prudent and will not set an accurate threshold velocity. Modeling erosion and corrosion control as well as calculating wall shear stresses are more important than determining an API RP 14E C-factor velocity limit alone (SPPS does this). People tend to overlook that and go wrong.

The API RP 14E equation applied by itself is no better than a rule of thumb - API RP 14E itself states that it is not valid if solids are present as well as the fact the corrosion rates change the C-values that should be used. However, when you understand the erosion, corrosion, and shear stresses in a system, together with C-factor limits, maximum velocity or threshold velocity limits can be set.


Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[BigInch]

***************************************************
I don't know where this came from, so don't ask.
***************************************************
max pipeline velocity for erosion control

v fps = 100 / (density pcf) ^0.5

100 is a value appropriate for continuous service
*****************************************************

Material Resistance to erosion
resistance increases as you go down the list

Bronze
Aluminum bronze
Nickel
Alloy 20
Montel
Hastelloy C
316 stainless steel
304 stainless steel
K-Monel
17-4 PH
416
304/316
Inconel
440 stainless steel
Chrome tungsten carbide
Ceramic

http://virtualpipeline.spaces.msn.com

 

[GregLamberson]

BigInch

That sounds like what I have seen as well, gas velocity (single phase flow and multiphase flow) should not exceed 100 fps. And in fact, the SPPS model calculations will not validate at > 100 fps.

Along the same vein, calculated wall shear stress should not exceed 1,000 N/m2 (Pascals).

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[BigInch]

I wasn't happy with my answer above, so I decided to dig it out of the Saudi ARAMCO specs. (L032) Here's what they use.

5 Exception to the maximum velocities are proprietary piping (e.g. metering skid, surge relief skid, etc.) or piping requiring flow balance in branch segments (e.g., firewater spray/sprinkler systems). Where velocities are not otherwise limited by Table 1, the maximum fluid velocity in carbon steel piping shall be limited to the following:

5.1.1 Single-Phase Gas lines

For in-plant piping, except during a relief and flare flow, the maximum velocity in gas lines shall be limited to 18.3 m/s. In-plant noise may be a problem when velocities in gas lines exceed this limit. Higher velocities are acceptable when the piping layout configuration is relatively simple and has a minimum number of fittings and valves subject to review and approval of the Engineering Specialist in the Consulting Services Department.
For cross-country pipelines, when noise is not a concern, the maximum gas velocity is an economic balance between acceptable pressure drops, the desired gas flow rates and other factors.
Flow velocity in gas lines shall not be less than 4.6 m/s to minimize accumulation of water at the bottom of the pipe.

5.1.2 Liquid lines

Flow velocity in single-phase liquid lines for services other than shown in Table 1 shall be limited to 4.6 m/s.
Flow velocity shall not be less than 1 m/s to minimize deposition of solids and accumulation of water at the bottom of the pipe.
Higher flow velocity may be used in special cases or in intermittent services subject to review and approval by the Engineering Specialist in the Consulting Services Department.

5.1.3 Gas/Liquid two-phase lines

Except for liquid relief and blowdown lines, flow velocities in flowlines and other lines transporting gas and liquid in two-phase flow shall not exceed the fluid erosional velocity as determined by equation (1):
(1)
where:
Ve = fluid erosional velocity, feet/second
dm = density of the gas & liquid mixture at operating pressure and temperature, lbs/ft³
dm =
where:
P = operating pressure, psia
Sl = liquid specific gravity at standard conditions (water=1; use average gravity for hydrocarbon-water mixtures)
R = gas/liquid ratio cu-ft/barrel at standard conditions
T = operating temperature, OR
Sg = gas specific gravity at standard conditions
(air = 1)
Z = gas compressibility factor, dimensionless
C = (empirical constant)
C = 100 for continuous service
C = 125 for non-continuous service
(for solid-free fluids where corrosion is not anticipated or when corrosion is controlled by inhibition or by employing corrosion resistant alloys, values of "C" up to 150 to 200 may be used for continuous service. When "C" values higher than 100 for continuous service are used, periodic surveys to assess pipe wall thickness should be considered).
Once the erosional velocity is known, the minimum cross-sectional area, A, required to avoid fluid erosion is determined from equation (2):
A = (2)
Where:
A = minimum pipe cross-sectional flow area required, square inch per 1000 barrels liquid per day.
The minimum velocity in two-phase lines should be about 10 feet per second to minimize slugging of separation equipment. This is particularly important in long lines with elevation changes.

5.1.4 Steam lines

For insulated steam lines, the maximum velocity for continuous service shall be as follows:
Low Pressure Steam, 50# to 150# 175 ft/sec
Medium Pressure Steam, 150# to 400# 130 ft/sec
High Pressure Steam, 400# to 600# 100 ft/sec
For vent steam, the maximum velocity is limited to 200 ft/sec.

5.2 The maximum allowable fluid velocity in 90-10 CuNi piping varies according to the size of the line as shown in Table 2.

5.3 For sizing of firewater systems, the maximum velocity of the water, based on the nominal capacity of the outlets (hydrants and monitors), shall not exceed two times the maximum velocity listed in Table 1 for the material of the pipe.

http://virtualpipeline.spaces.msn.com

 

[SJones]

Most probably based on Mamdouh Salama's work at Conoco and published at SPE, OTC etc etc.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[GregLamberson]

The problem is often one of operations & management as there is obviously strong economioc incentive to raise the acceptable range for C factors which will immediatley increase production and ROR for the project. What needs to be looked at is using less ocnservative C factors (larger) to increase production while not increasing the risk of erisoion failures.

The opnly way to do that is to look at all types of erosion failure mechanisms with an iterative calculation of a safe threshold velocity. The C factor by itself should not be the all in but only a step in the process.

The threeshold erosional velocity is the linerar velocity above which resultsi n the unacceptable removal of base metal from the piping or production tubing. The standard is 5 mpy, but can be lower or higher depending on the specific project needs, life of system, ability to monitor and replace equip.

The main mecahnisms that contribute to the materials penetration rate are sand erosion, corrosion, liquid impingement, and wall shear stress. Therefore the process of selecting the right velocity becomes iterative by calculating the limituing velocities for each one of the mechansims.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[BigInch]

Greg, I meant MY first answer above.

http://virtualpipeline.spaces.msn.com

 

[GregLamberson]

Oh I know, I've just had some involvement in this subject recently and just wanted to ramble a little - it's a slow day.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[KernOily]

Got to resurrect this. The design for this system is entering the final phase and final pipe sizes must be selected.

I have reviewed the above info (thanks a ton for that, guys) and I still don't have any conclusions.

1) The ARAMCO steam data does not say if the steam is saturated or superheated.

2) A max value for wall shear stress is given above as 1000 N/m2. What is the source of this?

3) For the annular flow regime, there are no liquid particles or droplets.

4) Wall shear stress is very low - less than 0.5 psi, this at 200 ft/sec, 160 psig, and steam at 70% quality.

I have no solids, or very few anyway, and no corrosion issues at all. Based on this, I think I can justify the use of high C-values of 200 or more from the RP14E guideline.

I think I'm in uncharted waters here. Opinions/counsel/harsh comments/out-and-out insults welcome.

Thanks guys. Pete

 

[KernOily]

Oops, I meant to post this reply in a related thread over in the Piping forum. Looks like it got cross-posted. Sorry about that! Pete

 

[peedco]

Recently I have started my new job in the world most longest ETHYLENE PIPELINE Project. Since the geographical and topographical characteristic and climatic conditions at different segment of right of way of the pipeline is different from each other, it has made is as the most complicated one in operation point of view.
Ethylene is compressed supercritical gas in summer conditions, when it passes the pipeline located in mountainous area and it is compressed supercritical liquid in winter conditions, when it passes same rout. So it is completely different, comparing to the natural gas pipeline.
For this reason I am wondered which type of machines (compressors or pumps) we should select for transferring of ethylene, to provide required head and maintain the pressure of the ethylene at the required level at different section of the pipeline.
If any one who has experience in Ethylene pipeline please help me to find:
*)Which criteria I should consider for selection of the right machines (compressors or pumps) for transferring ethylene?
*)Which skills we should consider in design of pipeline to minimize risk of two phase flow in abnormal operating conditions?
*) Do we need pig launcher and receivers for pipeline what should be the pigging procedure?
*) What safety factor we should consider for Right Of Way regarding the supercritical conditions of ethylene which is different from natural gas.