Dear Ravi,
Following up on Dr. Majid Abdi's nice explanation below, several key factors that play a role in erosion are:
1. Single- or multi- phase flow in the facility (based on P,T, fluid composition)
2. Solids type (hardness), size distribution, and concentration [usually the most uncertain measurements to get from field are solids concentration which directly affect erosion rates estimation]
3. Tortuous flow paths in several piping component types (elbow, tee, sudden contraction/expansion, etc.), pipe material hardness, and diameter of flow path
4. Velocity of solids (dependent on relative velocity of the fluids and particle size)
5. Most of our industry-standard erosion correlations (for example, DNV-RP-0501) predicts erosion extent by +/- 100% even for single-phase carrier fluid STRICTLY for sand size > 150 microns (large sand particle).
6. Most of these correlations grossly under-predict erosion extent by fine sand particles (size < 100 microns); there are limited lab data and field anecdotal evidences that fine sand erosion is as appreciable as large particle erosion.
7. The topic of 'prediction of erosion in multiphase flows' is much at its infancy as of now.
8. API-14E is certainly NOT the criterion to use (it was originally developed with a good intention to provide some basic guidance -- rule of thumb -- in the absence of data or models). In my personal opinion, it is being used and abused by our industry.
9. Apart from several seminal papers on wear/erosion in the last century, one of the few good (practical) references for you on the topic of erosion is: Erosion in Multiphase Production of Oil & Gas
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| Erosion in Multiphase Production of Oil & Gas |
| ABSTRACT The ability to predict the rate of erosion in the multiphase production of oil and gas is important for sizing lines, analyzing failures, and limiting production rates. The commonly used API-RP-14E criterion is shown to be inadequate for two reasons: (i) in some cases, it gives a false sense of security, and (ii) in other cases, it unnecessarily limits production. |
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Thanks for initiating a discussion on this topic...
Best wishes and regards...
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Hariprasad J. Subramani
Flow Assurance Engineer
Chevron Energy Technology Company
HoustonTX
Original Message:
Sent: Feb 06,2016 09:15 AM
From: Majid Abedinzadegan Abdi
Subject: Gas - Erosion Velocity And Pressure
Ravi,
this ia loaded question. Although all the parameters are some how related responding to your question in a few line is very difficult. The arrival pressure and the line inlet temperature and pressure dictate the temperature and pressure profile in the line and consequently the state of the fluids in the line. Depending on the fluids composition the flow could be in single or multiphase which would determine whether there is a risk of erosion. With reduced pressure the gas tends to expand and the fluids velocity tends to increase. This together with the solid content are critical factors in determining the extent of erosion.
All in all the system needs to be looked at from various perspectives.
I hope this could have helped a little bit.
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Majid Abedinzadegan Abdi
Lead Engineer, Facilities and Process
Husky Energy Inc
St. John's