abrassive wear in temporary surface lines 1

[lemster]

Hello,
currently im studying the abrassive wear in killmud surface lines.High flowrates nescessary (80fps) are not unusual. I found some models that i can use for a prediction of erosionrate. My scope of work consists also of finding out what guidelines other service companies have with solid particle abrassive wear.

I had some contact with Baker hughes and FMC technologies.They use both the guideline of a maximum fluid velocity of 40fps. Both companies do not know where it is based on. it is just a rule of thumb, even no references.
My question is: Does anyone heard of this maximum fluid velocity before? and could you give any references?

Kind regards,
Lemster

 

[LittleInch]

That (25m/sec) is a very high flow velocity for liquid lines (I assume it's liquid). I have done some studies for lines with sand in and you normally need quite a lot of details on the particle sizes, concentration and strength of the sand, but at those sorts of velocities you will be talking very short life spans. Other options you may want to consider are internal lining (or use of) PE or UHMWPE which is specifically designed for abrasive duty. Avoid sharp bends, elbows or tees where flow is coming in at 90 degrees - you'll wear a hole in one of those in no time at all, or just try and reduce your velocity to something a bit more reasonable.

Also try very hard not to call any pressurised pipe "temporary" - it leads to all sorts of poor design, construction and testing - call it "limited life" or "phase 1" or anything but "temporary". As a designer you actually have no guarentee that your "temporary" pipe won't be there in 10 years time.....

The velocity limits you mention are probably field based practical limits to avoid wearing out pipes and fittings in a short period. The other aspect is that at flow rates much above 4-5 m/sec, you could generate huge surge pressures if a downstream valve closes such that your piping would almost certainly rupture if there are no surge relief systems fitted.

Basic guidelines are remove the solids if you can, if not limit the velocity to such a level that it keeps the solids entrained, but no more and use the correct materials.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[lemster]

Little Inch,

Thank you very much for your response!
The reseach i currently do is to see how long they can pump with this temporary kill-lines. if everything goes well, it will not take longer than 5 hours to kill the 'blowing out' well when a reliefwell is drilled. By the way, it is a dynamic kill operation. a dynamic kill operation is done by a relief well wich is drilled near to the well that is blowing out. The lines(15000psi) are "portable" to say it in another way.

thanks for the effort

Kind regards,

Lemster

 

[rconner]

I am aware an early reference to “40 fps” is from “Design and Construction of Sanitary and Storm Sewers” (WPCF Manual No. 9 or ASCE MOP #37, 1982 and maybe even before). I may have even seen something similar/earlier in a concrete pipe design manual. I believe the specific quote in MOP #37 reads as follows:

“For clear water in hard-surfaced conduits, the limiting velocity is very high. Velocities in excess of 40 fps (12 m/sec) have been found harmless to concrete channels.” (It is not stated whether those were actually somehow measured velocity, or back-calculated from someones slope and formulae assumptions). From what little information that has been supplied here, it's very possible this doesn't apply to your service. I will note however that that phrase was followed immediately in that manual by:

“Erosion of inverts may result from much lower velocities when sand or other gritty material is carried.” (It then goes on to say that in continuous high velocity flow conditions where grit erosion is expected to be a problem the limiting velocity often is taken to be about 10 fps (3 m/sec))

 

[lemster]

rconner,
thank you for your view.
Maybe they have the theory in common of 40 ft/s. but yes, it sounds that it doesnt apply to Ductile low alloy steel. I will search further. Maybe i find something on other companies.

have a nice day!

Kind regards, Lemster

 

[dicksewerrat]

So you can state thet you will be able to 'KIll the blowout' in 5 hours. Look at the BP issue in the Gulf of Mexico. Test some pipe. Build a straight pipe with a couple 45 degree bends and pump this mud throughthe test section for a 24 hour period. See what happens. Then you will be sure. Theory is great till something turns to SH__.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com