Pumping from Barge using Flexible pipes on Floats

[dcnnng]

Grateful if any expert can advise what are the suitable flexible pipes and the connecting details for the pumping system pumping water from a barge to land using flexible pipes supported by floats near shore with a difference of 2.67 metres between high and low tides. The pumping duration would last for about 8 hours for a total of 1,000,000 litres. If this proposal is not wokable than what are the alternatives. Thank you for all advices.

 

[BigInch]

A general system such as you propose can be designed and many similar systems are used for loading/unloading petroleum, in naval landing support for supply of water and fuel and are also common in dredging operations. The greatest problem will be maintaining the barge and hoses or flexible pipelines in place when they are exposed to wind, wave, current and barge movements.

Is this to be a permanent installation or will it be a mobile setup?

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[unclesyd]

Echoing BigInch's response rubber hose is used all around the coast here.

If you are going to have an extended period of use you might want to checkout HDPE pipe. I'm seeing more and more of it being used on different jobs around this area.

http://www.oxfordplasticsinc.com/marine.htm

 

[dcnnng]

Dear BigInch,
Though it is supposed to be temporary unitl the permanent water supply mains have been completed. The daily 8 hour pumping operation would last for at least 6 months or more. It is not expected to exposed very strong wind and wave because it is within a bay. Of cousre the fluctuation between the low and high tides of 2.67 metres or 8.8 ft coupled with mild wind and wave come into play. So how can ensure that the piping would not be stand up under such conditions? Your furhter advice will be very much appreciated! Thank you.

 

[dcnnng]

Dear Unclesyd,
Thank you for your response. As mentioned in my earlier post, the fluctuation between the high and low tides amounting to 2.67 meteres or 8.8 ft really cause the problem because the the one end of flexible pipes supported by indulating floats is to be connected to the pipeline on fixed land embankment/seawall unlike the dredging pieline whereby all are moving up and down accodring to the tides, wave and wind. How can we solve the problem?

 

[BigInch]

This doesn't sound too complicated now, but this project could turn into a major problem depending on the scale and local wind, wave current and sediment conditions you actually find out there. How long is this pipeline from the beach to the barge? A 1000 m3 barge is a pretty good size piece of equipment to hold in place, even with a small current and no waves. What is the water depth at the mooring point?

Actually, being within a bay can have more profound negative effects than open water. Ocean waves entering a bay are "shoaled" to heights greater than open water wave heights and can create some nasty currents. Breakers can create considerable drag on floating pipelines in the wave zone. Tidal currents can be quite extreme, especially when concentrated. When you do some coastal structure design, you soon realize that there are few forces as powerfull as what a tiny amount of moving water can throw at you, even at currents of 2 kn or less. Depending on the structure. just the drag forces can be very high. If you don't have a specific study try checking for local navigation weather records to get a long term data history of wind speed, direction, wave heights and current data for, at the very least, 10 years to make your own maximum condition forecast. I've had large tankers blown away from a petro terminal bouy loading station in a small well protected bay, with minimal waves, no tide and hardly any currents, just due to a passing thunderstorm. I can't emphisize this enough.

Will the barge be moving on and off station after it finished its delivery and return the next day? If it is moving on a frequent basis, maybe you should make some permanent mooring bouy, rather than drop anchors in reef, rock or bottom sediments with poor anchor holding properties. That is another important point, as a moving barge will rip up a pretty good size piece of steel pipe. Not all bottom sediment will hold a barge anchor. You will also want good knowledge of the bottom properties, either for anchor holding properties or for design and installation of a few dolphins or a mooring bouy and perhaps for burying the pipeline if necessary. Find out if wave action will liquify any areas of the bottom sediment.

How long a pipeline are you thinking about? This makes quite a bit of difference on how you can hold it in place. You may be able to float it, float segments between dolphins, or maybe it will need to be buried out to a mooring structure of some kind. It may also be possible to float it, but with anchor cables to the bottom in some places. You must also determine if the pipe can be floated directly from the beach, which is difficult because of wave zone breakers and currents in that area or if it will need to be buried in that zone.

Loading operations will also affect design. If the pipeline can be dropped and the barge held in position until waves die off that may be the way to do this, but if the unloading operations must continue, it may be better to bury the pipe, deeply through the beach and wave zone, then maybe somewhat less out to a dolphin and place a riser with a connection for the barge out there.

The type of hose connection to the barge will be determined by the type of station keeping the barge will use, if moored to dolphins it is rather stationary, whereas a 1 anchor point or 1 bouy mooring will require greater pipeline connection mobility and maybe a swivel joint, where a 2 bouy system may not. A number of dolphins might be able to give the barge easy station keeping ability.

You should also consider maintenance requirements, spare bouys, spare pipe segments, spare connections, cables etc and a place to securely store these materials. Marine pipelines in the wave zone are high maintenance items and spares and appropriate tools should be on hand.

There are quite a lot of things to think about of which I've only covered some in the above. I think it would be a good idea to have an engineer with some marine pipeline and terminal experience onboard (or hanging around close by) if this project is to be a critical water supply point or if it is of large scale. Things can quickly get out of hand depending on the exact findings about the conditions in the local area and the length of the pipeline.

One good thing is that the permanent installation will require the same knoweledge of the local conditions, so you will have a head start on gathering data for that project.



BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[dcnnng]

Dear BigInch,
Thank you for your prompt reply. The barge is only 160ft x 52 ft. The pipeline from the barge to shore/seawall is about 40 metres. The water depth is about 30 ft. There is no dolphins nor mooring bouy. Would this info help you to give me more advice? Thank you!

 

[BigInch]

OK not so terribly complicated being that the pipeline length will be relatively short. And not a tremendously big barge, but it must hold station somehow. (I think) barges can need up to 10 times water depth for secure anchoring, depending on bottom conditions, so they may have to back off more than the 40 meters. Check with the operator as to how close to the seawall they will be safely able to anchor in your wave heights and currents. They will need to deploy at least 2, perhaps 3 anchors and possibly 4, so the anchoring pattern will determine how close they can move in.

US Navy transfers fuel from two moving ships using quick coupling hoses tied to a suspended cable (don't know the exact details), but I suspect something like that may be possible, if the barge can be adapted. Its much easier to resist wind forces than waves and currents moving in and around seawalls.

If you still like to float the hoses, it is quite possible to do that. Offshore loading bouys have self-buyoant hoses that can be towed around by small boat and picked up by a line from a tanker, hoisted aboard and connected to the tank manifolds. 50-100 meters is not so long and the hoses will be able to self-resist most currents without intermediate anchoring, but ops may have to stop in large or breaking waves.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[dcnnng]

Dear BigInch,
Thank you for your quick reply. Assuming that the barge can be reasonbly stationed with 4 drop anchors and we have 2 options, Option (1) - Pipes on floats. What type of pipe is suitable? Would HDPE pipe be used? Please give in details of the types of pipes and connections between the pipe on floats and pipe fixed on the seawall with an expected fluctuation of 8.8 ft between high and low tides
Optoion (2) - Using buried pipes. What type of cheapest buried pipe is suitable? Can you please give in details of the types of pipes and connections between the fixed buried pipe, riser and pipe from the pump on barge with an expected fluctuation of 8.8 ft between high and low tides?
Thank you for your valuable advice and assistance.

 

[chicopee]

I can not add too much to what is said above but I do remember this incident when one of the contractors in Bridgeport, Ct. had tied his small tug boat and not allowing enough slack to his mooring lines. Boat listed and sank. Contractor paid a stiff fine to the US Coast Guards. Dont make the same mistake.

 

[BigInch]

dc,
Sorry its really not appropriate to add any more. This is an engineering tips forum; no design work. At this point you need to find an engineer to work up the details for you.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[dcnnng]

TQ BigInch. Really appreciated.