Need advice on big inch w/ bell-and-spigot joint in hot water service

[KernOily]

Looking for opinions and experience here... Client wants to run 8 miles of 42" pipe, 0.394" wall, for 500,000 bpd of hot water (165 F) service. He is proposing to use A36 spiral-welded pipe with an AWWA-type bell-and-spigot joint. This joint has two fillet welds: the weld on the pipe OD is the main strength weld and the weld in the ID is a smaller fillet (seal) weld to keep crap out of the space formed between the bell and spigot.

We are concerned that this setup may crack the fillet weld upon thermal expansion, seismic events, startup and shutdown, etc., those loads acting in combination with the residual stress left over by the making of the two fillet welds during construction.

We can design out a lot of the problem with special expansion joints, use preheating, etc., but I think the best thing to do is use a buttwelded joint instead of the bell-and-spigot. So, I am trying to sell that idea to the owner.

Any of y'all have any experience with anything like this? In the meantime we are doing an FEA model of the joint to try and qualify it for this service. This line has both underground and above-ground segments.

Thanks in advance for any help/advice/opinions/nasty comments.

Thanks!
Pete

 

[Ashereng]

Pete,

This is just a suggestion. Take if for what it's worth.

Pipe gas to where you are going 8 miles down the road, and then boil the water there. You already plan to have a water line, so adding a fuel gas line shouldn't incurr more infrastructure cost.

Just a thought.



"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
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[vzeos]

74Elsinore:

I don't know much about AWWA B&S joints but I'm just curious...If you are going to install steel pipe why not just butt weld the pipe? Butt welding would be stronger.

Also, since you are installing the pipe underground and it will be operating at elevated temperature (presumably insulated), I assume you will use a coating-anode (or coating-impressed current) system for cathodic protection. The B&S joints may interfere with cathodic protection, depending on there design.

 

[unclesyd]

I would contact these people as they mention all types of joints used with their spiral welded pipe.
Good people to work with.

http://www.acipco.com/aswp/

 

[trashcanman]

Ashereng (Petroleum) 6 Jun 06 15:32
Pete,

This is just a suggestion. Take if for what it's worth.

Pipe gas to where you are going 8 miles down the road, and then boil the water there. You already plan to have a water line, so adding a fuel gas line shouldn't incurr more infrastructure cost.

Just a thought.


I second the motion. Much more energy & cost efficient.

 

[KernOily]

Thanks for your replies guys.

"Pipe gas to where you are going 8 miles down the road, and then boil the water there."

Well that sure would be nice, but. This line is a water disposal line. It carries oilfield produced water from a crude dehydration plant to a disposal facility.

"If you are going to install steel pipe why not just butt weld the pipe? Butt welding would be stronger."

No doubt. This project is schedule-driven, not cost driven. The owner has Northwest Pipe all spooled up to start cranking out this pipe and B&S is their forte. They can get B&S pipe made a lot faster than buttweld pipe. Also, the field fabrication will go much faster because the placement of the two fillet welds will be faster than the line-up and weld-out of the buttweld joints. No hydraulic line-up clamps and such.

"I assume you will use a coating-anode (or coating-impressed current) system for cathodic protection. The B&S joints may interfere with cathodic protection, depending on their design."
The line will have impressed current as well as an internal and external lining. Since the B&S joints are fillet-welded that will ensure conductivity across the joints. There is no packing in the joint.

The buttweld joint is still my preference. I have been retained to verify the adequacy of the proposed B&S/fillet weld joint. We'll see what comes from the FEA model.


Thanks!
Pete

 

[Ashereng]

Client wants to run 8 miles of 42" pipe, 0.394" wall, for 500,000 bpd of hot water (165 F) service.

Your reference to "hot water service" threw me off. It probably should have said PW to disposal.

Anyway, back to spiral weld. We don't do that anymore. Then again, my lines are not anywhere near 42".

Sorry, can't help much.

Let us know what your FEA comes back with.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[KernOily]

"Your reference to "hot water service" threw me off. It probably should have said PW to disposal."

Yep, sorry about that. I was trying to keep the discussion general. Didn't work.

Got the FEA done. Joint fails in tension across the weld due to pressure thrust (due to presence of slip joint) and axial seismic. Not enough weld (not enough leg) in the fillet. based on that we have recommended the joint be switched to a butt-weld.




Thanks!
Pete

 

[Ashereng]

Yup. Like I said above, we don't do spiral welds anymore.



"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?