Use of screwed casing pipe as pressurised piping

[LittleInch]

OK, casting the net out here a bit to see if there is any direct or indirect experience of using casing pipe with typically screwed end connectors as horizontal pressurized piping onshore.

Sizes are in the range 4" upwards

This is not my idea I hasten to add, but the question has been asked so I need to respond in as technical a manner as I can.

Some issues I can think of include:
Sealing
ability to apply sufficient torque horizontally
Difficulty in lining up when horizontal
Stress concentrations at the joints

So the question is:
Has anyone done this before with oil and gas service?
What type of equipment did you need?
what were the pluses and minuses?

Ask questions and I'll see if I can answer.
I'm waiting for details, but would like to know any general usage or attempts to use casing pipe for screwed pipe.

thanks LI

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[dhengr]

LittleInch:
I assume you are talking about a tapered pipe thread, like a NPT on normal commercial mechanical applications pipe. Would couplings work better than male/female threaded ends in terms of strength and stress concentrations? A big issue is protecting threads until the last minute. What lengths of pipe? I understand the difficulty of alignment, but the idea of vert. coupling doesn’t sound easy either, in the field, how far ahead of the final horiz. pipe positioning do you do this, and/or pipe bendability? Why not take a 50' long light steel frame or a WF beam, as a moveable skid in the trench, a fairly straight assembly platform. Maybe even a hand held laser line device placed at/in a couple fixed locations on the skid for alignment horiz. and vert. 1" +/- in 10' should allow threading, shouldn’t it? Skid’s front is shaped like a sled front end, bot. is shaped like a halfpipe, a skid steer (backhoe and a chain?) pulling it along in the trench would provide a perfect/compacted bed for the pipe. 20' of assembled pipe on cradles/saddles on the tail end of the skid, and 30' of new pipe in cradles on the front end, and clamping and tightening equip. at the 20' mark. This clamping equip. is all on a sliding frame on top of the skid, designed to be able to react the tightening torques, and all operated with hydraulic equip. The hydraulics and Teflon should pretty well provide controlled tightening to your proof testing for strength and pressure. This sliding frame moves a couple ft. lengthwise to get to exact end of pipe, and then can move a bit to tolerate tightening length change. After tightening, lift the pipe a bit and pull the skid forward in the trench 30'. One side of the skid could actually be pre-loaded with a couple lengths of pipe. Teflon tape works pretty well for sealing in the commercial world. Can you get wider/slightly thicker Teflon tape for this larger application? Plumber’s pipe dope? I’ve done some plumbing without too many leaks, but never done what your are suggesting. Sounds like an interesting project and concept for relatively low pressures.

 

[LittleInch]

dhengr,

Thanks for response.

I'm not sure yet what type of connector, either screwed or with a connector and I think it CAN be done, but really looking for any experience of actually doing it, or seriously considering it.

I think there is a good reason why you don't see it, even on well sites where they use hammer union or similar for horizontal pipe lengths and not drill casing, but I'm just trying to see if there is experience out there about this or not.

Normal discussions on screwed pipe tend to indicate most people stop at 2" or 3" at best. I'm looking at 4" +...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[auzie5]

We’ve installed lots of fiberglass flowlines that have threaded joint connections but never steel flowlines.

Not sure what location this pipeline is being considered for but in Canada, CSA Z662-15 Clause 4.5.2 limits the use of threaded joints as follows (see below). I assume ASME B31.4/ASME B31.8 has a similar limitation on threaded connections?

4.5.2 Threaded joints

Threaded pipe-to-pipe and pipe-to-component joints shall not be used for

a) permanently buried installations, except for auxiliary joints (such as drains, valve body bleeds, and
instrument taps) directly into components;

b) pipe larger than 114.3 mm OD;

c) pipe larger than 60.3 mm OD with a maximum operating pressure greater than 3.5 MPa; or

d) piping in HVP or CO2 service, except for joints in instrument piping.

Notes:
1) Threaded joints should be avoided where crevice corrosion, severe erosion, cyclic loading, bending, or unusual loading conditions can occur.
2) For limitation for sour service pipelines, see Clause 16.3.5.

 

[bimr]

Casing is a generic term for multiple products. The answer to your query depends on what type of casing that you have.

One would expect the casing to be much more expensive to procure than standard steel pipe. You will have to protect the pipe and threads from corrosion.

https://www.slideshare.net/akincraig/petroleum-engineering-drilling-engineering-casing-design

 

[racookpe1978]

The threaded drill pipe casings use that (very expensive, very specialized) well drilling tower and pipe rack stand to thread their 40 foot sections end-to-end to drive casings vertically.

Horizontally, you'd need "exactly" the same, but then would have to move the rig (pipe rack, threading fixture (moves for for each joint), anchoring fixture (for the already threaded pipe), and all power supplies and tooling from joint to joint. On a vertical drilling rig, all of that stays in place for the days/weeks of drilling. Further, the threaded pipe would have to be lifted and moved and reset to its final position = a LOT of stress and movement of the last three joints just threaded = LOTS of chance for leakage in the final pipe.

Not a good idea for anything but emergencies or disaster recovery.

 

[LittleInch]

All,

thanks for your input. The location of this is Africa and looking through B 31.4, only the offshore sections limit threaded connections to <2".

It turns out the casing is a variety of drill casing sizes, with grades ranging from 56 to 110, so not compatible with piping sizes, with Buttress Thread casing to simple API style (no fancy shoulders or threads), but needs a lot of torque to make it up (4,000 to 8,000 Nm) and get the extra length from hand tight to the magic triangle on the pipe indicating full tightness within the box coupling. Seems you can weld it but with a lot of difficulty for high strength steels.

Bimr - thanks for the link - I think I had found it during a search, but pretty useful

Rakoope - Good point that I'm bringing out in the study - basically you would have to make a portable jig to get the alignment spot on.

Anyway I'm trying to kill the idea stone dead, but wanted to see if anyone had made it work - doesn't look like it so I'm off the hook on that one. Only reasonably possible way is to joint it / screw it in as best you can then seal weld it...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.