Successful J-tube pulls at the world’s deepest conventional platforms require complete confidence in the equipment being used. Your team needs the assurance that pipes and flowlines are electrically insulated and corrosion-proof.
That’s why Mark Tool’s Splashtron-coated pipelines are guaranteed to withstand the process of raising pipeline to the deck of a fixed offshore platform’s jacket structure over and over for the lifetime of the installation.
J-tubes (so named because they’re shaped like the letter “J”) are vertical sections of pipe that connect offshore production piping to seabed pipelines. They eliminate the need to make underwater connections between the riser pipes and subsea pipelines since those are pulled up through the J-tubes. J-tubes are especially common with installing small-diameter flowline and pipeline bundles.
J-tubes (courtesy of COB Industries)
A J-tube consists of the following components:
- Vertical Tube (the tube from seabed to above water level)
- Bottom Bend (the curvature of the J-tube at the seabed)
- Bell Mouth (the bell-shaped opening at the end of J-tubes (also found in I-tubes); it guides the cable at the seabed
J-tube seals (or “plugs”) are typically installed in the J-tube just behind the bell mouth entry, then secured to the host line by integral clamps. They can then be pulled into the J-tube via the host line.
Mark Tool combines the coating in the tube with a bottom J-tube seal to make the annulus airtight, center the pipe in the tube and confine your corrosion inhibitor solution to the inside of the tube (between the host line and the J-tube bore).
Since J-tube seals prevent the loss of corrosion inhibitor within the J-tube annulus, Splashtron seal elements have to provide an “interference fit” to hold the host line and the J-tube bore and provide the seal. No subsea activation is necessary.
Laying pipe on the seafloor can be done in a number of ways. The “tow-in” technique suspends the pipe in the seawater via buoyancy modules; then tugboats tow the pipe into place.
The “S-lay” technique (used for shallow-water installation) eases pipe off the stern of the barge. The pipe is welded horizontally (or near horizontally) on a lay barge and runs off a stinger in an S (reverse) curve.
Animated Overview of J-Tube Installation
In deeper water, the “J-lay” method can be used where the pipe is welded in the vertical and there is a single curve near the seabed.
For installation, the umbilical (the flowline) is connected to a “pull head” used to pull the umbilical through the J-tube up to the topsides. Sometimes the risers pulled through J-tubes are flexible; more often they are rigid.
In shallow-water pipe installation, concrete is poured over the pipe to hold the installation in place. With deepwater installations, the insulation and pipe thickness are usually enough to keep the line in place.
Key features of deep-sea J-tubes:
- Used to install deepwater subsea pipelines
- Suitable for installation of large diameter and concrete coated pipelines as well as bundles of small-diameter flowlines and pipelines
- Used for fatigue-sensitive pipes (such as risers)
- Used to install special items such as PLETs;
- Have a high lay capacity
- Are typically not suitable for shallow water pipeline installation
Splashtron is ideal for pipelines pulled through J-tubes and for the J-tubes themselves. It’s also an excellent coating for platform structural members (legs and diagonals), conventional risers, conductors and the lining of riser clamps.
Mark Tool’s tough, long-lasting elastomer is applied to structural members during fabrication to give you complete protection against the erosive action of abrasive seawater, the harsh attack of ozone and ultraviolet rays, impacts from boats and floating debris and the biofouling effect of marine life on offshore installations.
Splashtron gives you a resilient coating that won’t crack or disbond as pipe flexes or bends. It typically requires no routine maintenance for the life of the platform, riser or pipe. It contains no carbon black to impair electrical insulation, has excellent insulating properties (thermal and electrical) and can be used at temperatures from -45°F to 200°F.
If you’re interested in learning more, Mark Tool Co., Inc. would be proud to give you a quote for your business needs—just fill out this easy form today, and we’ll be in touch.