CRC-Evans has experience innovating, custom-designing and building pipeline construction equipment for laybarges. We’ll help you equip your laybarge with nearly everything you need, from line-up modules that allow complete horizontal and vertical pipe movement to support assemblies that remove sagging and support the joined pipe.

Our broad custom-design capabilities allow you to work with a single source for all your equipment needs. Plus you gain the benefit of Total Project Support, which allows you to tap the expertise of our experienced engineering and technical staff, from planning to installation to start up and beyond.

The use of double jointing on laybarges has proven to increase the amount of pipe which a barge can lay per shift. The advantages of using this system are as follows:

- Eliminates number of welds made on lay ramp
- Provides high quality submerged arc welds
- Allows inspection of welds before pipe is inserted in main line
- Reduced manpower and equipment requirements on main line

Pipe to be double jointed will have the standard API 30 degree bevel. The bevel will be modified with a Pipe Facing Machine to include a .250" (6.4 mm) flat land with 30 degree external bevel and 37.5 degree internal bevel on pipe with wall thickness less than 0.625" (15.9 mm). On pipes with wall thickness 0.625" (15.9 mm) and above, a compound external bevel of 30 and 15 degree angles will be used.

Prior to double jointing, pipes are stored on fixed pipe supports where the pipe ends can be beveled. The pipe is moved in to the Line-Up Station by means of transverse carriages, where the line-up clamp is inserted. The pipes are aligned on the line-up modules and damped. Elevating turning roller units then lift the pipe and the external sub-arc floating head is lowered into position. Rotation is started and the first external weld bead is made. After this weld bead is complete the pipe is lowered back onto line-up modules and the clamp is removed. The double jointed pipe is then transferred to the next station by carriages which can be either the internal weld station or an external weld station or a station where both an internal and external weld is made, depending on arrangement of the system. After this second station the double-jointed pipe can be transported to a third station where another external weld is made.

The internal station also contains elevating turning roller units that rotate the pipe during welding operation. When these units have elevated the pipe, the internal welding head travels to the weld area and makes the internal weld, using a modified sub-arc welding head mounted on the end of the boom unit.

Only three stations are mentioned; however some systems have as many as five stations.

After welding is complete and the weld has been inspected by x-ray or other method (not supplied by CRC-Evans), the pipe is transported to a storage area or main ramp area to be used.

The following equipment may be required:

ENDO Conveyor Modules
Transverse Carriages
Line-Up Modules
Line-Up Clamps
End Prep Support Unit
Pipe Facing Machines
Elevating Turning Rollers
External Weld Stations
Clamp Nest
No-Tack Unit
Internal Weld Station