By: Paul Bowers, SPED Calgary Chapter Director-At-Large
Getting delayed in traffic at 2AM on a weekday night on a major highway isn't all that common, but when it does happen it's often due to some gargantuan industrial equipment being escorted to its destination or waypoint. Piping designers are often also industrial plant layout designers, meaning that they work towards determining how a facility is laid out and the units within are configured. This includes the spacing and locations of pipe racks, equipment, buildings, roadways, storage tanks, etc. It's all well planned, and there now exist programs to visualize construction - animation type software that can simplify to some extent the logistics of millions of pieces fitting together. For example, different sequences of large equipment erection and placement can be simulated to discover the most efficient order of site activities.
Over the past decades modular fabrication and construction techniques(as opposed to 'stick-built', field-erected) have become popular since this method offers the advantages of better quality control, simpler construction on site, flexibility in scheduling and many other benefits. Modular design requires more engineering time and planning earlier on in the project with the goal being a "bolt-together" facility at site.
Some of the most impressive examples of modular fabrication are floating and fixed offshore platforms for undersea oil and natural gas extraction, but in this article land-based facilities are the topic.
Process equipment, building and piperack modules are generally constructed in specially-equipped facilities called 'Mod Yards'. These facilities are laid out so as to provide easy access by tractor-trailers and the modules are built on templates that match the footprint of the foundation or piling that (is supposed to) exist on site. The Mod Yards feature structural steel and piping fabrication capabilities, appropriate cranes and mobile lifting equipment as well as pressure testing and painting facilities. Modules under construction can be enclosed and heated during cold periods to enable work to progress in relative comfort. In Alberta, Canada, modularized units' equipment and piping are heat-traced, insulated, painted and wired prior to leaving the mod yard.
Shipping and infrastructure limitations determine how large and/or heavy a road or rail-transported module can be. The most common obvious restrictions are width (roadways, tunnels) and height (bridges, overpasses) as well as weight (bridges, load-bearing capacity of roadway surfaces). Length is also a consideration, for tractor/trailer/load turning radii requirements.
Route planning for large module transportation is critical - the occasional costly embarrassment (in money and schedule impact) occurs when modules must be cut apart and/or disassembled to pass between, through or under structures.
Maximum road shipping clearances vary within North America, but a common size envelope is 8'-6"W x 13'-6"H x 65’-6”.
Obtaining permits from authorities for passage through municipal regions along the shipping route is also crucial. Local government officials can add days (or worse) to delivery time.
Often the module structure itself forms part of the overall transport vehicle as is the case with Schnabels. With Schnabels, the shipped structure can be suspended between two independent support points on separate wheeled end “cars” (as opposed to simply sitting on top of a flatcar or trailer bed). Some Schnabel systems are hydraulically articulated so as to be able to raise, lower and twist the suspended load independently to compensate for grade slope and centre of gravity.
Areas of northern Canada known for oil and gas extraction have time-of-year restrictions for the movement of heavy loads. This is due to soil material known as muskeg (Algonquin for “grassy bog”), which, if present at and/or near the construction site, must be sufficiently frozen in order to support the cargo and transport weight. Wildlife such as moose, (make moose-shaped dents in vehicles), bears (chase field personnel), and beavers (chew through shipping cradles and cribbing) must also be taken into account.
A common business buzzphrase is "Think outside the box." With modular design, a lot of thinking *inside* the box is needed to ensure everything fits and is accessible for operations/maintenance.