Getting delayed in traffic at 2 a.m. 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 they work toward 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 are now 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 and field-erected) have become popular since these methods offer 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 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 pipe-rack modules are generally constructed in specially equipped facilities called “mod yards.” These facilities are laid out to provide easy access by tractor-trailer, and the modules are built on templates that match the footprint of the foundation or piling that 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), height (bridges, overpasses) and 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-feet, 6-inches wide by 13-feet, 6-inches high by 65-feet, 6-inches long.
Obtaining permits from authorities for passage through municipal regions along the shipping route is also crucial. Local government officials can add days (or more) 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.” 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 center 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, 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 (can make moose-shaped dents in vehicles), bears (can chase field personnel) and beavers (can chew through shipping cradles and cribbing) must also be taken into account.
A common business buzz phrase 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.
For more information on SPED, visit www.spedweb.com or call (832) 286-7678.
