When designing and installing new tanks and pressure vessels, chemical plants can be better secured and supported via clear communication with transport engineering and project logistics teams
Tasked with storing or holding various critical gases, vapors and liquids at high pressure, tanks and pressure vessels are at the heart of every production process used in the chemical process industries (CPI). However, before these critical pieces of equipment can be put into operation, they need to be manufactured, safely transported and installed at their destination — all within strict schedules and rigid budgets and according to the highest industry safety standards. Whether for new construction, maintenance, urgent repair or replacement, the reliable and timely delivery of tanks and vessels is critical to chemical production processes (Figure 1), mainly because plant downtime is extremely costly. This is all the more important when you consider that damage to the cargo during transport can also result in plant downtime or high financial compensation claims.
FIGURE 1. The efficient and prompt delivery of tanks and vessels is crucial to chemical production processes, whether for new builds, routine maintenance, emergency repairs or replacements
Although the share of logistics-related costs looks comparatively low in relation to the total investment in major chemical projects, both project logistics and transport engineering play a crucial role. This is because even the smallest supply-chain disruptions, delays or interruptions can cause immense delays and costs for individual projects that need to follow strict project schedules and planning outlooks to which all subsequent production processes are aligned. Simple but crucial, project logistics and transport engineering play a critical role in ensuring adherence to the project schedule — for example, by defining the safest and most feasible route based on an infrastructure study or a 3-D simulation of the installation process.
Challenges
To transport tanks and vessels safely, effectively, in the most environmentally friendly way and within the estimated project schedule and budget, a number of aspects need be considered simultaneously from the outset. The main challenges lie in the movement and handling of the often oversized and heavy-lift (OSHL) components across various interfaces, modes of transportation and infrastructure, as well as in their installation on site. The interaction of the size, weight and nature of the tanks and vessels with the different transportation modes, equipment used or routes chosen is crucial to successful transport and delivery. This needs to be taken into account at the investment stage to minimize risks, costs and time.
Early infrastructure studies
From global manufacturing complexes to remote installation sites, chemical processing projects are located in a variety of regions with widely differing infrastructure. These range from easily accessible regions with modern infrastructure to regions with very limited, old or no infrastructure. This is why conducting robust infrastructure studies as early as possible in the investment stage of a capital project can prove extremely valuable. These types of studies should look at the full journey equipment takes to reach its final destination, whether by road, inland waterways or oceans.
Road transport
Bridges offering limited height or load capacity, tunnels, narrow roads in or near towns or villages, sharp turns, overhead cables or road furniture (such as barriers, street lights, traffic signs and so on) can make it extremely difficult or impossible for OSHL tanks and pressure vessels (Figure 2) to pass through. Engineered infrastructure studies are therefore essential at the investment stage to examine the overall feasibility of the project and identify limiting factors. Such studies form the basis for the logistics concept and its subsequent smooth implementation.
FIGURE 2. An infrastructure study should evaluate all roads that an oversized tank or pressure vessel will traverse, looking for obstructions like tunnels, sharp turns and other barriers to ensure the smoothest delivery to the site
These studies can also be exceptionally comprehensive. For example, a recent infrastructure study covered a total of 12,000 kilometers of road in seven countries. To determine the dimensional limits and corresponding maximum technically feasible transport envelopes, engineers must investigate and identify the most suitable routes, bottlenecks and risks. In the study referenced in this example, located in Uzbekistan, nearly 1,700 bridges and over 1,500 obstacles (such as tunnels, various road furniture, overhead signs, cables and sharp turns) were identified, assessed and documented with more than 2,000 photos and calculations. All the facts, figures and data required to optimize the design and safe movement of freight were compiled in a full project feasibility study, which provided technical advice and guidance on project limits and technology requirements as a crucial basis for decision-making in the planning and investment phase.
Inland waterways
For short sea and inland waterway transport in particular, infrastructure experts are currently observing an increased demand for combined barge and tug-and-tow concepts, especially from the chemical industry. Barge transport is increasingly being used as a cost-effective and easy-to-handle alternative due to its high loading capacity, loadability and storage space. Barges are also well-suited for improving the carbon footprint of transportation due to the potential for using lower-carbon fuels — an increasingly important issue since many industries are encouraged to look for ways to reduce their carbon footprint.
The use of inland waterways, like rivers and canals and the need for suitable moorings limit the routes available for inland waterway transport. In addition, the simultaneous increase in low water levels or flooding caused by heavy rainfall mean that a growing number of routes are no longer navigable at certain times of the year or are navigable only to a limited extent and with special equipment.
As weather (and weather forecasting) become increasingly uncertain for inland waterway transport, especially for OSHL cargo like tanks and pressure vessels, it has become vital to identify all contingencies and risks at the project planning stage in order to identify and provide alternative solutions for safe and scheduled transport. These include the identification of alternative routes or modes of transportation, temporary storage or trans-shipment options, or the use of specially designed or modified tug-and-towage equipment with shallower drafts (the vertical distance between the waterline and the hull).
Ocean transport
When it comes to transporting tanks and pressure vessels overseas, the use of specialized heavy-lift marine vessels plays a key role (Figure 3). No other means of transport is as effective at transporting such large equipment and handling so many varied OSHL components over such long distances.
FIGURE 3. Transporting oversized equipment overseas requires specialized marine vessels that can handle not only the load of the equipment itself, but also the wide variety of associated equipment components
In order to maximize the efficiency of ocean transport, many critical aspects need to be considered. Tailor-made method statements, transport arrangement drawings, detailed motion analyses, ballasting and mooring calculations, ramp arrangements, lifting and rigging calculations or stowage and sea-fastening designs are required to ensure the safe loading and discharge, stowage and load securing of the often impressively large and complex tanks and vessels for the ocean voyage. All technical calculations and simulations depend on 100% accurate cargo dimensions and weights, and even the slightest deviation can have a serious impact on equipment selection, operational processes and the cargo — and therefore the overall project.
Powerful and cost-intensive, fully and partially chartered vessels are critical to project delivery. At the same time, due to many advance bookings and an increasing shortage of suitable heavy-lift marine vessels with the appropriate capacity and equipment for complex OSHL cargo, vessel identification and securing for the required place and time has become an increasingly critical factor in recent years and can vary from a few weeks to up to several months, depending on the cargo and port details. For example, if the cargo is to be shipped on a deck carrier or semi-submersible vessel, lead times of over a year can be expected.
In this context, the timely and complete communication of the fabrication and shipping schedules, the required delivery sequences and arrival dates, as well as all relevant cargo details, are more important than ever to ensure safe, efficient and timely project delivery within the project schedule and budget from the outset. This information is used to design the execution concept, which clearly defines what type of tonnage is required, which suitable carriers are in control and what the availability and booking lead time of this tonnage will be.
In addition, the port conditions and restrictions need to be reviewed to ensure that the selected transport-vessel type can technically call at the port. This is not just a matter of water depth and tidal variations, but also the number of suitable berths, the pier’s layout and whether there is sufficient space to deliver or receive cargo to or from the oceangoing vessel. If, for example, a port limits the choice of ocean vessels too much due to certain restrictions, more suitable ports in the vicinity and with the required possibilities for pre- and on-carriage requirements may need to be identified.
Cargo design impacts on logistics
Whether traveling via inland waterway, land or ocean, and whether transported by truck, barge or oceangoing vessel, the design, size and weight of tanks and pressure vessels determine and limit the range of transportation modes, equipment and routes available. These factors also have a significant impact on a project’s feasibility, logistics design and implementation, budget, schedule and cargo safety. Smooth interaction between transport engineering and project logistics is therefore extremely important for completing technical calculations and simulations of freight movements across all infrastructures, transportation modes and interfaces, and for the design of engineered logistics studies and method statements. Close collaboration between transport engineers and project personnel is crucial for the evaluation, organization and smooth implementation of these logistics concepts in the field, including the timely provision of all required equipment and resources.
Impacts of transportation mode
In the same way that cargo design influences the logistics concept, transportation modes and equipment influence cargo design. By comparing the various transport options for the various tanks and pressure vessels and checking the individual feasibility, both the transport engineers and the project logistics managers can provide valuable advice to the client on what to expect in the logistics chain and where bottlenecks may occur in terms of cargo, equipment, handling or installation. This means that critical steps can be taken at the cargo design stage to ensure a smooth subsequent supply chain — whether it is the addition of special lashing, lifting or load-securing points, the position and quantity of transport saddles or the specifications, instructions and limits of possible modularization.
Also, for prefabricated tanks and pressure vessels, smart engineering offers a wide range of technical solutions to make their transportation safe and efficient — from pre-rigged lifting slings that avoid working aloft, which reduces equipment requirements and time and also increases safety, to the smart positioning of lifting points, such as trunnions or hurdles, which allow cargo to be loaded with the majority of the heavy-lift fleet and thereby drastically saving ocean freight costs.
All of these measures offer great potential for cost savings, as well as risk and schedule minimization.
Installation
The transportation and installation of tanks and pressure vessels at operational plants is always a challenge, because existing structures often obstruct the movement and maneuvering of larger cargo. Site surveys and 3-D and swept-path analyses, as well as thorough operational planning, allow for a smooth delivery up to the foundation.
The final installation process varies greatly, depending on the environment, cargo details and available equipment. Installation processes like jacking and skidding, installation by one or two cranes (for instance, tailing operations, which are described in more detail later in the article) or installation with a gantry system have their pros and cons. These should be considered from an early stage onwards, as they potentially affect the design requirements for the cargo or the pre-assembly status of a pressure vessel.
The importance of close cooperation and dialogue with transport engineers and logistics experts right from the cargo design stage can also be clearly demonstrated during installation processes. For example, tanks and pressure vessels are typically transported horizontally (Figure 4) to the construction site on special trailers. During installation, the OSHL components, which often weigh several hundred metric tons, must be moved from a horizontal to a vertical position. This is typically achieved through a tailing operation, a technique where a crane or other lifting device stabilizes the rear of a large or long load while another crane or lifting system lifts the front. Trunnions are typically affixed to tanks and pressure vessels for lifting purposes, usually with soft slings.
FIGURE 4. Tanks and pressure vessels are often transported horizontally and must be transitioned into a vertical orientation prior to final site installation
Experience shows that gaps in the communication between the design team and the installation and logistics team can have serious effects on a project, as protruding parts of a pressure vessel may interfere with the lifting equipment during the erection process. This seemingly minor problem could have significant implications for the project schedule, budget and safety. Facilities may not be completed on schedule or may not have the ability to be quickly restarted after downtime. High additional costs may be incurred for complex cargo modifications on site, or for hired cranes or lifting equipment. Close cooperation and dialogue between the process equipment developers and the transport engineers and logistics experts from the design stage onwards are therefore crucial for ensuring the transport and installation process runs smoothly and safely.
The key to the timely, safe and effective delivery of tanks and vessels, and to meeting chemical-plant production-process needs, project schedules and budgets from the outset, lies in achieving the greatest possible mutual understanding of each stakeholder’s processes, and in maintaining close, timely interdisciplinary communication and collaboration. ■
Acknowledgement
All images provided by deugro
Authors
Gert Jensen is the senior vice president of operations with deugro USA, Inc. (Email: [email protected]). He has over 25 years of experience in global project freight forwarding and has been actively engaged in managing and sponsoring capital projects globally within the oil and gas, petrochemical, power generation, mining and renewable sectors. He has extensive know-how in all aspects of project logistics, including feasibility studies, route surveys, port operations and supervision, vessel chartering, heavy haul, barge and rail transport, commercial and technical bid preparation, client/supplier negotiations, contract management and oversight.
Hagen Hennig is the technical director at dteq Transport Engineering Solutions (Email: [email protected]). Hennig is a certified Master Mariner and Port Captain. He holds a diploma in maritime transport, as well as an M.Sc. in maritime management. He has successfully managed and personally participated in a large number of projects and shipments of all sizes and weights to numerous global destinations, including the remote Arctic Circle.