When to Involve Chemical and Process Engineers in Process Plant Engineering and Construction Change Order Claims

This blog post is the third in a four-part series on the role of chemical and process engineers in evaluating process plant engineering and construction Change Order claims.

The first post discusses the typical chemical and process engineering scope of work and when to engage a chemical or process engineer in a Change Order claim, and the second post details tasks to be performed in Change Order evaluation.

This third post identifies six examples of Change Order claims in which a chemical or process engineer is uniquely qualified to evaluate the technical, schedule, and cost impact of changes. The fourth post will include two more examples and will also include questions that chemical and process engineers can help answer about Change Order entitlement and schedule and cost impacts.

Example 1: Plant Capacity and Equipment-Related Design Changes

• Change to capacity or specification. As an example, during FEED, crude oil feed capacity is 250,000 bpd. During detailed design, the owner raises the feed to 400,000 bpd, increasing the size of the crude oil distillation unit, vacuum unit, and other processing units. This change also increases requirements for power, cooling water, processing equipment, and other utilities.
• Addition of a knockout drum to a main flare header system upstream of a flare stack to meet new environmental discharge guidelines and improve liquid separation during relief events. For example, an original flare system is designed with single header routing to an elevated flare with no dedicated knockout drum installed in the main header, and the system relies on unit-level knockout drums only. The addition of a knockout drum improves removal of hydrocarbons and water from the flare header, reducing carryover to the flare tip and ensuring compliance with EPA flare gas standards. The changed design requires rerouting of the flare header, designing and installing a foundation for the new knockout drum, and the required piping and instrumentation changes.
• Addition of spare pumps for redundancy.
• Change in rotating equipment drivers. This may include swapping an electric motor for a steam turbine or vice versa, which alters layouts, foundations, and steam requirements and tie-ins.
• Vendor-driven redesigns. For example, a compressor vendor submits load data revised from what was calculated during FEED, requiring thicker foundations and larger electrical motors.

Example 2: Technology Licensor Changes

• Catalyst supplier modifications change the volume of catalyst required, changing the size of the reactor.
• A licensor changes a reactor internal specification, requiring redesign of nozzles and supports.
• A process guarantee licensor mandates higher separation efficiency, requiring larger distillation trays and column resizing.

Example 3: Process and Piping Changes

• Feedstock changes caused by change in client market strategy or crude availability. Examples include switching from light to heavy crude oil, requiring equipment sizing changes, metallurgy changes, larger piping, different heat integration, pump redesigns, additional instrumentation, etc.
• Process flow changes that require revising PFDs or P&IDs. Examples include adding bypass lines or rerouting flows for safety or operability.
• Pipe sizing changes because hydraulic studies reveal pipe sizing underestimation. This leads to larger-diameter piping, rework of supports and isometric drawings, scrap or rework of prefabricated spools, extra welding, and added supports.
• Higher pressure or temperature requirements, driving thicker pipe walls, revised stress analysis, and changes in insulation or expansion loops.

Example 4: Civil or Structural Changes Caused by Equipment, Process, or Piping Changes
For Example 4, chemical or process engineers would not assess these changes but would instead verify that process changes resulted in these impacts to civil or structural disciplines.

• Foundation changes caused by equipment that is heavier than originally specified. These changes may require deeper piles, larger concrete pads, and more concrete, steel, labor, and rework.
• Structural steel revisions due to larger pipe racks, more cable trays, or heavier equipment loads, resulting in additional steel tonnage and rework costs.

Example 5: Site Layout Modifications
For Example 5, chemical or process engineers would not assess these changes but would instead verify that process changes resulted in these impacts to these disciplines.

• Shifting locations or spacing between tank farms, flare stacks, or substations to meet updated safety or regulatory spacing rules.
• Larger equipment affecting spacing between pieces of equipment. For example, in designing the layout of solids handling equipment, slopes of chutes between pieces of equipment and distances between pieces of equipment at different structure locations may need to change.
• A late risk review adding a reinforced blast wall between process units, changing layouts and delaying steel erection.

Example 6: Electrical and Instrumentation Changes
For Example 6, chemical or process engineers would not assess these changes but would instead verify that process changes resulted in these impacts to electrical and instrumentation disciplines. However, with respect to instrumentation, the process engineer can speak to the requirement for control schemes and their operating principles.

• Power load growth caused by adding larger motors or new substations after initial load studies. This leads to larger substations, cables, and transformers.
• Control philosophy changes such as switching from pneumatic to electronic controls, adding Safety Instrumented Systems.
• Cable tray and routing revisions are often a knock-on effect of late piping changes.
• Instrumentation changes, such as adding new analyzers, meters, or control valves after HAZOP or LOPA reviews.
• Valve and control logic changes, such as when an owner requires new safety interlocks after initial P&IDs are issued. This change affects the control system logic, requiring reissue of IFC drawings.

Richard J. Long has a B.S. in Chemical Engineering and an M.S. in Chemical and Petroleum Refining Engineering.

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