Cleaner fuels with teamwork

An innovative approach to the use of 3D plant design software and partnerships between contractors, designers and operators helped Parsons Energy and Chemicals complete a major project for Conoco, as Martin Brooks explains.

The London office of Parsons Energy and Chemicals broke new ground when it was awarded a lump sum turn key (LSTK) contract in June 1999 for the engineering, procurement and construction of a plant to reduce the sulphur content of diesel (diesel hydrodesulphurisation) at Conoco's UK Humber refinery.

The project's target is a safer, more ergonomic, and easier to maintain plant with improved total life cycle costs. The plant, being designed to conform to European Community clean fuels legislation, is scheduled for completion in April 2001.

The major factors in achieving this are collaborative teamwork with both client and major subcontractors, and optimal use of Intergraph's 3D Plant Design System (PDS). Overall project advantages include cost-effective design, increased value for Conoco, and positive influence on engineering and construction standards within the industry.

Faster, better proposal

A 3D PDS model, previously developed by the front-end engineering (FEED) contractor, formed the basis for Parsons' proposal. Parsons Energy & Chemicals uses PDS as its default design tool, and Conoco specified the system as its 3D design tool of choice. This compatibility enabled Parsons to 'bring the proposal to life' by using, for the first time, a model produced out-of-house.

Parsons London, with its non-customised library of 3D equipment items, was well-positioned to exploit the FEED model. 3D pictures and walkthrough videos helped convey the scope of work. The realistic views also sparked design ideas which would have been impossible to achieve in the proposal's timeframe using 2D paper documentation. Resulting improvements in safety, operational, and access features were passed on to the client.

The project required all engineering design in 3D from the proposal stage. This increased design integrity, because the single master design model allowed all disciplines to share the same 3D background layouts for such features as cable routings and instrument location plans. On award of the project, the proposal model was immediately in use, with no re-input of data.

Mixing disciplines

Parsons and Conoco opted for an open, integrated working method for the project. The project's 3D-design team comprises qualified engineers and designers from various disciplines. Commitment to the overall good of the project and cross training in PDS and FrameWorks software helped remove inter-discipline barriers.

Use of Intergraph's DesignReview to 'walk through' the model helped consolidate collaboration. 'The ability to manoeuvre around the model and visualise the finished plant has been a real bonus,' says Mike Tinsley, Conoco's project engineering manager. A 37' monitor on a wheeled table provided easy access to the plans. It's a common sight at the DesignReview station to find the piping fabricator locating field weld positions, Conoco operations checking valve access, or the heavy lift contractor reviewing module lift sequences.Engineering quality

Targeting absolutely minimal site rework, Parsons reviewed lessons learned from previous projects and made use of Conoco's operational experiences to improve the construction and commissioning effort. Accordingly, Parsons' 3D task force specified items for the model that might affect clash or field rework, such as steelwork connections and temporary supports — and even strategically placed operator men.

Integration between the PDS model, the Intelligent P&ID package and — for the first time — the pipe stress analysis software further contributes to the project. The technology enables more time for designers to design and engineers to engineer, with significantly more 'right first-time engineering'.

With the above-ground layout for all disciplines produced from the model, deliverables 'looked' different. The client, main contractor and sub-contractor collaborated in accepting that new methods of working would also change the type of deliverable produced.

Driven by construction

Construction requirements — including fabrication and construction locations spread across the north of England — drove much of the engineering effort. PDS's file-based set-up particularly suits a modularised project. Each pre-assembled unit/rack and dressed vessel has a separate equipment, steelwork, piping, electrical, and instrument modelbase. Hook-up piping is also in a separate file. Although requiring additional modelbase files, this method improves material management and weight control. Module-by-module drawing extraction matches construction planning requirements.

Animated sequences in DesignReview simulate lifts with models of the rigging, heavy lift crane and transporters. This helps identify obstructions or 'ship loose' items before the final lifts, reducing the risk of extended crane rental. The DesignReview set-up replicates the finished plant with realistic colouring and indicates design features such as safety zones. DesignReview facilities will be installed in the module construction yard and transferred to the site before construction. The final model will help Conoco with plant training, safety, and planning future upgrades.

Model-driven tracking

During the proposal stage, Parsons decided to use PDS with Parsons' 3D-progress measurement system. The system feeds information directly into the master level 3 schedule, based on model progress, and helps track model status against key project payment milestones.

A simple yet scientific spreadsheet tool, the system measures the progress of the 3D model — not the deliverables. Parsons recognised that most man-hours are spent modelling, and old methods of tracking progress by document type do not apply meaningfully to 3D working methods.

Parsons also recognised that the model's completeness relies on the supporting information. Thus the system builds in a weighting factor for the status of vendor data and process P&IDs. For example, to measure equipment model progress, the system multiplies the completeness of the equipment model against a weighting factor for each item's vendor status.

All data is fed into a single spreadsheet that reports the status overall and by discipline and plots the progress graphically, correctly sequencing events in the model.All in all, the approach is leading to time and cost savings during design and construction and will prevent downstream surprises —essential for an LSTK project.

Martin Brooks is chief engineer for plant layout and piping at Parsons Energy and Chemical London.