Workflow, Documentation, and Planning of Piping Systems in Industrial Plants: A Technical Guide for Engineers

Piping engineering is one of the pillars of industrial plant design. Far from being limited to drawing lines on layout drawings, this specialty coordinates a vast network of interdisciplinary interactions, makes key decisions at critical project stages, and represents a significant percentage of both the cost and time commitment in engineering and construction. This guide presents a comprehensive technical overview of this discipline’s workflow, associated documentation, and planning, focusing on the context of medium- and large-scale industrial projects.

To facilitate understanding of how the various documents interact and are applied in piping system design, the following section presents illustrative examples, reference percentages, and general workflows. It should be noted that procedures and data may vary considerably between organizations and individual projects.

The Relative Importance of the Piping Discipline

Piping represents approximately 15% of the total material cost of an industrial plant, surpassed only by main equipment. However, if we consider the investment in work-hours, the impact is even greater: during the detailed engineering phase, nearly 25% of hours are spent exclusively on this discipline. And during construction, that number can rise to 40%, especially in sectors such as refineries, petrochemicals, and pharmaceutical plants. This weight makes the piping engineer a central player, with a coordinating role that ranges from the development of general layout drawings to the final review of the 3D model.

Relative costs of various components of a plant

Functional Structure of the Piping Team

A piping engineering team is typically structured into four main blocks:

1. Layout Design and List of Materials: Responsible for the general layout of equipment, material selection, regulatory compliance, and coordinating space, operation, and maintenance criteria.
2. Routing Design (2D/3D): Responsible for developing the line layout and general plant arrangement, using CAD tools and three-dimensional modeling platforms.
3. Stress and Flexibility Analysis: Evaluate the structural response of systems to loading conditions such as internal pressure, deadweight, thermal expansion, wind, and so on.
4. Document Quality Control: Oversee final deliverables through sequential review processes, ensuring their compliance with project standards.

This organization can be scaled or simplified depending on the scope and complexity of the project.

Key Documentation: The Foundation of All Detailed Engineering

The development of the piping system is supported by a series of documents issued by different disciplines. The most relevant documents include:

• Design Basis: A dynamic document that defines codes, standards, design philosophy, operating conditions, and criteria by discipline. Omitting this document can compromise the entire execution of the project.
• PFD and P&ID: Process Flow Diagrams and Piping and Instrumentation Diagrams are the basis for generating the 3D model and for selecting components. Each line must be interpreted by considering slopes, elevation levels, logical flow sequence, safety requirements, and operating conditions.
• Line List: A key document for design, stress analysis, and material tracking. It includes operating parameters, layout, insulation, painting, and nozzles.
• Equipment List and Data Sheets: Created in the early stages of the project, these documents contain the technical information necessary to design mechanical connections and define physical interfaces.
• Mechanical, Structural, and Civil Drawings: These drawings allow for the development of foundations, pipe racks, support structures, and assembly details. For example, the definition of operating and design loads is directly coordinated between piping, civil, and mechanical engineering departments.
• Area Classification Drawings: Essential for installations in hazardous (explosive) areas. They directly affect the location of electrical components and instrumentation.

Typical Workflow for the Piping Discipline

The figure below accurately describes the piping workflow in a typical chemical plant project.

Typical Piping Workflow in an Industrial Project

The most important stages are highlighted below:

1. Document Reception and Review: Design bases, line lists, environmental conditions, and site studies are analyzed. P&ID review begins, and technical observations are issued.
2. Implementation and Preliminary Structures: Locations are defined, equipment and piping loads are calculated, and the development of the preliminary 3D model begins. Pipe racks, utility crossings, and crane movements are coordinated.
3. Initial Design and Stress Analysis: Initial routings and flexibility analyses are performed, and minimum heights between floors are established. At 30% completion, the interdisciplinary review (MR30%) is performed.
4. Interdisciplinary Coordination: The piping group coordinates with civil, electrical, instrumentation, and processes groups. Hook-ups, interferences (clashes), and construction details are defined. MR60% and MR90% models are reviewed.
5. Issuance of final documentation: Isometric drawings, MTOs, construction documentation, and the final 3D model for assembly are delivered. In some cases, the final review is omitted, and action items continue after MR90%.

3D model for performing a stress and flexibility analysis

Key Interdisciplinary Interfaces

The success of piping design depends on this discipline’s ability to act as a link between other disciplines. For example:

• The Process Group coordinates P&ID marking, special parts lists, and material criteria.
• ​​The Mechanical Group defines nozzles, supports, connection loads, and anchoring details.
• The Civil Group develops drawings with general information, for foundations, and for steel structures.
• The Instrumentation and Control Group defines assembly details and cable routing, and avoids material duplication at common interfaces.
• Procurement issues specifications for piping, valves, and special parts to suppliers for consultation.

Each of these interactions require technical precision, regulatory knowledge, and strong management skills.

Technology and Tools in Piping Engineering

The use of CAD tools and 3D modeling platforms such as SmartPlant, PDMS, and E3D has radically transformed the way industrial plants are designed. These technologies allow for complete digital models to be generated, capable of identifying interferences, reviewing maintainability, and anticipating assembly problems before arriving on-site.

In addition, they allow for automatic generation of isometric drawings, bills of materials, clash reports, and access simulations. This not only reduces the risk of errors but also speeds up execution and improves overall project quality.

Conclusion

Piping engineering is not only a technical specialty but also a strategic function within an industrial project. Mastering it requires a combination of specific technical knowledge, interdisciplinary understanding, and coordination skills.

For the piping engineer, understanding the workflow, fluently handling documentation, and actively participating in interdisciplinary reviews are key to development in this field. This field is quite demanding, but also highly rewarding, especially in a context where precision and planning define the success or failure of a project.

For more information:

Plant Layout and Piping Arrangement in Industrial Plants

Introduction to Piping Engineering in Industrial Projects

Master of Piping Systems Engineering

ASME B31 | Design of Piping Systems for Industrial Plants