Inventor Tube and Pipe Design: Routing Piping Systems in Assemblies

Industrial machinery and process equipment rarely consist of mechanical components alone. Hydraulic circuits, pneumatic lines, coolant circuits, compressed air distribution, and process pipework are integral parts of almost every significant mechanical assembly. Designing these systems within a 3D CAD environment — rather than leaving them as an afterthought on a 2D schematic — catches interference issues before fabrication, produces accurate pipe lengths for procurement, and creates documentation that maintenance teams can actually use. Inventor’s Tube and Pipe module provides exactly this capability, enabling engineers to route rigid and flexible connections through assemblies with full parametric control.

This guide covers the complete Tube and Pipe workflow: setting up pipe runs, placing components from the fitting library, routing rigid pipe and flexible tubing, managing spec-driven design, and extracting the bill of materials and isometric drawings that fabricators and installers need.

Autodesk Inventor Professional is available at GetRenewedTech for £39.99, with the Tube and Pipe environment included as part of the Professional toolset.

Understanding the Tube and Pipe Environment

Inventor’s Tube and Pipe tools exist within a dedicated environment accessed through the Environments tab on the ribbon. Before you can route pipes, you need to be within an assembly file (IAM) — pipe routing does not happen at the part level. The module operates on the concept of pipe runs, which are collections of segments, fittings, and connection points that define a single continuous path from a source to a destination.

A pipe run consists of:

• Straight pipe segments: Lengths of rigid pipe or tube between fittings
• Fittings: Elbows, tees, reducers, unions, valves, and other components placed along the route
• Route: The 3D path that defines where the pipe travels through the assembly
• Spec: The pipe specification that governs which fittings and pipe sizes are available for the run

Setting Up Pipe Specifications

Pipe specifications (specs) are one of the most important concepts in Tube and Pipe. A spec defines which pipe sizes, wall thicknesses, materials, pressure ratings, and fitting types are permissible within a particular run. This is directly analogous to the piping specifications used in process engineering — a spec ensures that an engineer cannot accidentally specify a carbon steel elbow on a stainless steel pharmaceutical line, or an ANSI 150# valve on a 300# pressure line.

Inventor ships with a range of pre-defined specs covering common pipe standards:

• ANSI/ASME B16.5 (American flanged and fittings)
• ISO 1127 (stainless steel tube)
• BS 1600 / BS EN 10255 (UK carbon steel pipe)
• DIN 2458 (European steel pipe)

For most UK industrial projects, you will either use an existing ISO or BS spec or create a custom spec tailored to your organisation’s standard materials and pressure classes. Custom specs are created using the Tube and Pipe Authoring tool, where you define pipe size ranges, wall schedules, end types, and the fitting components associated with each size.

Creating a Custom Pipe Spec

To create a custom spec, navigate to Manage > Tube and Pipe Styles and create a new style. Within the style definition, you specify:

• Nominal pipe sizes: DN15, DN20, DN25, DN40, DN50, DN80, DN100, etc.
• Wall thickness schedule: Schedule 40, Schedule 80, or specific wall thicknesses per size
• Material: Carbon steel, stainless steel 316L, CPVC, etc.
• End connection type: Butt weld, socket weld, threaded, flanged
• Fitting library path: Where Inventor looks for fitting components for this spec

Once defined, the spec is selectable when creating new pipe runs, and Inventor enforces spec compliance throughout the routing process — it will only offer fittings from the correct family and only in the sizes the spec allows.

Creating Pipe Runs

To start a new pipe run, enter the Tube and Pipe environment and select New Run. The Create Pipe Run dialogue asks you to:

1. Name the run (e.g., “Coolant Supply – Primary Circuit”)
2. Select the pipe spec to apply
3. Choose the nominal size (e.g., DN25)
4. Select whether the run is rigid pipe, flexible hose, or electrical conduit

Multiple runs can exist within a single assembly. A typical hydraulic power unit assembly might have separate runs for high-pressure supply, low-pressure return, case drain, and pilot pressure — each with its own spec and size, but all visible within the same assembly context.

Routing Rigid Pipe

Routing rigid pipe in Inventor uses a 3D sketch-based approach. Once you’ve created a pipe run, the Route tool opens a 3D sketch environment where you define the pipe’s path by placing points and segments.

Routing Methods

Inventor offers several routing methods for rigid pipe:

• Automatic Route: Inventor attempts to route the pipe automatically between two connection points, avoiding geometry and following orthogonal paths. This works well for straightforward runs but often needs manual adjustment for complex assemblies.
• Custom Route: You manually define the 3D path by clicking points in space, typically snapping to component connection points, work planes, or edges of existing geometry. This gives full control over the pipe path.
• Route from P&ID: If you have a Piping and Instrumentation Diagram created in AutoCAD Plant 3D or similar, you can import the logical pipe run data and use it to drive the 3D routing — ensuring that the 3D model stays consistent with the process design.

Adding Fittings

As you route pipe, Inventor automatically places elbows wherever the pipe changes direction, selecting the appropriate elbow radius from your pipe spec. You can insert additional fittings — tees, flanges, valves, unions — by selecting the point in the route where the fitting should go and choosing from the spec-filtered fitting library.

Valves and instruments placed as fittings maintain their connection points, so if you move the pipe route, the valve moves with it and the connecting pipe segments update automatically. This parametric behaviour is what makes Tube and Pipe genuinely useful for design iteration: if the pump moves by 150mm, the connecting pipework updates rather than breaking.

Routing Flexible Hose and Tubing

Not all connections in an assembly are rigid. Hydraulic cylinders need flexible hoses that allow for movement; pneumatic actuators connect via push-fit tubing; instrumentation uses small-bore flexible lines. Inventor handles these through the flexible routing option within a pipe run.

For flexible hose, you define the minimum bend radius (from the hose specification) and Inventor generates a smooth curve between the two connection points that respects that minimum radius. The 3D path can be dragged and adjusted to achieve a realistic hose routing that avoids interference with surrounding components.

Flexible tube routes automatically update when connected components move, making it straightforward to check that a hydraulic cylinder’s hose connection can reach through the full extent of the cylinder’s stroke without the hose being overstretched or kinked at the minimum bend radius.

Interference Checking for Pipe Routes

One of the principal benefits of 3D pipe routing within an assembly is the ability to run interference detection. Navigate to Inspect > Interference Detection and select the pipe run components as one set and the surrounding mechanical components as the other. Inventor identifies any locations where pipe, tubing, or fittings physically overlap with structure, brackets, moving parts, or other pipes.

On complex machinery with multiple pipe runs, interference checking before fabrication can prevent costly rework. A pipe that clashes with a maintenance access panel, for example, would be a significant problem once the machine is built — catching it at the CAD stage takes minutes to resolve.

Extracting the Bill of Materials and Fabrication Data

Once your pipe runs are complete, Inventor can extract detailed fabrication information:

Pipe Bill of Materials

The BOM lists all pipe segments and fittings with quantities, sizes, specs, and materials. Pipe segments are listed with their cut lengths, which feeds directly into procurement and cutting schedules. The BOM can be exported to CSV or placed as a table on a drawing sheet.

Isometric Drawings

Inventor can generate pipe isometric drawings — the standard format used by fabricators and installers to understand how a pipe run goes together. An isometric drawing shows the pipe path in a 3D-like representation with all dimensions, fitting sizes, materials, and weld positions annotated. These are produced using the Tube and Pipe Isometric Drawing tool and can be customised to follow your organisation’s drawing standards.

Spool Drawings

For larger installations, it may be practical to break the pipework into spools — pre-fabricated sub-assemblies that are welded or assembled in the workshop and then connected on site. Inventor supports spool definitions within the pipe run structure, and each spool can be extracted as its own isometric drawing with its own BOM.

Integrating Tube and Pipe with the Wider Assembly

Tube and Pipe runs exist within the Inventor assembly environment, which means they participate in all the standard assembly functions: mass properties, centre of gravity calculations, and drawing views. When you create a general arrangement drawing of the complete assembly, pipe runs appear correctly in all views — orthographic, section, and detail. Pipe run components appear in the assembly BOM alongside mechanical components, giving a single integrated parts list for the entire machine.

For organisations using Autodesk Vault for data management, pipe run files are stored and managed alongside all other assembly components, with full revision history and access control. This is particularly important on projects where the pipework evolves through multiple design revisions as process requirements are refined.

Practical Workflow Tips

• Route mainlines first: Start with the largest-diameter, highest-priority pipe runs and route the smaller ancillary lines around them. This prevents the common problem of routing small instrument lines through the most convenient path and then finding the main process line has nowhere to go.
• Use work planes as routing constraints: Define vertical and horizontal work planes at key elevations (e.g., pipe rack centreline elevation, floor level plus maintenance clearance) and snap route points to them. This produces neat, organised pipe routes rather than arbitrary 3D paths.
• Check minimum bend radii early: Particularly for flexible hoses, check that the specified hose can actually follow the intended path. If the connection points are close together and require a tight bend, you may need a longer hose or a different routing path.
• Name pipe runs descriptively: “Run1”, “Run2” is not helpful when you’re navigating a complex assembly. Use names that reflect the fluid service and direction: “HYD-HP-Supply-Pump-to-Manifold”.

Who Uses Inventor Tube and Pipe?

The Tube and Pipe module is used across a wide range of industries:

• Hydraulics manufacturers: Routing HPU pipework, cylinder connections, and valve manifold plumbing
• Food and beverage equipment: CIP (clean-in-place) systems, product transfer lines, steam and condensate circuits
• Oil and gas: Skid-mounted processing equipment with pressure piping in multiple services
• HVAC and refrigeration: Refrigerant lines, chilled water circuits, condenser water systems
• Chemical processing: Reactor feed and discharge lines, utilities circuits, waste streams

In each case, the ability to route pipework within the 3D assembly and detect interferences before fabrication represents a significant reduction in design risk and rework cost.

Getting Started

If you’re working with Inventor and piping systems are part of your design scope, the Tube and Pipe environment repays the time invested in learning it many times over. Autodesk Inventor Professional at £39.99 from GetRenewedTech includes the full Tube and Pipe module. For teams that also need process simulation or wider plant design tools, the Autodesk PDMC Collection at £149.99 provides an integrated suite that spans concept through to detailed design and manufacturing documentation.

Summary

Inventor’s Tube and Pipe module transforms how engineers design and document piping systems in mechanical assemblies. By routing pipe and hose within the 3D model context, it enables real interference detection, produces accurate cut lists and BOMs, and generates the isometric drawings that fabricators rely on. Spec-driven design ensures consistency and code compliance throughout, while the parametric nature of the routing means design changes propagate correctly rather than requiring manual reconstruction.