C3d Pipe Networks

Civil 3D Pipe Networks

Use this skill when working with gravity or pressure pipe networks - creating networks, pipes, structures, labels, styles, or interference checks.

Accessing Pipe Networks

CivilDocument doc = CivilApplication.ActiveDocument;

// Gravity networks
ObjectIdCollection networkIds = doc.GetPipeNetworkIds();
foreach (ObjectId netId in networkIds)
{
    Network network = ts.GetObject(netId, OpenMode.ForRead) as Network;
    ed.WriteMessage("Network: {0}\n", network.Name);
}

// Pressure networks — separate method, separate type
ObjectIdCollection pressureNetworkIds = doc.GetPressurePipeNetworkIds();
foreach (ObjectId netId in pressureNetworkIds)
{
    PressurePipeNetwork pressNet = ts.GetObject(netId, OpenMode.ForRead) as PressurePipeNetwork;
    ObjectIdCollection pipeIds   = pressNet.GetPipeIds();
    ObjectIdCollection fittingIds = pressNet.GetFittingIds();
    ObjectIdCollection appurtIds  = pressNet.GetAppurtenanceIds();
}

Pipe-Specific Ambient Settings

SettingsPipeNetwork oSettings =
    doc.Settings.GetSettings<SettingsPipeNetwork>() as SettingsPipeNetwork;

// Get pipe rules
ed.WriteMessage("Pipe rules: {0}\n", oSettings.Rules.Pipe.Value);

// Set default units
oSettings.Angle.Unit.Value = Autodesk.Civil.AngleUnitType.Radian;
oSettings.Coordinate.Unit.Value = Autodesk.Civil.LinearUnitType.Foot;
oSettings.Distance.Unit.Value = Autodesk.Civil.LinearUnitType.Foot;

Settings classes: SettingsPipe, SettingsPipeNetwork, SettingsStructure (all inherit from SettingsAmbient).

Parts Lists

Parts lists contain families of pipe and structure types:

PartsListCollection partsListCol = doc.Styles.PartsListSet;

foreach (ObjectId plId in partsListCol)
{
    PartsList partsList = ts.GetObject(plId, OpenMode.ForWrite) as PartsList;
    ed.WriteMessage("Parts List: {0}\n", partsList.Name);

    // Get pipe families
    ObjectIdCollection pipeFamilies =
        partsList.GetPartFamilyIdsByDomain(DomainType.Pipe);

    foreach (ObjectId pfId in pipeFamilies)
    {
        PartFamily family = ts.GetObject(pfId, OpenMode.ForWrite) as PartFamily;
        ed.WriteMessage("  Family: {0}\n", family.Name);

        // Access size filters and data fields
        SizeFilterRecord sizeFilter = family.PartSizeFilter;
        SizeFilterField material = sizeFilter.GetParamByContextAndIndex(
            PartContextType.Material, 0);
    }
}

Creating a Pipe Network

string networkName = "My Network";
ObjectId networkId = Network.Create(doc, ref networkName);
Network network = ts.GetObject(networkId, OpenMode.ForWrite) as Network;

// Set reference surface (for pipe rules like rim elevation)
network.ReferenceSurfaceId = surfaceId;

// Get parts list
ObjectId partsListId = doc.Styles.PartsListSet["Standard"];
PartsList partsList = ts.GetObject(partsListId, OpenMode.ForWrite) as PartsList;

// Get pipe family and size
ObjectId pipeFamilyId = partsList["Concrete Pipe"];
PartFamily pipeFamily = ts.GetObject(pipeFamilyId, OpenMode.ForWrite) as PartFamily;
ObjectId pipeSize = pipeFamily[0]; // First size

// Get structure family and size
ObjectId structFamilyId = partsList["Rectangular EndSection"];
PartFamily structFamily = ts.GetObject(structFamilyId, OpenMode.ForWrite) as PartFamily;
ObjectId structSize = structFamily[0];

Creating Pipes

// Straight pipe
LineSegment3d line = new LineSegment3d(
    new Point3d(30, 9, 0), new Point3d(33, 7, 0));
ObjectId newPipeId = ObjectId.Null;
network.AddLinePipe(pipeFamilyId, pipeSize, line, ref newPipeId, false);

// Curved pipe (Civil 3D 2023+)
PipeCurveGeometry curveGeom = new PipeCurveGeometry(...);
ObjectId curvedPipeId = network.AddCurvePipe(pipeFamilyId, pipeSize, curveGeom, false);

Breaking and Moving Pipes

// Break a pipe at a point, inserting a structure at the break
ObjectId newPipeId = ObjectId.Null;
network.BreakPipe(pipeIdToBreak, breakPoint, existingStructureId, ref newPipeId);

// Move parts between networks
ObjectIdCollection partIds = new ObjectIdCollection();
partIds.Add(pipeId);
network.MoveParts(partIds, destinationNetworkId);

// Find shortest path between two parts
double minLength = 0;
ObjectIdCollection pathIds = Network.FindShortestNetworkPath(
    startPartId, endPartId, ref minLength);

Creating Structures

Point3d location = new Point3d(30, 9, 0);
ObjectId newStructId = ObjectId.Null;
network.AddStructure(structFamilyId, structSize, location,
    0 /* rotation */, ref newStructId, true);

Connecting Pipes and Structures

// Connect pipe to structure at start or end
pipe.ConnectToStructure(ConnectorPositionType.Start, structureId, false);
pipe.ConnectToStructure(ConnectorPositionType.End, structureId, false);

// Connect structure to pipe
structure.ConnectToPipe(pipeId, ConnectorPositionType.Start);

// Connect pipe to pipe (creates a new junction structure automatically)
ObjectId newJunctionId = ObjectId.Null;
pipe1.ConnectToPipe(ConnectorPositionType.End, pipe2Id,
    ConnectorPositionType.Start, structFamilyId, structSizeId,
    ref newJunctionId, true /* applyRules */, false /* force */);

// Disconnect pipe at an endpoint
pipe.Disconnect(ConnectorPositionType.Start);
// Disconnect structure from a specific pipe
structure.Disconnect(pipeId);

// Pipe endpoints
ObjectId startStruct = pipe.StartStructureId;
ObjectId endStruct = pipe.EndStructureId;

// Structure connections
int count = structure.ConnectedPipesCount;
string[] pipeNames = structure.GetConnectedPipeNames();
bool flowsIn = structure.IsConnectedPipeFlowingIn(0);
bool flowsOut = structure.IsConnectedPipeFlowingOut(0);

Note: Connecting pipes directly creates a virtual Structure as the joint. Disconnect a pipe before connecting to a different structure.

Dynamic Part Properties

Pipe oPipe = ts.GetObject(pipeId, OpenMode.ForRead) as Pipe;
PartDataField[] dataFields = oPipe.PartData.GetAllDataFields();

foreach (PartDataField field in dataFields)
{
    ed.WriteMessage("Name: {0}, Desc: {1}, Type: {2}, Value: {3}\n",
        field.Name, field.Description, field.DataType, field.Value);
}

Pipe Styles

ObjectId pipeStyleId = doc.Styles.PipeStyles.Add("My Pipe Style");
PipeStyle style = ts.GetObject(pipeStyleId, OpenMode.ForWrite) as PipeStyle;

// Plan view sizing
style.PlanOption.WallSizeType = PipeWallSizeType.UserDefinedWallSize;
style.PlanOption.WallSizeOptions = PipeUserDefinedType.UseDrawingScale;
style.PlanOption.InnerDiameter = 0.0021;
style.PlanOption.OuterDiameter = 0.0024;
style.PlanOption.EndSizeType = PipeEndSizeType.UserDefinedEndSize;

// Colors
style.GetDisplayStylePlan(PipeDisplayStylePlanType.OutsideWalls).Color =
    Color.FromRgb(255, 191, 0); // orange
style.GetDisplayStylePlan(PipeDisplayStylePlanType.InsideWalls).Color =
    Color.FromRgb(191, 0, 255); // violet

// Hatching
style.GetHatchStylePlan().Pattern = "DOTS";
style.GetHatchStylePlan().HatchType = HatchType.PreDefined;
style.PlanOption.HatchOptions = PipeHatchType.HatchToInnerWalls;

// Assign to pipe
pipe.StyleId = pipeStyleId;

Structure Styles

ObjectId structStyleId = doc.Styles.StructureStyles.Add("My Struct Style");
StructureStyle style = ts.GetObject(structStyleId, OpenMode.ForWrite) as StructureStyle;

style.GetDisplayStylePlan(StructureDisplayStylePlanType.Structure).Color =
    Color.FromRgb(255, 191, 0);
style.PlanOption.SizeType = StructureSizeOptionsType.UseDrawingScale;
style.PlanOption.Size = 0.0035;

// Assign via property
structure.StyleId = structStyleId;
// or: structure.StyleName = "My Struct Style";

Pipe and Structure Label Styles

// Pipe label styles
var pipeLabelStyles = doc.Styles.LabelStyles.PipeLabelStyles;
// Contains: cross section, plan/profile view, default styles

// Structure label styles
var structLabelStyles = doc.Styles.LabelStyles.StructureLabelStyles;

Creating Labels with Specific Styles

Individual pipe and structure labels can be created with a specific label style, or the style can be changed after creation via Label.StyleId.

// Plan pipe label with specific style
ObjectId labelId = PipeLabel.Create(pipeId, 0.5 /* ratio */, labelStyleId);

// Plan structure label with specific style and location
ObjectId sLabelId = StructureLabel.Create(structureId, labelStyleId, labelLocation);

// Profile pipe label with specific style
ObjectId ppLabelId = PipeProfileLabel.Create(
    profileViewPartId, profileViewId, 0.5 /* ratio */, labelStyleId);

// Profile structure label with specific style
ObjectId spLabelId = StructureProfileLabel.Create(
    profileViewId, profileViewPartId, labelStyleId);

// Section pipe label with specific style
ObjectId secPLabelId = PipeSectionLabel.Create(
    sectionViewId, pipeId, sectionPipeNetworkId, partIndex, labelStyleId);

// Section structure label with specific style
ObjectId secSLabelId = StructureSectionLabel.Create(
    sectionViewId, structureId, sectionPipeNetworkId, partIndex, labelStyleId);

// Change an existing label's style
Label label = ts.GetObject(labelId, OpenMode.ForWrite) as Label;
label.StyleId = newLabelStyleId;

// Get existing labels on a pipe or structure
ObjectIdCollection pipeLabels = pipe.GetPipeLabelIds();
ObjectIdCollection structLabels = structure.GetAvailableStructureLabelIds();

Pressure Network Labels

Pressure label classes have different signatures from gravity labels. Note argument order differences:

// ── Plan/profile labels ────────────────────────────────────────────────────
// Pipe: ratio before styleId
ObjectId pipeLabelId = PressurePipeLabel.Create(pipeId, 0.5 /* ratio */, pipeStyleId);

// Fitting and appurtenance: styleId first, then ratio + direction vector
ObjectId fittingLabelId = PressureFittingLabel.Create(
    fittingId, fittingStyleId, 0.5 /* ratio */, new Vector3d(1, 0, 0));

ObjectId appurtLabelId = PressureAppurtenanceLabel.Create(
    appurtId, appurtStyleId, 0.5 /* ratio */, new Vector3d(1, 0, 0));

// ── Section labels ─────────────────────────────────────────────────────────
ObjectId pipeSectLabelId = PressurePipeSectionLabel.Create(
    sectionViewId, pipeId, sectionNetworkId,
    0 /* partIndex */, 0.5, new Vector3d(1, 0, 0),
    labelStyleId, (DimensionAnchorOptionType)0, 0.0);

ObjectId fittingSectLabelId = PressureFittingSectionLabel.Create(
    sectionViewId, fittingId, sectionNetworkId,
    0, 0.5, new Vector3d(1, 0, 0),
    labelStyleId, (DimensionAnchorOptionType)0, 0.0);

ObjectId appurtSectLabelId = PressureAppurtenanceSectionLabel.Create(
    sectionViewId, appurtId, sectionNetworkId,
    0, 0.5, new Vector3d(1, 0, 0),
    labelStyleId, (DimensionAnchorOptionType)0, 0.0);

Detecting Existing Pressure Labels

// Plan/profile label detection — takes the part id only
ObjectIdCollection existingPipe  = PressurePipeLabel.GetAvailableLabelIds(pipeId);
ObjectIdCollection existingFit   = PressureFittingLabel.GetAvailableLabelIds(fittingId);
ObjectIdCollection existingApp   = PressureAppurtenanceLabel.GetAvailableLabelIds(appurtId);

// Section label detection — takes sectionViewId + partId + sectionNetworkId
ObjectIdCollection existingPipeSect = PressurePipeSectionLabel.GetAvailableLabelIds(
    sectionViewId, pipeId, sectionNetworkId);
ObjectIdCollection existingFitSect  = PressureFittingSectionLabel.GetAvailableLabelIds(
    sectionViewId, fittingId, sectionNetworkId);
ObjectIdCollection existingAppSect  = PressureAppurtenanceSectionLabel.GetAvailableLabelIds(
    sectionViewId, appurtId, sectionNetworkId);
// If the part is not in the section, GetAvailableLabelIds throws — wrap in try/catch

Profile View Part Discovery

Gravity and pressure networks use different APIs to discover which parts are drawn in a profile view:

Gravity (reflection fallback required)

// Primary: typed override collections (version-dependent property names)
PipeOverrideCollection pipeOverrides = profileView.PipeOverrides;
foreach (PipeOverride o in pipeOverrides)
{
    ObjectId pipeId = o.PipeId; // direct property on PipeOverride
    Pipe pipe = tr.GetObject(pipeId, OpenMode.ForRead) as Pipe;
    networkIds.Add(pipe.NetworkId);
}

StructureOverrideCollection structOverrides = profileView.StructureOverrides;
foreach (StructureOverride o in structOverrides)
{
    // Property name varies by C3D version — use reflection with fallback names
    ObjectId structId = GetObjectIdProperty(o, "StructId", "StructureId", "PartId", "FeatureId", "SourceId");
}

// Fallback: GraphOverrides (untyped) — also needs reflection
System.Collections.IEnumerable graphOverrides = profileView.GraphOverrides;
foreach (object o in graphOverrides)
{
    ObjectId partId = GetObjectIdProperty(o, "PipeId", "StructId", "StructureId", "PartId", "FeatureId", "SourceId");
}

// Reflection helper
ObjectId GetObjectIdProperty(object source, params string[] names)
{
    var type = source.GetType();
    foreach (var name in names)
    {
        var prop = type.GetProperty(name);
        if (prop?.PropertyType == typeof(ObjectId))
            return (ObjectId)prop.GetValue(source, null);
    }
    return ObjectId.Null;
}

Pressure (clean API, no reflection needed)

// GetPressureNetworkPartsInGraph returns ObjectIds of ProfileViewPressurePart wrappers
ObjectIdCollection partsInGraph = profileView.GetPressureNetworkPartsInGraph();

foreach (ObjectId profilePartId in partsInGraph)
{
    ProfileViewPressurePart profilePart =
        tr.GetObject(profilePartId, OpenMode.ForRead, false, true) as ProfileViewPressurePart;
    if (profilePart == null) continue;

    // .ModelPartId links back to the actual PressurePipe/Fitting/Appurtenance
    Entity modelPart = tr.GetObject(profilePart.ModelPartId, OpenMode.ForRead) as Entity;

    if (modelPart is PressurePipe pp)
        networkIds.Add(pp.NetworkId);
    else if (modelPart is PressureFitting pf)
        networkIds.Add(pf.NetworkId);
    else if (modelPart is PressureAppurtenance pa)
        networkIds.Add(pa.NetworkId);
}

Interference Checks

Interference check styles control the display of intersections:

ObjectId intStyleId = doc.Styles.InterferenceStyles.Add("My Interference Style");
InterferenceStyle intStyle = ts.GetObject(intStyleId, OpenMode.ForWrite)
    as InterferenceStyle;

// Symbol display
intStyle.GetDisplayStylePlan(InterferenceDisplayStyleType.Symbol).Visible = true;

// Marker style
ObjectId markerStyleId = intStyle.MarkerStyle;
MarkerStyle marker = ts.GetObject(markerStyleId, OpenMode.ForWrite) as MarkerStyle;
marker.MarkerType = MarkerDisplayType.UseCustomMarker;
marker.CustomMarkerStyle = CustomMarkerType.CustomMarkerX;
marker.CustomMarkerSuperimposeStyle = CustomMarkerSuperimposeType.Circle;
marker.SizeType = MarkerSizeType.AbsoluteUnits;
marker.MarkerSize = 5.5;

// Model options
// InterferenceModelType.TrueSolid - 3D model of intersection
// InterferenceModelType.Sphere - sphere at intersection

Existing Interference objects can be read to get the two intersecting network IDs:

Interference interference = ts.GetObject(interferenceId, OpenMode.ForRead) as Interference;
ObjectId net1 = interference.Network1Id;
ObjectId net2 = interference.Network2Id;

Note: Creating/executing new interference checks programmatically is not exposed in the .NET API. Use the Civil 3D UI to run interference checks, then read the results via the Interference class.

Pressure Pipe Networks

Pressure networks use separate classes from the AeccPressurePipesMgd assembly:

// Create a pressure network
ObjectId pressNetId = PressurePipeNetwork.Create(db, "My Pressure Network");
PressurePipeNetwork pressNet = ts.GetObject(pressNetId, OpenMode.ForWrite)
    as PressurePipeNetwork;

// Set references
pressNet.ReferenceSurfaceId = surfaceId;
pressNet.ReferenceAlignmentId = alignmentId;
pressNet.PartsListId = partsListId;

// Add parts
LineSegment3d line = new LineSegment3d(startPt, endPt);
ObjectId pipeId = pressNet.AddLinePipe(line, pressurePartSize);
ObjectId fittingId = pressNet.AddFitting(location, fittingPartSize);
ObjectId appurtId = pressNet.AddAppurtenance(location, appurtPartSize);

// Get part collections
ObjectIdCollection pipeIds = pressNet.GetPipeIds();
ObjectIdCollection fittingIds = pressNet.GetFittingIds();
ObjectIdCollection appurtIds = pressNet.GetAppurtenanceIds();

// Set styles on individual parts
PressurePipe pPipe = ts.GetObject(pipeId, OpenMode.ForWrite) as PressurePipe;
pPipe.StyleId = pipeStyleId;

PressureFitting fitting = ts.GetObject(fittingId, OpenMode.ForWrite) as PressureFitting;
fitting.StyleId = fittingStyleId;

PressureAppurtenance appurt = ts.GetObject(appurtId, OpenMode.ForWrite) as PressureAppurtenance;
appurt.StyleId = appurtStyleId;

// Set default label styles at network level
pressNet.PipePlanLabelStyleId = pipeLabelStyleId;
pressNet.FittingPlanLabelStyleId = fittingLabelStyleId;
pressNet.AppurtenancePlanLabelStyleId = appurtLabelStyleId;
pressNet.PipeProfileLabelStyleId = pipeProfileLabelStyleId;
pressNet.FittingProfileLabelStyleId = fittingProfileLabelStyleId;
pressNet.AppurtenanceProfileLabelStyleId = appurtProfileLabelStyleId;

// Swap part size
PressurePartSize newSize = ...; // from parts list
pPipe.SwapPartSize(newSize);

The pressure pipe network API follows similar patterns to gravity networks but with separate style collections for pipes, fittings, and appurtenances (three separate style selections needed). Pressure parts use PressurePartSize instead of family/size ObjectId pairs.

Network Catalog Custom Properties

NetworkCatalogDef supports declaring custom part parameters:

NetworkCatalogDef.DeclareNewParameter(
    "globalContext", "displayContext", "paramName", "paramDesc",
    PartCatalogDataType.Integer, PartParamUsageType.Dynamic,
    "defaultUnits", false /* singleton */, false /* catManagedList */);

NetworkCatalogDef.DeclarePartProperty("globalContext", DomainType.Pipe, PartType.Pipe);

Gotchas

• ReferenceSurfaceId is used primarily for pipe rules (e.g., rim elevation relative to surface)
• Network.Create takes the network name as ref string - Civil 3D may modify the name to avoid duplicates
• Individual pipe/structure labels CAN be created with a specific labelStyleId and changed after creation via Label.StyleId
• Executing new interference checks is not exposed in .NET, but existing Interference objects can be read
• Parts list items are identified by GUID - PartFamily can only contain one domain (pipe OR structure)
• When creating a pipe style, add Try/Catch: Add() throws if name exists, use Item() to get existing
• Connecting pipes directly creates virtual structure joints automatically
• Pressure networks use PressurePartSize for part sizing instead of family/size ObjectId pairs
• Pipe.StyleId has only a setter override on Pipe/Structure; the getter is inherited from Entity

Label Filtering (from this codebase)

The LabelFilterHelper in SharedTypes.cs maps parts list prefixes to label style prefixes:

• Gravity: pipes + structures (two style categories)
• Pressure: pipes + fittings + appurtenances (three style categories)

Related Skills

• c3d-root-objects - Accessing networks through CivilDocument (GetPipeNetworkIds / GetPressurePipeNetworkIds)
• c3d-label-styles - Pipe/pressure label style navigation and class hierarchy table
• c3d-profiles - Profile views where pipe profile labels are placed
• c3d-sample-lines - Sample line groups and section views where pipe section labels are placed
• c3d-corridors - Corridor-pipe interactions
• c3d-pressure-networks - Dedicated pressure network skill with detailed fitting, appurtenance, and pressure parts list coverage