PIAS Manual  2021
Program for the Integral Approach of Shipdesign
Pipe lines and piping systems

Although Layout was initially designed for defining and visualizing the geometry of internal spaces, it was expanded around the 2020s to include pipeline modelling functions. This created a system that is intended and suitable for:

  • Integrated bulkhead/deck & compartment & pipe modelling and visualization.
  • Including the effects of pipes on damage stability, and deriving intermediate stages of flooding on basis of the connections between compartments.
  • Time-domain damage stability analysis, including the effects of fluid velocity and resistance in the piping networks.
  • The exchange of PIAS' piping data with engineering software is still on the wish list. However, due to the lack of a common interface format for this kind of data, this is not expected to become universal.

For the sake of clarity, the piping-related manual has been split into two parts; the part concerning geometry and compartment connections fits here, in Layout, while the more fluid-flow related part better fits in the chapter on internal flooding in case of damage, see Internal flooding in case of damage, through pipe lines and compartment connections.

The data structure and naming conventions of PIAS' piping is inspired on the ISO-15926 standard, which has an origing in the process industry. The primary elements are:

  • Equipment, which is a thing, not being a compartment, connected to a pipe line but not part of it. Such as an engine or a chiller. In the end, PIAS performs no actions with equipment, it is just defined in PIAS for the completeness of definition and drawings.
  • A piping system, which is an administrative collection of pipes of the same type, for example “ballast” or “HFO”. Such a system can optionally belong to a weight group — as also applied for compartments and weight items in PIAS, and as discussed in Define weight groups. A piping system can also be assigned a color, e.g. according the ISO 14726 standard.
  • A piping network, which is one closed system of connected pipes, which belongs to a piping system. A network is the core of the piping dada structure.
  • A piping segment, which is one branch of a piping network, and extends between two points without sub-branching inbetween.
  • A piping connection, which is a part located at the extremities of a piping segment. Such a connection comes in five types:
    • Branch, where multiple piping segments meet.
    • Opening, external (so, to the outside). A nice feature of this type is that such an opening will also be included in the list of openings per compartment (see Special points / openings), as wel as the overview menu of openings, List of openings and other special points. In both lists you will be able to change the location of the openings, but for obvious reasons are not allowed to modify other properties or remove the opening.
    • Terminator, which closes a dead-end segment.
    • Compartment, or, more precisely, a connection to a compartment at a certain location. So, a compartment may have multiple connections.
    • Equipment, or, more precisely, a connection to a piece of equipment at a certain location.
    For each connection also its position can be given, as well as the resistance coefficient, optionally including or excluding the resistance due to the energy loss at the outlet of a pipe (see Fluid outlet energy loss}.
  • A piping component, which is a part located in a piping segment. These come in two types:
    • Point components, located in a (virtual) point (from which als the coordinates can be given):
      • Waypoint, which is a geometrical point without further properties. Can be applied to define the pipe geometry.
      • Elbow.
      • Valve, including open/closed indication.
      • Pressure relief valve, including the opening pressure. An important reason to include this type is for the modeling of fire control bulkheads, which are considered to be watertight until a certain water level (=pressure), and collapse at higher levels.
      • Reducer, including the regular flow direction (from high to low pressure), as well as the regulared pressure at the exit. Its way of operation depends on the flow direction:
        • If the flow is in regular direction, then for the hydraulic calculations the set pressure at the exit is applied.
        • If the flow is in the opposite direction, the reducer is assumed to be closed if the pressure at the regulated side (=the original exit) is higher then the set pressure. Otherwise it is open, where the hydraulics arte being computed with calcuthe standard resistance coefficient.
      • Check valve, including the free flow direction.
      • Vent check valve, including the free flow direction.
    • Pipe components, which exist between two point components. This type has just a single member:
      • A pipe section, which is simply a straight pipe between two point components.
    Furthermore, for components also their resistance coeffcient can be given as well as their dimensions.

With this structure, complex pipelines can be modelled and connected with openings and compartments. To increase the ease of use, PIAS' pipeline system contains a number of auxiliary functions and concepts that are not essential, but can be useful, such as:

  • A complete pipeline definition contains the coordinates of all its parts. Sometimes, however, it will be sufficient to define only the connections, without coordinates. In such cases networks or components can be specified to be without geometry. This can be used, for example, when specifying a standard standard vent right above a tank, in which case the exact location of the connection of the vent pipe to the tank is not important (at least, if one is satisfied that the geometry of the pipeline network is not involved in the damage stability computation).
  • A ship model defined without these pipelines will still contain openings and sounding pipes. In the essence, these obviously maintain a relationship with pipelines. To facilitate the upgrading of such a model, there are auxiliary functions to convert these entities to pipelines, see the [Generate] functions in Piping systems.
  • For complete flow calculations, the shape, size and resistance coefficient of all pipes and components must be provided. Since in reality there can be considerable uniformity in this respect, these data can also be provided at a higher level, e.g. for an entire pipe system, in order to save typing. This is further explained in Layered definition of flow-related parameters.

The piping's initial menu contains the following options:

Incidentally, there is another place where the pipe lines can be made visible, and that is in the three-dimensional presentation — as discussed in Threedimensional presentation — from which an example is included below.

layout_3Dpiping.png
Piping included in the rendered view.

Piping systems

This menu lets you specify a number of properties of pipeline systems. As indicated in the introduction, a system is a collective name for pipelines of the same type, for example “bilge/ballast”. Properties in this menu that need explanation are:

  • Presentation, which can be used to specify whether and how the system will be included in the 3D presentation and subdivision plan.
  • Selected, which indicates whether this system will be included at damage stability calculations.
  • Sounding, which indicates whether pipes of this system are considered to be sounding pipes of compartments. If that is the case then those pipes are automatically added to the sounding pipes of the compartment they are connected to. This is convenient because then those pipes only need to be specified once. In the sounding pipe definition menu of that compartment those pipes will also be visible, but they cannot be changed there.
  • For the cross sectional properties, reference is made to Frictional resistance from pipes lines.

In addition, this menu has three more functions, the first two of which are primarily intended for conversion of older projects (although their use is not necessarily limited to that):

  • [Generate / Openings], which, starting from already defined (de-airation) openings of compartments, generates pipelines that contain these openings. This function is clearly intended for the upgrading of elder ship files (with only single locations of openings defined) to a more complete definition which also includes the pipe between compartment and opening. Of course, the generated pipeline shape may need further detailing with elbows or other geometry (because that information was not available initially).
  • [Generate / Sounding pipes] is analogous, it converts the existing (loose) sounding pipes of the compartments into pipelines that fit into the integral pipeline system as discussed here. However, this option has not yet been implemented.
  • <Enter>, which, if the text cursor is on a particular network, takes you one level deeper, to the details of that thereof. Into the piping network menu which is discussed below.

Piping networks

layout_pipingGUI.png
Piping network GUI.

Equipment

Check the input

General piping settings

Here, parameters are defined that are generally used for the pipelines, or for the damage stability calculations that are carried out with them lateron. These are:

  • The method of calculating pipe outlet energy losses. There are two conventions for this, i.e. IMO res. A266 & MSC. 362(92) on the one hand, and MSC. 245(83) on the other. A further explanation of this issue can be found in Fluid outlet energy loss. These energy losses have an effect on the time-domain calculation at damage, and one may wonder why this parameter is not located at the damage stability settings. The reason is that this choice determines whether or not explicitly resistance coefficients should be specified for pipe outlets, and this is done here, in Layout. This is why it makes sense to include this general setting in Layout as well.
  • Default characterization of the cross-sectional size with respect to cross flooding, a parameter explained in Damage stability criteria to be applied.
  • Default resistance coefficients of components & connections, and of pipes.

The latter two parameters are components in a chain of flow parameters, as discussed in Layered definition of flow-related parameters.

Output of geometry and connectivity of piping

This option prints all networks (regardless whether selected) on paper (or what the user has set instead).

layout_pipingoutput1024.png
Example of the output of a network.