International Conference on Computer Applications in Shipbuilding 2017, 26-28 September 2017, Singapore

AUTOMATIC PIPING ARRANGEMENT DESIGN CONSIDERING PIPING SUPPORTS
AND CURVED SURFACES OF BUILDING BLOCKS
H Kimura, Kyushu University, JAPANSUMMARY
In this paper, a new piping path planning system is proposed in order to automate piping design corresponding to pipe
supports and curved hulls. In the proposed system, candidates for positions and directions to which pipes should be
passed are given in advance as 'candidate points' from the circumstances of pipe racks and support. Then, the systemselects the appropriate candidate points automatically to generate piping paths keeping constraint of many factors, e.g.,gravitational flow, or geometrical limitation of the pipe-bending machine, etc. Therefore, it is quite practical. The
proposed system is implemented to a computer program, and the performance of the system is demonstrated throughseveral simulations.

1.

INTRODUCTION

Pipe arrangement is considered one of the most timeconsuming works in the production of vessels, buildings
and plants. In recent years the advancement of 3D-CAD
systems has helped designers to arrange pipes. Especially,
they can grasp the pipe location visually and check theinterference between pipes and structures by using thesystem. Designers have to make right decisions in orderto generate optimum piping routes and suitable positions
for equipment during the process. However, the mostpart of the pipe routing problem, which is to design thebest routes of the pipeline, demands veteran designer’s
experiences because the problem involves many
regulations or requirements to be concerned. It has
become increasingly difficult to secure skilled designers
and problems of technology transferring to young
engineers are also occurring. Automation of piping
design is one promising method for solving these
problems.
Many previous works of automatic piping design havebeen done in many approaches. Some of these studies,such as Ito [1], Park et al.[2], Asmara et al.[3,4], Paulo etal.[5], and Lin et al.[6] applied for Cell Decomposition
approach that is composed to divide the design area into
meshes and connect them from the start point to the goal
point. There are two main advantages in applying thisapproach. The first is possible to apply maze solving
algorithms to find solutions. In the maze algorithms,
there exist methods to assure to find optimum solutions
such as the Dijkstra’s method. The second is possible toset different cost values in each cell. From this feature,
the algorithm can draw pipelines near to a ship’s hull,
while avoiding aisle spaces as possible. In previous
works that used Cell Decomposing approach, the meshsize was restricted to be larger than the pipe diameter.
Ando et.al[7, 8] presents a new pipe arrangement
algorithm of which mesh sizes are not restricted by thepipe diameter, but it cannot cope with the pipes along the
curved structures. In piping design, consideration mustbe given to the position and direction in which pipes are
passed, in order to properly support pipes from pipe

© 2016: The Royal Institution of Naval Architects

racks or structural members with support. In this paper, a
new piping path planning system is proposed in order toautomate piping design corresponding to pipe supports
and curved hulls.
2.

ASSUMPRIONS AND PURPOSE

The following assumptions are given in the pipe routing
problem:[Topology of target pipelines]
All pipelines are represented by a tree structure, that is,all pipelines are composed of one root (start) point andmultiple leaf (goal) points. If the number of the leaf pointis one in a pipeline, no branch exists in it. The piping
route in the same pipeline is represented by multiple
routes from the common root point to the leaf points. As
a result, the piping routes are overlapped from the root
point to the branches in the same pipelines. The position
and the shape of the branches in the pipeline are given byanalyzing the multiple routes.
[Pipes' diameter]
The pipes' diameter is invariable in the same pipeline.
You may feel that this assumption is not practical,
however, we can easily modify the pipes after the routing.
[Design points]
In advance, we put design points which indicate possible
positions and directions of the way of pipes for eachpipeline. That is, the design points are candidates of the
waypoints of the pipes. In actual piping design, the pipes
are put at the position that is certain distance away fromstructures. Also directions of the pipes on the pipesupports are along the (curved) structures, especially inships. For the automatic pipe routing, putting the design
points is a promising approach to cope with thesesituations.
[Obstacles]
Structures or equipments are regarded as obstacles. The
geometric information of obstacles is represented byseveral primitive shapes, that is, triangles, boxes, spheresor cylinders. It is not allowed that arranged pipes
interfere with these obstacles.

International Conference on Computer Applications in Shipbuilding 2017, 26-28 September 2017, Singapore

The algorithm searches pipe routes with following design
objectives:
1) To connect the pipes from start points to goal points
without interference between obstacles or the otherpipelines.
2) To minimize the total length of pipes,
3) To minimize the number of elbows and bends,
4) To maximize the length of the overlapping pipes in thesame pipelines. The overlapping pipes in the same
pipelines contribute to cut material costs.

Shapes of real pipes are constrained by the limitations of
the pipe bending machines. Pipes are bent with arbitrary
angles, but there exists a limit of the maximum angle.
The radius of the bend is constrained by the pipebender’s moulds. When pipes are bent, straight parts
between the bend are required to grasp the pipes.
3.2

PATH PLANNING FOR SINGLE PIPE

In order to regard the pipe arrangement as a single
purpose optimization, a routing cost which is
proportional to the total length of routes is provided.
Costs elbows and bends are given in advance. The
proposed algorithm tries to find optimal routes withminimized sum of these costs.
3.

PIPING PATH SEARCH ALGORITHM

3.1

PREPARATION FOR PIPING

Figure 1: An example of a pipe unit connecting two
design points (A and B) with two bends. The centre linesof the straight pipes are put along the AC, CD and DB.

Figure 2: Left side: A piping example between two
waypoints with two bends. Right side: A piping example
in the same waypoints with two 90-degree elbows.
A pipe in Figure 1 shows a sample that connects two
design points which have arbitrary positions anddirections. Notice that geometrically, all the pipes withtwo bends can connect arbitrary two design points whichhave any positions and directions. Two pipes shown in
Figure2 are examples which have the same start and goal
positions and directions. In the left pipe in Figure 2, thebends have certain angles, but the position of the bend isgiven in advance such as AC:CD:DP=1:2:1. In the rightpipe in Figure 2, bends are constrained to use only 90
degree elbows, and the position of the bends are derived
from mathematical calculations.

Figure3: Process of the routing algorithm for single pipe.

© 2016: The Royal Institution of Naval Architects

International Conference on Computer Applications in Shipbuilding 2017, 26-28 September 2017, Singapore

Figure 3 shows an overview of the proposed algorithm
for single pipe arrangement. First, we put design points
which indicate possible positions and directions of theway of pipes for each pipeline considering pipe supports,
pipe racks or structures. The design points are given
manually in advance, however, it is easy to generate it
automatically. In the next step, the system tries togenerate weighted and directed graph by judging that
arbitrary two design points (and directions) can bephysically connectable or not. Conditions of theconstruction constraints or gravitational flow or pocketsof the pipe is also considered in the judgement of theedges. When the weighted graph is generated, the systemapplies a shortest path search algorithm, e.g., Dijkstra’s
method or A* search method. Note that both the graphgeneration and the path search can be executed
concurrently. The calculation result in the directed graphis converted to the path of the single pipe.

route of two pipelines (pipe A, pipe B) have the same
diameter. For the sake of clarity, the route search withina two-dimensional plane is performed. In this case, since
the diameters of the two pipes are equal, there are two
possible search order, one from the search from pipe A as
shown in the upper part of Figure 3, and the other frompipe B. The resulted route plan is completely different
depending on the pipe search order.
3.3 (a) Influence on the Arrangement by Selection from
Multiple Optimum Solutions
In one piping route search, there are cases where there
are multiple solutions as optimal solutions of routes. In
this case, depending on which route is selected fromamong the optimum route candidates, the arrangement
finally obtained may be greatly changed in some cases.

3.3
STANBLE BLOCKS IN PATH PLANNING
FOR MULTIPLE PIPELINES
Usually there exist multiple pipelines in practical pipearrangement problems. However, when we apply thepath planning algorithm presented in the previous section
to the pipes one by one, we would get largely different
piping arrangement design depending on the following
two reasons.
3.3 (a) Influence on the Arrangement By Search OrderIn practice of piping design, a route search is generally
performed in order of expensive pipes. When thematerial is equivalent, it is arranged from a pipe with alarge diameter. However, when there are multiple pipesof the same diameter, arbitrariness arises in the order ofprocessing, and the final route plan changes dramaticallydepending on the order.

Figure 5: Influence of selection from optimum routes.
Figure 5 shows the case of searching the route of thelarge diameter pipe B and the small diameter pipe A on
the 2-dimensional plane. Here, as the optimum pathcandidate for pipe B, the upper route in the figure and thelower route are considered. In the figure below, due tothe influence of the route of the pipe B, the pipe A
greatly bypasses. Since there are few obstacles in thedesign target space at the beginning of the route search,
there are more optimum route proposals. However,depending on which one of these route proposals is
chosen, it can be seen that the result of the subsequentpipe arrangement change drastically.
3.4
PATH
PLANNINGFOR
MULTIPLE
PIPELINES: TOUCH AND CROSS METHOD

Figure 4: Influence of routing search order.
Figure 4 shows an example in which the piping routeacquired by the search order is different whereas the© 2016: The Royal Institution of Naval Architects

Touch and cross method is known as a heuristics forwire-routing in electric circuits. The basic idea of thisalgorithm is that the arrangement of shortest paths
without considering interferences has important
information to avoid the other pipelines (or to overlap thesame pipelines). Here shows the process of the Touchand Cross method:
1) Find optimum paths ignoring interference between
the pipelines.

International Conference on Computer Applications in Shipbuilding 2017, 26-28 September 2017, Singapore

2)

Redraw all pipes one by one, adding penalties ofinterference between the other pipelines to the costs.
The penalties are proportional to the interfered
volumes. Also in the cost calculation of the piping,when the target pipe is overlapped with pipes which
are the same pipelines, the cost in the overlapped
section is discounted as Cost  1

N dup , where

N dup is the number of overlapped pipes.
3) If all the pipelines do not interfere with each other,
then finish. Else, increase the rate of the penalties ofinterference and go to the step 2).
The proposed path-planning method for single pipeshown in the Section 3.2 is applied to search piping pathsin the step 1) and 2). Figure 6 and 7 are examples of thepiping path searching process using the Touch and Cross
method on the two dimensional space. In the early stageof the process in Figure 6, all the pipes are interfered, but
it is gradually solved by redrawing the pipes in order of
A, C and B. In contrast, the length of the overlapped
section is gradually increased by redrawing the pipes inorder A, B, (C), A and B in the same pipeline as shownin Figure 7.

4.

EXPERIMENTS

4.1

PIPING ALONG CURVED STRUCTURE

Using the proposed algorithms, pipes of φ100 (orange),
φ400 (yellow), φ600 (green) are placed along a walllike structure consisting of a half cylinder with a radiusof 3000 and a flat part with a length of 2000.
Arrangement of the design points are: at 400 intervals in
the height direction, and in the direction of radius of thecylinder, away 200 from the wall, the points are put at
400 intervals, and in the circumferential direction,
divided 180 degrees into 20 (at 9 degrees intervals), then
the total number of the design points are 870. The pipes
have constraints of the bends that radius of the bend is2400 or 1200 at the φ600 pipe, 1600 or 1200 at the φ400 pipe and 300 or 150 at the φ100 pipe. Note that theangle of the bend is only 90 degrees in the φ100 pipe,
and the others are arbitrary degrees of pipes. The
minimum length of the straight pipe section between thebends (or elbows) is 200 in the φ600 or φ400 pipes and
100 in the φ100 pipe. Figure 8 shows a result by astandard PC with 64bit Microsoft Windows7,
IntelCOREi7-2.7GHz processor, 16GB memories and the
proposed system is developed on Java-1.8.0 environment.
It takes about 1 or 2 minutes for the calculation, but it
was sometimes failed to obtain piping paths without
interfering pipes depending on the initial paths of the
Touch-and-Cross method. Notice that the orange pipe isarranged along the curved wall despite using only the 90
degrees’ elbows.

Figure 6 Process of Touch and Cross method to avoid
interfering pipes.

.

Figure 8 A result of the path-planning along curved
structure.

Figure 7 Process of Touch and Cross method to arrange
low-cost branched paths in the same pipeline.

© 2016: The Royal Institution of Naval Architects

International Conference on Computer Applications in Shipbuilding 2017, 26-28 September 2017, Singapore

4.2

PIPING CONSIDERING SUPPORTS

Two pipes of φ200, one pipe of φ150 and two pipes ofφ100 are arranged in a cage lining side by side along awall on the side inside a passage shaped space of width1500 depth 4000 height 2000. Assuming that pipe
supports of two positions in the horizontal position of
100 and 400 from the ceiling and pipe supports of twostages in the vertical direction of 100 and 400 from one
wall side are installed at 500 intervals in the depth
direction, the design points are placed in advanceassuming use of these pipe supports. A rectangularparallelepiped of width 800, height 1300 from the floor
and depth 4000 was set as aisle space opposite the wallwith supports, and invasion of pipes is prohibited there.

All pipes’ pieces are constrained to connect two design
points placed at a distance of 2000 or less because of
construction limitations. Figure 9, 10 and 11 shows thearrangements of design points for φ200, 150 and 100
respectively. The number of the design points are 112 for
φ200 and φ150, 210 for φ100. The transparent darkred box represents the aisle space. The pipes haveconstraints of the bends that radius of the bend is 400 or
300 at the φ200 pipes, 300 or 150 at the φ150 pipe, and
200 or 100 at the φ100 pipes. The minimum length of
the straight pipe section between the bends (or elbows) is
100 in all the pipes.

Figure 12 A result using free angle bends.

Figure 9 Candidates of design points for the φ200 pipes.

Figure 13 A result using only 90 degrees’ elbows.
Figure 10 Candidates of design points for the φ150 pipe.

Figure 14 Another view of the solution in Fig.12.

Figure 11 Candidates of design points for theφ100 pipes.

© 2016: The Royal Institution of Naval Architects

Figure 12 shows a successful calculation result under thecondition that all the pipes use free angle of bends.
However, 18 out of 20 trials failed to explore. Figure 13
shows a result using only 90 degrees’ elbows. Notice that

International Conference on Computer Applications in Shipbuilding 2017, 26-28 September 2017, Singapore

although the bends are 90 degrees, some pipes arearranged diagonally. Thanks to the provision of different
design points for each pipe diameter, pipes with different
diameters can be fixed with the same pipe supports asshown in Figure 14. It takes about 3-5 minutes for the
calculation under the same computational condition as
the Section 4.1.
4.3

PIPING WITH BRANCHES

The proposed system is applied to a path planningproblem of multiple drones. Figure 16 and 17 represent a
calculation result of the path planning of three drones.
The number of the design points is 2000, and it takes
about 25 minutes for the calculation. In order to generate
short-cutting paths, the system makes a directed graphusing long edges that are generated by connecting two
distant design points. For this reason, the directed graphgrows very large, and it takes a lot of time to solve it.

Two pipelines (green and yellow) which are composed of
one root point and three leaf points are arranged behindthe ceiling of a building as shown in Figure 15. The
number of the design points is 1288, the number of theprimitives of the obstacles is 28, and all pipes are
restricted to use only 90 degrees elbows. It takes about
18 minutes for the calculation under the same
computational conditions as the previous sections. The
red sections in each pipeline represent branch pipe-parts
which are detected by the path planning system. In thisexperiment, all ten trials resulted in quite similar piping
paths.

Figure 16 A path planning result of 3 drones.

Figure 17 The obtained drones’ paths with design points.

Figure 15 A simulation result for two branched pipelines.
The proposed system is also applied to a real practicalproblem that consists three pipelines with six leaf points(total 18 pipes), 108 primitives of the obstacles and 4002
design points for each pipeline, however, it takes 8 days
for the calculation under the same computational
environment as the previous sections.
4.4

5.

DISCUSSIONS

5.1

ARRANGEMENT OF THE DESIGN POINTSIn this system, design points are assumed to be arranged
appropriately in advance, and the quality of the piping
routes obtained by the system and the calculation time
are largely affected by it. If it is too many, thecomputation time and required memory dramaticallyincrease, and if it is too few, the quality of the solution
goes down, or in the worst case the route cannot be found.
In piping design where gravity flow is considered often,
it is better to narrow the vertical direction of the pitch
between the design points than the pitch of the horizontal
direction.

PATH PLANNING OF MULTIPLE DRONES© 2016: The Royal Institution of Naval Architects

International Conference on Computer Applications in Shipbuilding 2017, 26-28 September 2017, Singapore

It is troublesome to input if manually assigning via
design points, and if it is arranged uniformly in thedesign target space, it becomes a piping route passing
through a place where it is difficult to install support. We
are currently developing a system that automaticallygenerates via design points to positions where theinstallation of pipes becomes easier from the position andshape of structural members and supports.
5.2
CHOICE OF THE INITIAL SOLUTION IN
THE TOUCH AND CROSS METHOD
In the first step of the touch and cross method, all pipes
are arranged with the shortest (i.e., the lowest cost) paths
ignoring interfering each other. In this time, when a pipe
has several shortest paths, the system must choose one
from the paths. The choice of the initial paths would
affect the quality of the final solution of the touch andcross method.
5.3
REDRAWING PIPE ORDER IN THE TOUCH
AND CROSS METHOD
In the touch and cross method, redrawing order of thepipes also largely affects the quality of the final solution.
In our experiences, following the order of the pipes’length is a good strategy, because the longer piping pathtends to have the more number of shortest paths which
would avoid the other piping paths. However, when thisstrategy fails, repetition of the same strategy no longer
passes. The proposed system takes mixture strategy ofthe pipes’ length order and a random order. Research of
the appropriate strategy is an important future work.
5.4
DEALING WITH BRANCHESTOUCH AND CROSS METHODINCONCLUSIONS

On the routing problem for one pipe, a new algorithm todeal with supports and arrangement along curved
structure is proposed. It is assumed that design points
that represent directions and positions for the candidatesof the piping waypoints of the pipe are arranged inadvance, and the system generates weighted graph© 2016: The Royal Institution of Naval Architects

7.

ACKNOWLEDGEMENTS

The author thanks SUGA CO,LTD and SHINRYO
corporation for valuable comments on the piping
arrangement algorithms. This research is partially
supported by the Matching Planner Program
MP28116808445 from Japan Science and Technology
Agency (JST).
8.

REFERENCES

1.

ITO T. and FUKUDA S., ‘A genetic algorithm
approach to piping route path planning’, Journalof Intelligent Manufacturing, 1999.

2.

PAEK J. H. and STORCH R. L., ‘Pipe-routing
Algorithm Development: Case Study of a ShipEngine Room Design’, Journal of Expert
Systems with Application, 2002.

3.

ASMARA, A. and U. NIENHUIS ‘Automatic
Piping System in Ship’, International
Conference on Computer and IT Application(COMPIT), 2006.

4.

ASMARA, A. and U. NIENHUIS ‘Automatic
piping system Implementation’, International
Conference on Computer and IT Application(COMPIT), 2007.

5.

PAULO T. M. and LOBO V. J. A. S., ‘A Tool
for Automatic Routing of Auxiliary Circuits in
Ships’, Portuguese Conference on Artificial
Intelligence (EPIA), 2009.

6

LIN C., WANG L., PENG J., “Engine Room
Pipeline Arrangement with Consideration of
Equipments Operability Space by Genetic
Algorithm”, International Conference on
Computer Application in Shipbuilding (ICCAS),
2011

7.

Y. ANDO and H. KIMURA ‘An Automatic
Piping Algorithm including Elbows and Bends’,
International
ConferenceonComputerApplication (ICCAS), 2011.

8.

Y. ANDO and H. KIMURA ‘An Automatic
Pipe Arrangement Algorithm ConsideringTHE

The touch and cross method for branching pipes seems
working well in the experiments, however, it would be
biased easily to wrong solutions depending on the initialpaths of the touch and cross method.
In practical piping design, there exist unfavourable
shapes of the branch-pipe parts, e.g., the branch forces
the main stream to strike on the wall, etc., however, theproposed system does not consider it. Also in the branch,
the diameters of the pipes at the entrance and the exit of
the branch are different, but currently the proposedsystem cannot deal with it because considering it in theautomatic piping arrangement is too complicated.
Modification of the pipes’ diameters in post-processing
is a promising way.
6.

checking whether two design points can connect by apipe which satisfies the constraint of the pipe bender.
After that, the system generates piping path from ashortest path search in the weighted graph. For
arrangements of multiple pipelines with branches, a new
approach that is composed of the proposed routing
algorithm and the touch and cross method is alsopresented. Experimental results show the proposedsystem can withstand practical use.

International Conference on Computer Applications in Shipbuilding 2017, 26-28 September 2017, Singapore

Elbows and Bends’, International
Design Conference (IMDC), 2012.
9.

MarineAUTHOR BIOGRAPHY

Hajime Kimura holds the current position of Associate
Professor at the Department of Maritime Engineering,
Kyushu University. His previous experience includes
optimization in shipbuilding.

© 2016: The Royal Institution of Naval Architects