SVIBOR - Project code: 2-08-395


Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69


SVIBOR - Collecting Data on Projects in Croatia

Project code: 2-08-395


Main researcher: HRIEŠIK, ANDREJ (16621)

Type of research: applied
Duration from: 07/01/92. to 12/31/96.

Papers on project (total): 11
Papers on project quoted in Current Contents: 1
Institution name: Tehnički fakultet, Rijeka (69)
Department/Institute: Department of Technology and Organization
Address: Vukovarska 58
City: 51000 - Rijeka, Croatia
Phone: 385 (0)51-332-844
Fax: 385 (0)51-515-403
E-mail: hriesik a

Summary: In the subject work, which represents the first part of a pluriennal research, the actual piping manufacturing state on ships is analyzed. The pipes quantity in size and mass in a 112000 DWT chemical tanker building is throughly shown. The dynamics of purchasing the rough pipes related to dynamics of piping manufacturing and fitting on board the ship, has been analyzed. In that, the differences in the quantities estimated by the design office related to those really mounted on board, come out. The data gathering and their corresponding analysis, relate to the quinguennal and decimal period between years 1981 and 1990. The results have been analyzed, graphically processed and collected in more diagrams and tables. The amount of scrap the necessary alterations, the repairs and other defects in piping manufacturing have been determined. The distribution and the dynamics of the pipes consumption from the Contrat signing to the vessel commissioning, have been graphically shown in particular. The collected data are indispensable as input functions for mathematics modeling the manufacturing process and the manufacturing system. Mathematical model for optimizing the manufacturing process has been settled, containing the following processes: process state functions, process limiting functions, optimizing chriteria and objective functions. The model will lead to the manufacturing process control optimization. Perfoming the model solution will be the subject of the second and third part of this work. Hereby, a presentation of the subsequent part of work on a project has been given. Optimal plate edges heat treatment procedures and machining of the same by use og special milling machines has been investigated. Actual situation in shipbuilding industry has been analysed, with an emphasis on indispensability of introduction of CAD/CAM technology, with a view to rounding up the pipes treatment automatic systems. Worked out has been a mathematical model of multifactor experiment for particles separation. Also investigated has been the systems employing pneumatically driven hand grinding machines, and electrically driven hand grinding machines fed by increase frequency alternativecurrent. Optimum solutions have been searched in respect of 16 objectives. Modified Zangenmeister's method showed to be most appropriate, yielding in a noteworthy contribution to scientific approach in researching of this technology. The results have been presented numerically as well as in graphs through a computer aided elaboration. Results of a tests application of a new grinding trechnology using increased frequency el. current have also been elaborated. Obligatory introduction of a flexible system has been argumented.

Keywords: Automatization, Machining System, Optimization, Pipe, Shipbuilding, Compressed Air, Hand Grinder, High Frequency Current, Profiling of Plate Edges, Steel Plate

Research goals: The main scope of the research is to create a scientific basis for making decisions on investment cycle, with the aim of increasing the degree of automation in the piping manufacturing process. In that it is important to search after an optimum in each manufacturing sequence. In respect that reference is made to cut down the cost of the preparation cycle and of the manufacturing itself, as well as to lower the scrap, to increase the cash flow by minimising the stocks, to improve the storage organzation from a manual to a computerised level, to introduce CNC tehnology of machining and quality control, etc.. On a considerable number of graphs diagrams and tables one can see the totality of problems as well as the schedule of the actual manufacturing process condition. On a particular diagram the schedule of design work, of machining and installation of pipings board the ship is presented. Also a special schedule appeiend to a chemical tanker of 112000 DWT from the signing of the Contract to the commissioning of the vessel to the Owner has been elaborated. Particularity a quinquennial and a decennial period of machining and installation of piping different sizeshave been analysed. This will represent an important input function for modelling the production capacity. Distribution of pipes according to dimensions and mass for different vessel types(bulkcarrier, tanker and chemical tanker), has been elaborated. The following results are expected from the research:relatively large discontinuity in loading the production complexand the labour; the purchasing of pipes and equipment throughwholesale trades is unsafe, and it is also not organised on-linewith the productions facilities; low capital flow because of nonconformity of the pipes purchasing terms with those of theirinstalling; the introduction of CNC technology in the workingprocess is at an initial stage; the percentage of scrap of thenecessary repairs, of alterations, etc., is rather high, so it isnecessary to introduce new quality control organisation for thepiping; there are still reserves to take a profit of increasingthe fitting of the piping in the ship blocks (modules), insteadof doing that after the launching of the ship. Objectives ensuing from preliminary communication call for optimum production in actual conditions through application of particular systems and subsystems. It was thus necessary to investigate optimality of plate cutting and pipe machining systems employing plasma and oxyacetilene devices, as well as those involving special milling machines. Modern machines, along with the CNC machines, are quite preferably to be given absolute priority. Pneumatically driven hand grinding machines, today more or less prevailingly in use for certain number of operations, represent technological subsystem in this field. Introducting of electrically driven hand grinding machines that employ el. current of increased frequency is rather not recommendable without a prior comprehebsive and thorough analysis of all relevant parameters, inasmuch as adaption of those machines calls for substantially high investments. Investigative research of the mentioned two systems (pneumatically and increased frequency el. current) should supply results of particular significance for technological improvements, improved ergonomically aspects, production economy, costs savings, and consequently, a reduction in products prices. It is due to the variety of ship designs, meaning various purposes built ships that inexorably is to require for the flexible, automated lines for machining of plates, profiles, pipes and eventually other elements, to be introduced.


  1. Name of institution: Brodograđevna industrija "3. maj" Rijeka
    Type of institution: Economical/Production
    Type of cooperation: Joint publishing of scientific papers
    City: 51000 - Rijeka, Croatia

  2. Name of institution: Brodogradilište "Uljanik" Pula
    Type of institution: Economical/Production
    Type of cooperation: Occasional exchange of information
    City: 52000 - Pula, Croatia


  1. Name: Optimalizacija obradnih sustava ručnih brusilica brodogradilišta
    Type of achievement: Technology
    Authors: Mr. sc. Anton Šestan

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Last update: 10/03/95