Kimyasal tankerlerde tank kaplamaları seçimine yönelik sayısal analiz
Numerical analysis on selection of tank coatings in chemical tankers
Yazar: MURAT MERT TEKELİ
Danışman: DOÇ. DR. EMRE AKYÜZ
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Deniz Ulaştırma Mühendisliği Ana Bilim Dalı / Deniz Ulaştırma Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2022
Konu: Denizcilik = Marine
Dizin: Gemiler = Ships ; Kaplama malzemeleri = Coating materials ; Sayısal analiz = Numerical analysis ; Tanker piyasası = Tanker market ; Tanklar = Tanks

Özet:
Günümüzde büyüyen kimya endüstrisi, ham madde ihtiyacını arttırmış, bununla birlikte üretilen ham maddenin deniz yolu taşımacılığındaki ağı oldukça genişlemiştir. Bu artışın sonucu olarak daha kullanışlı ve verimli kimyasal tankerlere talep günden güne artmaktadır. Kimyasal tanker işletmeleri için en önemli kriterlerden birisi yükü emniyetli bir şekilde bir yerden bir yere ulaştırabilmektir. Bu ulaştırma sırasında yükte meydana gelebilecek istenmeyen değişikleri en az seviyede tutabilmek için tank kaplamaları çok önemli bir yere sahiptir.
Kimyasal tankerlerde kullanılan kaplama tipleri genel olarak; epoksi, çinko silikat, paslanmaz çelik ve marine line olarak 4 gruba ayrılır. Her bir kaplamanın kendine ait özellikleri olup, tercih edilecek kaplama tipi bu özelliklere bağlı olarak seçilir. Bu çalışmada, alternatif olarak ele alınan her bir kaplama tipi tek tek ayrıntılı olarak incelenmiş ve elde edilen uzman görüşleri ve literatür taramaları sonucunda her bir kaplama tipi için ortak özellik olan 7 adet kaplama kriteri belirlenmiştir. Bu kaplama kriterlerlerinden, yapılan değerlendirmeler sonucunda en etkili olandan en az etkili olan kritere doğru bir sıralama yapılmıştır. Bu kriterlerin önem sırası dikkate alınarak, kaplama tipi olarak seçtiğimiz alternatifler kıyaslanmış, güncel durumda kullanışlılık bakımından en uygun olan tank kaplama türü bulunmuştur.
Tank kaplamaları için uzmanlar ve yapılan literatür çalışmaları neticesinde belirlenen kriterler, çok kriterli karar verme metodu olan 'Analitik Hiyararşi Süreci'(AHP) kurallarına bağlı olarak tespit edilmiştir. Bu uygulamada, her bir uzmana anket doldurtulmuş, bu ankette her bir kriterin diğer kritere göre üstünlük derecesini 1 ile 9 arasında verilecek bi puanla notlandırması istenmiştir. Bu notlandırma sonucunda, her bir kriterin ağırlığı bulunmuş ve tank kaplaması açısından önem sıralaması yapılmıştır. Yapılan bu değerlendirmelerin sonucunda, tüm kriterler ağırlıklarının toplamı 1,00 olacak şekilde tank kaplamaları için en önemli kriterin 0,25 ağırlığıyla Kargo Temizliği olduğu belirlenmiştir. Kargo Temizliği kriterini sırasıyla 0,24 ağırlığa sahip Kaplamaların Mekanik Özellikleri, 0,23 ağırlığıyla Kaplamalarda Bakım ve Onarım Eylemleri, 0,14 ağırlığıyla Kaplamalarda Soğurma ve Dışa Vurma Özellikleri, 0,08 ağırlığıyla Kaplamanın Havalandırma ve Nem Gidermedeki Rolü, 0,05 ağırlığıyla Kaplama Uygulamalarındaki Zorluklar ve en düşük etkiye sahip olarak 0,02 ağırlığıyla Kaplamanın Maliyeti olarak hesaplanmıştır.
Günümüzde kullanılan tank kaplamaları, kriter seçimine katkıda bulunan uzmanlar tarafından, TOPSIS metoduna uygun olarak, anket aracılığıyla dilsel ifadeler kullanılarak değerlendirilmesi istenilmiştir. Doldurtulan anketler sonucunda, ortaya çıkan dilsel ifade ortalamaları, bulanık yöntemle normalize edilerek sayısal bir ifadeye dönüştürülmüş, sonrasında ise kaplamalar için önem arz eden her kriterin ağırlığı değerlendirilerek ağırlıklandırılmış normalize bulanık matris elde edilmiştir. Yapılan hesaplamalar sonucunda, her bir kaplama türü için ağırlık değerleri bulunmuş, değeri yüksek olandan düşük olana doğru bir sıralama yapılmıştır. Ortaya çıkan sonuçta en yüksek ağırlığa sahip alternatif 0,423 ile Paslanmaz Çelik olmuştur. Paslanmaz çeliği takiben 0,357 ağırlığıyla Marine Line, 0,247 ağırlığıyla Epoksi ve en düşük olarak 0,153 ağırlığıyla Çinko Silikat kaplama türü bulunmuştur.

Abstract:
Today, the growing chemical industry has increased the need for raw materials, and the network of produced raw materials in sea transportation has expanded considerably. As a result of this increase, the demand for more useful and efficient chemical tankers is increasing day by day. One of the most important criteria for chemical tanker businesses is to be able to safely transport the cargo from one place to another. Tank coatings have a very important place in order to keep the undesired changes that may occur in the cargo at a minimum during this transportation.
Chemical cargoes are transported by sophisticated tankers that can transport different types of chemicals around the world. These chemical tankers have a slightly different design than other tankers. Because the products they carry require special tanks coated with stainless steel, zinc or epoxy. Chemicals are labeled with different IMO classes and this class indicates the degree of danger of the chemical product. IMO class I ships can carry the most dangerous goods, IMO class II ships the second most dangerous and IMO class III the least dangerous goods. The boundary between a product tanker and a chemical tanker is very difficult to define, but IMO class I and II vessels are often referred to as chemical tankers.
Chemical tanker operations differ from other liquid bulk transport in that multiple cargoes of different characteristics and natural hazards can be transported at once, and multiple products can be handled at one berth, typically including the discharge of both cargoes. The use of chemical tankers is more complex than oil tankers. Transporting bulk chemicals by sea requires not only specialized vessels and equipment, but also specially trained crew, both theoretically and practically, to understand the properties of various chemicals and be aware of the potential hazards of cargo handling. A modern chemical tanker is primarily designed to carry some of the hundreds of hazardous products covered by the International Bulk Chemical Code. There are three main types of chemical tankers. The first is parcel chemical tankers, which typically have more than one small cargo tank. Then there are the regular chemical tankers that carry less complex chemicals. They are equipped with fewer cargo tanks and less complex pump and line arrangements, often lined with steel rather than stainless steel. As the last type chemical tanker, it is a special chemical tanker usually dedicated to specific trades and carrying a single cargo such as acid, molten sulfur, methanol, palm, wine and fruit juice.
Chemical tankers are built to serve cargo other than crude oil and cargoes that require substantial cooling or pressure tanks. Chemical tankers carry not only chemical products, but also products such as vegetable oils, molasses, wine, animal fats, solvents, and some clean petroleum products and lubricants. Additionally, chemical tankers can carry inorganic substances such as phosphoric acid, sulfuric acid and caustic soda. The chemical tanker is a very special type of vessel due to the complexity and nature of the cargo. Chemical tankers can carry highly corrosive cargoes such as sulfuric acid, caustic soda, acetic acid and pure naphtha. Therefore, more attention is paid to cargo tanks and their ability to ensure the integrity and purity of the cargo. Chemical tanker owners often invest large sums in new construction chemicals tankers. Generally, stainless steel is considered the ideal building material as it is non-corrosive and easy to clean.
For the correct choice of coating system and proper handling of cargoes, it is recommended to provide a basic knowledge of the chemical properties of the most common cargoes, as the behavior of products within the same groups of organic compounds can vary greatly. For example, methanol softens most organic coatings, but higher molecular weight alcohols are much less effective.
All of today's organic coatings for cargo tanks are bi-component types, resulting in a chemically cross-linked film that cannot be re-dissolved. However, strong solvents can soften cured coatings, causing swelling and in some cases even calcification from the substrate. For example, methylene chloride is such a strong solvent for organic coatings that it is used as a paint remover. Therefore, it should not be transported in tanks covered with organic coatings.
An additional factor affecting coating suitability is the water solubility of solvents. Most organic coatings used for cargo tank protection can tolerate some degree of softening from solvent absorption, provided sufficient time is given for the absorbed solvent to evaporate and regain its original hardness. However, if the retained solvent is water soluble and tanks are washed with water or loaded with an aqueous cargo before the film has completely dried, bubbling due to osmosis may occur.
On the other hand, a one important factor affecting coating suitability is the water solubility of solvents. Most organic coatings used for cargo tank protection can tolerate some degree of softening from solvent absorption, provided sufficient time is given for the absorbed solvent to evaporate and regain its original hardness. However, if the retained solvent is water soluble and tanks are washed with water or loaded with an aqueous cargo before the film has completely dried, bubbling due to osmosis may occur.
In this study; Measurable criteria that can affect the process of choosing 4 different tank coatings used today in chemical tankers have been determined, and the degree of impact and priority order of these criteria on the coating preference have been determined with the opinion of field experts. These criteria were determined by consulting the field experts and by conducting a detailed literature review, taking into account the most probable problems that may arise in tank coatings and the problems that may occur as a result of these problems. The said criteria are; The Mechanical Properties of the Coating, the Maintenance and Repair Actions of the Coating, the Difficulty of Application of the Coating, the Role of the Coating in Ventilation and Dehumidification, the Absorption and Expansion Properties of the Coating, Cargo Cleaning and the Cost of the Coating. Among these, the most effective one on the tank lining was selected, and support was received from a total of 13 field experts, consisting of the captain, the chief officer, the ship operator and the tank coating specialist.
During the interviews with the experts, they were asked to fill in the questionnaires prepared within the scope of the thesis. Obtained expert opinions were evaluated within the scope of Analytical Hierarchy Process, one of the criteria decision making methods. Each of the 7 criteria determined was compared with each other, and a scaling between 9 and 1 was made. As a result of these evaluations, it has been determined that the most important criterion for tank coatings is Cargo Cleanliness with a weight of 0.25, with the sum of all criteria weights being 1.00. Cargo Cleanliness criteria were determined by the Mechanical Properties of Coatings with a weight of 0.24, Maintenance and Repair Actions in the Coatings with a weight of 0.23, Absorption and Expression Properties of the Coatings with a weight of 0.14, the Role of the Coating in Ventilation and Dehumidification with a weight of 0.08, and the Coating with a weight of 0.05. Difficulties in Application and the Cost of Coating with a weight of 0.02 with the lowest impact.
After the criterion weights were determined, each of the 4 coating types used in chemical tankers today, consisting of Epoxy, Zinc Silicate, Stainless Steel and APC Marine Line, were evaluated separately within the framework of these criteria, and the result found in the last step was normalized with the criterion weights. In the selection of the determined coating type alternatives, the TOPSIS method, which is also a multi-criteria decision-making mechanism, was used since the determined criteria were not based on numerical data. Since it is more suitable for the evaluation and decision-making mechanisms in the minds of the experts, it was preferred to present the evaluations with linguistic expressions rather than numerical comparisons. In other words, fuzzy logic approach was used in order to obtain the results more objectively and accurately. In the blurring method, the highest linguistic expression determined for each criterion, Very High (VH), corresponds to 0.9-1.0-1.0 and the lowest score is Very Low (VL) 0.0-0.1-0.1 corresponds to its value. Within the framework of these numerical data, all criteria for each alternative were evaluated by experts through a survey, and the alternative with the highest weight was Stainless Steel with 0.423. Following the stainless steel, Marine Line with a weight of 0.357, Epoxy with a weight of 0.247 and Zinc Silicate with a weight of 0.153 as the lowest, were found.
This work; It is thought that it will be beneficial by providing analytical solution to chemical tanker operators, shipyards and tank coating companies operated by experts. Experts who contributed to the study; selected from chief officers, ship operators and tank coating specialists. It is planned to test the study with the data set in the next stages and to compare the results. In addition, it is planned to expand the study with fuzzy logic type-2 method adaptation and compare the results.