Kimyasal tanker terminallerinde operasyonel risk değerlendirmesi: bütünleşik ahp ve topsıs yöntemi ile bir model önerisi
Operational risk assessment in chemical tanker terminals: a model proposal using integrated ahp and topsis method
- Tez No: 1019948
- Danışmanlar: DOÇ. DR. BURAK ZİNCİR
- Tez Türü: Yüksek Lisans
- Konular: Denizcilik, Marine
- Anahtar Kelimeler: Yük gemileri, Cargo vessels
- Yıl: 2026
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Lisansüstü Eğitim Enstitüsü
- Ana Bilim Dalı: Deniz Ulaştırma İşletme Mühendisliği Ana Bilim Dalı
- Bilim Dalı: Deniz Ulaştırma Mühendisliği Bilim Dalı
- Sayfa Sayısı: Belirtilmemiş.
Özet
Kimyasal tanker terminallerinde gerçekleştirilen yükleme, tahliye ve gemi-kıyı arayüzü operasyonları; yangın, patlama, toksik maruziyet ve çevresel yayılım gibi çok boyutlu riskler içermektedir. Bununla birlikte, uluslararası düzenleyici çerçeve içerisinde kimyasal kargoların sınıflandırılması büyük ölçüde deniz çevresine olası etkileri üzerinden yapılmakta; terminal sahasında anlık olarak ortaya çıkabilecek fiziksel ve insani riskler ise aynı ölçüde bütünleşik bir karar yapısı içinde ele alınmamaktadır. Bu durum, çevresel kategorizasyon ile terminal operasyonel öncelikleri arasında bir ayrışma doğurmakta ve terminal karar vericilerinin yalnızca mevzuat temelli sınıflandırmalarla operasyonel risk önceliğini belirlemesini güçleştirmektedir. Bu tez çalışmasının amacı, kimyasal tanker terminallerinde elleçlenen seçili sıvı kimyasal kargoların göreli operasyonel risk düzeylerini, fiziksel, insan sağlığına ilişkin ve çevresel kriterleri birlikte dikkate alan bütünleşik bir model aracılığıyla değerlendirmektir. Bu amaç doğrultusunda, Çok Kriterli Karar Verme tekniklerinden Analitik Hiyerarşi Prosesi (AHP) ve TOPSIS yöntemlerinin birlikte kullanıldığı hibrit bir model geliştirilmiştir. Çalışmada alternatifler, MARPOL Annex II kapsamındaki farklı risk profillerini temsil edecek şekilde seçilmiş 13 kimyasal kargodan oluşmaktadır. Değerlendirme kriterleri; fiziksel riskler altında parlama noktası, buhar basıncı, reaktivite ve statik akümülatörlük; insan sağlığı boyutunda LC50 ve vekâleten kullanılan oral LD50; çevresel boyutta ise sucul yaşam toksisitesi ile biyolojik birikim potansiyelini temsil eden Log Kow olarak belirlenmiştir. Kriter ağırlıkları, üç mühendis ve üç kimyagerden oluşan, ortalama yaklaşık 15 yıllık mesleki deneyime sahip altı uzmanın görüşleriyle AHP yöntemi kullanılarak hesaplanmıştır. Elde edilen ana kriter ağırlıkları fiziksel riskler için 0,6963, insan sağlığı için 0,1609 ve çevresel riskler için 0,1429 olarak bulunmuştur. Alt kriterler içinde en yüksek küresel ağırlığın statik akümülatörlük kriterine ait olduğu görülmüştür. AHP ile belirlenen ağırlıklar daha sonra TOPSIS analizine aktarılmış ve 13 kimyasal kargonun göreli operasyonel risk sıralaması elde edilmiştir. Analiz sonuçlarına göre Ethyl acrylate, Hexane, Methyl ethyl ketone, Methyl acetate ve Heptane en yüksek riskli ilk beş alternatif olarak belirlenmiştir. Buna karşılık Propylene Glycol, Diethanolamine ve Phosphoric acid listenin alt sıralarında yer almıştır. Elde edilen sonuçlar, MARPOL çevresel kategorizasyonunun terminal sahasındaki operasyonel önceliklerle birebir örtüşmediğini göstermiştir. Özellikle çevresel açıdan daha düşük kategoriye sahip bazı solventlerin, fiziksel risk bileşenleri nedeniyle terminal açısından daha kritik sıralarda yer aldığı görülmüştür. Bu bulgu, terminal operasyonlarında riskin çoğu zaman uçuculuk, yanıcı atmosfer oluşumu, ateşleme duyarlılığı ve akut inhalasyon tehlikesi gibi unsurlar etrafında şekillendiğini ortaya koymaktadır. Çalışmada ayrıca sınırlı bir duyarlılık analizi gerçekleştirilmiş ve özellikle veri atama tercihlerinin alt sıralardaki alternatifler üzerinde etkili olabildiği, ancak modelin genel risk mimarisinin korunduğu görülmüştür. Sonuç olarak bu tez, kimyasal tanker terminallerinde operasyonel risk değerlendirmesinin yalnızca çevresel sınıflandırmaya bırakılmaması gerektiğini; terminal emniyetini daha gerçekçi biçimde temsil eden çok kriterli ve göreli bir önceliklendirme yaklaşımının karar süreçlerine önemli katkı sağlayabileceğini göstermektedir. Bu yönüyle geliştirilen hibrit AHP-TOPSIS modeli, terminal yönetiminde kargo kabulü, operasyon öncesi risk gözden geçirmesi, SIMOPS planlaması ve acil durum hazırlık düzeyi gibi alanlarda kullanılabilecek tamamlayıcı bir karar destek aracı niteliği taşımaktadır.
Özet (Çeviri)
Chemical tanker terminals constitute one of the most critical operational interfaces in maritime logistics, as they involve the transfer of hazardous liquid cargoes between ship and shore under conditions where fire, explosion, toxic exposure, environmental release, and operational incompatibilities may occur simultaneously. In practice, terminal operators are often required to make rapid and defensible decisions regarding cargo acceptance, operational precautions, supervision intensity, and emergency preparedness. However, the existing international regulatory framework does not always provide a decision structure directly aligned with terminal operational priorities. MARPOL Annex II and the associated GESAMP-based categorization system primarily assess liquid chemicals according to their potential impact on the marine environment, whereas terminal operations frequently confront immediate physical and human safety hazards such as flammable vapor formation, static electricity accumulation, vapor release, inhalation exposure, and runaway reaction scenarios. This creates a gap between environmental categorization and operational safety prioritization. The present thesis was developed in response to this gap. Its main objective is to propose a comparative, multi-criteria operational risk model for selected liquid chemical cargoes handled in chemical tanker terminals. Rather than relying solely on environmental categories, the study integrates physical, human health, and environmental dimensions into a unified decision-support structure. In this respect, the thesis argues that a cargo that appears relatively less critical from an environmental regulation perspective may still represent a high operational threat at the terminal due to its physicochemical behavior, ignition sensitivity, or acute inhalation hazard. The study therefore focuses on relative operational prioritization rather than absolute hazard declaration. To achieve this objective, a hybrid decision-making framework based on the Analytic Hierarchy Process (AHP) and TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) was developed. The rationale for using AHP lies in the fact that although the values of the criteria themselves are objective laboratory- or literature-based data, the relative operational importance of these criteria in terminal conditions requires expert judgment. By contrast, TOPSIS was selected as the ranking tool because the alternative cargoes are described by heterogeneous criteria expressed in different units and scales, making direct comparison difficult without a normalization-based multi-criteria method. The hybrid structure therefore combines expert-informed weighting with a data-driven ranking procedure. The study was designed around a purposive sample of 13 liquid chemical cargoes selected to represent both different MARPOL Annex II categories and different hazard profiles relevant to terminal operations. These cargoes were chosen not as a random statistical sample, but as a meaningful decision set that could capture diverse operational behaviors such as high volatility, low flash point, static accumulation tendency, reactivity, inhalation toxicity, corrosive behavior, and environmental persistence. The final set included Ethyl acrylate, Hexane, Methyl ethyl ketone, Methyl acetate, Heptane, Toluene, Toluene diisocyanate, 2-Ethylhexyl acrylate, Phenol, Propylene glycol methyl ether acetate, Phosphoric acid, Diethanolamine, and Propylene Glycol. Eight evaluation criteria were used in the model. These criteria were structured under three main dimensions. The physical risk dimension included flash point, vapor pressure, reactivity, and static accumulator behavior. The human health dimension included acute inhalation toxicity represented by LC50 and acute systemic toxicity represented, as a proxy, by oral LD50. The environmental dimension included aquatic toxicity and bioaccumulation tendency represented by Log Kow. The criteria were selected after an extensive literature review and were conceptually separated in order to avoid double counting. For example, vapor pressure was treated as an indicator of hazardous atmosphere formation potential, whereas LC50 represented the biological severity of inhalation exposure. Similarly, aquatic hazard and bioaccumulation tendency were treated as distinct environmental mechanisms. The data matrix was constructed through a standardized data collection procedure. PubChem served as the main access platform, while the underlying source documents such as ILO-WHO International Chemical Safety Cards (ICSCs), safety data sheets, and technical product information were used for cross-checking and completion. Flash point values were standardized, as far as possible, on a closed-cup basis, and vapor pressure values were standardized at 20°C. Reactivity scores were derived from NFPA-based reactivity indicators. Static accumulation was treated as a binary criterion using the industry-accepted threshold of 50 pS/m. LC50 values were standardized to ppm/4 hours whenever possible, and oral LD50 values were used as a proxy for acute systemic toxicity due to the limited availability of comparable dermal toxicity data. Aquatic toxicity was transformed into an ordinal scale using GHS hazard statements, while Log Kow was used as a practical proxy for bioaccumulation tendency. The AHP stage of the study was based on judgments collected from a panel of six experts, composed of three engineers and three chemists, with an average professional experience of approximately 15 years. The expert group also included one participant with IMDG Code training experience and two participants qualified in the preparation of safety data sheets/chemical assessment documentation. Pairwise comparisons were performed using Saaty's 1–9 relative importance scale, and the individual matrices were aggregated by geometric mean. Consistency ratios were calculated for the relevant matrices and were found to be within acceptable limits. The main AHP results clearly showed that physical risks dominate expert operational perception in the terminal context. The weight of physical risks was calculated as 0.6963, followed by human health risks with 0.1609 and environmental risks with 0.1429. Within the physical dimension, static accumulator behavior emerged as the most influential criterion, followed by flash point, vapor pressure, and reactivity. Within the human health dimension, LC50 was weighted significantly higher than LD50, indicating that inhalation exposure is regarded as more critical than acute systemic exposure through physical contact in terminal conditions. Within the environmental dimension, Log Kow received a higher weight than aquatic toxicity, suggesting that experts considered not only immediate ecotoxic effects but also longer-term environmental accumulation potential. These findings are highly significant because they quantitatively support the thesis argument that terminal operational priorities do not fully overlap with the environmental logic of MARPOL Annex II. The expert judgments suggest that in terminal practice, the most urgent concerns are related to ignition mechanisms, vapor release, flammability, and short-term human exposure, rather than to environmental damage alone. This does not diminish the importance of MARPOL, but it indicates that environmental categorization is not sufficient by itself as an operational prioritization tool for terminal safety management. The AHP-derived weights were then used in the TOPSIS stage to rank the 13 selected chemicals. In this study, the positive ideal solution was not interpreted as the“best”or“safest”alternative in the classical TOPSIS sense; instead, it was defined as the most critical operational risk profile. This adaptation was necessary because the objective of the thesis was to identify the cargoes requiring the highest level of operational attention in terminal conditions. Benefit-type and cost-type criteria were therefore interpreted according to risk direction rather than desirability. The final TOPSIS results indicated that Ethyl acrylate ranked first with a final score of 0.5910, followed by Hexane (0.5886), Methyl ethyl ketone (0.5219), Methyl acetate (0.5176), and Heptane (0.5016). Toluene, Toluene diisocyanate, 2-Ethylhexyl acrylate, Phenol, Propylene glycol methyl ether acetate, Phosphoric acid, Diethanolamine, and Propylene Glycol followed in descending order. This ranking clearly showed that the chemicals appearing at the top were mostly those characterized by low flash point, significant volatility, hazardous vapor formation potential, and/or static accumulation tendency. The ranking also showed that environmental categorization and operational prioritization do not necessarily converge. For instance, chemicals categorized as Y or Z under MARPOL could rank above a Category X product when their physical terminal-related risks were more critical. This result is one of the most important contributions of the thesis. It demonstrates that a cargo may be environmentally less restrictive according to MARPOL and still present a higher operational threat to terminal safety. In other words, environmental severity and operational immediacy represent related but distinct dimensions of chemical cargo management. The thesis therefore provides quantitative support for the idea that terminal operators need an internal operational risk lens in addition to regulatory environmental categorization. A limited sensitivity analysis was also conducted. The most notable test concerned the flash point assignment for Phosphoric acid, a non-flammable product. Two scenarios were compared by assigning a finite high flash point value of 599 K and an extreme high value of 999 K. The results showed that the overall high-risk structure of the model remained broadly stable, while some lower-ranked alternatives changed position. This indicates that the model is relatively robust at the upper end of the ranking but more sensitive to value assignment choices among lower-risk alternatives. Such a finding is methodologically meaningful because it shows that the ranking is not arbitrary, while also highlighting the importance of transparent assumptions where direct experimental data are limited. From an operational perspective, the findings suggest several implications. First, terminals should not treat all chemical cargoes with a uniform safety intensity. Instead, they should adopt a relative operational prioritization logic. Second, cargo acceptance and pre-transfer risk review procedures may benefit from explicitly incorporating flash point, vapor pressure, static accumulation, reactivity, and inhalation hazard in addition to MARPOL category and general SDS information. Third, emergency planning should not focus solely on spill containment; for certain cargoes, ignition control, hazardous atmosphere isolation, vapor cloud management, and rapid operational shutdown may deserve equal or greater priority. Finally, the model supports the argument that terminal safety management should be informed by a structured multi-criteria decision approach rather than by single-parameter classification. The thesis also has several limitations. The study is based on 13 selected cargoes rather than the full IBC Code Chapter 17 list. Some criteria required proxy values or upper-bound assignments due to incomplete data. The expert panel, while qualified and adequate for AHP purposes, was limited to six participants. The model is also static in nature and does not directly incorporate dynamic variables such as real-time weather conditions, pumping rates, operational congestion, or simultaneous activity patterns. Nevertheless, these limitations do not invalidate the model; instead, they define the context within which its results should be interpreted. Future studies may expand the number of alternative cargoes, incorporate measured BCF values instead of Log Kow where possible, and use more systematic sensitivity analysis on both data assignments and weight structures. The model may also be re-tested through fuzzy AHP and fuzzy TOPSIS, or integrated with dynamic operational data to produce a more adaptive terminal decision-support tool. In conclusion, this thesis demonstrates that operational risk assessment in chemical tanker terminals cannot be adequately represented by environmental categorization alone. By integrating expert judgment and heterogeneous cargo data through a hybrid AHP-TOPSIS framework, the study proposes a practical and analytically transparent model for relative operational prioritization. The model does not replace existing regulations; rather, it complements them from the perspective of terminal safety and operational reality. In this sense, the thesis contributes both to the academic literature on maritime risk assessment and to the practical decision-making needs of chemical tanker terminal operations.
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