PSI - Issue 27

3

Aditya Rio Prabowo et al. / Procedia Structural Integrity 27 (2020) 77–84 Prabowo et al / Structural Integrity Procedia 00 (2019) 000 – 000

79

Corrosion

Incorrect operation Outside force damage

Excavation damage

4%

43%

6%

9%

10%

17%

11%

Natural force damage Material/weld/equip failure

Others

(a) (b) Fig. 2. Explosion statistical data and accident cases: (a) Data of Pipeline and Hazardous Materials Safety Administration (PHMSA) related to oil and gas pipeline accident (Biezma et al., 2020); and (b) condition of reservoir tunnel after the explosion in Zengwen reservoir (Li et al., 2020). It is also well noted that the fire hazard contributes to mine accidents. On the other case, i.e., oil and gas pipeline accidents (see Fig. 2a) presented by Pipeline and Hazardous Materials Safety Administration (PHMSA), the material condition is taken as part of the most contributing cause to the accident. Welding and corrosion state on material and structure is found to be the main causes that closely relate to the structure and material integrity. Besides material and structural factors, components of human error and lack of supervision may be derived from the data as 17% of the cause is due to incorrect operation. Explosion accidents in critical infrastructures may cause a wide range of socio economic problems after the incident, including the technical recovery of the infrastructure. Presented in Fig. 2b, Zengwen reservoir experienced severe damage in which operation of the reservoir needs to be halted until reconstruction is finished. The explosion in highly secure facilities is not happening suddenly but in a chain process. Taking the case of Danyang Power Plant, at least three sequences took place until the explosion caused significant casualties. Based on an even sequence diagram (ESD) in Fu et al. (2018), the fuel of the fire is gas, which is leaked from a steam pipeline in which a crack on the weld joint is identified as a source leak. If necessary, reparations are conducted in time, the accident may not take place. As the accident still occurs, then, it can be concluded that no actions were taken in time, and led to the pipe explosion in event sequence 2. During the explosion, shockwave and hot steam hit the central control room and surrounding the leak source, and finally caused property damage. 3. Notable investigations on ship and offshore The occurrence of the explosion accident in marine infrastructure is possible, which one of them is on Floating Production, Storage, and Offloading (FPSO). Table 1 presents the root causes of three accidents, and the case of Brazilian’s Cidade de São Mateus has the most root cause. Compared to the case of Danyang Power Plan, the case of the FPSO is more detailed in the description, which initially concluded that parallel root of cause in explosion accidents exists. The roots are dominated by human error, failure in equipment and lack of regulation/guideline during operation. In the case of Macondo accident, contractors are involved as it contributed in documentation and management aspects, and instrumentation for operation is inadequate which incompetent works may lead to miss-operation. Similar to the Macondo, Heimdal gas leak also experienced un-professional document handling and working permit, but other roots, i.e., deficiency of working task, access, and verification are also followed by the previous roots. Based on the classification, explosion accidents are just a negative result due to a series of root causes. This statement is more understanding to be described in the form of illustration (previous works of Baalisampang et al. (2018)). Swiss cheese model (SCM) represents the cheese as a contributing factor that may be the root of the cause. Hollows on them indicate failure and poor state of the factors, and red arrows in the event sequence. If all factors contain failure or inadequate state, and the event sequence successfully continues to breach each factor, then accident occurrence will be unavoidable. Development in explosion analysis is given serious attention, which numerical approach is considered as a powerful instrument to re-create an accident, such as the offshore explosion case of Deepwater Horizon.